Leaking conservatory roof

[D_Hailsham]

My son has a lean-to conservatory across the back of his mid-terraced house. In February 2007 the whole roof had to be replaced due to storm damage (insurance paid ). Later that year the house walls were cavity insulated, although at the back they were only able to do the part above the conservatory.

Last winter water started to appear on the back wall of the house. It seemed to be coming from the main cross member tying the roof to the house. The installer came (10 year warranty) and diagnosed it as a failure of the seal. Which was repaired using a sealant gun.

The same problem has arisen again in this very wet weather (the conservatory faces due south). The installers came along last week and this time said the problem is due to failure of the pointing. They said they had filled some of the worst holes with sealant, but the back wall really needed re-pointing.

I would have thought that any water permeating the bricks would creep down through the cavity insulation (which stops about where the roof joins the back wall) and then drop down the cavity to the damp-proof course. There is no sign of any water at that level or of any water leaching out of the wall. It all seems to come from the main cross member tying the roof to the house.

Does any of this make sense? Is it a pointing problem or a conservatory roof problem?

 

[Nige F]

Cross member probably goes into the cavity thru`brick . Basically, wherever it is , it`s probably the extreem wind/rain we are having. And yes, the pointing could be getting "tired"

 

[jm2000]

ok this is just my opinion. I have worked on construction sites now for most of my working life. my brother and father are brickies and i am their Hod Carrier. during the week we work on mainly Industrial buildings. At weekends we do our private jobs - extensions, garden walls, conservatory bases...you get the idea.

In all the time we have been doing this, remember my father is retiring this year and my brother is near 40 as i am....we have never fully filled a cavity...it is there for a reason, the reason is for moisture to run down to the substructure and to keep the internal brick/block dry. To us filling a cavity is not good news in a wet climate. it may be fine when the brick or the render is good but the moment you get any moisture in that cavity it is then soaked up by the insulation and sits there. with no where to go but though the dry inner leaf.

So what can be done..like has been said already it could be the pointing...but is the wall above this point sound...does it need to be water sealed..if the brick work or the render is old it may need watersealing. this can be bought at most diy stores and is brushed on and dries clear.

If any brick have blown, common on older houses, the brick soak up water at a faster rate. have these brick replaced. and the water seal the wall.

If the paint on the outer walls has not been painted in a few years it may need repainting.

If you've ever spilt half a pint of water on a news paper you know just how much that paper doesn't hold water and how much water you still have to clean up....well that cavity wall insulation i pretty much the same, and it doesn't need a lot of water to form a large damp spot on a cavity wall.....i hope i've helped