Leaking around uPVC window - advice appreciated

[Bert Coules]

I raised this in another thread, where I asked about resealing the silicone around a uPVC window. Since then, another window in the same wall has also started to leak through the top junction with the wall, and I could see nothing wrong with the sealant.

So I stripped off the top length of the 2" wide plastic return strip (is that the correct term?) and pulled out the silicone behind it. This revealed what is presumably the underside of the outer brick wall, covered in what feels like mortar (filling the gap between window frame and brickwork). This mortar was sopping wet - quite saturated - and very crumbly.

Here's a picture:

It's not as clear as I'd like, but the white area is the top of the frame and above that is the top of the window cavity, with the strip of mortar and the plaster (or at least the bits that didn't come away with the silicone).

Now I'm not sure what to do. Should that mortar be there? Should I strip it out and fill the gap with something else? Is expanding foam waterproof? Or is there another alternative? Many thanks for any thoughts - and I hope you're all having an excellent Christmas.

Bert

[Bert Coules]

OK, new information. I was mistaken: what I'm seeing is the underside of the bricks: the top frame of the window is separated from them by a bead of clear silicone. What I took to be a continuous layer of disintegrating mortar was actually debris from the crumbling mortar between the bricks which has been spread along by rain water seeping through.

It seems then then I should replace the mortar and the silicone. Or - perhaps as a temporary measure - could I remove just some of the mortar (working from the inside) and use a generous amount of silicone to fill the gaps between the bricks? Not ideal, obviously, but I'd rather not be outside working up a ladder with the weather the way it is at the moment.

Again, thanks for any thoughts.

Bert

[Bob Minchin]

How/why is the water getting into the cavity in the first place. Is there a window above where the sealing has failed.

The pointing could have failed and combined with severe recent weather to allow rain to penetrate the wall above the window and run down.

In a modern construction there would be a cavity tray - usually incorporated into the lintel with weep vents in the lowest course of outer brickwork to allow any water that makes its way in to drain back out over the window head. Many UPVC companies dont seem to fit a window head moulding or fit/check cavity trays in older installs.

You could possibly insert a strip of lead flashing to make an improvised tray across the full width of the window plus 100-150mm at each end and remove the mortar in between every other vertical brick joint in the lowest course over the window to drain the tray to the outside.

hth Bob

[harryagain]

Above is all correct. The water is getting in at some point above your window. This needs to be identified and fixed. Could be: Faulty pointing/rendering. Leaking/blocked gutter. Roof leak. Leaking mastic on any windows above. Leaking internal/external plumbing/drains. Etc, etc.

You have to look at and eliminate all this things until you find the problem.

[Bert Coules]

Thanks for the new answers. I'm fairly certain that it's the pointing that's to blame: there are no windows or gutters above the window, the roof is fine, there's no adjacent plumbing or any other source of water that I can think of.

The window was put in around twelve years ago, and there's no cavity tray or any other provision for a run-off. I like the idea of a lead flashing drip tray: I'll look into that tomorrow.

Bert

[Andy Burns]

Is that from inside?

Another photo with a wider field of view might help to visualise it.

IME (which only applies to a single house really) for wooden windows the bottom sill is likely to be fully bedded in mortar, the side just a few blobs, none at the top, just whatever plaster found its way above the frame during plastering

If fitted with a replacement PVCu window, I'd expect any significant gap to be filled with foam, then siliconed outside, caulked inside, perhaps extra PVCu trim pieces fitted to cover wide gaps/missing chunks of plaster depending on the level of damage.

[ARW]

Bert, what are the black things I have highlighted in red

[Brian Gaff]

Erm, from the description, what is actually holding the bricks if there is a gap?

Brian

[Bert Coules]

It wasn't easy to see at first, but once I'd cleaned up the mess a bit it seemed to me that the bricks are actually resting directly onto the top of the frame, or as near as dammit. There's certainly silicone there, but whether it's just a thin bead along the junction or more of a full-depth barrier, I don't know.

Presumably, when the original window came out and the uPVC one went in, there must have been a period where the brickwork was totally unsupported, mustn't there?

Bert

[Bert Coules]

...or am I being stupid in thinking that there seems to be no lintel?

Bert

[Andy Burns]

No evidence of the metal lip of a lintel visible under the bricks from outside?

[Bert Coules]

How thin could that be and still do the job? I've never noticed one, but then I've never actually looked. I'll check in the morning.

Bert

[Andy Burns]

Mine are about 3mm, might not be visible without chipping off a little mortar.

[Bert Coules]

If the theory that the mortar is faulty is correct, that might be tempting fate... Though actually, I would probably have seen evidence of a metal lintel from the inside, I'd have thought. But I'll check properly tomorrow.

Bert

[harryagain]

All bricks are classified as to their frost rating. And other things.

[fred]

Have a look at the pic here:

The strength member is the tall part that lives in the cavity and the thin steel lips form shelves that the bricks above rest on. The inside to outside slope serves the same purpose as a cavity tray, deflecting any penetrating water to the outside.

Not saying you have one of these but that is the way to do it if you need to have a visible brick finish.

If you are rendering the face then you can use these too or use a concrete lintel and render over it.

[Bert Coules]

Fred,

Thanks for that. It now seems pretty well certain that there is no lintel whatsoever over the window in question.

Bert