How to repair gap between window and old wooden frame?

Question

Hi everyone,

I’m looking for some advice on how to seal and possible repair the gap between my window and the old wooden frame.

The surrounding wood looks quite deteriorated in places, and there appears to be rusting around the window frame itself. A couple days ago I noticed some ants around my window, which I suspect are coming in through a hole in the corner (see photo).

I’m quite inexperienced in this area and am hoping to fix this properly. Any advice regarding how to approach this problem, and any sealants/ materials needed would be greatly appreciated!!

Nailbag · Answer

Hi @hojicha

The priority is going to be locating the source of the water ingress that’s caused the rotting timbers. This could be simply from the external window frame or higher from an issue with the roof or guttering. In either case I would consider a plumber as they can identify the cause and if it’s roof/guttering than can repair on the spot. If it’s something to do with the window frame then that’s where you can decide on DIY or getting a local handyman.

Being a novice, my advice would be to go down the Handyman path as repairing window frames both internally and externally can be quite involved to do correctly so that it lasts long term.  It doesn’t cost anything to get a quote. So, even if you got them to establish the extent of the repair required you could then decide on if it’s something you’re  prepared to have a crack at yourself. Perhaps they do the outside and you do the inside for example following @EricL instructions.

Nailbag

Dave-1 · Answer

Good Afternoon @hojicha

The steps that @EricL has outline are the same ones I would suggest. There appears only damage that is a slight concern in the first photo so definitely the screwdriver test is needed there :)

Ants will find so many paths into a place :) that is their job and ours is to block it off if possible. Id start with the screwdriver test and then work my way around the window pushing into the timber gently to see if its spongy.

Dave

EricL · Answer

Hello @hojicha

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thanks for sharing your question about your window frame gap.

Thank you for sharing those photos, they really help in the assessment of your window frame. It appears that you possibly have a slow leak around your window frame which has caused it to deteriorate and develop mould and mildew. We can clearly see this happening along the edge of the timber frame where the steel meets timber, specifically at the top section.

Patching or sealing it with silicone now is like covering a potentially large wound with a band aid. I propose doing a basic integrity test of the surrounding window frame. Use a flathead screwdriver and push it against the mouldy and rotted sections of your window frame. If the screwdriver sinks deep into the timber, then it has rotted through. But if the wood puts up a fight and is still firm underneath then it is possible that it is just surface damage and could be repaired.

Your first goal is to try and locate the path or entry way where rainwater is passing through. Once you find the source of the leak it must be addressed. Once the leak is secure you can then address the damaged window frame. If the damage is minimal and is only surface damage the rotted section must be scraped off. I then suggest using

https://www.bunnings.com.au/earl-s-250ml-wood-hardener_p1585306

to treat the damp timber. Once the wood is restored, I recommend using

https://www.bunnings.com.au/turbo-175ml-builder-s-bog_p1670144

to fill in the gap. Wait for the bog to cure and sand the surface to level it, clean off all the sanding dust with a damp rag before priming and painting the surface.

The final step will be to put a silicone bead on the inside and outside (if possible) of the window frame to protect it from further moisture damage.

However, if you find that the damage is quite extensive. I propose engaging the services of a carpenter/builder and getting a quote for the repair of your window frame.

Let me call on our experienced members @Nailbag, @Dave-1, @TedBear, @JoeAzza and @DIY4Knuckleheds for their recommendations.

If you have any other questions we can help with, please let us know.

Eric