I have recently changed my hand made astro dome for a Sirius labs 2.3 metre astro dome. It sits on a 2.5 metre astrolab that due to my lack of foresight has a flat roof which works brilliantly as a shallow water basin!
So of course it has a small leak which in accordance with Murphy's law sits directly over all my PC and monitors (which thankfully were wrapped away in plastic)
The Sirius Observatories dome sits on a 10cm high, 2.3 metre diameter mounting ring. This mounting ring sits on a circular wooden frame in the roof of the square astrolab. I wrapped the join with the roof in 10cm wide, 1cm thick foam tape running tree times all around the join and taped solidly in (not shown in pictures below) . The roof is 5 mm fibrous cement sheet roof nailed to the wooden frame. The fibrous cement is covered with clear polycarbonate and siliconed in, and bitumen painted and again covered in plastic ground sheet... and the sucker still leaks in exactly the wrong place!
So I would like to build a waterproof membrane from say 8cm up the 10cm high dome Mounting ring and shape it so it slope down to the edge of the square astrolab. The edges of the square astrolab lie between 8cm (at the mid point of each side of the square) to 25 cm at the furthest (along) the diagonal on the corners of the square astrolab.
Can folks suggest the best way / material to economically and sensibly waterproof this sucker to ensure rain water flows off the roof?
I could potentially do any of:
- Buy a ground sheet - cut a 2.3 metre diameter hole in it - throw it over the dome and tape it to the edges of the square astro lab (very, cheap, dirty and probably only a temporary fix)
- Pack from the mounting ring to the edges of the square with foam, cardboard or plaster, shape it slopes so water runs off and waterproof this somehow
- Shape it as per the above then fibreglass it (but I am pretty bad when it comes to fibre glassing)
Appreciate any suggestions folks can give me! Pictures of the problem child follow