Best type of cavity wall insulation when electric cables not in a conduit

Jojo153 · 16-12-2017 09:38PM #1

Hi

We are going to get our cavity walls filled. We noticed (when we were getting new windows installed) that our electric cables seem to be running down the cavity and are not in a conduit. Can we still fill our cavity walls in this instance? Or is there a particular type of insulation which might work?
Would really love to hear some opinions.
Thanks.

MicktheMan · 21-12-2017 11:44PM

Refer to the agrement (or equivalent) cert of the product to be used.

caesarthechimp · 11-01-2018 08:04PM

PVC cable in contact with EPS insulation (eg standard white aeroboard) degrades. There is some chemical reaction that attacks the PVC insulation and makes it crack/go brittle.
Polyurethane type boards and foams do not have this problem.

If you were pumping in EPS bonded bead, the resinous bonding agent "might" be enough to prevent direct contact between the PVC and the EPS. But there is a lack of information about all this, unfortunately.
If you want peace of mind, go for a closed cell polyurethane foam.

Calahonda52 · 11-01-2018 09:56PM

so what about the requirement to have power cables sleeved when encased in insulation?
They are designed to lose heat to air.....

Lumen · 12-01-2018 10:46AM

caesarthechimp wrote: »

If you want peace of mind, go for a closed cell polyurethane foam.

Which closed-cell PU foams have NSAI or equivalent certification for use in (presumably block) cavity retrofits where there is cabling in the cavity?

BryanF · 12-01-2018 11:54AM

caesarthechimp wrote: »

PVC cable in contact with EPS insulation (eg standard white aeroboard) degrades. There is some chemical reaction that attacks the PVC insulation and makes it crack/go brittle.
Polyurethane type boards and foams do not have this problem.

If you were pumping in EPS bonded bead, the resinous bonding agent "might" be enough to prevent direct contact between the PVC and the EPS. But there is a lack of information about all this, unfortunately.
If you want peace of mind, go for a closed cell polyurethane foam.

Can you back any of this up?

OP I doubt very much the electrician ran the service in the cavity. If they did, start looking at a re-wire.

listermint · 13-01-2018 09:59AM

BryanF wrote: »

Can you back any of this up?

OP I doubt very much the electrician ran the service in the cavity. If they did, start looking at a re-wire.

https://www.voltimum.co.uk/articles/q-day-pvc-cable-conduit-when-0

Polystyrene suffers from cable degredation due to the plasticiser in the polystyrene transferring into the pvc of the cable sheeth degrading it on long term contact

Calahonda52 · 18-01-2018 11:14PM

listermint wrote: »

https://www.voltimum.co.uk/articles/q-day-pvc-cable-conduit-when-0

Polystyrene suffers from cable degredation due to the plasticiser in the polystyrene transferring into the pvc of the cable sheeth degrading it on long term contact

I read it the other way around

"If PVC cable passes through expanded polysytrene insulation, it requires to be inside conduit to prevent migration of the plasticiser from the cable to the polystyrene."

listermint · 22-01-2018 05:16PM

Calahonda52 wrote: »

I read it the other way around

"If PVC cable passes through expanded polysytrene insulation, it requires to be inside conduit to prevent migration of the plasticiser from the cable to the polystyrene."

Fair point! Same result

Best type of cavity wall insulation when electric cables not in a conduit

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