Insulation

brianmax88 · 13-12-2018 12:00am #1

Is 50mm insulated slab on internal wall overkill if i have 150mm cavity insulation? My father and i have different opinions. He thinks as soon as the heat goes through the block its lost. I think 150mm in the wall is enough that insulation is alot better now than when he built

sydthebeat · 13-12-2018 8:31am

brianmax88 wrote: »

Is 50mm insulated slab on internal wall overkill if i have 150mm cavity insulation? My father and i have different opinions. He thinks as soon as the heat goes through the block its lost. I think 150mm in the wall is enough that insulation is alot better now than when he built

The insulated board would cause more problems than it would solve.

You're right, he's wrong.

brianmax88 · 13-12-2018 9:39am

sydthebeat wrote: »

The insulated board would cause more problems than it would solve.

You're right, he's wrong.

What problems would it create? Other than been a nightmare fixing into.

Dudda · 13-12-2018 6:42pm

Depends on the type of insulation. 150mm beads isn't massive as it's a thermal conductivity of about 0.033w/m.K while 150mm of Kingspan or similar PIR is better at about 0.020 w/m.K (lower is better)

If it's beads and you're looking at pumping the cavity check if you can go to the 200mm cavity. I don't like the idea of just meeting the regulations and would like to see more if possible. Insulation can be difficult to add later and it's the one part of a building that can pay for itself over time (up to a point as going overkill may never make a return).

The issue with the insulated plasterboard is it moves the condensation due point inwards. Basically moisture on the air condenses at some point when it cools as it moves outside through the wall. At some point it will turn to water and you want this point to be close to the outside. I doubt it's an issue if you've a 150mm filed cavity but the likes of Kingspan or Xtratherm (or whoever you were thinking of getting the insulated plasterboard slabs from) would be able to do an interstitial condensation risk analysis assessment for you for peace of mind.

brianmax88 · 13-12-2018 9:30pm

Dudda wrote: »

Depends on the type of insulation. 150mm beads isn't massive as it's a thermal conductivity of about 0.033w/m.K while 150mm of Kingspan or similar PIR is better at about 0.020 w/m.K (lower is better)

If it's beads and you're looking at pumping the cavity check if you can go to the 200mm cavity. I don't like the idea of just meeting the regulations and would like to see more if possible. Insulation can be difficult to add later and it's the one part of a building that can pay for itself over time (up to a point as going overkill may never make a return).

The issue with the insulated plasterboard is it moves the condensation due point inwards. Basically moisture on the air condenses at some point when it cools as it moves outside through the wall. At some point it will turn to water and you want this point to be close to the outside. I doubt it's an issue if you've a 150mm filed cavity but the likes of Kingspan or Xtratherm (or whoever you were thinking of getting the insulated plasterboard slabs from) would be able to do an interstitial condensation risk analysis assessment for you for peace of mind.

I will be going for 150mm xtratherm in the cavity. The stuff with the plastic or whatever it is on the outside

Dudda · 14-12-2018 12:28am

brianmax88 wrote: »

I will be going for 150mm xtratherm in the cavity. The stuff with the plastic or whatever it is on the outside

Oh that's fine so. Ya the stuff on the outside allows moisture out. What you have planned so is grand and don't need anything inside.

brianmax88 · 14-12-2018 12:32pm

Dudda wrote: »

Oh that's fine so. Ya the stuff on the outside allows moisture out. What you have planned so is grand and don't need anything inside.

Thanks i dont want to be spending money if itos not needed. It will be tight enough as it is.

BryanF · 15-12-2018 11:21am

brianmax88 wrote: »

Is 50mm insulated slab on internal wall overkill if i have 150mm cavity insulation? My father and i have different opinions. He thinks as soon as the heat goes through the block its lost. I think 150mm in the wall is enough that insulation is alot better now than when he built

Quality control of the cavity insulation install is essential. Assuming this as above drylining is not necessary - and anyway not continuous. I’d be more concern with air-tightness, have you looked at this, did the energizer provide construction details?

dathi · 15-12-2018 12:44pm

BryanF wrote: »

Quality control of the cavity insulation install is essential. Assuming this as above drylining is not necessary - and anyway not continuous. I’d be more concern with air-tightness, have you looked at this, did the energizer provide construction details?

https://www.youtube.com/watch?v=ecctpF0Nf8c
sorry bryan

BryanF · 15-12-2018 1:01pm

* engineer

Thanks dathi

Calahonda52 · 15-12-2018 3:52pm

brianmax88 wrote: »

Is 50mm insulated slab on internal wall overkill if i have 150mm cavity insulation? My father and i have different opinions. He thinks as soon as the heat goes through the block its lost. I think 150mm in the wall is enough that insulation is alot better now than when he built

vs

brianmax88 wrote: »

I will be going for 150mm xtratherm in the cavity. The stuff with the plastic or whatever it is on the outside

Lumen · 17-12-2018 7:05pm

CavityTherm?

http://www.cavitytherm.com/why-choose-cavitytherm/added-assurance/

Engineered gaps on the exterior face seems like a recipe for thermal looping, but what would I know.

I guess the top of the cavity would be closed...

sydthebeat · 17-12-2018 7:34pm

Lumen wrote: »

CavityTherm?

http://www.cavitytherm.com/why-choose-cavitytherm/added-assurance/

Engineered gaps on the exterior face seems like a recipe for thermal looping, but what would I know.

I guess the top of the cavity would be closed...

Thermal looping only occurs on the warm side

Insulation

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