Observatory Plans, Advice & Issues

MAPUG-Astronomy Topical Archive     AstroDesigns    MAPUG-Astronomy.net

For member-designed observatory plans, see Member Products & Designs (also linked from homepage) 
Observatory Plans URL  --huge list of observatory websites
Article -- Design Phase of Building Your Own Observatory, by Jay Ballauer  --outside link
Article -- Construction Phase of Building Your Own Observatory, by Jay Ballauer --outside link
Observatory Design On-line PDF Document 
Roll-Off Observatory Design Based on a Utility Trailer --separate page 
Plastic Shed Observatories --separate page 
Conversion of Garage Loft to Observatory --outside link 
Tele-Station by Pier-Tech --outside link (commercial roll-off observatory) 
Observatory Domes Vs: Roll-Off Roof 
Temperature, Thermal Effects, Dewing & Similar Problems  --separate page
Observatory Ventilation Issues --2 parts 
Wall Height of a Roll-off Roof Observatory? 
Dome Recommendations --4 parts 
Advice on HomeDome Observatory Domes  --4 parts 
New Dome Manufacturer-- Clear Skys Inc. 
Remote Control Observatories Publication --on Remote Control topic page 
Starting a Robo Scope Directory --on Remote Control topic page 
Running Power to Remote Observatory  --16 parts on Remote Power topic page 
"Off the Grid" Observatories --6 parts on Remote Power topic page 
Pier Location in a Dome for Wedge-Mounted LX200  --2 parts 
Observatory Design Considerations--2 parts 
Plans for Building an Observatory on the Roof of a House 
Issues in Building an Observatory on Top of a House 
Cost Estimating --2 parts 
Observatory Design Books & Other Sources  --5 parts 
Determining SkyShed Observatory Dimensions 
Zoning, Covenants, and Deed Restrictions Concerns  --8 parts 
Keeping Insects out of a Closed Observatory? 


Subject: Observatory Plans URL  Top

From: Bill Arnett <billaa_tznet.com>

I've searched the Web to plan a backyard observatory and found a few to learn from. I've made a simple WWW page listing what I've found so far: (Please let me know you know of any others.) Editor's note: this is a huge list now.

   <http://obs.nineplanets.org/obs/obslist.html> Note: should open a new browser window over this one.

   Another good site is: <http://atmpage.com/>


Subject: Observatory Design On-line PDF Document    Top

From: Robert Genung <rgenunga_trgenung.free-online.co.uk>

You'll find a really helpful .PDF document, "At Home in a Dome," at Home Dome website:

<http://www.homedome.com/> Note: should open a new browser window over this one.

Don't let the title put you off. Download the whole .PDF doc (about 44 pages), and you'll find a wealth of info.


Subject: Observatory Domes vs. Roll-Off Roof      Top

From: Doc G

I have worked with both roll off buildings and with domes for some years. I originally built a roll-off building because I liked the idea of having the entire sky visible to the unaided eye. On a dark night this is a wonder to behold. It is also nice to be able to slew from one part of the sky to another without having to worry about moving a dome.

That said, I would NEVER again build a roll-off structure. The dome protects against wind, is darker inside, and gives appreciable protection from the sky on clear nights. In a colder climate especially, your body is protected against radiation to the cold sky. I am in Wisconsin and have found that being totally exposed on our wonderfully clear winter nights is a severe trial. The comfort factor of a dome is appreciable. Dewing is much less because the scope is not exposed to the dark sky either. For more of Doc G's thoughts, click here.

I now highly recommend a dome-type structure. This is especially true since the newer domes are entirely automated. I have just ordered a Pro Dome from Technical Innovations. These domes are well developed and have all of the features you need for full automation.

Editor's note: there is a good dome manual at:
   Note: should open a new browser window over this one.


Subject: Observatory Ventilation --part 1 of 2  Top

From: Doug George <dga_tcyanogen.com> Date: Aug, 2004

Mark Lancaster wrote:
> Okay, I'm confused. I've always heard that you *do not* insulate so that
> the building interior is reasonably close to outside ambient. In the
> last year, perhaps on this list or the observatory list, some members
> have indicated that they *do* insulate, and condition the buildings
> interior air to keep it close to the "expected" night temperature, keep
> the humidity down, and perhaps the bugs. Which is it? I'm close to
> constructing my own shelter, and would like to get it right the first
> time.... I would certainly appreciate a consensus on this.

Either will work. Actively cooling to the expected nighttime temperature is perhaps the most effective method. The CFHT uses this method, although they keep it at about 0 degrees C -- which is warmer than nighttime temperatures -- simply for reasons of economy. On the other hand, unless you have something the size of the CFHT it's probably overkill.

A few years ago I built a 12' x 12' observatory with extremely good ventilation -- lots of hidden vents along the floor line and vents in the roof. It also has a highly reflective roof. The combination keeps the observatory only a few degrees above ambient even in full sunlight -- it feels wonderfully cool when you step inside, rather than stinking hot like most sheds. When night falls the outdoor temperature falls, and the observatory temperature falls with it. So there isn't a big change when you open the roof, and the seeing is excellent from the get-go. When I built the observatory my local seeing mysteriously got MUCH better!

One idea to keep dust, etc., out of the observatory is to build it with hollow walls that are well ventilated. A friend of mine built his observatory that way, and it seems to work very well.


Subject: Observatory Ventilation --part 2 of 2  Top

From: Doc G

If you are going to condition the buildings where a rather large temperature differential exists between the inside and the outside during the day some insulation will make holding a large temperature differential more efficient. If the temperature differences are not large between day and night, some fans will be adequate. It is always the case that the night is cooler than the day. Sometimes this will be 10 to 20 degrees and sometimes it might be 40 or 50 degrees. For the former, fans should do the job. For the latter, differential cooling might be worth while.

The only advantage of insulation is to make it easier to hold a temperature differential. The disadvantage of insulation is that it tends to hold the heat of the day and will impede cooling at night.

This is a complex topic so what is best for any situation will vary quite a bit. In all cases a very large air flow through the building during temperature changes is essential to quick equilibrium of inside and outside temperatures. Larger scopes, say 12" and over, really need integral fans to attain thermal equilibrium quickly. You need large air flow, big fans, to do the job. Turbulent air transfers heat up to 100 times faster that slow moving air. I rather think that the issue of insulation is not as important as moving a lot of air. If I were in a hot daytime situation, I would seriously consider using an air conditioner to get the scope down to night time temperatures as quickly as possible.

