renewing/replacing felt flat roof

[Steve York]

I have a felt 'flat' roof on an extension. It does not leak but is nearly

20 years old and I'd like to ensure that it remains waterproof. I like the sound of adding an EPDM (rubber) membrane on top of the roof to keep it waterproof but am finding it difficult to choose between the three methods of fixing the membrane to the roof surface. The first - and easiest method - involves covering the membrane with 20mm round ballast at the rate of 50kg per square metre. With a 20sqm roof that will add 1000kg to the roof! I'm not sure that's a good idea. The second method involves glueing the membrane to the existing roof surface (felt covered with solar reflective paint) but I'm not entirely convinced how well this would work on what is not an entirely even surface. The third method involves screwing plates into the roof joists (a bit hit and miss I bet) to hold down an under membrane and then glueing the top membrane to the one beneath it. Has anyone any experience of these three methods and what would you recommend? Thanks.

[Bookworm]

Have you considered a Moisture Trigger Polyurathene Coating over the felt. I used to sell this very sucessfully some years ago. In fact the felt roofs of the NEC are coated with this material. Simple to apply, with roller or brush. Solar reflective with excellent adhesion to firmly adhered felt. It breathes so no moisture trap which you can get with EDPM Rubber Membranes, (they dont breathe).

I do not represent any company that sells it now. Decothane by Liquid Plastics Ltd is one excellent one and another is made by Tor Coatings Ltd of County Durham.