How to seal window glass?

phiaxs

   

Hi everyone!

I’m in the middle of staining and varnishing my window frames. I’ve noticed the previous owner has tried to caulk between the window glass and timber frame. There’s a gap at the bottom part of the window and there’s some small movement when I press on the glass. Is it a good idea to seal all sides of where the glass and frame meet with Sikaseal glass and weather sealant? Should it be done on the outside or inside? Can I apply it after I stain and varnish?

Thanks for your help as always!

JacobZ

Hi @phiaxs,

Thank you for your question about sealing your timber windows.

You should finish your staining and varnishing before applying any sealant. This is because the sealants you can use won't work accept stains particularly well. If you apply the sealant over the stain, you will still get a nice clean finish.

Can you get a photo of the window from the outside? Specifically, how the glass sits in relation to the timber frame.

Does the glass sit inside a channel? 

Or is there a step in the timber that the glass is pressed against?

Traditionally timber windows were glazed from the outside using Linseed Oil Based Glazing Putty. When the putty is pressed against the glass it will stop water ingress and hold the glass in place. There are a number of tutorials on YouTube you can use to see the technique.

If your window has a step instead of a channel, I'd suggest using the putty on the outside and Sikaseal 300 Glass And Weather Seal Silicone Sealant on the inside.

If the glass sits in a channel, you can use a bead of Sikaseal 300 Glass And Weather Seal Silicone Sealant on both the inside and the outside of the glass. This bead is more about stopping water entry than holding the glass in place.

Please remember to take all due care when working around glass as it can shatter if it is struck at a weak point such as the corners. Wear gloves, long protective clothing, enclosed shoes and eye protection to minimise the risk of laceration.

Let me know if you have any further questions.

Jacob