You do not really have to guess at the night Time temperature. The weather reports about night time temperatures are generally quite accurate since it is very short term prediction and is based on solid data that exists during the day. There are other reasons for not insulating and not air-conditioning, but the anticipated nighttime temperature is not one of them.

Just because one is an "amateur" does not mean that they do not have an investment of 50K$ to 100K$ to nurture, protect and utilize in the most effective manner. Today's "amateurs" come in many sizes. Air handling and air-conditioning are effective and not necessarily high cost solutions to the temperature problem. The day of keeping expensive and delicate equipment in a hot, stuffy shed are over for many "amateurs."

When humidity is a big problem, you have to be sure that the interior, scope and equipment, is not below the dew point temperature. Otherwise everything fogs up for a while when you open the building.

Each climate, indeed each day in may places presents its own problems. Things differ from day to day. I would say if humidity (the dew point) is close to the ambient temperature you are best off simply moving a lot of air to get thermal equilibrium as quickly as possible. In humid climates, the night time low temperature tends to drop and then limit at the dew point temperature. There may be no good solution at all to some air conditions. One simply has to close down for the night when the dewing gets too bad.


Subject: Wall Height of a Roll-off Roof Observatory? --part 1 of 2  Top

From: Bert Katzung <katzung1a_tattbi.com>

I have a different type of roof (fold-off) on my observatory, but I find that wind protection is very useful (and fortunately, easy to arrange with my roof). So I would make the east and west walls high enough to block off the lower 10 to 15 degrees of the horizon (unless your horizons have much cleaner air than mine). Another option is to put wind barrier panels along the sides that can be raised and lowered. The north peak can be pretty high, since everything there will rotate into view at some time of year. So that leaves the south end as the most critical. From the altitude of the major southern constellations (Sag, Sco, etc.), you can calculate what the angle of the scope will have to be to get them and that will give you the maximum height you can get away with for the south end. I found that making the south end (a peak in my structure) fold down worked well. You can see the arrangements in the observatory page on my website: <www.astronomy-images.com>

----- Original Message -----
From: Turgut Kalfaoglu <turguta_tegenet.com.tr>
> Is there a rule-of-thumb for the wall height a roll-off roof observatory?


Subject: Wall Height of a Roll-off Roof Observatory? --part 2 of 2

From: Anthony Kroes <akroesa_tvenomtech.com>

It is always a tradeoff between blocking too much sky, and keeping the scope low out of the wind.

I have some neighboring farm lights, low skyglow, and a lot of wind, so for my 12" LX200, I figured on about a 20 degree loss of sky from the horizon (LA = Loss Angle) was acceptable and then I did the trigonometry. Who said we would never use that stuff in real life?! I started with the height of the scope base as mounted on its wedge and tripod to calculate how high to build the pier. This also gave me the DEC axis height from the floor. Subtract half the diameter of the OTA and you have the wall height (WH = Wall Height) to look completely horizontal and not loose any sky or have the OTA blocked in any way. Measure the distance from the crossing of the DEC axis and RA axis (inside the tube) horizontally to the walls (SW = Scope to Wall distance) and you have all the info you need to use to calculate the additional height to add to the wall (AH=additional height) to get the desired coverage.

(SW * Tan(LA) = AH
WH + AH = Height of wall from floor

For my 10' by 12' roll-off (pier is offset 1' to the South so the E, W, and S walls are all 5' from the pier) the 20 degree protection cost me an extra 22" on the walls ( 60" * Tan(20) = 22"), bringing them to a final height of 6'2". Don't forget to calc in the stuff that may not be mounted right away like the rails for the roof wheels. They may adjust your framed wall height.

Also, while your pier may be evenly spaced from the walls, don't forget that the RA and DEC axis on an LX200 on a SuperWedge do not cross directly over the center of the pier. I made that 'mistake', and because I made my walls the same height all the way around, I can actually get a touch closer to the horizon looking South compared to East or West because the distance is a few inches greater. I didn't worry about North (same height as all the others) except to make sure in my calculations that the roof would roll off far enough for the scope to get an unobstructed view of Polaris.


Subject: Dome Recommendations --part 1 of 4     Top

From: Doc G, Date: May 2001

I found the ProDome considerably more difficult to assemble that I had expected. The drawings are not very good. I too would have liked to see some photos. I and my group of helpers spent about 105 man hours getting the dome together. I Spent another 10 hours doing the electrical work.

The quality is very good, but the manual is not as clear as it might be. What is it about manuals that make them so difficult to decipher? Three of us read each section of the instructions and then voted on what was said.

I sent about a dozen posts to home dome asking for clarification or commenting on what would help to make the manual clearer. Some of the diagrams are rather amusing as well as confusing. Photos would help a lot.

Nevertheless, we have a nicely working dome at this time. If I were to ever do this again, I would get the pre-drilled version. It was very difficult to do all of the measuring accurately and actually drill the fiber glass.

The only thing I do not like about the dome at this time is the terrible noise the motors make. The noise suppression covers help, but only a little. The shutter mechanism is rather a kluge, but works surprisingly well. I was pleased with the shutter operation.

We probably spent extra time since we were very careful to get things right the first time. We did make one error on the shutter assembly but fixed it all right later.

All in all however, it is a nice dome.

Home Dome site: http://www.homedome.com/
Note: should open a new browser window over this one.


Subject: Dome Recommendations --part 2     Top

From: Jon Brewster <jon_brewstera_thp.com>

For the record, I now have my Boyd Dome operational.

It took a day to unpack, and a day to build for 2 of us. The instructions were terrible. No pictures. Must be an industry standard. Automation seems to work great. Software by our friend Brent of Satellite Tracker fame.

Editor's note: Boyd Domes is out of business, but Clear Skys Domes seem to be a very similar design.


Subject: Dome Recommendations --part 3 

From: Paul Gitto <PaulGittoa_taol.com>

When I ordered my ProDome, I ordered the pre-drilled version, and I'm glad I did. I hired a contractor to finish the assembly on site, and it went up very quickly. The money I spent for pre-asssembly assured that the dome went up per specs, and saved costs on the other end.

I believe the manual is written by the founder of the company, John Menke. They are very hands on mom & pop shop, and they farm out the fiberglass construction. They also modify the manual as per customer suggestions. I've owned the dome for over 4 years, and it works like a dream.


