Leaky roof, please advise.

[illogitech]

Hi there.

We had a ground floor infill extension done a while back between two parts of the house where there was an alley. You can see the extension in picture one, it's the roof on the left. The roof on the right is 15 years old and is over a downstairs bathroom and a utility room.

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Unfortunately water is coming into the bathroom below when it rains heavily. This room also has a ceiling mounted extractor which is piped into the roof vent (closest one to camera in picture 2). Rain falls through here too and theres a constant draught that comes down through here into the downstairs bathroom. Oddly the roof does not leak in the extension nor does it leak in the utility room.

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I've had three roofers around to take a look but have been given conflicting advice. Please could somebody advise me on what the problem could be and what I should do to fix it as I don't want to splash the cash if I don't need to, at the same time I don't want to get a bodge done.

Apologies for the poor pics, I hope they're clear enough.

Thanks!

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[catlad]

The pictures are not clear enough for me to give you much of a reply, but it looks a poor design to me.

 

[xdave]

If it only leaks in heavy rain then it sounds as if the water is overshooting the valley and coming under the tiles on the opposite roof at the joints, e.g. between the bottom and second courses. It is also possible that the volume is overflowing the valley and backing up under the bottom course of tiles. To diagnose you need to look out of the roof windows during heavy rain and check. If it is safe to do so you could climb onto the roof, but take care as wet roofs are dangerous to walk on.

As catlad said it does look rather a badly designed roof - this problem would have been foreseeable at the design stage. Installing a vertical barrier down the middle of the valley would prevent any overshoot, but it could equally cause additional problems with water ingress if the original roofs were not detailed properly along the valley.

What advice have the people you've had round to view the roof given?

 

[joe-90]

At a guess I'd say that rather flat lead gully can't handle the water volume off two roofs and is spilling over.

 

[illogitech]

Thanks for the replies.

The pics were the best I could do I'm afraid (self timer and a tripod with an outstretched arm.. haven't got a ladder!).

The first two guys who saw the roof said it was badly done; the tiles on the roof on the right were the wrong ones for the pitch of the roof and that I need Wessex tiles. They said water was being blown in from the gully and finding its way in between the lower tiles. Also my flashing needs fixing and my lead gully needs changing to fibreglass (well the second roofer said fibreglass and the first said rubber).

The third person said the first two were wrong and trying to con me (his words) and that I have broken tiles and bad flashing, that's all.

The difference in quotes was a fair bit.

I hadn't bought up the issue with the draught through the extractor fan (kept slipping my mind) - would there be anything to fix that too?

 

[cotswoldbuilders]

Is there any steps in the valley, or is it one piece of lead.

If you have a stepped valley the risers should be minimum 50mm, with the lower steps bossed and dressed up over the following step, next step overlaps.

If its in one piece, think about a different material, ie epdm in one piece and take it up the roof more.

The pitch on the r/h looks a bit shallow.

 

[illogitech]

It doesn't look it has any risers - it may be a few pieces of lead stuck together without steps.. or it might be one piece, I'm not sure. Here's a picture looking down the valley:

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The pitch of the lower row of tiles on the r/h roof are almost flat. Would that cause water ingress?

 

[cotswoldbuilders]

If the leads in one piece, over time with movement its going to split.
If its lapped and sealed, it wont last long.
Id suggest raising the roof pitch, the bottom tiles are almost flat.
Also a wider valley would be good for access and maintanance, which is why I suggested epdm, as with the steps required for lead, plus the heights required, you wouldnt get past the roof windows.
As the others have said, its a poorly designed roof.

 

[illogitech]

Thanks for the advice. Would fibreglass (GRP?) be an ok option as well or would EPDM be better?

I don't think the pitch of the roof on the right can be raised as that would affect the neighbours - unless you mean take the bottom row of tiles off extend the valley and the pitch that way?

 

[Nige F]

That RH roof is so low pitched it`s a flat . Quite seriously I would strip all the tiles and get the lot covered with high performance felt - or zinc/ali - cue Hardmetalking , is he lurking here That could incorporate the bodged leaded gutter and a vent pipe for the fan and you could upgrade the insulation in the roof void too

 

[joe-90]

Nah. Felt looks like a shed.

CotswoldB is making good sense.

 

[Nige F]

EPDM then

 

[illogitech]

Is GRP not good then (for the valley/gully/gutter)?

 

[joe-90]

It's great stuff but why are you so obsessed by it?

 

[illogitech]

It's on a quote I got but as I know nothing about these things I just wanted some input on how suitable it would be for my roof. Not obsessed, honest!

Here's the job description:
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I'm really considering giving this guy the job.