I have a damp patch in my extension..what is wrong with my roof

2 Mar 2016
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United Kingdom

hello. I've got a wet patch on the wall ceiling of my extension which would seem to suggest a leak. I've checked my gutters and the roof tiles all appear to be properly in place. There is a crack in some of the cement (I have no idea of the technical terms for the bits of the roof)

Attached are photos - including a close up of the crack. Do you think this is the source of the leak (it's not a big one) and what would be the fix?
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image links don't appear to be working so I've attached them here


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I'd very much doubt if that small crack in the cement would be causing much grief......any leakage there should go into the soffit box area anyway.
However, make it good anyway, and if there's any problem with frosting or whatever up there, a coat of Evercryl or similar makes it totally waterproof.
Can you get into the loft void at all......and maybe give us a pic of the patch inside?
Just a thought regarding the pitch of the roof - are things worse in high winds?
John :)
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my wife just went out and had a look and the pitch is around 20%. There isn't a loft void as the inside of the extension has a high ceiling up to the roof. I can get more pictures later. It's really not much of a leak, just a few discoloured patches that seem to indicate that some water is getting through....
attached a photo of the inside. As you can see there's just a minor discolouration in the corner of the ceiling and wall... but there's definitely water getting in


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The odds are that water is penetrating at that corner in the first photo.
Fibre cement slates allow a free run-off of roof water and any slight dip in the roof at that corner will allow water to oversail the verge.
The undercloak and mortar bedding should run into the gutter. Yours is stopping short of and below the gutter.
The PVC corner piece and maybe the PVC fascia are not fixed plumb - there's a gap. This needs taking apart and re-fixing properly.
The pointed mortar bed looks rough and is wet soaked - lift some slates (its easy to do) and re-bed with new mortar. Dont attempt any pointing - it will fall off next year or so.

The underfelt doesn't run into the gutter - do you have underfelt? I cant see any underfelt.
The gutter should run past the verge and be set lower on the fascia.

does 40 42 or 45 mean anything to you? If not, forget about it.
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thanks for the replies. It looks like I'll have to get a roofer in to have a proper look.
There is 300mm of wall between that leak and the verge or gutter. That makes it less likely to be anything to do with the mortar verge or fascia.

You'll need to take the slates off at the eaves to check the felt/ membrane.

Water could also be running down a rafter from further up the roof.

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