Subject: Dome Recommendations --part 4 of 4    Top

From: Micahel McNeil <cnoa_tcaltel.com>

I was in the past going to get the ProDome, but after meeting Col, on this group, I got his dome. Will be here soon. What's nice is that he assembles all the takes it apart, and has all marked with simple 1 or 2 page instructions. All holes are drilled, no need to spend weeks doing the job, and also less people, to install it in a few hours. And even more so, its less money, even with shipping cost. That is the website: <http://www.astrodomes.com/>


Subject: Advice on HomeDome Observatory Domes --part 1 of 4  Top

From: Doc G, Date: May 2002

I have installed a 10' Pro Dome along with the motor drive and the DDW (Digital Dome Works). I could write a book about the good and not so good things about it.

I strongly suggest you have it predrilled. Putting it together and doing the drilling etc. is a very, very difficult job, in my opinion. Even with the help of several very excellent helpers, it took 30 hours over a period of 4 days to get it all perfectly aligned. I was very fussy about the alignment and felt that some of the parts did not fit as well as they should.

A number of the brackets required some machining to bring them up to the standards that I required. The electric shutter drive and the motors required considerable additional skill to get them adjusted to work as they should. I had to purchase additional bolts because I felt some of those provided were too short.

I got the Pro Dome version which has additional base rollers. I strongly recommend that you get the extra rollers. After careful assembly, the dome worked very well and has stood up mechanically for almost a full year now under regular use.

I had some difficulties with the DDW which requires a dome motion sensor. The sensor was wired backwards and thus the DDW did not work at all. After fixing this, I found that the DDW was temperature sensitive. It did not work at temperatures below 35 F. It turned out that the PIC had a programming error. This was fixed with a new PIC after some considerable amount of testing and a time delay. I discovered the temperature problem myself and reported it to Technical Innovations. This is no longer a problem since the programming has been fixed.

The dome slaves to the LX200 telescope but only for short slews. When a large slew is done by the telescope, the dome will not follow and the DDW reports an error condition and shuts the dome down. I have been informed that this problem is being worked on and that a new PIC will be provided. I do not know the time frame for this fix, but I am hoping it will be soon. Our application requires large slews for the most part.

We use the dome in the slave mode and with a computer. Both mode of operation work similarly. Except for the large slew problems, the DDW now works well. We do not use the weather station or automatic opening/closing features.

The construction and tweaking of the dome did require considerable mechanical work and considerable electrical smarts. At this time, the Pro Dome is working well. It is sturdy and stable. In general Technical Innovations was helpful in solving problems. Technical Innovations in under new management, as of this year, and I have no first hand experience with the new management. Except I did get a promise to get a new PIC out to solve the slewing problem. I will keep you informed about progress on this matter.

Home Dome: <http://www.homedome.com/>
Note: should open a new browser window over this one.


Subject: Advice on HomeDome Observatory Domes --part 2

From: Donald Franck <DFrancka_taol.com>

Go to my site below...it has pics and facts on the Home Dome:


Subject: Advice on HomeDome Observatory Domes --part 3  Top

From: Ted Van Sickle <tvansicklea_ta-sync.com> Date: Feb 2003

I built a 10' Home Dome last September. Everything that Tom has said (below) is true. Especially about the pre-drilling. Actually, Technical Innovations, TI, assembles the dome completely, disassembles as much as necessary, and then ships the unit. There are literally hundreds of holes, and they all line up at assembly time. Also, some very important items are assembled when it arrives. There must be at least 25 castors mounted. Well worth the cost. I expect that it cut the assembly time by a factor of three.

As far as leveling, we set a post in the center of the dome and adjusted its height to the desired height of the wall. Then a 6' carpenter's level from the center post to the wall was used as the walls were shimmed until the wall height all the way around its perimeter was level with the top of the post. It worked well. Making the wall round was tough. Mine is round, but I think that the adjustments to make it round bordered on good luck.

I have not bought the Robo Dome yet. I am in Florida for the winter. That will be my first purchase when I get home. I did buy the motor drives for both the shutter and the dome. They work well, but they are very loud.

I am using a homemade pier. There is a Milburn wedge on the pier and I have a classic 12" LX200 for the telescope. The theory is that the center of rotation of the telescope should be at the center of the dome. After a couple of measurements with the scope on its tripod, I decided to place the center of the pier 6" South of the center of the ring. It seems to work well there.

I put, I think, 1.5", maybe 2", conduit in the floor to pass all control cables and power to the telescope from the wall. This conduit is plenty large and it comes up into the center of the pier. I have NOT seen any sign of interference in this short run. I put in two smaller conduits from the house to the dome, one for power and the other for a Cat 5 ethernet cable. All power for the equipment in the dome is derived from a car battery, and the power from the house is used only to charge the battery and provide a little light.

By the way, only two of us put the dome up, and I think that it required only 6 hours. The dome is a most wonderful place for observing the glory of the night sky.


Subject: Advice on HomeDome Observatory Domes --part 4 of 4   Top

From: Tom Mote <pytoma_ttexas.net>

I have had some experience with the Home Dome. I assume that whatever dome you purchase will require you to do considerable assembly, and I have a couple of suggestions.

  1. If your budget allows, pay a little extra to get a kit which has all the holes pre-drilled. My Home Dome didn't have that option, but I understand that they do offer it now. We spent a sizable portion of the assembly time in locating and drilling holes and wore out several drill bits, also.
  2. If you are now doing any CCD imaging, or if there is any possibility that you ever will, purchase any available option for remote, motorized control of the rotation of the dome.
  3. Don't even consider trying to use a hose device called a "water level." They are cheap but useless!

One of the most difficult aspects of dome assembly is actually three things,

  1. insuring that the base rings are as circular as possible,
  2. the base rings are as nearly perfectly level as possible [and here is where an inexpensive laser level is worth several times the $20 or $30 it will probably cost you] and, to a lesser degree,
  3. the rings are well centered on the telescope.

Another area to investigate is snow loading and wind loading. Many are fortunate in not requiring snow load data, but most of us are subject to wind load considerations.

Finally, I found that three is an ideal crew size for the assembly of a 10' dome. More than three tends to become a gaggle with people falling over each other and, while all of the actual physical work can easily be done by one or two people, a third person to simply do the instruction reading, and act as a gopher, can make things easier. Actually, I was the "reader/gopher" with my son and another young man doing most of the real labor.


