Flat roof

[Zehroni]

Dear All,

I have noticed that the flat roof at the rear extension of my house is sagging (see picture). What is the best and most cost-effective way to remedy this issue?

Is there a material that I can pour into the low spot to fill the gap and make the roof level so that water can drain away to the sides?

 

[danfre]

Probably been leaking for a while and ruined the timber below the felt

 

[stevie888]

The answer you don't want is no. The deck is shot and needs replacing. Since you are replacing a large part of and existing t hermal element you need to bring the insulation up to code too.

 

[Zehroni]

Probably been leaking for a while and ruined the timber below the felt

There are no signs of dampness on the ceiling of the extension.

 

[Zehroni]

What would be the rough estimated cost of replacing the flat roof, including insulation? It is 3.48 m × 2.64 m = 9.2 square metres.

 

[^woody^]

That felt looks to be in fair condition. However the deck is rotten.

If there are no leaks, then that felt has either been fitted to that defective deck, or you've got poor ventilation and timber rot.

The felt may well have many more years life left, but there is risk of a sudden failure if the support worsens. And if it is rot, it would need urgent action as the joists would be at risk - and any repair would need to deal with the cause too.