Hi everyone, I have enjoyed lurking on this site for a while now and know that there is always a lot excellent advice from some very knowledgable people.
I would like your opinions on how to permanently and cost-effectively fix a penetrating damp problem. I have lived in a 1970's chalet style house since 1993 and there has always been a damp problem in the top corner of the flank wall of the main bedroom. This wall is formed from a chimney stack running the full depth of the dormer. Over the years, I have had various people look at the roof felt, chimney pointing, flaunching, and had the flat roof converted to pitched tiled. The revised roof has a lead box gulley formed above the original roof height; the original roof and felt flashing were left in situ. Hopefully the picture in my profile will help to make this clear.
I am convinced this is penetrating damp and not condensation - it is worse after heavy rain and pushes off the vinyl wall paper. I have seen wet spots appear in the plaster half way down the wall, presumably coming through the brick pointing. The chimney serves just the lounge and is now rarely used; it has only been used with a gas fire. It has what looks like a terracotta flue inside the cavity and the stack is built using yellow Milton Hall bricks. These bricks do seem to be particularly porous / absorbant.
I'm thinking that some kind of render applied to the chimney stack would stop water getting in. I'm not sure if my initial thought of waterproof render would be a good idea as it would trap in a lot of existing damp. I don't know how durable render would be - could it crack, how would it stand up to frost etc.? How would the chimney oversail be handled? Would the flaunching be over-rendered at the same time? What other options - some kind of breatheable, flexible coating, Lime render? Knock the whole thing down and rebuild with cavity trays?
Thanks for any ideas or advice.
I would like your opinions on how to permanently and cost-effectively fix a penetrating damp problem. I have lived in a 1970's chalet style house since 1993 and there has always been a damp problem in the top corner of the flank wall of the main bedroom. This wall is formed from a chimney stack running the full depth of the dormer. Over the years, I have had various people look at the roof felt, chimney pointing, flaunching, and had the flat roof converted to pitched tiled. The revised roof has a lead box gulley formed above the original roof height; the original roof and felt flashing were left in situ. Hopefully the picture in my profile will help to make this clear.
I am convinced this is penetrating damp and not condensation - it is worse after heavy rain and pushes off the vinyl wall paper. I have seen wet spots appear in the plaster half way down the wall, presumably coming through the brick pointing. The chimney serves just the lounge and is now rarely used; it has only been used with a gas fire. It has what looks like a terracotta flue inside the cavity and the stack is built using yellow Milton Hall bricks. These bricks do seem to be particularly porous / absorbant.
I'm thinking that some kind of render applied to the chimney stack would stop water getting in. I'm not sure if my initial thought of waterproof render would be a good idea as it would trap in a lot of existing damp. I don't know how durable render would be - could it crack, how would it stand up to frost etc.? How would the chimney oversail be handled? Would the flaunching be over-rendered at the same time? What other options - some kind of breatheable, flexible coating, Lime render? Knock the whole thing down and rebuild with cavity trays?
Thanks for any ideas or advice.
I have ripped out all the old lead valley, and outlet and pipe out of the wall and am reforming it with marine ply and fibre-glass and a running outlet and a bigger pipe to take the water away...I will put all photos I have taken on my album when finished.. I am sorry this post has been so long but I hope it shows you to look for things you would never have thought of 