Subject: New Dome Manufacturer-- Clear Skys, Inc.  Top Button

From: Ed Stewart

Noticed in the April 2003 Sky & Telescope, page 143, an ad for Clear Skys, Inc. 8.5' dome. See:

<http://www.clearskysinc.com/>  Sold by Meridiant Telescopes:
<http://www.meridiantelescopes.com> Email: <mtgproductsa_tcomcast.net>


Subject: Pier Location in a Dome for Wedge-Mounted LX200 --part 1 of 2 Top Button

From: Steve Stefanik

From: Keith Schlottman wrote:
> I'm setting up a 10" LX200 in a very small (6') dome. It will be equatorially
> mounted on a super-wedge and pier. I'd be interested in hearing
> from other dome owners where the center of their pier is in relation
> to the center of the dome. It seems like the pier should be slightly off-center
> to the South.

Yes, you are correct in your assumption that the pier should be "offset" in relation to the geometric center of the dome. Your LX200 should be centered on the center of the DEC axis at the end of the fork arms (where the DEC manual setting circle and/or DEC motor is located). This would mean that the pier would be offset toward the south (as you face the control panel of the LX200) as you deduced. Simply use a plumb-bob tied or taped to the knob on the setting circle and suspend it to the floor to mark the spot.
Check it out at <http://www.mv.com/ipusers/astron/observatory.htm>


Subject: Pier Location in a Dome for Wedge-Mounted LX200 --part 2 of 2

From: Jon Brewster <jon.brewstera_thp.com>

> The fork mount has a fixed point halfway between the declination bearings.
> No matter how you point the scope, that point will remain fixed; so it needs
> to be in the center of the dome. That will mean having the pier offset to the south.

I choose instead to center the pier and offset the wedge at the top of the pier. This way if I ever go away from a fork mount LX200 I don't have to redo the pier.

My pier can be seen at: <http://www.proaxis.com/~sandstone/Astro/Observatory/ObsPier.htm>

It cost my a couple of hundred bucks to have it fabricated at the local welding shop, but I'm sure happy with it. I may have to swap the steel out some day, but the concrete can stay untouched.


Subject: Considerations on Building an Observatory --part 1 of 2  Top

From: Mike Dodd <mdodda_tmindspring.com>

> Does anyone know where I can purchase design plans or blueprints for
> constructing an observatory?

I think most people design their own. Here's the link I used to get ideas:
<http://obs.nineplanets.org/obs/obslist.html> Note: should open a new browser window over this one.

> MAPUG-Astronomy.net had some great examples of observatories that looked like
> they would fit my needs as well as my budget - which is in the 10K range....
> ...but I did not see any floor plans.

I think each observatory has to be designed for the individual's needs, since there are so many reasons to build an observatory. Here are a few factors that come to mind:

  • Solo or family viewing? Affects the overall size, since you need space for several people, and possibly benches or chairs for those not actively viewing.
  • Local environment. A dome isolates you better than a roll-off roof, but can be more complicated to use and maintain.
  • Local horizon. Affects wall height, which can change the entire design.
  • Visual or astrophotography? If the latter, you might need a separate control room for the computer and related equipment. Or do you want a completely remote-controlled observatory, in which case all you need is a tiny shelter for the scope.

    > I am looking to build a cabin and am wondering if anyone has
    > experience with connecting a shed-like structure to a cabin?

I would advise against this, or at least suggest first looking into a detached structure. Why? For starters....

  • You may have a better horizon elsewhere.
  • Other close-by family activities could be distracting (nothing like listening to the Simpsons on TV through the wall as you admire the Orion Nebula).
  • You may have light pollution from nearby cabin windows (i.e., can you turn off all the lights in the cabin when you go out to observe?).

If you need plans so a carpenter can build the observatory, I suggest you find an architect and explain what you want. Be prepared for some give-and-take (hopefully he'll have lots of questions for you to think about). If you know what you want astronomically, the architect should be able to translate that into blueprints.

Finally, the cost.... I'd be surprised if you'll have to pay more than $5,000 to have plans drawn and an observatory built. A $10,000 budget sounds more than ample; maybe you'll have enough left over to buy some CCD equipment.


Subject: Considerations on Building an Observatory --part 2 of 2   Top

From: Larry Blair

>Does anyone know where I can purchase design plans or
>blueprints for constructing an observatory?

Go to Joe Garlitz's web page. You can download the blueprints:


Subject: Plans for Building an Observatory on the Roof of a House   Top

From: Steve Stefanik <stefansa_tastron.mv.com>

Check out: <http://www.mv.com/ipusers/astron/observatory.htm>


Subject: Issues in Building an Observatory on Top of a House --part 1 of 7   Top

From: Jim Duke <jdukea_tcisco.com>

--- Christian Molnar <cmolnara_tiship.com> wrote:
> We've been looking at a few new houses, some being
> built, and some a few years old. The ability to
> have a permanent setup is a high priority on our
> list, either a shed observatory or a dome or roll
> top roof setup. On the new houses, it would be very convenient,
> because I'd work it into the deal. I've talked to a couple of the
> builders that we're looking at and they are completely open to it.

I find this topic is one which is very difficult to offer advice for, even though I've been through this process. Because there are an extremely large number of factors involved both with respect to building/buying a home and in building an observatory. When the 2 are combined it can be extremely difficult to decide what is the "right" thing to do.

I have built my current home with the observatory design as the central feature of the home. I have only done visual observing and very limited CCD imaging to date (mostly based on time constraints). As yet I have not had any difficulties from heat plume from the house, and I live in Central Texas which can get pretty hot. Nor do I have any issue with vibration from any walking, jumping, slamming doors, etc. The pier (which is poured separately from the house foundation) is pretty tall which could lead to damping time issues from a bump against the pier or scope, but I have not had any problem with this up to this point.

It's a lot easier when you are designing from scratch, because there are design elements (placement, material choice, etc.) which can compensate for just about any adverse effect you can think of, for example, since my dome is in the center of the building, roof physical layout, roof composition, attic venting, and roof slope have all been factored in to reduce the possible negative effects of heat dissipation, while still maintaining the aesthetics and accessibility that were important to me. It is a compromise that I've made against competing requirements, and I can always build another observatory outside later, but it would be difficult to add another one to the house after it was built.

To specifically address some of the items you singled out:

1) Basic dome structure choice (roll-off, slit opening dome, full opening dome, hinge roof, etc.)

I find this to be more of an aesthetic issue, than a functional one. I wouldn't consider any design that wasn't field proven to be effective keeping water out, regardless of if it's on my house or in my yard. I find roll-offs to be somewhat less aesthetically appealing, and that could affect resale in case you decide or need to sell later (another reason not to put an observatory on the house unless your really sure about it). There are a couple of physical advantages that I happen to like about slit opening domes which drove me to go that direction, first they provide additional protection from wind versus designs which do not allow the walls to act as barriers, and second they provide additional protection from stray light, but I also use a dome that is slaved to my scope, and I would not have chosen a slit opening dome without that.

