How to seal gap between brick wall and ceiling?

[Quilly]

Our internal walls are brick. 

There's a small gap between the cornice and the wall which allows small dirt and bugs to fall through from the roof space. We're looking to seal up this gap somehow. Is there a way to do this from the roof space? 

I've attached two pictures. The first shows the view from inside the roof space. The second shows the gap between the cornice and the wall. The paper is there to show that the gap is really there as the paper goes all the way though from roof to room. 

  

[Nailbag]

Hi Quilly. If this is along an outside wall it will be too tight to access from the internal roof space so, you will to access the area from outside. Things to note now is can you access that wall via a ladder (with a spotter) and what is your roof cladding? If its a colour bond (metal) roof, then its its not going to be practical for the average DIY'r. If it's a tiled roof, then it's a matter of removing the last two rows of tiles noting one row will have a single nail securing each tile. Lifting the tile from the front edge will loosen the tile up. This will allow you to then use a general purpose silicone gap sealer from the internal roof space.

A far simpler solution would be to run painters tape along the bricks just under the cornice. Then fill the gap with a white internal flexible gap sealer. To smooth off the finish, give the silicone a light spray of diluted liquid dishwater soap. Then, use the rounded end of an ice-cream stick (about $2.50 for a pack from Bunnings) and run that along the silicon and wipe the excess on to a rag or old newspaper as you go. Now slowly remove the painters tape. You should find the white silicon will blend in well with the ceiling white colour of the cornice. But it can be painted once dried.

Hope this helps

[MitchellMc]

Welcome to the Bunnings Workshop community @Quilly. It's sensational to have you join us, and many thanks for your question about filling a gap.

A great suggestion from @Nailbag there about sealing internally and caulking the gap with a flexible sealer like Selleys 480g White 3-in-1 Silicone Sealant. The other option, if you can reach the gap in the ceiling, is to run a small amount of expanding foam along it. Stick the nozzle slightly inside the gap and squirt a thin bead of foam as you move along. It won't take much as it expands. Ensure you don't stick the nozzle too far into the gap or squirt out a whole heap of foam, as you risk it expanding into the downstairs room.

Please let me know if you have any questions.

Mitchell
 

[Quilly]

Thanks for the advice. These walls are not outside walls so we can access the area within the roof space without any issues. 

We have measured the gap in the roof space and it is about 1cm wide. 

[Quilly]

Thanks for the advice. Which expanding foam would you recommend for this job?

[MitchellMc]

So sorry, @Quilly. I forgot to include a link. I'd recommend this Poly 750g Expanding Foam Aerosol Can. There are triple-expanding versions, but since the gap isn't large, I'd go with this standard version.

Mitchell

[Nailbag]

Great advice from MitchellMC. Just make sure you only use the smallest volume of expanding foam (cheapest is as good as the exy ones about $12) It expands over time to over 30 times!. But you can trim it afterwards once cured with a long flexible blade if required. less is best though to start with. 

Personally I would stick with silicone as the foam can push the cornice outward unevenly along the length. And when trimmed it's not smoothed more honeycombed so I would stick with silicon.

[Akanksha]

Let me also extend a warm welcome to the Bunnings Workshop community, @Quilly. It's a pleasure having you join us. 

Please don't hesitate to post anytime you have any questions or need a hand getting the most out of the site. We are always happy to help. 

Great to see you've received advice from our members on sealing that gap. Just a note to be careful if you're using a ladder to access the ceiling. You might want to check out our guide How to use ladders safely for tips. 

Looking forward to be a part of your D.I.Y journey. 

Akanksha

[Jason]

Great to see you back on the site sharing advice after a long absence @Nailbag. Please don't hesitate to post anytime you have something to contribute or need a hand.

Jason

[Nailbag]

Thanks mate, plan to be contributing a lot more moving forward as I have lots to share. I have recently stepped away from 30+yrs of corporate life in the power tool industry (training a lot of Bunnings TM's during that time) and many owner build reno's to turning my hand to home improvements working for myself 👍