Setting up the observatory – roll-off roof and walls (part 2)

In a previous post, I constructed the wooden frame for my upcoming astronomical observatory.

It is now time for the next part, the walls and most importantly the roll-off roof. As usual, I built them using DIY materials. The entire process took 3 days.

Materials

2.5L protective wood paint (primer and varnish) for the walls and wooden roof support structure.

Walls:

5x OSB boards 2500x1250mm and 15mm in width (
- The boards will be cut as follows:
  - 3 boards in 3 pieces of2000x1250mm with 3 pieces of 500×1250 left out. These are used for the lower half of the structure placed horizontally on 3 sides except for the one containing the entrance.
  - 1 board in 2 pieces 2000x620mm with a piece of 500x1250mm left out. These will be used for the upper half of the structure placed horizontally on 3 sides except for the one containing the entrance.
  - 1 board in 1 piece of 1870x1250mm placed vertically on the side containing the entrance. The entrance will have a 670mm opening (with an additional of 40+80=120mm from the wooden posts) where the door will be constructed. A piece of 630x1250mm remains and will be used to partially cover the upper half of the remaining side (the other 2 were covered by using the board cut previously). 10mm will have to be cut from the smaller edge obtaining a piece of 620x1250mm placed horizontally. To cover the remaining area (630x750mm) we will use material from the 4 500x1250mm pieces left unused. 2 pieces will be used. One will be cut with a dimension of 500x750mm and the second with a dimension of 120x750mm. They will be placed horizontally one over the other forming a piece of 620x750mm.
100x wood screws2.5cm and 4cm long

From the 5 initial OSB boards, we will be left with 3 unused pieces, 2 of 500x1250mm and 1 of 380x1250mm. These will be used for the entrance door that will have a surface of 790x2000mm from which the actual entrance will have 670x1920mm. I will cover the door in another post.

Roof:

2x metal roof tiles of 1240x2240mm (or similar)
20x screws for metal roof tiles (I decided to replace some with longer wood screws for better grip)
9x sawn timber 4000x100x22mm. Each piece will be cut in half obtaining 18x 2000x100x22mm pieces
3x 3000mm long galvanized steel gate track. 1 piece will be cut in half obtaining 2 4.5m long tracks. A bit longer than the 4m observatory to allow 0.25cm on each side of excess for the water to drain safely away from the structure.
6x gate wheels, 3 on each side
4x end stops for the gate wheels for each end of the two tracks
12x clamps for the steel tracks, 6 for each track
24x 10cm long screws for fixing the clamps (2 for each)
2x steel carabiners and 4x wood screw threads

Roof assembly

I found the roll-off roof to be the most challenging part of the entire structure, surpassing even the mount pier.

The roof frame

The wood frame supports the metallic roof and holds the wheels that slide on the door rails. I used 7 out of the 18 2m long timber pieces.

The wheels (bottom), stopper (middle), and rail clamp (top) I used for my roll-off roof.

Installing the rails

On each side, I installed 4.5m rails each made of 2 pieces (1x 3m and 1x 1.5m) held together by a rail clamp. The clamps were fixed by using 2 long screws for each. I could have gone without the clamps by drilling holes in the rails and fixing them directly with long screws on the wooden posts but I came up with the idea after installing them.

The order of installation was crucial. I first installed the stoppers at 30cm from each end of the rails. For that, I needed to drill 2 holes on each end to fix them using the screws provided. Then I inserted the rail through 6 clamps and placed it on the top 4m long horizontal wooden post making sure that 25cm of the rails on each side extend beyond the post. Once I fixed the clamps using long screws I placed the second rail on the other 4m wooden post (without fixing it in place) and placed the frame on both. I then slid the frame on the rails making sure they remain parallel by adjusting the second rail accordingly. Once I was satisfied that the rails are parallel I fixed the second one with the long screws as well.

The rails are installed on top of the wooden frame. Not all clamps are installed in this image. (just 3 on each side). The second clamp from the right joints the 3m and 1.5m rail pieces together.

A view from the above one of the rails. A clamp, a stopper, and 3 wheels are visible. You notice that the rail is not aligned with the wooden frame. The reason is due to slight errors in positioning the vertical posts of the wooden structure. Even a few centimeters off leads to misalignments. However, as long as the rail can be safely installed on the frame this should not pose a problem.

Screws holding the clamp. You can also see the stopper fixed using the 2 visible screws between the rail and the wooden post. The screw from one of the wheels is also visible on the left on the rail.

The roof frame on the rails. You can see the screws of the wheels. Each underside of the frame located over the rail was cut in a slope to enable it to easily slide over the clamps (as you can notice the clamps are slightly above the rails hindering the movement of the wooden frame).

Once the frame was fixed, I stacked 4 2m timber pieces on the sides (1 on one side and 3 on the other) to provide an inclination for the roof and then I connected the parts with another 5 2m timber pieces over the initial 5 horizontal ones. I was left with 2 2m long timber pieces.

Since the roof is roll-off I needed to secure its grip by using 2 wood screw threads attached on each side, one on the vertical wood post and another on the wooden roof frame. I then used 2 steel carabiners to connect the threads

Lastly, I placed the 2 metallic roof parts on the frame.

Wall assembly

I left this one for last as it was the easy part. Once all parts were cut using a circular saw according to the required dimensions (see above) all I did was to fix them using the wooden screws and a screwdriver.

Fixing the OSB boards. The uncut board was first placed and then measured for cutting. While the provided dimensions are theoretical I found it best to take the exact measurements before cutting. Small variations are present from the installation of the wooden frame. You can notice that the mid-horizontal wooden post is placed at the right height to fix both the upper and lower parts of the walls.

After fixing the OSB boards I proceeded with applying the protective wood paint coat and fixing the joints including the gap between the floor and the OSB boards with UV and water-resistant universal silicone.

The end result

The building except for the door was now finished. It looked excellent considering that it was the first time I built something this complex.

The observatory with roll-off roof and walls.

And here is a video I made of its basic components and demonstrating its functionality:

I am happy to provide consultancy services (for a fee) for people interested in building their own DIY observatory. I can advise on materials, and construction, and provide plans (my own or custom-made).

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