Cost could also be a factor, however, we are talking about integrating an observatory into your home, when you consider cost of your observatory as a percentage of overall cost of a house, it's going to be pretty small anyway.

2) Home observatory pier/mount isolation techniques. Here I suggest (as another member did) read "at home in a dome" from technical innovations, it does a really good job discussing several different pier isolation techniques. I chose to use a separately poured pier, but this can be difficult if your not doing a custom design, and certainly not feasible for an existing home. I would not put this as my deciding factor, just as an issue to deal with, and use one of the existing designs that is best suited to your situation.

3) Heat plume.

For me it has not been a problem, but it was factored into my design. Also I specifically excluded a chimney and fireplace from my house design, another way to reduce issues and complexity from the situation. I'm not familiar with Seattle so don't know what type of roof materials are common there, but they all have different properties, also an observatory can be located such that this is minimized (for example a corner room of the house, preferable on the south side). Also I don't know the population density or house spacing in the area you are considering, but I would imagine that neighboring heat plumes might also be something to consider as well.

Again being in Central Texas, the concerns are related to heat build-up during the day and dissipation at night, other heat issues are not paramount (for example in a winter location heat leakage in winter due to heating system might be an issue)

Also my design keeps the observatory thermally isolated from the rest of the house, and my home automation system is designed such that temperature control is automated to bring the observatory temp to outside temp starting one hour before sunset, and keep pace with the outside temperature until the dome is activated. (then I let nature take it's course)

Only thing I would re-iterate, is that in my opinion, integrating an observatory into a home is a significant decision, and not one I would make lightly, it can affect aesthetics, and resale value of your home, and it will come with it's own set of challenges on top of a project that is already filled with challenges. But on the other hand It can have significant benefits.

Another possible suggestion: Do a raised platform observatory. I have not done this but I've seen pictures of ones done this way. Build a raised observatory outside one of the south corners of the house, attach it actually to the house. It can be supported wither from the walls of the house or from below. Bring a concrete pier up through the bottom of the observatory. Entry could be from below using stairs or through the house using a door. (not sure if we're talking 1 or 2 story building here).

This way you have good visibility except on the house side which will be limited only by the slope of your roof, and heat dissipation should be in just a portion of the sky (based on which corner you use on the house)


Subject: Issues in Building an Observatory on Top of a House --part 2

From: Chuck C. <divenutsa_tgte.net>

Also, this websites has many examples of what has been done:

and Yahoo has a message group on Observatories:


Subject: Issues in Building an Observatory on Top of a House --part 3 of 7  Top

From: Gene Horr <genehorra_ttexas.net>

Christian Molnar wrote:
> You mention the heat plume. That is one of my main questions.
> I just can't understand how heat rising from the house wouldn't
> ruin any and all imaging sessions. But people do build observatories
> on top of buildings.
> There must be things I don't know about what can be done to avoid this.

They're building them for looks/convenience. Or from what I've seen dealing with architects who have no idea of the issues involved and they are designing for looks.

I had the opportunity last year to do some help for a team installing a mid-six figure system in a new house. The telescope team advised a separate building. The architect wanted it part of the main house for "visual integrity." Since the building is located at ~ 30 degrees north the team advised putting it on the south side of the house. The architect placed it on the north side. At least the architect allowed the separate four piers for the mount. Then attached the exterior walls to them. When the team found that out after the fact and started screaming at the architect, his reply was "I checked with the structural engineer, we are nowhere near the load limit."

The owner is sitting there with architects and engineers telling him one thing, and people who are not architects nor structural engineers telling him another. You can't blame him for deciding to listen to what credentials say are the experts.


Subject: Issues in Building an Observatory on Top of a House --part 4

From: Jim Duke <jdukea_tcisco.com>

I would definitely make sure that the architect used on this type of project either be willing to do the research himself (or herself) or willing to defer to the real experts. In my case my architect was willing to listen to the issues that needed to be solved, look at the research available and help make suggestions, however in the long run, all design decisions related to the observatory were driven by me and not the architect, simply because he did not have the expertise to do so.

The down side to all this, is having gone through this, and having the burden for much of the design considerations myself, I'm not sure I would use an architect next time. (Given that I had to provide the answers for all the complex questions, I'm not sure I got the value I paid for in that regard).


Subject: Issues in Building an Observatory on Top of a House --part 5 of 7  Top

From: Emilio Robau <ejra_tconsult-rwa.com>

Very few architects, civil engineers (of which I am one), structural engineers or other design professionals know what is needed for an observatory. The design issues associated with a successful long focal length visual or imaging observatory are dramatically different from the typical situation. Vibrations, heat emissions and other concerns would not be a typical design consideration for the standard and even not so standard residential design.

I would say that the owner, if knowledgeable needs to drive the design decisions related to the observatory. If not knowledgeable, the owner still needs to drive the design by selecting someone who has experience and sticking to that person's recommendations. This person would overview the architect's initial plans during the schematic design phase of the work and make recommendations for improvements. Additional review would occur until the construction plans are completed. Services during construction would also be nice. Only in the case of an architect who is also an amateur astronomer would I allow the architect to take the lead. Architects are best at spatial relationships and aesthetic design. Someone else usually helps them in actually getting a design that is constructible. If you get a good architect they are also good at directing the entire project and project administration at least for the vertical portion of the work. I would not leave the research to the architect. I don't think they will be able to ramp up on the leering curve.


Subject: Issues in Building an Observatory on Top of a House --part 6

From: Jon Brewster <jon.brewstera_thp.com>

> I would say that the owner, if knowledgeable needs to drive
> the design decisions related to the observatory. If not
> knowledgeable, the owner still needs to drive the design by
> selecting someone who has experience and sticking to that
> person's recommendations.

Then you have to follow through to make sure the builders follow through. They think they know how to build a house. I built my house around my scope. A small dome'd hut on a high deck off the master bedroom:


I needed to personally manage the concrete forming including top of pier bolts. I don't know anything about building, but the grunts didn't know anything about what I was trying to accomplish, and they don't follow architects instructions all the time. Then I had to keep all building elements away from the 18' tall pier, then manage all cabling to keep the data cables away from the power cables, etc., etc.

