Flat Roof leaking - no obvious holes or blistering

[gwernybwch]

I've got a flat roof which is slightly leaking after heavy rain. I would estimate that it was *refelted about six years ago and top coated / bitumened about three years.
I've got up on the roof and had a good look and can't see any obvious holes or signs or blistering.
It has detached itself from the lead flashing a little in places.

There are places on the roof where puddles form.
Is it a case that the felt gets so saturated from the puddles that it begins to leak?
Any other possible reasons why it would leak?

* If I remember rightly it was refelted over the old felt and base boards.

Thanks in advance for any replies.

 

[Alastairreid]

Your decking looks like it has collapsed in a few areas.

 

[gwernybwch]

Thanks the reply.

Sorry for being dumb, but what is decking? Is it the sheet board below the felt?

If it has collapsed how does that result in the water getting through the felt?

 

[bobasd]

that could be a failed roof.

there's ponding.
there's very little fall visible.
some of the felt seems to have been applied in bits and pieces.
i cant see the claimed lead flashing but there's signs of the small felt upstand detaching from the house wall - can you do a couple of close ups of the upstand and the lead?

felting over original failing felt, and maybe water damaged decking boards is not the best practice.
the roof is pretty "bumpy" which suggests moisture in the felt layers.

is the fascia and guttering in good condition? can you take photos of them from three sides of the building?
check inside the main abutting wall inside the building for signs of damp.

decking is the boarding typically over the roof joists.

whats below the roof - garage - kitchen etc?
if there is visible water damage signs below can you pic & post it?

do you know if its a cold roof or a warm roof?

 

[Alastairreid]

When the boards which the felt is torched onto (the deck) gets damaged by water ingress it sags between the joists..as yours appears to have done.

 

[gwernybwch]

Thanks all for the replies.

It is hard to actually get a photo of it, but there is a about 30cm length where the edge of the flashing isn't sealed to the felt, but if you really get down and look under it, it *looks like* there is a bond there.
I'm guessing that water will always find a way in.

From what I reading there is water getting in under the felt and has damaged the boards below and is eventually seeping into the kitchen.
Sounds like it is a renewal job - rip off the old stuff, new boarding (decking) and resurface.
Maybe the facia boards and leading. Insulation might need replacing. Might be damage to the joists as well

This roof is the kitchen extension and joins the living room. There has been a damp corner where they joined for several years. Each builder I've asked about it as told me that it was due to the disused chimney. So over the years I have had the chimney repointed, then capped and finally removed but the damp never really went away.
Think that I have hopefully now found the reason for that problem as well

 

[oldbutnotdead]

I can't actually see any true flashing, just a very small upstand. You've got a crack in the render on the left in pic 1, that might not be helping things either
If the upstand is actually a cover flashing (so the felt continues up the wall behind it) there'd be no need to seal it to the roof. Throwing Acrypol or similar at it might give you a short term fix, long term it needs redoing properly

 

[Alastairreid]

And you can upgrade to a warm roof if renewing.
Insulation above joists

 

[^woody^]

If there are no holes then the only way in is via the laps. Coat the laps with Acrypol.

 

[datarebal]

take a look around the roof after its rained. put a bit of pressure on the laps with your foot.
If its leaking you should see bubbles or even water jet out.

to be honest though it looks in pretty poor shape

 

[gwernybwch]

Thanks all for continued replies, it is greatly appreciated.

I've attached a couple of photos on the flashing. It was coming away worse than I thought. As a quick fix, I have tried to seal it with gutter sealant today.

@oldbutnotdead You say that there isn't true flashing but only a small upstand flashing. Do you think that when I have the job redone that I should also specify that new (wider) flashing needs to be fitted?

There are a few hairline / settlement cracks in the render of the house. I have tapped them a few times over the years and they have never sounded hollow, but I guess that they aren't helping things.

@datarebal I did have a bit of a careful step around on the roof, but there wasn't anything noticeable. Having said that the amount of water that has got into the kitchen would only be about a teacup, so I guess the roof is at the early stages of failure.

@Alastairreid I'm not sure that I will be able to upgrade to a warm roof (adding a new layer of joists above?) as the top of the flat roof is almost touching the window sill of the back bedroom as it is.

 

[oldbutnotdead]

If the roof had some fall then the poor weathering wouldn't be such a problem...you shouldn't have to specify adequate weathering, a competent builder should budget for a standard upstand/cover flashing as a matter of course. Generally whatever the roof covering is should be continued up the wall for 100mm then a cover flashing (lead) chased into the brickwork on top of it. Best using a fillet with felt, the 90 degree angle from roof to floor is an obvious failure point. What's the inside ceiling height like at the moment- strictly speaking if you renew the roof cover you have to consider upgrading insulation to current standards, it'll be worth it anyway if there's no insulation in there at the moment

 

[foxhole]

Probably getting rain thru the blown render then running thru brickwork into house .

 

[gwernybwch]

So as an update on this. The roof continued to leak to the point where I couldn't wait for the total kitchen renovation planned for the summer, so I got a roofer in to re-do the flat roof.
I'm not able to be at the house when he does the job, but sends me pictures as it is on-going.

He sends me a picture of them putting on what looks to be some kind of rubber under-layer (followed by new 'decking' and then the top rubber layer).

Looked to be a good job, I paid him and he went along his merry way.

Now I come to do the kitchen renovation, rip down the internal ceiling(s) and lo and behold, the old (water damaged) decking hasn't been removed and the rubber under-layer is visible.

Obviously it isn't a top job, but is it something that I ought to be worried about?

Thanks in advance for any replies.

 

[ted456]

Bad jobhes taking the pi.
roof should have been turnrd into a warm roof but cant unless the old OSB is stripped.
roof should have been stripped down to joists and tapered firring pieces fixed but hes not fixed firrings because its not been stripped which means you still have no falls.
no angle fillets have been fixed at house abutment.
EPDM should run up the angle fillets and have a 150mm upstand with cover flashing.

if you think its worth it can you show any flashings, edgings or trims if he installed them?
and pics of fascias?