[Angela]

Hello,

My property is a 1950s bungalow with concrete floors and cavity walls. I have had loft insulation and an air source heat pump installed recently. The cavity walls have been capped with timber.

The next step is to insulate the wall cavities with beads. I have two questions:

1. What do I do with air bricks into the cavity wall? Do they need to be blocked up so that no beads can escape? Why are they there in the first place, when the floors have always been concrete?

2. We may build an extension in the future which would mean removing some of the current walls. I’m worried about the beads spilling out at that point. Do we need to install some kind of barrier inside the walls, and if so what material would we use for that? Or do the beads solidify so that they would stay in place, even if the wall gets partially taken down later on?

I would be very grateful for any advice.

Thanks,

Angela

[Energy Chap]

For point 2 first – The insulation will include an adhesive that will stick the beads together. When the extension is built the builders would cut through and then put cavity closers on the wall. Best to let them know that the wall has the beads in though.

For point 1 – It is difficult to tell with out seeing the vents as to what they actually are. I would point them out to the cavity wall surveyor and the installers and they will let you know what they intend to do. The surveyor may be able to check where the vents go with the Borescope they use to look inside the walls.

Can you upload some photos of the vents? Are the vents just at ground level? Are they just by rooms that have chimneys?

• This reply was modified 1 year, 5 months ago by Energy Chap. Reason: added questions

[Ellen Oliver]

Hi Angela,

Regarding the air bricks, it is likely that there is an underfloor ventilator for the beam and block floor. This should not be filled to ensure you sufficient ventilation within your floor space, but it won’t be an issue in terms of the cavity insulation as it is a box system that passes through the wall.

The EPS bonded bead insulation adheres together when blown into the wall, so there shouldn’t be any issue with it escaping, and it should not create a significant mess during renovations. Alternatively, there are professional companies available that can remove the insulation if needed.

Feel free to give us a call for any more advice. Hope that helps!

Ellen

[Author]

Posts