Leaking Roof

GreeBo

After the weather from the last few days it appears I have a leak in my roof.
The house is a semi-d with a lean-to style roof at the front that basically extends the hall/sitting room out an extra 4-5 foot.
Its a tiled roof that's part of the original house design.
I had issues with it about 3 years ago and had some of the flashing and the ridge redone.

Last night I noticed large (2foot) wet patches on the hall ceiling.
Investigated today and about 6sqft of ceiling has had to come down (soaked through and lost all integrity)

I've had a good poke around and from what I can see the timber wall plate is soaked in a few places which leads me to believe that its either the flashing again or the felt and that the driving rain of the last few days was too much for it.
There was a lot of water, insulation was soaked.

At this stage Im unsure what to do next, do I need to get insurance guys out before I do anything?
Next, can anyone recommend me a roofer in South Dublin?

Cheers.

mickdw

Is your house build with hollow blocks or a double wall?

There is an issue with hollow block structures in that the block will soak water (plaster will not seal out water) This is usually ok in sheltered areas and so the hollow block build in acceptable in some locations. If however the block does soak water, this means the water has bypassed the roof and is then working its way into the house.

If you have a double wall structure, there should be cavity trays fitted over your flat roof (based on the description of layout). The idea of these trays is to stop water running down through the outer wet block wall and sending it out over the flat roof again. Many houses are built without these due to lack of understanding. Often this will only show up in extreme conditions

Of course it is possible that its a flashing problem and may be a simple fix

GreeBo

I think you are on to something with your description... thanks for the input!

Let me try to paint a better picture.
At the front of the house the bottom story is further out than the second story, this extra bit is covered by the lean to roof. Note that there is no flat roof under this, its the bare plaster ceiling of the hall/sitting room below. (I know, classy construction)

The front of the house up to the first story is a double wall of block gap brick.
Above the lintel is just block.
The house is very exposed to this sort of driving rain, It's rendered and has 3-4 coats of Dulux weather seal on it, and is in good condition, certainly compared to most of my neighbours.
I also noticed (while taking down half the ceiling) that it also looks like there is water on the inner side of the block work, above the lintel. This would seem to support the porous block theory.
One thing that seems strange is that I cant detect any wetness running down the blockwork beneath the timber plate. The plate itself is soaked but the wall beneath doesnt seem to be. Perhaps the timber is absorbing it before the wall does, but that timber is very wet and the ceiling/insulation/etc are also very wet so I cant figure how its getting down the 3 foot between the plate and the ceiling.

I already have real issues with this "design" as when the wind blows through this attic type space, it has free reign to get inside the rest of the house and under the floor boards. There is nothing at all to stop this. If/When I get the roof stripped I want to fit a WBP attic floor in here to try to prevent this (over the insulation) Is this madness?

Next question, what do people do about the leak, is it a roofer or other job?


<edit>
Interesting article on the effects of drylining/insulation on rain/hollow block construction.
I just finished adding 70mm kingspan board to the upstairs walls of the house. Looks like this makes the rain issue worse.

GreeBo

Should I just coat the painted plaster with a Thompsons Water Seal type product?
Im somewhat concerned about firstly putting this on top of paint and also if I will ever be able to repaint the wall again.

Hotwheels

I'd check the lead flashing along the front first for any sagging...as its a low roof GreeBo if you have a ladder hop up and have a look. Or go out one of the bed room windows...if you can...

The flashing may be letting in water that's dropping onto the ceiling below..soaking in that way....Is it a bay window in the sitting room?

it's not likely the water is getting thru the plaster, unless its cracked or something....

While there check around the reveals of the windows, and under the window sills. Water can make its way in there with the wind behind it...

GreeBo

yeah Ive been out there and cant see anything obvious.
A lot of the lead was replaced about 2 years ago and it still seems fine. The only bit I could suspect would be the wind lifting the bottom layer of flashing and the rain driving up underneath it, however there *should* be felt underneath to catch this so...

btw its not a bay window.

There are no cracks in the plaster and the paint doesnt seem to be lifting anywhere that would indicate water getting in...a bit of a mystery really.

The window sill is made of a bunch of red bricks on their side, not a great idea in my opinion so Ive coated it in Thompsons Water Seal a couple of years ago and it seems fine now. Also no issues around the windows.

No water in at all today or yesterday, though its been more wind than rain around here so the timber and blocks have pretty much dried out...Kinda really need it to rain while I have the ceiling opened up, otherwise I'll be paying a roofer etc and have no idea whats the issue.

PeteHeat

Hi Greebo,

I expect you will find the wind driven rain has been going over the top of your roof tiles and the underlay was acting as the main waterproofing, problem with a house of your era is the type of underlay rots over time especially where it lies behind the facia board.

Sounds like the water is getting through the felt at the low level which would eplain why you see water on the wall plate but not the blocks as the water is most likely leaking on the outside of the block.

There is no easy fix as it involves removing the roof tiles to replace the damaged felt.

.

GreeBo

Thats possible alright, though the top layer of felt/underlay is actually a double layer as the last time I was in there it looked pretty shoddy to me. (The flashing etc was repaired after I added the extra felt so its not that I didnt put the flashing back correctly)

Still waiting on the damn rain to arrive again...

suitseir

I have flashing which has failed as per a post I put on boards in early November. The builder who built this dormer bungalow has located the weakness in the flashing and has decided to replace it. It is not on the main roof, per say, it is on the annex over the front door but has left a watermark on the wall in the hallway, which is open plan so it is a bit unsightly. I have submitted an insurance claim so hopefully, I will hear from them soon. As the job will entail taking of roof slates and replacing etc. which will necessitate scaffolding, its all a bit daunting. However, when you see the damage done by the flood waters elsewhere, I think our problems are small and solvable. I noticed that OP said that the flashing in your house was replaced already and yet, with this unprecedented weather we have been having, it still managed to work its way through! So I guess I am not looking at my repair job as the solving of my small problem!!:(