Cavity Blocks Insulation

Deep Thought

Hi

Following on from a previous thread

Our house has cavity blocks

Can these be insulated successfully using foam or beads etc?

Thanks

Spread

Short answer ........ NO

Al Capwned

Nope....

Either externally using something like this

Or on the inside of the external walls using something like these....

BryanF

alproctor wrote: »

Or on the inside of the external walls using something like these....

theres a little more to it than the above where you have single external block leaf. what happens when moisture hits the cold block wall?

whizbang

Short answer ........ NO

I think this is based on cost effectiveness ??
but:
Is there any point in putting a layer on top of the cavity to prevent air movement out of the cavity. My gut says it should reduce heat loss, but does anybody have any real experience of this. (-I'm replacing soffits shortly, so should be easily done)

BryanF

whizbang wrote: »

I think this is based on cost effectiveness ??
but:
Is there any point in putting a layer on top of the cavity to prevent air movement out of the cavity. My gut says it should reduce heat loss, but does anybody have any real experience of this. (-I'm replacing soffits shortly, so should be easily done)

no this is based on common sense!! cavity (breeze) blocks have a thermal concrete bridge for a large % of each block, what's the point of filling an air gap with an insulation that's not covering the entire wall? its only increasing the likely hood of surface condensation!! as regards blocking the movement of air, yes it may increase the thermal performance of the blocks but without assessing the condition of the wall and DPC the reduction in air-movement may reduce moisture evaporation. for the science see http://www.josephlittlearchitects.com/documents/hollow%20block%20wall%20assessment_BLC_260609.pdf

whizbang

Thanks Bryan,
i had read that briefly before, it seems to take no account of air movement vertically thro the cavity. It seems to assume the cavity is closed at the top.

With the winds we have been having lately, i'm noticing little puffs and whistles from strange places in the house, mainly skirting boards. I have checked outside and, as much as possible, sealed off any air holes into the cavity.
so i know i'm still loosing heat by air movement rather than just conductivity.