How to cut window seal/gaskets on inner corners?

[noobiediyer]

I need to replace the window seal on the interior side of a glass door. The old seals were cut at right angles in the corners which didn't look very nice so I was thinking of cutting the new seals at 45 degree angles to make a neater join. But I then found this YouTube video (

) which shows, rather than making a cut all the way through at 45 degrees, it takes a V piece out (without going all the way through) and this seems even neater. I don't have the special tool they have on the video but I could do this manually as I only have a couple of windows to do.

Thoughts on the best way to cut window seal/gaskets on the inner corners?

 

[noobiediyer]

And in case it's relevant, I have a wedge shape gasket like this: https://www.handlesandhinges.co.uk/4mm-wedge-compression-back-gasket-double-glazing-rubber-seals

 

[diy_fun_uk]

I would do it as per video. If inserting 4 separate pieces there could be a slight risk of shrinkage meaning the corners might be slightly exposed i.e. no seal over them.

 

[crank39]

If your fitting wedge into an internal corner just cut halfway through it from the back, just one straight cut not a V and then bend it to open the cut up, also to allow for some shrinkage make the distance between snips about an inch longer than you need, put the corners in first and then fiddle the rest in along each side

 

[noobiediyer]

If your fitting wedge into an internal corner just cut halfway through it from the back, just one straight cut not a V and then bend it to open the cut up, also to allow for some shrinkage make the distance between snips about an inch longer than you need, put the corners in first and then fiddle the rest in along each side

I think I know what you mean, I might need to test out the corner cuts with an off cut piece but cool, thanks.

Not sure I understand about making the snips an inch longer than needed though. I currently have all the gasket as one really long piece. I wasn't planning to measure up and cut it from the long piece. I was going to starting installing from the long piece all the way around the window and cut it when I know exactly where the two ends will meet in one of the corners. That seemed like the best way to do it, no?

 

[diy_fun_uk]

I think I know what you mean, I might need to test out the corner cuts with an off cut piece but cool, thanks. Not sure I understand about making the snips an inch longer than needed though. I currently have all the gasket as one really long piece. I wasn't planning to measure up and cut it from the long piece. I was going to starting installing from the long piece all the way around the window and cut it when I know exactly where the two ends will meet in one of the corners. That seemed like the best way to do it, no?

Gaskets can and do shrink, this can cause gaps to appear over time. To avoid this, you should ensure the gasket is slightly longer than required. For example, let's say the dimension for the gasket (when measured on the frame) is 40cm top and bottom, 60cm left and right sides. So the overall length of gasket required is 200cm. However what you'd want to do in my example is cut a length of gasket maybe 210cm i.e. 2.5cm longer for each run, with your corner cuts spaced accordingly. When you're then compressing the gasket into the frame, this 'extra' allows for shrinkage and reduces risk of gaps appearing.

Obviously you'll allow that bit more (or less) than my example depending on the dimensions of your window.

And ensure you don't stretch the gasket out when measuring it, lay it out at its own tension.

 

[cdbe]

I think there's a specific % to add to gasket length to account for shrinkage, but can't tell you what it is - goldfish memory!

 

[noobiediyer]

When you cut the gasket with the extra excess, where does that extra go? I'm finding the gasket just buckles if I don't cut it to size. I can probably do an extra 5mm but more than that, then it's causing problems.

 

[diy_fun_uk]

When you cut the gasket with the extra excess, where does that extra go? I'm finding the gasket just buckles if I don't cut it to size. I can probably do an extra 5mm but more than that, then it's causing problems.

Just go with your 5mm then and see how you go. If there are issues x months/years down the line you can rectify.

It's not an exact science, also depends how cold/warm the gasket is when handled and installed.

Don't overthink it