Chimney Back Gutter problem

[MrDuck]

My 1930 chalet bungalow has a long-standing problem with damp leaking in around one of the chimneys. After taking advice I have had the chimney rebuilt with lead trays and new soakers but still have a problem with damp seeping in around the back gutter area. This photo shows the roof and East chimney:
View media item 47980
Out of frustration I opened up the tiling at the back of the chimney a few days ago and here is a picture of what I found:
View media item 47981 You will note that the roofing felt runs under the back gutter (which you can see the top edge of) rather than over it. My understanding is that this is wrong.

I believe (verified by tests) that the cause of the continuing damp is that wind-blown rain is working its way under the tiles above the chimney and then running down the roofing felt, under the back gutter, and into the house. The big question is - How do I fix it? I have looked at lots of information but found none that shows clearly how the tiling, felting and leadwork should be arranged in the back gutter area with my sort of tiled roof. If I try and bring the felt up over the rear of the back gutter it will run over the wooden edge that supports the short tiles, and will have nail holes for the tiles through it as well. This seems very wrong but I can't work out what is right.

Any help very much appreciated. More photos can be provided if required.

 

[catlad]

A simple solution may be to take a couple of rows of tiles of behind the chimney, and were the felt runs under your back gutter, slice the felt along the wood thats supporting the lead, if that means taking out a few of the thin counter batons so you can slice the felt do it, then you can gently lift the felt back and insert a small piece of baton to hold the felt up which should be enough to divert the small amount of water around your chimney.

 

[freddiemercurystwin]

The roofers who did that lead should be shot!

 

[seasickstevie]

You really need a wedge-shaped / tapered (in cross section) batten (think it's got a name) to bring the felt over to smooth the way, so the water / moisture doesn't have an obstacle in its path.

You'll need a small piece of felt to overlap, because where you slit the felt (vertically) will need extra coverage - and the felt's been damaged with nails.

You're going to need to take a few rows off.

 

[Nige F]

Looks like you got the Travelling Fraternity of Roofers - I wouldn`t mind roofers taking over leadwork from old plumbers like me - IF they worked to the standards I was taught - but then they are born dodgy , most of them Especially Sussex . Well I can see they made a feature of the chimney tray - I`m going to do one for a M8 ( when this rain stops ) I might just post a photo of it . It`ll follow the brickwork down over the step flashings @ the side and come out over the front apron

 

[joe-90]

Can't see why you only have a wind blown problem in one area (that looks sheltered). It would have been there from when the house was new if that were true. Have you checked the ridge tiles?

 

[noseall]

Irrespective of the felt detail, water should not enter the building and should be primarily weathered by the tiles and lead.

You will often see felt under lead the same as you will often see felt under tiles, because lead is only used where tiles won't bend or form.

If it is wind blown, (unlikely) you will need to extend the lead.

 

[MrDuck]

Many thanks for so much advice so quickly. A few comments:

1. The house is more exposed than it may look as it's in the middle of farmland quite high up and Northerly winds with rain seem to be what causes the problem. It can rain hard without Northerly wind and there is little or no leakage. The leakage is clearly a long standing problem as the old chimney had been repointed and had new stepped flashing fitted (which has been retained) to suit monsoon conditions, and there has been replastering around the chimney in the bedroom upstairs. Water penetration is now so bad and over such a long period that we now have a damp chimey breast in the kitchen on the ground floor as well as the usual problems in the upstairs bedroom. 'Experts' have told us that it's 'hygroscopic salts' and that we should cover it up with waterproof membranes etc. but I am certain that there is a real leak which needs fixing first.

2. The ridge tiles have been looked at and rebedded but with no improvement. The concrete tiles are quite eroded due to moss/frost/age etc. so that there are larger than normal gaps between them which obviously doesn't help. My local roofers also tell me that I shouldn't have a problem with wind-blown rain but if I pour a lttle water down the felt it immediately appears inside the house in exactly the same spots that get damp after heavy rain with wind. Either way, if water can come down the felt I don't want it inside the house.

3. I had thought of the idea of slitting the felt and bringing it up over the back of the layboard and back gutter lead but got worried about the short tiles that will then sit on top of it. These tiles should be nailed for security (and are now) but the nails will go through the felt into the layboard which doesn't seem right. Should I use some Code 3 lead and some mastic to make a better job of it than a section of overlapping felt? Or maybe I should route the felt or lead over the course of short tiles. I want to do this once and do it right (or get a competent person in to do what is needed) so any advice on detailing will be much appreciated.

4. There is a further problem with the piece of batten that has been fitted on top of the back gutter to support the bottom of the short tile course. This is likely to block any water coming down off the felt so I presume I shall have to rework this as well - is this right?. Best practice seems to be to have fitted the support wood under the lead but I am reluctant to mess with the tray at this stage.

Again, many thanks for your responses.

 

[peaps2]

is it an open fire, stove or unused?

 

[joe-90]

Your chimney breast is nothing to do with it - that is caused by condensation.

 

[Norcon]

My chimney was leaking a few years back as damp was taking wall paper off. It has no lead tray.

I just plastered the entire chimney brickwork (with red dye added) right down over the old lead.
Its right up there with the best of bodges but it stopped the leak.

 

[MrDuck]

There are two flues in the chimney, one is unused (but ventilated), the other has a wood burner fitted, but rarely used. The chimney breast has got so damp lately that water has been seeping through the paper and running down. Surely that can't be condensation? It correlates with dripping water in the undereaves space above. We have no condensation elsewhere - the house seems dry and has only two occupants.

I suspect we have two problems- a genuine leak that needs fixing and a hygroscopic problem that persists. I need to fix the leak first!

 

[peaps2]

did you have the chimney pot bedding looked at when it was pointed? It cracks and causes water to get in.

Stove flues can also cause condensation, you can stop this by lining the chimney with vermiculite.

 

[MrDuck]

The whole chimney has been rebuilt from the roof level upwards, and modern cowls fitted to exclude rain. The leak is from outside the chimney as I can see it dripping down the side under the sarking board and making the woodwork damp.

 

[Nige F]

Can't see why you only have a wind blown problem in one area (that looks sheltered). ?

Don`t know much about Sussex, then Joe