If I had declared victory after the architecture phase, I'd have been doomed. But maybe that was just my local bozos.


Subject: Issues in Building an Observatory on Top of a House --part 7 of 7  Top

From: Gene Horr <genehorra_ttexas.net>

Jon Brewster wrote:
> If I had declared victory after the architecture phase, I'd have been
> doomed. But maybe that was just my local bozos.

Nope. They're all Bozos. And yes, I've been involved in the construction industry for decades. Keep in mind that there are often dozens of companies involved and even if you have a full time construction manager present he or she can't be watching every single worker every minute of the day.

A few other factors to keep in mind are:

1) Seal the floor, including the access door. One installation had a tall "silo" structure with the observatory on top. The "silo" was hollow and sealed off from the house by exterior doors with weather stripping, but there was still a chimney effect blowing air up through the floor access. Eventually they had to add a sealed door in the floor.

2) Leave plenty of spare conduit room (separate from mains!) and pull strings.

3) Add at least two duplex mains outlets at the mount itself for the mount, cameras, etc. Have spares available. You never know what the future will bring.

4) If the dome is powered and large consider a chain drive rather than the rubber wheel type. It's more expensive but you'll have far less problems.


Subject: Observatory Cost Estimating --part 1 of 2  Top

From: Ralph Megna

Let me also recommend against approaching any observatory project using a "per square foot" method of cost estimating, unless you start with a number somewhere north of $150 per sf.

There are just too few square feet involved in most amateur observatories to use square footage as a reliable guide.

I might note that there is an economical way to get a roll-off observatory, and that is by adapting a prefab metal garden shed. The cost of the shed is about $500. Obviously, to that number you must add the cost of footings, floor, pier, electrical, etc. One interesting benefit to this approach is that many local zoning codes exempt garden buildings of less than 120 sf from any regulation.


Subject: Observatory Cost Estimating --part 2 of 2  

From: Dave Schanz <dave23scha_tvalleytranscription.com>

So far the general consensus seems to be that the whole project cost is a variable. How much the finished project costs is highly dependent upon what you are building. That much is obvious. The only relatively fixed cost is the cost of materials. The rest is dependent upon numerous factors - decisions you have to make. For instance, I did a LOT of research prior to installing my concrete pier. I looked at every web site I could get into and studied the pier construction for ideas. Then I decided how I wanted to design and install mine. The cost was estimatable, but only _after_ I decided what design _I_ wanted and how I wanted to build it. For instance, would I buy concrete by the bag and mix by hand, or, rent a mixer? Or, would I have the concrete premixed and delivered? Did I want to dig the hole myself or rent a backhoe. How deep and how big a hole? How big a diameter pier and how tall? What reinforcement would I use and how much would I need? How much concrete would I need? How about the top plates - aluminum, steel or stainless? Could I drill the holes myself or would I need a machine shop to help out? And what about the anchors to mount the mounting plates? Again, carbon steel or stainless? What diameter? The list goes on and on. You have a lot of decisions to make with a metal pier too.

It's darn hard to give you a reasonable "rule of thumb" estimate for any part of the construction of an observatory because those of us that have built them know there _are_ so many variables involved. How much yours will cost will require you to sit down and design exactly what you want -- right down to the number and kind of light bulbs, then, with a bill of materials in hand, head over to the lumber yard, scrap metal yard, hardware store and rental places if necessary and get prices for everything, then get estimates for anything you aren't comfortable doing yourself (electrical, trenching for electrical, etc.), then add the cost of any required permits and estimate your final costs from there.

Then, as Doc mentioned, you might want to add 25% because if you are like most of us, the design will change as soon as you start building it. Also, if you have a wife and don't you involve her in the design, you'll likely need to add another 25% on top of that!


Subject: Observatory Design Books & Other Sources--part 1 of 5  Top

From: Paul Gitto <pg190a_tcometman.com> Dec 2002

Here's the info and link on the new books on observatories:  <http://cometman.com/dome.html>

The book is known as: "More Small Astronomical Observatories", you'll also get the first one now out of print book on CD. Two books in one! It's a Patrick Moore's Practical Astronomy Series book. The Arcturus Observatory has a chapter featured in this book. Plenty of photos, details and hints on designing your observatory.


Subject: Observatory Design Books & Other Sources --part 2  

From: Greg Jones

I don't know if anyone has mentioned it but I have a copy of "Small Astronomical Observatories, Amateur and Professional Designs and Construction" Published by Springer-Verlag Berlin Heidelberg New York 1996. ISBN 3-540-19913-6" edited by Patrick Moore. It's a great book, containing a collection of construction details photos, etc. from around the world. I picked this copy up at Borders Books some time ago.


Subject: Observatory Design Books & Other Sources --part 3

From: Ralph Megna <ralpha_tdigi-empire.com>

If you are considering an observatory, you owe it to yourself to check out Mark Baines' site -- he has done a superlative job of documenting the conversion of a metal garden shed to a practical roll-off observatory:  <http://www.linnhe.net/>


Subject: Observatory Design Books & Other Sources --part 4

From: Hap Griffin <lgriffina_tsc.rr.com>

Check out this site with three double observatories. The 12 x 12 roll-off-roof buildings cost us about $2000 each with piers and electricity...a bit more for the deck.  <http://www.machunter.org/>


Subject: Observatory Design Books & Other Sources --part 5 of 5    Top

From: Don Tabbutt <dona_ttabbutt.com>

Many members wanted to see the pictures of Michael Dziak's unique observatory, but he didn't have a web site to post them on. So he and I got together and posted them on the MAPUG Images site, which I host.

You can see the picture's of Michael's observatory here:  <http://www.tabbutt.com/mapugimages/photos/>


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 1 of 8  Top

From: Michael Bushell <mbushella_tbibleworks.com>

I have a question -- I am getting close to a life-time dream of having my own permanent observatory. I bought a piece of property in the country, about an hour away, and even had an architect put together a modest plan for a 600 square foot observatory with a 12' dome. But now the county is telling me I cannot build that kind of building there. It's not zoned for that sort of thing and he is telling me that my chances of getting a variance are small. If it were an accessory building to an already existing residence, I would have a chance. But he says they are not likely to grant it.

