Cavity wall insulation

Page may contain affiliate links. Please see terms for details.

aberal

Veteran
Location
Midlothian
I'm an architect and am against cavity fill insulation in principle. Have you ever thought why there is a cavity there in the first place? It's to create a gap between the wet outer skin and the dry inner skin. Wall ties should be free of mortar droppings and should, technically be angled down from inner to outer to ensure that there is no bridge to allow no water to penetrate from outer to inner skin. Cavities are ventilated to ensure that they remain dry. Cavity fill insulation negates all that and creates a bridge between outer and inner skin that can , but not necessarily will, allow water to migrate. It's basically a risky thing to do. Also, how can you be sure that the cavity fill insulation, which you have paid for and assume that will fill the cavity, does indeed fill that cavity. I don't believe that its a fail safe process and have always assumed that large areas can be left unfilled either by accident or design.
 

al78

Guru
Location
Horsham
Be aware that you should not have cavity wall insulation if your house is timber framed.
 
If you ask for views then you are more likely to unearth the odd horror story, but mainly I think it is all OK these days.

The airflow thing can be an issue. You do not need air flow between the outer and inner walls (so can fill the space up) but on houses with wooden floors (on the ground floor) you need an air flow from the outside, through the wall and into the space under the floor. Problems can arise if that flow through the wall is blocked by the insulation. Damp (from condensation) then builds up under the floor and on the inside of the wall base.

Also, most people forget that cavity wall insulation requires building regulations approval by your local authority. Sort out if the contractor will sort this for you. It is little more than the authority rubber stamping the work by an approved contractor, but you will need the bit of paper when you come to sell your house (or will need to pay £70 for retrospective approval).
 
OP
OP
Trevrev

Trevrev

Veteran
Location
Southampton
I think a good sit down and think about this !
I'll get the loft re-done first during the summer, and do some more research about the cavity insulation.
Thanks for all your time.......Trev.
 
Top Bottom