Hi,
My flat roof (over carport) needs replacing. I know I need to use 18mm plywood and in another thread someone recommended to use aluminium primer to seal the edges. Would you also paint top and bottom with this; is it better than bitumen paint, and if so, why?
If you were applying felt with a bituminous adhesive, is it necessary to paint the wood with bitumen paint first or would this be duplication? IE is the bitumen in the adhesive sufficient to waterproof the wood?
I see that toolstation also sell a bitumen primer, so how many layers of bitumen are you supposed to use: primer, paint, and adhesive?
Regarding felt, I know not to use cheap shed felt, but I see that the sheds sell top coat and undercoats. Am I supposed to lay two layers: one undercoat with an overcoat on top? Does anywhere else sell them cheaper than the sheds?
Is it worth painting over the felt with another layer of bitumen paint?
Is there a slight slope on a flat roof? The current one seems to have small wedges above the joists to lift the one edge, not that they seem to have worked!
Finally, I was wondering about replacing the flat roof with a polycarbonate sheet or something similar. However, the flat roof is useful to stand on to repair the guttering, paint the fascias, etc. I wondered whether to line the joists with wood and then fit the plastic on top of this, so that if we ever needed access we could stand on the wood. In this case, would you just paint the wood; after all it would seem an unnecessary expense to felt it?
Thanks, Fred.