My question is whether or not any of you have had experience in dealing with zoning boards and what advice you would give. This whole thing seems almost obscene to me. It is a large property (50 acres) and bothers no one. It's crazy. Any thoughts on strategy? From light pollution to zoning laws it seems like all the cards in this society are stacked against people who just want to gaze at stars.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 2

From: Emilio Robau

I provide consulting services on zoning matters all of the time. Variances are a four letter work. They are usually only granted if a significant hardship can be proven. Usually the type of thing you are proposing could be accomplished as an accessory structure. You should look at what the minimum principal structure allowances are for the zoning allowance the land already has and try to call your observatory a principal structure with a residential component. Usually in rural areas the zoning regulations are rather simplistic and the minimum floor area is quite low. You may be able to build a one bedroom one bath observatory about 800 square feet and call it a residential structure and get away with what you want to do.

Getting an attorney or others involved will cost you more than the upgrade cost to go from 600 square feet to 800 square feet or larger if needed. Remember you only have to build a shell that looks good from the outside. If you try a variance do it yourself and represent yourself but success chances are often slim.

Before you submit your variance application get a feel for what the planning and zoning and board of county commissioners or city council members think of your proposal. This is critically important. I should bold the last sentence. You want to know what they think of your proposal and preferably how they will vote before you get up in front of them. You don't want to just plead your case cold turkey. This is a huge mistake and waste of time. Take the time to meet with each member individually before you waste your time on the variance.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 3   Top

From: Rick Richardson <Rick.Richardsona_tusermail.com>

City zoning boards can be more specific than the county boards. Though cities in this area like to claim future rights to areas they think might become part of their city. You buy before they claim it, then you are grandfathered. The county board would be lynched if they got too restrictive.

can be applied by developers where there will be a close association of houses, but not in simple sales of land. People were trying to do it too much so it was limited to special cases. If you buy into a development you are tied up. I was looking at a 15 acre lot on the outside of a development. The developer told me it was not covered by the covenant. My lawyer found out the county thought otherwise. Since it was part of the covenant, the only way to get released was to have over 2 thirds of the votes of a quorum. Half the lots were required and no where near that number of lots had been sold. So I kept looking and found a nicer darker cheaper acreage.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 4  

From: Michael Gartland <mgartlana_ticonn.net>

Ok...I am going to combine these two threads...for obvious reasons....and get on my soapbox for a minute....and get a little OT....my wife is on the local Zoning Board of Appeals, in a shoreline town up here in New England, you can imagine what it is like and she has seen it all...the property owner always gets, I repeat always gets the consideration....not necessarily the decision, but always the consideration...

First point...in a showdown between a municipality and a property owner, the property owner gets the nod...period...too many factors on his side...especially in court...every thing from reasonable use residing in common law to spot zoning violations by municipalities... Second point...if you get into a pissing contest with your local officials...see point one.

Here goes....why is there an issue with the zoning board? Never should there be a zoning issue for something like this, zoning boards control use and development. The zoning and plans of development are decided in generalized meetings...unless you are a developer who are looking to get a special exception, a special use, or a complete zoning change...then talking about having to go to zoning boards is way out of bounds for building a storage shed, or whatever you call it...

Second point, most of these types of structure additions and shed building things, if they need to, go to the Zoning Board of Appeals....but the ZBA basically takes care of non-conformance with respect to setback, height restrictions...etc. Unless you are adding a third story to a house on the shoreline (and blocking views), or encroaching with your "shed" on the property setback limits, then you do not need to go there either....

In other words...forget the poster who said to get chummy...you should not need to do any of that.....you already have use rights with respect to the property...If you are R-1, R-2, Special development zone...AG-S, AG-Unlimited, etc....you pretty much have no reason to go to any board for any kind of a exception or anything else...just make sure you understand the regulations and make them work for you...based on the zoning category for your piece of property..if your interpretation is reasonable...then you get the nod....if you want to build a storage building back in the middle of 50 acres of AG-S property, and use it to store anything you want (telescopes, rakes, tractors) then you are likely within any courts interpretation.

Also, with respect to the Hardship limitations on the ZBA....you would be amazed at what clears that regulation.....if I need to add a room for a child on the way and encroach upon a setback, on an already non-conforming property height issue, and it intrudes upon a neighbors shore sight line, and his property value...chances are you will get your exception....we have seen people do this and rip their entire house down except for one wall, and rebuild in place.....pissed everyone off, but totally in accord.......amazing what those court decisions will do....

And we can also get into spot zoning issues...like having a few pictures of non-conforming developments with respect to use or appearance regulations...and how they got that way...Mr. Jones' farm and feed with the 5 story silo...built right behind the gas station, on an R-2 zone...etc etc...


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 5   Top

From: <awallacejra_tcharter.net>

In Texas, I don't think the law works that way. If a property owner with deed restrictions violates one and is not sued, that does not automatically void the deed restrictions on all the other properties subject to the same restrictions. And, of course, developer deed restrictions have nothing to do with municipal or county zoning ordinances. I'd be real careful following your approach in Texas--you could wind up demolishing your observatory under threat of a lawsuit.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 6  

From: Michael Gartland <mgartlana_ticonn.net>

If your worried about a covenant, go to court and file a notification of amendment, and sue for right of use, most judges will writ this right out, some places this can be probated. It's your right, it's your property, others would need to file protest and show just cause, most of the times the judges will rule in favor of right of use. Usually there needs to be a "Real" association to have a chance in the protest...some entity that collects dues and commons support, examples are of course are condos, co-ops and gated communities. A big pillar or sign at the entrance saying "Cozy Springs" does not do it, that means there is only an association in name and not in tenant, no shared interest in any whole or part of the community. It's the same as the street name, doesn't mean crap...

If you own your property, don't be afraid of this legal crap, it's what these lawyers want.

Someone said that previous restrictions are always in place...what a bunch of crap.....they may always be in writing, but that doesn't mean they are always in force...in my state there are deeded rights going back 300 years...farms that got broken up, previous restrictions by formal landowners when the property got divided up, combined, divided up, combined, and divided up again, sold to family members, joined with other property owners, sold off again, etc etc etc. Covenants on growing, farming, building, singing, laughing, raising goats and a whole load of other stuff.....that people didn't want competition for, or just felt silly when they deeded out the property...I have seen deed restrictions that say, no gasoline powered engines are allowed on the property (right, can't park a car in my garage), no aircraft can be landed and taken off again (I guess I can land one in my front yard and truck it out, that is ok)...

This has nothing to do with zoning and town property rules...that is another issue, as I said before usually private use issues do not intrude there, unless you have property line, or setback concerns, or height restrictions, etc.

