Would you buy this house? Serious flat roof problem.

[Jonh1]

We are in the process of buying a 1960s house which has a flat roof (always said I would never buy anything with a flat roof but the area we want to be in is nearly all flat roofs – and we love the house!) Anyway, we knew it needed what we thought was just cosmetic work and we made our offer based on this but we had a homebuyer survey done which basically said the roof hasn’t been touched for about 30 years (an old couple had lived there since the 60s) and it will need replacing.

I will put in a couple of photos – as you can see there is pooling and the roof terrace at the back gets flooded when it rains.
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The damp on the ceilings is directly below the roof terrace but the surveyor didn’t pick up any damp under the main part of the roof (although he hadn’t picked up the damp under the terrace - we only noticed that after it had been raining!) The surveyor also picked up some damp in the back downstairs bathroom but didn’t suggest a cause and we can’t see any visible signs.
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There is also damp on the front and back walls caused by run-off from the roof.
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We are getting a roofer to have a look and give us a quote (we obviously want a serious reduction before we even consider continuing with the sale) but I just wanted to get some advice from anyone who has experienced similar problems. I guess the best scenario is that once the roof has been replaced the damp inside and on the outside walls will dry out and it won’t have caused any other problems. How likely is that or is the consensus that it is likely to be more serious than that? We have noticed damage to a couple of bricks at the back but we can’t see any serious damage to the bricks elsewhere.
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How likely is it that water is running into the cavity wall? What kind of damage could that cause? If the damp downstairs is also caused by the roof how serious could that be?

I know all this would probably be answered with a full structural survey but we really don’t want to spend any more money on surveys etc. as we are already seriously considering pulling out. Would really appreciate any advice or suggestions as I’m a little concerned we could be buying a money pit with problems continuing to appear years down the line.

Thanks.

Jon.

 

[kbdiy]

Personally I'd run away from that amount of dampness as you don't know how long it's been that way and what's lurking underneath. That could take some serious fixing and drying out.

 

[tony1851]

It certainly looks as though the roof need a new finish.
But once they strip the finish back, the roofer will almost certainly advise that the boarding has gone in several places, and probably that some of the joists are rotted as well.
Before you know it, you will be advised that a complete new roof is needed -
ie new joists, deckand finish, insulation, plasterboard ceiling, re-wire of light fittings etc. Building Control will also have to be involved. ££££.

 

[Xenon]

NW London ? You can see the deck has slumped under the Asphalt, so it will need a full re roof. Budget £100 m2

 

[ed110220]

It certainly looks as though the roof need a new finish.
But once they strip the finish back, the roofer will almost certainly advise that the boarding has gone in several places, and probably that some of the joists are rotted as well.
Before you know it, you will be advised that a complete new roof is needed -
ie new joists, deckand finish, insulation, plasterboard ceiling, re-wire of light fittings etc. Building Control will also have to be involved. ££££.

Is the roof deck board on timber or is it concrete? Many constructions of this rough age have flat concrete roofs.

 

[Jonh1]

Thanks all.

Pretty sure the roof is all board on timber Ed - although there is a concrete balcony just above ground level.

We are very tempted to run away - as has been said it could take some serious fixing! We do really like the place but obviously there is a limit on how much work/cost we are willing to accept.

I pretty much expect that we will need a full re-roof but I'm hoping (maybe wishfully) that there is no damage to the joists, ceilings etc.. Looks like the vendors are prepared to accept a serious discount - but obviously that just comes off the mortgage so we still need the cash. We can probably manage about 20K upfront (we already know we need a full rewire as well) but if the cost really starts to build up we are going to have to back out.

I'm also hoping there is no serious damage to the brickwork - is it likely the bricks will dry out with no problem once the roof is done? I guess we also need a timber and damp specialist as was recommended in the survey - although I'm guessing the roofer will be able to tell us whether the roof is likely to have caused any other problems. I notice a few places do free damp surveys which might at least give us an initial idea of problems?

Croydon by the way (SE London) although as far as trades people go it's pretty much London prices so we have to take that into account.

 

[Jonh1]

Thanks for all your opinions/suggestions so far but (thankfully) all in all we don't think it's as bad as we first thought! We had a roofer take a look although I'm not 100% sure with what he said.

He thinks the water coming through from the roof terrace is pretty recent and so shouldn't have caused too much damage. Basically because the house has been empty for a bit there has been no one to clear the leaves from the drains and therefore with all the rain we have had the water got high enough to come over the top. Once he cleared the leaves the water just drained away. He still thinks the boards will need replacing on the terrace though (although will need to pull up the tiles to check)

Now the main part of the roof: he jumped up and down on the roof for a while and said it was sound - other than it obviously needing re-felting. I asked about the ponding but he didn't think it was a problem as all the other houses in the block had ponding on their roofs as well. Is that a reason for it not to be a problem?! My understanding is that ponding on the roof (although not an immediate problem) drastically reduces its life span?

Looking into it a bit more apparently that style of house in the 60s often have problems with ponding as the 'falls' were badly done. Is there a way to fix that? I'm guessing somehow the gradient will need to be increased - which sounds like a big job - I'm guessing that's why he recommended we just put up with the ponding!

We are willing to spend a bit of money if it will increase the life of the roof as I guess that will be cost efficient in the long run. What are peoples' opinions of EPDM for instance?

All opinions/options/suggestions welcome!

 

[cotswoldbuilders]

Pondings not a good idea, when you have warm weather the materials are moving at different rates, that's when the felt starts splitting.

 

[Burnerman]

Unless people are blessed with x-ray vision, (and that includes surveyors) there's no knowledge of whats going on beneath that roof, but guaranteed there will be damage - there always is!
I'd budget for a complete re roof, including the boards beneath the felt and hopefully the joists will have survived.
Water coursing down the outside won't be a problem short term.
John

 

[Jonh1]

Pondings not a good idea, when you have warm weather the materials are moving at different rates, that's when the felt starts splitting.

Would redoing with epdm or similar solve that problem without all the expense of adjusting the falls (whatever that involves) - I guess ponding might not be such a problem then?

 

[Jonh1]

Unless people are blessed with x-ray vision, (and that includes surveyors) there's no knowledge of whats going on beneath that roof, but guaranteed there will be damage - there always is!
I'd budget for a complete re roof, including the boards beneath the felt and hopefully the joists will have survived.
Water coursing down the outside won't be a problem short term.
John

I did read somewhere that a good roofer can tell the condition of the boards by just walking on them - but I get your point - my problem is that if he thinks the boards are OK he might just re-felt over the top of the old felt - I've heard that this is often done - the idea being the more layers the better. I'm not convinced! I will definitely get an opinion from another roofer before we decide.

 

[Burnerman]

If the felt is laid on top of chipboard, its fairly obvious to see and feel where the problems are......the chipboard swells to twice its thickness and becomes spongy.
The quick fix is to felt over the top of it all and then run, but personally I'd want the boards lifted and renewed.....its not so good trapping the water inside! There's sure to be some decay on the joist ends too - there always is.
John

 

[cotswoldbuilders]

Id agree with John, the boards will need checking, its not good practise over felting on the unknown.

If you were going to epdm the roof, youd still have the ponding, ( although it wouldn't leak ) but the epdm needs to go down on good clean boards, we use osb3 T&G boards, so re-boarding will be needed, you should then get a 20yr warranty from an approved installer.