Another wood window frame question!

[Jonti]

I’ve had to cut out some rotted areas on corner of window frames (finally also found the cause) I’m making up inserts (seen here) and my plan is to mix up some water proof wood glue (possibly with sawdust to thicken it and help adhere to the old wood behind it). But my question is; should I open up the gaps in the joins more (about 1mm) and use a flexible filler like Arbo 1000 to ensure waterproofing at the joins. Or fill with the wood glue mix? The problem with any join is if it cracks then it will break the varnish and water will again get in. That’s my main concern. Wood fillers like Bremmer are generally too hard and I find they do crack, epoxy is softer but difficult to work with in smaller gaps….it must fill the depth of the gap (so 1mm x 9mm depth) I was thinking of using Arbo 1000 which is very flexible and paintable but it would mean a wider gap at each join. Just wondering if anyone has first hand experience of this? Pic enclosed just an initial rough fit of the insert.

 

[Jonti]

here is pic

 

[Hacker]

Personally I would fix with epoxy/thickened epoxy having wiped the surfaces down with acetone. When clamped you should get squeeze out that will show all gaps are filled. When cleaned up and varnished it will be as good as any of the other corners.

 

[Jonti]

It’s certainly an option epoxy, I can’t clamp it just press it in (tight fit option) but I do worry epoxy will just open up a crack after x1 hot summer and x1 cold winter and then cause varnish to crack and end up with water ingress again. It’s a tricky one as I don’t know how forgiving the epoxy will be between these joints with changes of temp and expansion- i know it will look good for a year…. but i’m trying to future proof it a bit.?

 

[Tranona]

Suggest using a sealant adhesive such as CT1 which you can get in dark brown. Does not need clamping to cure. Just bed the patch in with a gap round the edge and hold it in place with masking tape while it cures. In current temperatures overnight will be fine.

 

[Jonti]

Thank you all for suggestions… I do have a dark brown sealant adhesive (can’t recall which one) my original reason not to gook it in with a sealant/adhesive was because they might expand again due to heat lifting the repair sections out just enough to crack varnish. But maybe i’m being overly worried about that. Of course brown would match in better than black Abco 1000.

 

[tillergirl]

I would go with Tranona. Given the 'old' wood has extra moisture and impossible to clamp I wouldn't use epoxy. CT1 cures with moisture. You might get an alternative colour at Sealants Online -

 

[Jonti]

I’ve got these two “brown” adhesive/ sealant- certainly the Stixall is by far stronger. Too many options these days!

 

[pablooo]

I would recommend using a flexible filler or epoxy. I also had a gap at my window frame wich needed to be filled up, and I used a flexible filler which was waterproof. hope it helps