Any roofers on here? need advice

[Mabozza]

Hi all, hoping there might be some roofers or suitably experienced peeps on here who can offer some advice.

I've got an occasional leak at rear of house, 2x bedrooms at the back are showing water staining on ceiling (they were only decorated weeks ago....)
I've been up the loft and could see some wet patches on a couple of the rafters, and the insulation was damp or wet in places, so water is getting in.

looking to find out if this is plausible before I call someone out- What I think is happening is with certain wind direction and heavy rain, I think some rain water is getting up between the tile overlap and into the loft area - does that sound likely?

for reference - house is approx 19 years old, tiled roof. When house was less than a year old we had loose tiles at the front during a storm, they didnt come loose but were physically moving up and down, the builders sent out roofers and if memory serves, they applied sealant or something between the tiles to secure them - wondering if this is what needs to be done at the rear of house?

any advice etc appreciated before I call out a roofer

[MajorMantra]

Not a roofer but I've spent a lot of time mucking around with roofs...

A house that new will have a membrane under the tiles. That's the second line of defence for a modern roof. Even if water gets under the tiles, the membrane should stop it. It's possible the membrane is damaged somewhere, or water is finding another way in, such through crumbly mortar at the verges.

See if you can track the moisture, but be aware that it can be hard to trace as drips can track along timbers etc. and they often appear far away from the source of the problem.

Roofs don't normally need sealant under tiles, that sounds like a bit of a bodge tbh.

[Lotobear]

It does sound like a wind driven rain issue. Are the tiles 'single lap' (ie. interlocking side laps)?

Critical things to look at are head-lap and pitch - do they accord with the manufacturers requirements for the specific tile for your location/degree of exposure? Some tiles also need to be clipped to avoid 'chatter' during high winds and IME these are often missed - you can't see the clips as they are concealed beneath the side laps.

Really need further information to advise. How is the water getting in - is the underlay compromised?

[wolfracesonic]

If it was an installation problem I would expect this to be an issue that crops up every winter, especially where you are, rated the worst category for wind driven rain exposure (you’re welcome), so hopefully it’s an isolated problem, rather than a new roof! That said, the roof felt should be a back up, even though it’s not its primary purpose.
Have you had any sudden cold snaps? It may be a condensation issue on the underside of the felt; are the damp spots localised or spread about? I’ve seen the odd loft where it looks like someone’s sprayed the felt and rafters with a hose!
A few pointers but you really need someone on the roof, poking about.

[Ian Geary]

Not a roofer, but my limited roof experience is:

- ridge tile mortar compromised: water tracked down over the sarking felt to the edge of the wall, then down.

- broken flashing around a chimney: water tracking straight down in certain weather (easy to spot)

- I've also seen condensation within the attic space pooling, but that wasn't enough to cause staining on the ceiling below


Quick checks
- bathroom extractor fan- is it connected to an external vent? I've seen newbuilds where it wasn't

- can you see any damage in the felt underlay? Especially around the rooms in question

- look from outside (maybe with binoculars) at joints, (ridge, verge etc) though hard to spot as wind can push rain through very small defects.


One final thing: with our leaky chimney flashing, we got roofer quotes from £300 cash to bodge with silicone, to £30,000 as it needed an entirely new roof.

20 years later theatre same roof is fine- my dad repainted the flashing for me with mortar.

[Mabozza]

edit to format (originaly replied from phone...)

Thanks for all the replies!

Here's some answers to some of the questions:

- Has happened a few times over the years and only in extreme weather eg storm Boelo

- Inner membrane looks intact to me

- Condensation - insulation was soaking in some places, so more likely water ingress

- No chimney

- Tiles visibly overlap at top & bottom, assume some over lap or interlocking at sides underneath

- Bathroom vent - had initially thought water ingress may have been via this vent, but everything is connected and looks to be correct. - The 2nd room effected is to far along from the vent as well

I'm guessing I'll need to bite the bullet and seek a roofer and hope I get a good one

Edit to add - was speaking with a neighbour last night who has the exact same issue. He is of the opinion that water is coming through tile gaps in high winds and the membrane is compromised.

Edited by Mabozza on Wednesday 28th October 07:36

[WindyMills]

I've had it before where the specification called for smooth tiles, but granulated had been fitted at a pitch too low.

The team had also pulled the breather membrane tight.

Leaks started off small, then got bigger as moss accumulated.

I've also seen big leaks purely from condensation - we will need some photos.

[Sheepshanks]

wolfracesonic said:

If it was an installation problem I would expect this to be an issue that crops up every winter, especially where you are, rated the worst category for wind driven rain exposure (you re welcome),

Again bearing in mind the location, does the roof have timber sarking?

[Wacky Racer]

Quick question.

I'm going to rake out and re do some crumbly mortar on a valley on my roof next week, weather permitting.

Ratio sand/cement?

4:1 or 3:1?

Cheers.

[wolfracesonic]

Wacky Racer said:

Quick question.

I'm going to rake out and re do some crumbly mortar on a valley on my roof next week, weather permitting.

Ratio sand/cement?

4:1 or 3:1?

Cheers.

4:1 will do, 50/50 sharp sand, building sand, a drop of SBR if you want to splash out. Any mortar will crack either way, it’s sat on a timber roof and lead, both of of which are subject to and will accommodate movement, the mortar not such much.
A alternative is this Flexim roof putty, more flexible as the name suggests.
Whatever you use, try to to lift the tile edge up, squish in the product and let the tile back down compressing it.

[Lotobear]

or add some fibres to the mix

[Wacky Racer]

Thanks both.

[f3nns]

Could just buy some premix from B&Q/Wickes etc? Add water (usually 4:1 ratio of mix to water) and job done. Ive used this in the past to good effect.

[Mabozza]

WindyMills said:

I've had it before where the specification called for smooth tiles, but granulated had been fitted at a pitch too low.The team had also pulled the breather membrane tight.Leaks started off small, then got bigger as moss accumulated.I've also seen big leaks purely from condensation - we will need some photos.