External wall insulation on cavity built house?

flashforward

I was speaking to our Architect regarding insulation options for our 80s house renovation. The house is built with a 100mm cavity with 50mm aeroboard insulation in place.

He has said EWI works well with the likes of hollow block walls but in my case the heat will be lost in the cavity of my walls and the External insulation will have little effect.

Anyone have any experience or opinion here?

Googling EWI suppliers suggest they can insulate cavity walls.

BryanF

hollow block is suitable for ewi. as long as hollow block is air-tight internal and capped/overlapped with insulation at wall plate/eaves level

Metric Tensor

I think the OP has a cavity wall Bryan.

Your Architect is correct that the air movement in the cavity will negate a lot of the benefits of EWI but if you pump the residual void in your cavity with bonded bead, provided that's possible and appropriate, then you remove that issue and make the wall more suitable for EWI.

BryanF

Thanks MT
Same advice applies with addition of pumped beads.

BryanF

Thanks MT
Same advice applies with addition of pumped beads.

listermint

Pumped my 100mm Cavity, plus Installed 200mm EWI.

Very very happy with the results. Its cool on weeks like today and warm on months like March.

Calahonda52

Can you pump the cavity [ between block and TF] in a TF house?

BryanF

Calahonda52 wrote: »

Can you pump the cavity [ between block and TF] in a TF house?

No

Calahonda52

BryanF wrote: »

No

Thanks, its what I thought, instinctively:
what are the technical reasons?

BryanF

Calahonda52 wrote: »

Thanks, its what I thought, instinctively:
what are the technical reasons?

Breathability
Passage of moisture

Edit: like an attic timber needs to be vented.