Ponding on flat roof

[Glasgow]

We have been in our house for 3 years. We can walk out from one room on to the flat roof of an extension (though we seldom do as we are not sure about weight bearing ability). When it rains, a pool of water forms - this pool has been getting bigger and bigger as time passes and I am concerned that ultimately, a leak will start and cause damage to the extension ceiling.

Is there a way I can repair this cheaply? Would it be practical to use some sort of strong polythene sheeting (sloped) pinned to timber or something?

Thanks in advance

 

[Gees]

I am not a builder
If the pool is getting bigger the roof MUST be getting lower in the middle.
Is there no signs of this on the inside?
When the roof was put on there should have been a slight drop towards the guttering so the water would run off properly. Did the builder supply his own hay ( for the horses )

 

[masona]

Some of these flat roof have been fitted with chipboard instead of plywood.The problem with chipboard if you have no air cross flow then the chipboard will get condensation and start to bend where'er plywood won't and walking on it will worsen it & another possible reason is the ceiling joists are not 400mm centre.There's no way you can repairs this cheaply other than to put more chipping stones on top which won't really solves the problem long term.It will be cheaper in the long run to rip it up and put firring strip on top of ceiling joists for your rain fall then plywood or better still put a pitch roof on it which will need planning permission.

 

[Glasgow]

Thank you both for the input. I didn't have the pleasure of meeting the builder or checking out the condition of his spurs & stetson as we inherited the extension when we bought the house. There is no sign of water inside - yet. It would not be practical to put on a pitched roof as our lounge overlooks it.

All very depressing.

 

[masona]

Another thought.

If the felt is okay then maybe you can fill the pond area with hot bitumen + chipping on top.This would be the cheapest way.The only problem with this is you might find another puddle somewhere else!

 

[Glasgow]

Things are looking up! Thanks. There is currently no chipping on the roof - what purpose does it serve? Is there any danger that the weight of the additional bitumen could cause a problem itself?

 

[masona]

No danger at all providing nobody's is underneath when pouring as hot bitumen need to be 180 C for melting on to it.

Also have a look at this from previous post.

 

[Glasgow]

OK and thank you