flat roof (car port) repair

[Sam]

Hi,

We have got a flat roof car port. I understand these things only last ten years. It's beginning to leak in places and I've fixed the leaks when they appear. However if you walk on the roof, there are odd patches where it is not firm under foot, so you move along quickly! I presume this is where water has got through the felt and rotted the wood?

I think next spring it might be a good idea to tear off the felt and replace the wood underneath.

What I was thinking is rather than replace it with another flat roof, perhaps fit a batten to the wall of the house and run those sheets of corrugated plastic to give a sloped roof. Can you see any problems with this?

Would you bother putting wood over the joists? There's no need and it would block any light coming through the plastic but OTOH if you ever need to walk on the roof to decorate outside you would be able to, or possibly it could be used for storage in the narrow space between the wood and plastic. Or that space could be insulated, etc.

TIA.

[Andy Burns]

Depends whether you (or your neighbours) like to sleep when it's raining.

[Mary Fisher]

Ours is twinwall polycarbonate, not cheap but far better looking and durable than corrugated plastic. Our neighbour was happy to have it extended to his house wall and share the cost. It's supported on a framework of square tube steel and is elegant, people comment on how good it looks.

It also performs well. Spouse goes up once a year to hose it down to get rid of algae and bird nest debris (from the eaves). He made two crawl boards with old carpet on the underside to protect the plastic. When we and the neighbour (later) had new gutters it was strong enough to place ladders over the supporting framework.

The drives are very light and dry, it's an ideal solution. Neighbour grows tomatoes in his drive now. Spouse uses it as an extension to his workshop. Also, it afforded some extra insulation to the houses.

Mary.

[Dave Plowman (News)]

Only if badly made using crap materials. In which case they can fail even before this. A common problem is not enough slope on the roof so water lies in puddles. And poor quality 'felt'.

[robgraham]

I suspect that 10 years ago it may well have been made with felt over tar coated chipboard - seemed very convenient at the time and easy to work with but .... and of course you know what the 'buts' are with chipboard and water!!

Certainly my experience now shows this was a bad idea even with a reasonable fall!! If in fact the felt is all ready leaking and this chipboard material was used, I'll warn you that you will be lucky if you get it through the winter. I know that doesn't help you with what to replace it with but be prepared for either replacing it before the spring or for some sort of emergency repair.

Rob

[Dave Plowman (News)]

Yes - the chipboard *will* sag with moisture getting at it from the underside. Then puddles form. The result is final.