Same answer as before...without a commons association, the deed restriction has little to do with a pissed off neighbor, if he has no association with the cause of the restriction to begin with...the deed restriction is your concern the concern of the interested deed restricting party who would be the establisher of the restriction, related party, etc...A lot happens when developments are completed and the developers go somewhere else to spread their wealth of LP city dwellers and streetlight bringing rural wantabees out to where the buffalo roam.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 7   Top

From: Mike Dodd <mdodda_tmindspring.com>

>I have been reading a lot of comments regarding this matter but can only say
>that there is someone somewhere who earns a good living out of all the
>hidden planning laws.

Generally, there are two forces at work -- the state/county/local zoning laws and individual housing subdivision homeowner's covenants.

The zoning laws specify what sort of things land may be used for in certain areas. This is usually a good thing, since nobody wants a steel mill in their backyard. Sometimes local regulators get a bit snooty if a resident asks for something out of the ordinary, but I've found many who will work with you to make sure everything is OK.

Homeowner's covenants, on the other hand, can be a real pain in the neck. They are drawn up when a developer sub-divides some land, and are intended to "protect the value of the property," thus encouraging people to buy lots in the neighborhood. Often these covenants are quite restrictive because a developer may have certain notions of how the neighborhood should look. They may prohibit outside antennas of any sort (TV? Get cable), require that every home have at least (or no more than!) "X" number of trees, require homeowner association approval of house paint colors, etc.

So, while someone might get along with their neighbors, that might not be enough to permit him/her to put up a ham radio antenna -- or an observatory, if the covenants don't like out-buildings.


Subject: Zoning, Covenants, and Deed Restrictions Concerns --part 8 of 8   Top

From: Ralph Megna <ralpha_tdigi-empire.com>

>>I have been reading a lot of comments regarding this matter but can only say
>>that there is someone somewhere who earns a good living out of all the
>>hidden planning laws.
>Generally, there are two forces at work - the state/county/local zoning
>laws and individual housing subdivision homeowner's covenants.

Mike Dodd's synopsis is pretty much on-point. I've been doing real estate development and entitlement consulting for about 20 years and have only occasionally run into governmental restrictions that were completely stupid. On the other hand, homeowner covenants and the operation of homeowner associations can easily drive someone to drink.

Like so many fields of human endeavor, zoning laws and building codes have their own internal logic which, when followed, tend to make sense and lead to positive outcomes. Where that breaks down is when they are faced with something unanticipated -- like a home observatory. I am currently helping a local astronomical society with a situation where (somewhat bizarrely) a planetarium is allowed by conditional use permit, but no mention is made of an observatory. Our solution -- using another section of the zoning code -- is the path of least resistance, but we are also going to recommend that the county amend its ordinance to be more responsive, especially in rural areas where amateur astronomy is common.

If I can be of help to others, just email me a note.


Subject: Determining SkyShed Observatory Dimensions   Top

From: Wayne Parker <wparkera_tcyg.net> Date: Sept 2005

We tell people who are considering different sizes of SkyShed to set up their equipment at the height at which they would have it set up in the Shed, in a corner of a garage or where two walls meet. If you're leaning toward a 6'X8' Shed, set up with your center being about 4 ' from one wall and 3' from another. This is the distance two of the walls would be away in the Shed.

Place a mark on the walls at about 6' 3" (this includes the wall height and our "weather protector" boards on the outside of the wall). Now take a look at what angle your scope is at to clearly see just above the lines on the wall. This is about what you'll see in the Shed. Remember that you have 6' of clearance from floor to the top of the wall where the roof slides off so make sure your scope is set at a comfortable height, but one that will allow the roof to roll off without hitting the scope when the roof rolls past it.

You'll find that yes, you do loose about 20 degrees of sky maybe more, but not 40 to the north, assuming your going to roll the roof to north as the roof is not square, but peaked so that you only loose a lot of sky right at the peak. Not that this is a problem because everything rotates through the sky and you see it pretty soon if you can't see it right away.

We build many 6'X8' SkySheds, but mostly in urban settings, or for customers with a lot of trees who don't have a clear line of sight that far down towards the horizon.

If you've got the room (and the budget) our most popular sizes are 10'X10' and 10'X12', which in most cases are the limits of most customers "no permit needed" square footage. Most counties/parishes have a 100 or 120 square foot limit before a permit is required.

In my 10'X12' SkyShed with a 10 LX200 on a 40" pier, I loose about 10 degrees of mostly useless sky (because of atmosphere and other obstructions on the horizon). That is of course unless your a "horizon hopper" and need to get right down to the horizon, for instance to view to the south. In this case I recommend a south facing fold down wall. We are including fold down wall plans in our upcoming SkyShed Plans update.

Few people will be able to actually use the fold down wall plan though since in my experience of building many SkySheds we have yet to have a customer who had a good enough southern horizon to need a southern fold down wall. Even rural customers rarely have that good a southern horizon, unless you live in the desert, on a hill, or have a body water to the south, there's generally something obstructing the view on the horizon.


Subject: Best Way of Keeping Insects out of a Closed Observatory?  Top

From: Mike Dodd <mikea_tmdodd.com>

>What is the best way of keeping insects out of observatory when it is closed?

When I built my roll-off roof observatory, I covered the roof with Ondura, a corrugated asphalt material. The manufacturer sells a shaped foam insert to close the ends of the Ondura, and drastically reduces the openings for bugs.

The peaked roof has a ridge vent, covered with a piece of Ondura intended for this purpose. To seal this, I used a heavy plastic woven mesh (think monster ScotchBrite pot scrubber!) that lets air flow, but keeps bugs out. This mesh is available at home improvement centers like Lowe's. I also used it to close holes in the gable ends of the roof.

I glued, with construction adhesive, plastic screening in the opening between the pier and the observatory floor. Nothing gets in that way! I installed screened floor vents to provide at least some air flow when the roof is closed. The screening keeps bugs out very well, although the top surface collects junk and must be cleaned periodically (take out the vent and whap it upside-down on something).

There's no hope for the gaps along the sides, where the roof "wall" overlaps the observatory wall. I made mine as narrow as possible, but didn't bother to put in any sort of weather stripping or gasket (which might be possible).

Oh yes, I also spray the outside exposed wood surfaces with Ortho-Klor termite and insect killer once a year. This lasts a month or two, and discourages many bugs, including a pesky wood-boring bumble bee that makes 3/8" holes in wood (even pressure-treated).

I have no problems with wasps, but do get a bunch of flies in the spring, and some moths now and then. They tend to die in the closed observatory, and all I have to do is sweep the floor to get rid of them.


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