Should roofs ever have pools of water on them?

psd99

psd99

psd99

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Hi, I got a fibreglass roof which has spots of pools of water sitting on there (happens due to the rain)

I thought roofs should not have still water on them, as it can cause damage in the long run.

is that normal to have pools of water? If not what needs to be done to get the water trickling along?
 
Neighbours flat roof extension has a small pool of water. I would have thought they'd have a slight angle allow it to run off.
 
You're right they should do, but a small puddle that quickly goes away isn't the end of the world for the short term. Problem comes when the weight of water causes it to sag and bigger puddle forms and etc etc. You can tell those ones as they tend to have a quasi-permanent puddle on them.
 
If the water is a small puddle that goes after a day or so I wouldn’t worry about it.
Flat roofs are often designed to have a fall of 1:40 so they get built with a fall of 1:80.
 
the problem with the modern fibre glass resin roofs is that some installers try and use a self-levelling poured approach so install a flat deck to stop it all running to one side. It results in insufficient falls. It's a classic case of well-intentioned but poorly executed.
 
ik9000 said:
the problem with the modern fibre glass resin roofs is that some installers try and use a self-levelling poured approach so install a flat deck to stop it all running to one side. It results in insufficient falls. It's a classic case of well-intentioned but poorly executed.
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I’m a surveyor and see it all the time. I won’t live in a property with a flat roof. Roofs aren’t meant to be flat no matter what people will tell you. They fail significantly faster than their pitched counterparts no matter what you do.
 
How old is the roof?
EPDM roofs (as an example) normally have 20-odd year warranties (although how well served they are is not my expertise) it may be that the roofer or the manufacturer offers a warranty on the product so if there were any defect It would need to be sorted by the people that put it up.
 
Whats the best way to fit one of those new rubber flat roofs? Just watched a house opposite me have one laid on top of the old felt roof.

I'm thinking that the old felt roof could be holding damp in if it has been leaking and therefore you'd be trapping all that in by laying the new rubber roof on top. As it's a rental that is currently unoccupied, I can't see the landlord just had it done for cosmetic reasons.
 
That sounds like lazy workmen and a tenant worried about temporary case with no-roof finish in place. You might get away with it but I wouldn't let them do it like that on my house
 
Yeah just thought it was weird. If the old felt roof was perished and knackered i'd want it removed not hidden under the new roof.
 
ok so the puddles usually disappear after a day or two, but there are two patches on the roof that are quite dark now and that's where water will sit. Why does that happen?

The roof is fairly recent, installed in 2016.
 
Also I have another flat roof on my garage that has been there since the 90's

one of those felt roofs I think, funnily enough that never has puddles on it.
 
psd99 said:
ok so the puddles usually disappear after a day or two, but there are two patches on the roof that are quite dark now and that's where water will sit. Why does that happen?

The roof is fairly recent, installed in 2016.
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It's where all the muck accumulates. Try evaporating water in the bath regularly without wiping it down. Where does the scum collect?
 
psd99 said:
Also I have another flat roof on my garage that has been there since the 90's

one of those felt roofs I think, funnily enough that never has puddles on it.
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your flat roof won't be flat. it will have enough slope (falls) on it to stop the water accumulating.
 
Used to work for a property developer
He had a flat fibreglass roof fitted
To a property
I told him not to pay for it until I hose pipe
Tested it
Needless to say I wasn't popular with the company that fitted it
But it pooled badly in several places so my boss stuck to his guns and wouldn't pay until it was corrected
Just poor or lazy workmanship in my opinion and of course usually they have
Been paid before it rains and you see
If it's going to pool or not
And they won't do anything about it then
 
There are thousands of flat roofs especially on older properties where over the years they had extensions built on to accommodate bathrooms and indoor toilets that didn't exist back then the property was built. We don't all live in new built estates.

My bathroom has a flat roof and I suspect it was built on sometime in the late 60s or early 70s.
 
Correct and also a number of Victorian properties have flat roofs to the closest wing though sometimes that is due to alteration. What's your point though? We all know flat roofs exist?
 
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