Multiple Damp Patches on Roof

[chuckalicious]

Hi all. Moved into a new house a few months ago which has an interlocking concrete tile roof. The ridge needed repointing when we moved in but this has been done. House is about 30 years old.

We have had some very strong wind in the last few days with some heavy rain and I have noticed a number of Damp or wet spots in the loft on both sides of the roof.

The underside of the roof in the loft seems to made of felt like fibre board and it is these that are wet. They are dripping at some joints.

Looking more closely there are some historic Damp stains but looking from the outside there are no visibly broken tiles.

I have left a message for a number of roofers but as yet no one has called back and I'm unable to get up there myself.

As the issue is quite widespread what could be causing something like this? Any ideas so I'm prepared for the trades would be useful.

Thabks all.

 

[ree]

A 30yr old house will have underfelt - what the fibre boards are or where they are would need pics to possibly say?

How come the mortgage survey didn't pick up the historic, or any recent, stains?

Why not post pics of the roof surfaces, and from inside the loft?

 

[chuckalicious]

Will post photos when I get a chance. Scottish home report, which would seem is not worth the paper it is written on only picked up that some of the ridge pointing needed redone.

To be fair on first glance you wouldn't see them and when done it had been very dry for some time and has been until just last week.

Lots of shadows too so unless you're looking you wouldn't see them.

 

[alan333]

Some tile roofs built in Scotland (in the 70's, maybe beyond) were built with half inch fibreboard as boarding, then underslating felt, then battens/tiles etc. Over time the fibreboards move/shrink, or the trusses move slightly, such that the fibreboards slip off the trusses and sag into the roof space. The felt also sags and if one of the sagged areas has a sideways felt lap then you end up with an open path for any water to run straight in. Also if the vertical felt laps aren't very big they open a gap almost anywhere the boards have sagged.
Your tiles should keep most of the water out but in my experience there's always some trickle marks on the underfelt somewhere, where small amounts of water have been running. Some water can be blown up under tiles during storm conditions, especially if the tiles aren't so well interlocked as they were 30 years ago.
About 20 years ago we were called to a roof with soggy fibreboard, in a converted loft. IIRC it was foil backed fibreboard and condensation had caused most of the problem, but the customer got the surveyer to pay for it all since they missed it in their survey (before home reports). We removed and stored the tiles, re-boarded the roof, and put the tiles back, replacing one or two as we went. I can't remember if we re-used the battens or not.
Yours could turn into a big job, have a good read at your home report and/or survey.

 

[chuckalicious]

Thanks Alan. Not what I wanted to hear as it sounds similar in that some of the boards are sagging a bit. Not sure I'd have much come back with the surveyor without taking the risk of large legal fees.

Is the boarding needed?

Roofer coming round tomorrow so will know soon enough.

 

[alan333]

Is the boarding needed?

My new build of year 2000 doesn't have any boarding, but the felt has been pulled tight and the laps are well covered over two rafters.

 

[chuckalicious]

I'm guessing I don't have rafters - would the board be there instead?

 

[chuckalicious]

Think I'm getting mixed up with rafters and the wood that runs horizontally....

 

[chuckalicious]

Some more photos, hopefully. Having issues uploading from mobile.

 

[terrypin]

I don't see how rain can be blown up and under a tile, enough to travel 75mm or so up the headlap and enough to cause staining but, I do agree that there must be water ingress.

You should have the roof checked for broken/cracked/slipped tiles.
There's obviously enough water to cause staining and through chipboard so I'd expect a broken tile.

 

[chuckalicious]

And some more

 

[chuckalicious]

I don't see how rain can be blown up and under a tile, enough to travel 75mm or so up the headlap but, I do agree that there must be water ingress.

You should have the roof checked for broken/cracked/slipped tiles.

I will get it checked yes as I assume that sort of inspection and repair will be far cheaper than removing the whole roof...

 

[terrypin]

R

I don't see how rain can be blown up and under a tile, enough to travel 75mm or so up the headlap but, I do agree that there must be water ingress.

You should have the roof checked for broken/cracked/slipped tiles.

I will get it checked yes as I assume that sort of inspection and repair will be far cheaper than removing the whole roof...

Right, now I can see you have under felt(1f).
The leak will be above any patches, between the stain and ridge so start looking in those areas.

Ps, why are you thinking of having the whole roof off?

 

[chuckalicious]

Only because Alan above said that's what had to be done on another roof of similar setup. Also interesting that at either end of the roof (gable ends?) the boards look Damp from top to bottom. On inspection from outside it looks as if they protrued out into the open and aren't protected which I cant imagine is right.

 

[ree]

She or he is a surveyor - they dont do "first glances" they investigate.

Thats a gross error on the surveyor's part to miss such signs of damp - either the surveyor didn't go into the loft (not unknown) or they had another "agenda" when they did the report?

Now you say that this fibre board is poking out at the verges? Maybe, some pics of this?

Perhaps, get them back as soon as possible - in the meantime dont go "altering" the roof with repairs, they will have to re-inspect exactly what they first inspected.