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Roll-Off Roof Observatory Construction
Containing Part Numbers and Links to Help You Build Your Own

When I decided I wanted to get involved in astro-photography I soon learned that you really need a solid permanent mount for the scope. I decided to build a common shed with a roll off roof which has been done many times before within the astronomy community.

The shed will have a number of requirements, some necessary for astronomy, some necessary for me to maintain it as a shed in case it is no longer used for astronomy, and some are my own personal preferences. Overall I wanted the shed to be as solid as possible without any flexing in the floor and for it to last many many years.

I broke this project into three sections. The first was by far the most difficult and included all the digging and ground work as well as all the initial site measurements and leveling. The second phase was the actual building of the shed walls, roof, doors and installing the necessary ventilation which would make it somewhat functional for astronomy but not quite ready for astro-photography. The final phase included the wiring of electric, data, security some automation and the final the installation of the scope.

PHASE 1 - Ground Work & Base

Marked out the shed, the roof line (for drainage), center for the main pier and made sure everything was level and square.


Dug and set the four concrete footings for the shed. Dug the 4' wide, 4' deep hole for the main pier. This was a huge task that took me almost two weeks to complete. The first 18" was easy to dig loom where everything under that point was solid clay and rock which almost had to be chipped out 1/2 an inch at a time. I did not rent any equipment to save some cash but also doubt that a common earth auger could have helped anyway.


Set the base and rebar then leveled the Sonotube. The bell shaped base is a Bigfoot Systems BF36 and the Sonotube is 14" (which is recommended with a 10" pier), both of which I had to specially order from a local lumberyard.


Final preparations before mixing and pouring the 1120 lbs (1/2+ ton) of 5000psi concrete by hand which took just over 2 hours without taking a break.


Final concrete pier top plate, facing north and level. The 3/4" L-bolt assembly, technical drawing, instructions and wooden set pattern for a 10" pier where purchased by company that makes astronomy piers. Later after the L-bolts where set and the concrete had cured it was discovered that this pier company sent me the wrong wooden template (for an 8" pier and not the 10" pier). In the end I am not happy with the outcome or their lack of helping to resolve this issue. I recommend purchasing your own L-bolts from McMaster Carr which I list part numbers in my pier design.


Set a border of pressure treated 4x6's to contain a layer of rocks. Then laid down a plastic ground cover used on greenhouse floors which I purchased from LittleGreenhouse that allows water and moisture to pass but will help to block weeds from growing. Finally a layer of rocks was put down for drainage as well as help keep animals from burrowing/nesting under the shed. This was also a convenient way to get rid of a bunch of rocks I had collected while digging.


Most of the floor framing as well as the electric and data pipes to the pier are completed. I also ran the electric for a future outside 120V outlet even though it won't be used until its connected to the 120V service at the house. I wanted to look ahead and get everything done under the floor to make future cabling as easy as possible.


I choose to use pressure treated 2x8's with bolts and braces for strength and longevity. Note the double joists around the pier in the middle. This is so I can have some removable floor panels in case I ever upgrade/change the size of the pier or if the shed ever needs to be just an ordinary shed again in which case the pier can be removed and a new flat floor panel can be easily installed.


The shed floor and everything underneath it is completed. The floor boards are 3/4" pressure treated plywood. The cuts for the pier in the center boards will be completed once the metal pier is in place. At this point I can start construction on the actual shed itself.


PHASE 2 - Building the Observatory

I decided to make this observatory a little different from other roll off roof observatories. The framing is 4x4, 2ft OC instead of the more typical 2x4, 16in OC. This gave it more of a post and beam look which I liked in other similar designs I have seen. I also turned the 2x4 studs on their sides so it looked a little nicer. The shed is so strong that this change should not affect its overall strength. The walls are also taller than most observatories, but after much thought I believe it to be necessary to help block local light pollution. I also wanted the observatory to remain as much like a traditional shed as possible in case we sell the house. I did run into alot of warping wood and hope that once the weight of the roof is applied some lag bolts will put things back in line.


The pier has been built, delivered and installed! This pier was designed by myself but it was built by a fellow local astronomer Jim Brenek who has been a tool maker for much of his life. I was excited to see that the pier was perfect in every detail. Jim also made some modifications to my original design which worked out perfectly. The total cost of ALL parts including the powder coating should come out to be around $400... but labor costs to cut, drill and tap the holes as well as weld the plates together will vary depending on the machine shop.


The roof support beams and tracks are in place. I wanted to make the beams strong enough so that I could be open to various types of roof designs. I also wanted to have the option of easily removing the beams and leaving the outer skin of the shed intact. To remove the beams all I would need to do is cut the angle iron track with a Sawzall and remove four carriage bolts.

* NOTE: At this point my first child was born and contruction stopped for the winter. During this time some weathing damage was done to the exsiting structure (greying wood). With a little bit of of sanding and some primter/paint it should be fine once the project is finished.


The rafters for the roof are finished and ready for the roof panels to be installed. Because the load will only be snowfall using 2x4's should not be a problem for the small 4ft span. All of the walls are finally finished and the roof panels are secured. After much thought I decided against the traditional plywood/shingle roof to keep the overall weight down to a minimum as well as to help with heat buildup. This plastic roofing in its current configuration is rated to hold around 50lbs sqft which should be fine for my area.


The doors and locks have been installed so the observatory is finally weather proof and secure. The doors, hinges and locks are all heavy duty and are attached with carriage bolts. When the observatory is compleated this might be irrelevent because it will all be tied into the house security system as well as some of my own systems. At this point all exterior construction is finally finshed and most of the exterior has been primed and sealed for the winter.


All of the priming and painting of the exterior. The only thing left is to paint the trim which will be a light grey.



PHASE 3 - The Interior and Systems

The custom built 3/4" steal equatorial wedge was built and delived by Jim Brenek. I opted to go with a custom built wedge because the reviews of the Meade models mentioned some issues with vibrations when using stacked scopes. I also had trouble finding larger 3rd party wedges or I was not impressed with the designs.


The walls are pained and all of the electrical and data conduits are installed.


Primary lighting controls. The outlet and plug in the upper right corner are for the overhead track lights.


Scope (Not yet fully assembled)



Home Built Observatory Links and Resources:
Links to other 'Amateur Astronomical Observatories'
CloudyNights Forums (Observatory Section)

Roll-Off Roof Parts and Links:
Home Built Pier Diagram
Bigfoot Systems (Concreate Footing Forms)
LittleGreenhouse (Ground Cover Weed Barrier)
McMaster-Carr (V-Casters, anchors, Nuts and Bolts)
BatteryMINDer (12V Solar Charging Systems)

Other Noteworthy Observatories:
David Cash's Loft Observatory
Dog House Astronomy
Greiner Research Observatory
Hidden Loft Observatory
Observatoire D'Orange
Olympus Mons Observatory
The Outhouse
Pop The Top Observatory
Ptolemy's Cafe
Rancho DeLUX
Robinson Rd. Observatory
Solaris II
Star Watcher Observatory
Stoney Hills Observatory
Taconic Observatory
StarNavigator Astronomical Observatory
Woodlands Observatory