What is the best way to fill this gap?

jonscoots

Hi everyone

I've got a circa 1950's house with a laundry which may be an extension to the original house. Laundry is brick construction and there is a window which has a metal frame, and around that is a timber frame. Where the timber meets the brick, there is a sizeable gap (approx 4-5mm). I'd like this gap filled as I'll be renovating the inside of my laundry and would like to know the best way to do so for best sealing and longevity. 

Any advice or help is much appreciated.

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MitchellMc

Welcome to the Bunnings Workshop community @jonscoots. It's terrific to have you join us, and many thanks for your question about filling gaps.
 

It looks like there’s been a fair bit of movement between the timber frame and the brickwork, which is pretty common in older homes—especially if the laundry was added on later. Before filling the gap, it’s a good idea to check that the window frame is still securely fixed into the brick. Movement may have pulled some of the fasteners loose, so you’ll want to tighten or replace them if needed to make sure everything’s stable.

Once you’re confident the frame is secure, the best approach is to insert a backing rod (also called gap filler rod) into the gap so that it sits about 5mm below the surface. This not only helps reduce the amount of sealant required but also gives the sealant something to flex against. You can then go over the top with Sikaflex 11FC or a similar polyurethane sealant. It’s flexible, durable, and paintable, which makes it ideal for bridging gaps between dissimilar materials like timber and brick, especially where movement is expected. That should give you a clean, lasting seal before you move on with your renovation.

Please let me know if you have any questions.

Mitchell