On Fri, 17 Jul 2015 20:35:50 +0100, RayL12
wrote:


I have some/little experience with felted flat roofs.

Neither do I know to what extent the board/decking is drooping but,
dependent upon age, it does suggest they are a chipboard form. If so,
you are right to avoid putting any extra weight on the surface; even to
the extent of chancing walking on the supporting rafters. Though, you
could use a couple of planks across the rafting.

If the droop is pronounced, any water collection will accelerate the
process due to the weight; discounting the effects of any frost. In
which case, paint will not prevent further drooping and any subsequent
tearing.

The decking is, more likely, to be subject to the changes in internal
atmosphere rather than the external.

Should you decide upon having the roof replaced consider marine ply else
if applicable, converted to a slate/tile roof.



...Ray.
Thank you,
you are quite right, it is chipboard. At least this
was what was used on the original roof some thirty years back and I
would suspect that although the top surface is a different material
now, the chipboard approach is the same.

From my limited experience with flat roofs I suppose I knew that the
act of merely painting it would not be of any truly significant
benefit, I really wanted a few people to reply saying what a marvelous
solution it was, second in effect only to a brand new roof :-(

I think I will stick the paint on for now, if physical damage to the
sunken bits occurs then maybe I can get a local roofer to repair the
damage and replace the individual board[s] that droop. Since starting
my enquiries it seems that this is an option adopted by some people in
the locality.

Most of the roof seems good

The roof was laid with virtually no drop at all, I suspect this does
not help the situation.

The paint may help preserve the "good bits" and will provide a
"feelgood factor" in the respect that I am doing something instead of
just overseeing the deterioration passively.

I will give the Lidl sprayer a try and spray a meter square at a time
to limit the risk from static/ fire, although I suppose the sprayers
innards may dissolve rapidly?

Anyway thanks Ray, I'm very grateful for your advice, now if only it
were a little more positive :-)

Many thanks!!

AB