Many cavity walls can be insulated by injecting insulation material into the cavity from the outside.
Cavity wall insulation diagram.
Cavity wall insulation explained.
These pockets are more efficient at reducing heat transfer by convection than the big air cavity was.
Cavity wall insulation costs and savings.
Installing cavity wall insulation can save up to 245 per year on your energy bills.
A cavity wall is a type of wall that has a hollow center.
One function of the cavity is to drain water through weep holes at the base of the wall.
In most wall applications you will use r 13 or r 15 kraft faced fiberglass insulation rolls for these two by four stud walls.
They can be described as consisting of two skins separated by a hollow space cavity.
While rated differently these two types of insulation are close enough in thickness that they can both fit into modern two by four wall systems.
This immobilises the air within the cavity air is still the actual insulator preventing convection and can substantially reduce space heating costs.
The skins typically are masonry such as brick or cinder block masonry is an absorbent material that can slowly draw rainwater or even humidity into the wall.
They make it impossible for large convection currents to be set up.
Cavity wall insulation is used to reduce heat loss through a cavity wall by filling the air space with material that inhibits heat transfer.