Cavity wall insulation

gabd

Hi there

Just in the early building stages and would like to know which is the best insulation for inside cavity walls? Half cavity or full? which is best.

If going for half fill which is best, Kinspan, Quinns etc?

Thanks.

rooferPete

Hi gabd,

I expect Patrido will have some very good information for you on this subject, from his posts I have seen some very detailed figures about different systems.

What I have found from many self builders is they are moving more to the system of using a 50 mm closed cell insulaion board on the inside of the wall and fixing the plasterboard through the insulation to the inner leaf of the wall.

The idea that the block wall would act as a type of storage heater has been passed over at last and the idea of keeping the heat inside the home is now the more popular and practical view.

.

patrido

there are advantages to full fill, but partial fill is the tried and trusted method, and in terms of heat retained, you won't beat partial fill rigid boards from kingspan, quinn or xtratherm. there's really no difference between the three...

if cost is an important factor, call the sales dept in all 3 companies looking for the best price (then call the others back asking them to match the best price) - get a quote for the whole house, not just the walls. if cost isn't a factor, just buy whatever your local builders provider supplies.

Viking House

Partial fill cavity walling (2 four inch blocks with kingspan in the middle) is actually an outdated technology because it is impossible to get it right. What builder can guarantee you that the gap between the insulation and the inside wall in every part of your house is less that 1.5mm. The insulation is kept away from the internal wall by snots of mortar and the unevenness of the wall.

If the gap between the insulation and the wall is greater than 1.5mm then you get Thermal Looping (airflow between the insulation and the inside wall). This cuts the insulating effect of the Kingspan in half.

No builder or Architect can guarantee you a U-value lower than 0.5 (lower is better)with this system.

The building regulations in Scandinavia and Central Europe ban the use of Polysterene or Polyeurethene (Kingspan, Quinn etc) internally because they offgas harmful fumes.

Why not use a warm block like Poroton and insulate externally with Granitewool for a U-value of 0.15.

anon1

Check out icyene from gms insulation in longford. It is pumped into the cavity. It doesn't off gas.