How do I fix a length of upvc above a window to seal crack?

11 Nov 2004
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United Kingdom
Hi there

Looking for some advice. I have a big crack running the length of the lintel above one of my windows. All other windows had this problem and the glazier fixed a length of upvc cloak profile strip to the lintel and then sealed it with frame sealer.

I got a length of upvc cloak and tried to fix it with silicone sealer. The force of gravity did not allow the sealer to bond the upvc to the cement lintel.

Have removed the silicone but have no idea how to stick the strip. The strip is 95mm in width and 1.7 m length.

All other windows have been fixed with some sort of sealer as there are no nail marks.

Any advice would be greatly appreciated.


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Hi fluff, it will either be stuck up with silicone (my choice) or security/glazing tape.

Personally id use 2 thick lines of silicone for 95mm trim, one at the back and one near the front but no too close as it'll sqidge out when you push it up to the lintel, maybe you didn't put enough on fluff as it usually overcomes gravity until it starts to set. I wouldnt use no nails as it dries hard and may not stick well due to expansion and contraction
Hi crank

I used lots of silicone. Put it on in a zig zag way but it just didn't seem like it would hold. How long will I need to hold it until it goes off?

Do you think it will be ok just to cover up the crack with the strip. Just had a google to find out if it could be something structural but all the windows seems to have these cracks. The house is 45 years old. Do you see alot of windows with cracks along them?


Hi Fluff, could you post up a picture?

The silicone will start going off within half hour but 24 to be fully cured but it should hold with no help at all while its going off, you could try holding it up with masking tape???
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have attached a photo of the crack. I runs the full length above the window. Most of the windows in the house have had this problem and have either been hidden with upvc or have been recovered with mortar.


View media item 20834
Blimey thats a crack and a half :eek:

Again, id of thought a good bead of silicone on the trim would hold it up no problems, all i can suggest then is masking tape, from the window, over the trim and onto the concrete lintel, if you do try this then don't use parcel tape as when you peel it off it'll leave half behind and is a pain to get off........i speak from experience :D
me again.

Tried again and used masking tape to hold in place, but it just kept dropping.

I am using multi purpose silicone sealer. Is this the right stuff to use? I tend to use this for fixing most things.

thanks again

Is the lintel free of dust as this will act like a barrier and stop the silicone from sticking to something solid, or maybe try propping the trim up with a few bamboo sticks wedged up from the cill?
I have got other silicone stuff from B&Q.

Have you ever used Evostik Serious Stuff Ultimate Strength Grab Adhesive (in a black tube)? Considering using this.

Other option was Evostik Ultra Power Flexiable Adhesive (in silver tube).

Do you think either of these would make any difference?


Never used either of them sorry fluff, give em a go though but if they dont hold i dont know what else i could suggest :cry:

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