Water Ingress Past New Window

[TheScullster]

Hi all

As part of an extension re-furb we had 2 new windows fitted. I noticed that at the corner where the internal sill meets the window (actually there's a 3mm gap which needs filling), there were signs of damp. A "quadrant" shape water stain was expanding from the corner up the new plaster about 50mm radius. The builder returned and ran sealant down each side of the window - for good measure, I ran sealant along the top. I have since painted over the plaster, but note that the window sill is swollen in the corner.

The question is:

How can water be getting in? I have examined the state of the newly applied sealant and it all looks good and continuous. There is a generous drip overhang on the outside sill. Under the sill and all round the frame is rendered and painted - no obvious gaps.

Can the seals between the glass and uPVC frame be defective? Any other suggestions? Unlikely to be roof related as this is new tiled version.

I notice that the window sill has a lip just under the main frame which presumably stops water tracking back underneath. If water gets past the glass seals, where will it go? This lip looks like it will stop water getting out that drains "through" the frame. There are milled slots in the bottom of the frame (under the opening window) which appear to act as drains. These look as though they will discharge water on the inside of the concealed sill lip.

Can anyone follow this lot?

Any suggestions for making room water tight appreciated.

TIA

Phil

[Michael Mcneil]

Sounds like a duff fitting. If you are still getting leaks make the builder remove and replace them or take them out and refit them.

Or get better people in.

Next time get the advice you need to DIY from the regulars here.

[TheScullster]

Do you mean the sealed glazed unit or the entire window? Removing the entire window would be a hassle as it is now held captive by render!

I have DIYd quite a bit of this refurb, but, being an office worker, do not have the physical strength to carry out the heavier building work.

Phil

[Michael Mcneil]

Was all the blue protective paper removed after fitting?

Are the windows plumb, level and square?

It's difficult to give an answer to this sort of thing without seeing it.

[Phil Hughes]

In article , TheScullster writes

[snip]

My guess would be is that it is water getting in the seals, draining out of the drainage holes in the frame, then running off the ends of the sill as they haven't been sealed up.

Had a similar thing myself in a window. Fixing involved taking the frame out and sealing up the gap between sill and frame at the end.

[TheScullster]

"Michael Mcneil" said

Don't think so, I can still see some protruding from behind the plaster inside. What are the implications?

I did check the window sill and that looked bang on!

Thanks

Phil

[TheScullster]

Sorry I didn't describe things clearly enough, the sealant was continued from the frame edge along the ends of the window sills.

I don't see how water that drains from the frame can escape. As explained in the original post (perhaps not too clearly) there is a lip on top of the sill just behind the front of the main frame, presumably to stop driving rain being forced up under the main frame. Surely this also stops water from draining away from the deliberate drain slots cut on the inside of the frame below the opening window?

Unfortunately I didn't see these fitted. Does the sill go in first, then the window on top? To check that I understand you, there is a gap under the frame which extends up to the window opening. The sealant down the frame and alongside the sill effectively goes over the top of this gap leaving a path for water to run along the top edge of the sill just under the frame to the brick opening. Is this the gap that you had to seal?

TIA

Phil

[Phil Hughes]

In article , TheScullster writes

First of all, I should point out this is the only window I have ever (re)fitted, so I am no expert. Its also a while since I did it, so my memory might not be brilliant. However, from what I've read, what I found is generally applicable to all PVC frames. As we've found, its a bit difficult to explain in writing :)

The sill is fastened to the bottom of the frame with screws through the bottom of the sill into the frame. There are mitred holes right through the bottom of the frame that allow water that seeps into the frame past the seals to drain out. The water drains out into the gap between the frame and the top side of the sill, and then out to the front between the bottom of the frame and the top of the sill. Thus unless the gaps at the ends of the frame (where they butt up to the wall) have been sealed

*before* the frame and sill were installed, then potentially the water can run out of these gaps. The sealant you see on the outside will not fill these gaps.

Hope that's clearer. Maybe someone else can jump in here and confirm this is generally the case.

[Dave Plowman (News)]

Is this a window which sits flush with the outside wall? If so, it should have flexible sealer between the window and walls on the outside.

I DIY fitted a Screwfix UPVC window which is flush to the outside wall. and used the normal foam filler. I wanted to tidy up the brick edges with mortar and used a temporary wood strip to provide clearance from the frame. After removing the wood strip sealed between the window and the wall with the proper sealer. Same top and bottom, although no mortar needed there.