Dorset Dabbler

On the window I am looking it - which I believe is typical of the four affected by a damp joint around its frame - I can see that there is hardly any foam. Most of the gap between frame and brickwork has been filled with grey mortar, which is continuous from near the outside of the bricks to around half an inch inside the frame, where it meets the plaster. It's this mortar which has been getting slightly damp. The plaster itself is not board, but hard plaster applied to the brickwork of the house. It has not been suffering from damp staining in the same way. Although it clearly must span the cavity I can't see how the cavity is closed off without making a bit more of a mess of it than I need to (why make more work!) but I would suspect it's the original method, whatever that was in 1952, and seems to be perfectly sound. Thanks to all contributors - plenty to think about, and I'll be back on if I find I am still stuck. This was my first post and I must report that I really like this forum and the quality of its help!

John, I don't think so, I believe the stain problem I have is all adjacent to the exterior brick skin of the house, and is entirely outboard of the cavity. I will do some measurement though to verify this. Conventionally, should a damp barrier of some sort be installed around the window aperture to separate the plaster of the window reveal from the outside skin of brickwork? (in my case, I can see there isn't one).

PS, I see I didn't answer Russell griffiths, and I should have said that for it to look pretty is almost enough as the problem is confined to that 1/2 inch strip immediately inside the window - though I'd not want to simply cover it up, at the very least I will dig out the mortar from that strip to permanently get rid of the mould. It's what to put back in the gap (if anything) which I need advice on.

Thanks all for your informed comments. The only place where there's damp staining and mould is that 1/2 strip immediately inside the window. I've no reason to believe that the cavity is breached though part of the previous owner's renovation was to have cavity wall insulation injected, however there's no damp beyond the immediate surround of the window. I can see the appeal of the PVC strip, also of gap filling foam; would I have to look for some special type of foam or will any general purpose foam be damp proof?

Nothing untoward on the outside. The house is rendered from the windowsill level up, bare bricks below. The PVC unit is well sealed to the render, and the render is apparently sound onto the brickwork. The DPC is clearly visible and not bridged. The air bricks are good, and apart from this one location (on several windows) the house exhibits no other evidence of damp whatever. So yes, the outer skin of bricks is (very slightly) damp when it is wet outside, but isn't this just the natural absorption of damp from the air - which is why there's a cavity? Happy to be put right if this is not the case.

Nothing so glamorous as real building, I have a problem to fix. Go to "Windows and Glazing" and admire my damp stains!

I am looking for informed advice on the right product(s) to use around a uPVC window unit to bridge the gap between its frame and the plasterwork of the window reveal. Here's the situation: House is a 1952-built bungalow. As part of a general major renovation, the owner before us replaced the original wooden windows with white uPVC - this would be 10 years ago - employing builders to do the work. We have lived here 8 years, and for probably the last 5 there has been an increasing problem with staining and then black mould on the window reveal around a narrow strip (1/2 inch - 13mm - ish) next to the window. Here and there the staining leaches into the plaster too. It seemed clear that the wrong filler had been used to seal the internal gap between window and plaster and so this year I dug some out to have a look; it was indeed slightly damp, according to my multi-meter (but not to the touch) and so was the exposed mortar and brick behind it, but after a day or so of exposure to air it was dry again. The filler was ordinary grey powdery mortar, and was applied directly to the outer skin of bricks surrounding the window. Despite not being Sherlock Holmes I was able to deduce that the mortar was acting as a wick to the slightly damp outer skin of the house (is this right?) and that the artisan who installed the windows has bridged the gap by (a) not installing any sort of membrane and (b) using the wrong filler. (Again - is this right?). So, O wise people of the DIY forum, what product should I use to replace the mortar when I have dug it all out, please?

Greetings, I'm a lifelong believer in DIY as the first technique to try when confronted with anything which I would like to improve. Along with reasonable proficiency with hand tools I have also developed a good sense of when I am out of my depth and need to ask for help! I've joined this forum as I have a specific issue which I want to seek advice on, and I'll post it in the appropriate area, but I don't suppose it will be my only visit as this website seems to offer an excellent level of support for those doing home improvement projects. The "Dorset Dabbler" lives in a 1952-built bungalow in wonderful Bridport, West Dorset, and no, Broadchurch doesn't really exist.