This unique design of roll-off roof observatory, is easy to make, very compact and makes use of all the available space.

I spent months searching the internet for roll-off roof observatory designs and images but none were quite what I was looking for, so inspired by others I set about designing my own observatory.

The main criteria were:

  1. Easy to build – my time is precious 
  2. Cost effective – I had a limited budget
  3. Include a warm room
  4. Make effective use of the space
  5. Not look out of place in a typical suburban garden
  6. Be quick and easy to use – I’d previously had a dome and never really liked it.

I have been a member of the Crayford Manor House Astronomical Society for 25 years many members were helpful with ideas and Steve, recently retired, helped with the construction, the observatory design is named after the society, and I believe it to be unique.

Overview of observatory

Opening the Observatory

The top 1/3rd of the observatory, slides over the smaller warm room, both ‘rooms’ were made from standard garden sheds.



The warm room

The warm room is a standard 6′ x 6′ double door (barn door) garden shed, constructed in panels, the end panels came in two pieces allowing a single door to be fitted to each end, without any modification. The door into the warm room was converted from a hinged door to a sliding door.

Despite the shed being top of the makers range it was not that sturdy, so after fitting insulation to the walls and roof, the inside was lined with 12mm ply, and this transformed the rigidity of the shed. 

Simon's Crayford Type Observatory Warm Room

The warm room is fitted with mains electricity, LED light strips, carpet and decoration, it feels like a study rather than a shed, the desk, has an old 1960’s moon map from National geographic, this was sprayed with multiple costs of lacquer and has proved to be very robust. I heat the warm room with a small fan heater, it takes about a minute to go from freezing to ‘cosy’ I then normally turn the fan off and let the warm room slowly cool down, which takes a couple of hours.

The Observatory Roof

This sort of roof comes with four design challenges.

  1. How to keep the roof ridged
  2. How to keep the roof secure
  3. How to prevent the roof being lifted off by the wind.
  4. How to manage water from the roof gutters

Roof Rigidity

The design of the roof, with the sides attached is not naturally stable, so additional support was added to increase rigidity, and this seems to be working well, the Observatory is a couple of years old and I’ve not experienced any problems yet.

Simon's Crayford Type Observatory Roof strengthening detail

Roof Security

The roof automatically locks in place when closed using a standard ‘Yale type’ door latch. In the video below you can also see the storm fasteners that prevent the roof from lifting off and some additional strengthening for the sides of the roof. 

Simon's Crayford Type Observatory

Rain Management.

Rain from the roof, falls into gutters and a down pipe, which transfer the water to ‘hoppers’, made from standard guttering parts, to the downpipes fixed to the lower walls of the observatory.

Simon's Crayford Type Observatory, guttering detail


The Observatory

The observatory is made from an 8′ x 8′ shed, I had this reduced in size to 7′ x 7′, by doing this the angle of the roof could be made the same as for the warm room. The additional wood used as a base for the one inch angle iron rails lifted the roof enough to allow the clearance necessary for the observatory roof to slide over the warm room roof. 

The observatory walls were lined in 12mm ply to increase rigidity. finally the hatch is secured in place with a ‘Yale type’ door latch so that simply closing the hatch locks it in place. Overall I’m very happy with how it turned out.