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What are the best ways to fill these gaps?

Just Starting Out

What are the best ways to fill these gaps?

Hi community,


I’m trying to figure out the best way to fill in these two gaps; one under the window sill and the other between the baseboard and floor.


I’ve had a look at some other questions and online and feel that finding a foam gap filler may be the way to go, and then using a flexible gap filler but I’m still hesitant as the holes are bigger than the images might suggest.


The hole under the window frame is quite deep (about 2cm) and 3cm.


The gap on the floor is 1.7cm high and 2cm deep across. I’m not sure if you can see in the images but when angling the tape measure down I would not be surprised if it would go all the way down to the ground (we have sub flooring, I think that’s the proper term).


Are there any bits of advice to help? Would be helpful is someone could share a type of foam or insulation that we could use to fill this gap.


Last summer the heat brought in nasty roaches (have had pest people come through already) and want to prepare our home for any other creepy crawlies this summer.


Thank you.








Bunnings Team Member
Bunnings Team Member

Re: What are the best ways to fill these gaps?

Hello @diylife, 


Welcome to the Bunnings Workshop community. It's brilliant to have you join us, and thanks for sharing your question about how to fill the gaps near your window and flooring. 


I can see two possible ways for you to repair these gaps. First, I suggest thinking about removing your skirting boards and lowering them to the floor and re attaching them. This repair will require you to repaint the gap that will be left behind once the skirting board is moved down. However, it will still be necessary to use a gap filler on the areas where the skirting board does not pass through such as door frames.


I suggest doing the same thing for your window gap, you'll need to paint the unpainted part left by the window frame moving and you'll still need to use gap filler for those tile gaps that are uneven.


The second method I propose is to use a combination of self-expanding foam, timber moulding and Selleys No More Gap Filler. For example, spray the gap with self-expanding foam to get a very good seal to prevent insects from crawling in. You then cover the gap with a timber mould such as Porta 9 x 9mm 2.4m Moulding Tasmanian Oak Quad Select - 2.4m this will cover the front of the gap and the self-expanding foam. 


The Selleys gap filler will be used for those parts that can't be covered with timber moulding. It will be necessary to paint the timber moulding.  


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


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




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Home Improvement Guru

Re: What are the best ways to fill these gaps?

Good Morning @diylife 

Thats a bit of a gap, Especially the skirting board to the floorboards. It looks liek your place has had carpet before and now that its gone there is a gap.

Id follow @EricL 's suggestion and take the skirting off gently (Use a paint scraper wide blade and push it down behind the skirt and then inch a flat bladed screw driver along the blade to lever the timber away. (The paint scraper is there to protect the plaster from imprinting of the screwdriver)


It might sound a difficult job and the first time I did some I was terrified. But all in all it is one of the easier timber jobs to do especially if you are just reattaching the boards.


Make note of where the nails have gone through from the skirting board to the wall proper as this will help in reattaching.


As for the gap under the window sill, Id be tempted to cut a thin piece of timber that fits and then paint it and slot it up underneath. 




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