Flat roof leak help please

[Dan Vittori]

Hi all

Looking for some advice. The front garage in our house was converted to a bedroom about 10 years ago. The flat roof on the room was presumably done at the same time with felt roofing and grits topping. A leak has now started in the corner where the rain water from the main roof lands on flat roof. I have checked the flat roof today and their is a wide crack in the felt at the corner with the vertical face. In general the grit has been lost all along the edges with many cracks and couple of blisters. The rest of the roof appears to be in good condition. Attached are some photos showing failed corner and general condition.


Can someone please recommend a quick good repair technique for the already failed corner(first two photos). Also, for the long term, is the roof can be generally repaired to give a few years life or I need to start thinking about replacing it.

Best regards.

 

[vinn]

As a DIY'er you would be making a big ask to try DIY repairs to fix that roof.
It looks like small codge repairs have been tried in the past.

There's a possibility that some specialist flat roofer would attempt local repairs but probably wouldn't give a guarantee.
There's also the possibility that there is hidden damage in the roof itself.

If we were asked to give an opinion on such a roof we would only go for a complete strip & renew to modern standards.

 

[Elastomeric]

It's easily repairable. The cracking is on the exposed bitumen where they have mopped the drips up.

Get a tin of Acropol and follow instructions.

 

[Nige F]

Also put a short length of gutter under the rainwater pipe shoe to take the main roof water away from the leaking area.

 

[catlad]

It will probably stop leaking if you move the down pipe to a better location.

 

[vinn]

Moving the down pipe will help - but it wont stop the leaking.
Moving the down pipe might call for re-arranging the main house gutter falls.

Using a short length of gutter will simply divert the problem to another position.

Acrypol will work as a temporary measure on the exposed surfaces but its possible that there are cracks and blisters under the stone.

Blisters have been reported by the OP, & swellings can be seen on both sides of the roof - in other words, moisture has penetrated the roof in various places, & water damage to the deck is a possibility.

Acrypol will do nothing for established blistering.

Quite how "easily repairable" the job would be if you had to traipse back & forth doing "easily repairable" callbacks for the next few winters I wouldn't like to chance.

 

[Elastomeric]

If it's a blister, it's air. If it can keep in air, it can hold out water. He's a diy'er who wants a simple fix, for a roof that is, in the main, fine.

Over egging the pudding doesn't help. Does it?

 

[Nige F]

What about the cracks ? And the diverted water from the downpipe, and the swellings.

 

[datarebal]

I would re route the down pipe too, and as short term DIY fix Acrypol or the like. then save up for a new flat roof..

 

[vinn]

Blisters are typically water vapour - water vapour is a gas.

Fragile blisters will often allow moisture to penetrate the intact bubble.

 

[vinn]

What does "BOB" mean?

 

[JohnD]

it's a feminist term.

battery operated boyfriend.

 

[Nige F]

Barrel of Bitumen

 

[Dan Vittori]

Thanks all for your prompt responses. Much appreciated.

I am of the view that there is some life left in the roof. Have done some google search and thinking of using Isoflex liquid rubber product, 2 coats. Bit costly but Online reviews suggest this product last for years. I can either do the edge strips and cracked areas only or remove the stones and do the whole roof. Not sure if I need to put back stones to extend the life of this product. Any advice on use of this product or additional treatment needs will be very helpful.

For the down pipe, I can either redirect on side away from roof in public area as it is end terrace house or can extend it across the roof to drop in the gutter along the other edge of the flat roof (photo 6). Only concern is if water will splash out of gutter in heavy rains.

Best regards.

 

[Nige F]

Just do the edge strips and cracks. The downpipe just needs a short piece so that the volume/force of the water is spread on the roof. The stones are just a solar reflective layer(cheap+cheerful) Don't tread on the blisters, and keep off it all as much as possible.