What would you do about this roof?

[TheCuddlyOctopus]

We have a mid-terraced London house with a 'London' or Butterfly roof- it looks flat-roofed from the front but actually is a 'v' shape to a central valley (it's a pain- my recommendation if looking at a house with one is-don't).

It's leaked intermittently since we moved in 5 years ago- at first around the front parapet- we had that shored up- and now along the valley. We had a temp fix done which didn't really work and now have a couple of encroaching wet patches on the bedroom ceiling so it needs doing.

We have a couple of roofers look at it, both of who come recommended. Roofer 1 said he could strip out and replace the central valley- and thought that was probably where the leak was coming from- but couldn't guarantee it and the roof was quite old anyway with lots of crumbly render etc and thought it best to do the whole thing. Quote 2300 for the roof valley work or about 9k for a new roof. Roofer 2 thought the whole roof didn't need doing and the tiles were still fine- just the central gutter and the lead flashings and a bit of render. Charge about 3.3k for this.

There are no other leaks and the half of the loft space we have access to is dry. I don't think it is leaking elsewhere, but it's hard to investigate properly because of the structure.

We're not sure what to do- I really don't want to pay for a whole new roof if we don't need one (plus we can't really afford it right now- I'm about to change jobs but have a freelance stint in between so need access to savings to smooth things through-we could at the end of the year but I don't want more damage to the bedroom). But I also don't want to throw good money after bad.

It doesn't help that DP suddenly thinks he becomes a trade expert every time someone comes to quote and goes on and on about the quotes in a way that implies he suddenly knows better and everyone is out to rip him off (and then we have a row). But we are also terrible at picking trades so feel like we need some adult guidance (it's also awful trying to get anyone to come and have a look so any roofer recs. in SE London welcome).

Any grown-ups who can help?! What should we do? The additional complicating factor is that we will remortgage later this year and if we ever stop arguing about it may get some major work done- including a part loft extension (because of the structure this can only be done to about a 3rd of the space at the back). If we got a whole new roof it would be done at the same time as this, but this doesn't impact the repair. But we might not go ahead with that either.

Sigh. Very bad at decisions!

I can't help you, but did laugh at your expert DP. I've got one of those. Thank god mine asked my BIL, a plumber, for help balancing the radiators or goodness knows what would have happened with that.

I’d try to find a third roofer and get their opinion. Then you’d (hopefully) have two against one - which should help you decide.

Pay a qualified structural engineer or surveyor to inspect & advise true problems, solution options & likely cost is only way

I would also suggest getting a third roofer to have a look, and gauge their opinion / costs. That way you will have a 2/3 ruling (hopefully).

The other suggestion would be to approach a building surveyor? They may be able to give you their professional opinion on how to solve the problem. If you found one who had experience with similar style properties, it may be a common problem with this style roof. Or speak to some others on the street, if you have friendly enough neighbours or have noticed any other properties having work done.

@wowfudge it's infuriating! He was an expert on boilers a couple of months ago, and on roof struts before that. He works in an office. With books. We don't argue about anything else but house stuff makes me want to throw him out the window.

Yes, am trying to find an elusive third roofer! A few people on the street have had theirs replaced in the last year or so and a few others had the central valley replaced so kind of splitting the difference there. They are known to be problematic though.

We had a butterfly roof with the same problem - water collecting in the central valley and leaking in. We chose to flatten half of the roof. So we now have half a pitched roof with tiles and half a flat fibreglass roof. The flat part is slightly inclined so the water funnels away from the house to a drainpipe. It was the only way to permanently solve the issue.

@cosmiccomet that's really interesting- did it raise the roof line at all? We can't raise ours above the parapet line but it sounds like an ideal solution.

No it hasn’t raised the roof line. The flat roof is approx the height that the valley was. The pitched half hasn’t been touched. The council said they don’t normally like to approve flat roofs but in this case it solved a design flaw so they permitted it.

My DH is s Structural Engineer and I know he hates valley roofs! They inevitably collect water due to the shape and if it doesn’t drain off, there are problems. Therefore any repairs are temporary if there is no fall and no effective drainage. You won’t necessarily need a Structural Engineer to tell you this but you need professional advice on the best way to solve the problem.

If it was my house, I would get plans drawn up for the loft extension and get the roof altered at the same time. If you cannot afford to complete the loft, at least look at how the roof can be amended. You could do another repair but you have a design that isn’t great for longevity.

You don’t want a completely flat roof either. If there is a fall on it, drainage is much more effective and you won’t get ponding. You want to avoid water collecting and not draining away.

Yes mine has a very slight fall. To look at it you’d think it’s flat. But it has a very slight fall to make the water drain off the edge.

It's an awful design when you think about it- all the water in one place...

Third opinion sourced for tomorrow (I hope) so hopefully we will be in a position to make a decision over the next week or so.