Flat Roofing

[jensel]

I have recently replaced my flat roof when I was removing the felt it appeared that some of the stone chippings may have been mixed with cement I think to artificially over come a level problem for drainage. I have replaced the rotten boards and employed a contractor to re-felt however I now find I have ¾ inch of water remaining on ¾ of the roof my contractor suggest adding more chipping to help disperse the water is this the best solution to the problem, he also says that water left on the flat roof is no problem is this correct.

 

[DAZB]

What you should have done is given the flat roof a slight slope by fixing firring strips to the rafters which are basically long wedge shaped lengths of timber to give it a fall either to the back or the front before it was boarded and then felted. In the circumstances adding more chippings to displace more water does not sound like too bad an idea. If at all possible you don't really want water stood on your flat roof because a few years down the line it will find a way in but with it being a new roof and if the work is of a good standard then you should get 10 years minimum from it and much longer if a brand of the new polyester flat roof felt was used.

 

[masona]

Chipping stone does two things..........

All the chipping stone do is to break down the rain as it hitting the roof into fine mist which take the pressure of the roof and also heat resistance as the bitumen have a very high flash point which make it fire resistance.The water will still have a puddle under the chipping stones which you can't see! As Dazb said should've firring strip fitted.
Just a idea maybe you can build up with bitumen where the puddle is and stone on top again but then the water go on to the next puddle

 

[sossage]

I was watching "Grand Designs" last week and the couple that were renovating their house had ze Germans over to install a totally flat, flat roof that acted like a tray until it got full up, after which the water would drain through an overflow-type arrangement.

Apparently, the layer of water acts as extra protection from the elements etc.

Mind you, they had about 6 leaks in it .....

Any thoughts ? I quite fancy the "water garden" look on my roof !!

 

[skellem]

If the water stands too long won't it go slimy and also breed mosquitos in the summer months??

 

[Scoby_Beasley]

A wildlife pond it is then

 

[skellem]

Quack Quack??? hehe!