Wednesday, November 10, 2010

Insulating Our Walls

Our house is a 1950's build.  It has a cavity wall but no insulation in it.  Something like 30% of all the heat your home loses is through the walls, so insulating them is a easy and cheap (compared to double glazing) way to make your home warmer and cheaper to run.

The government is offering grants to people to get their homes insulated to save energy.  So we took advantage of this and got a company round to survey the house.  They can also do the loft insulation, but we'd already done some and you have to take up the loft floor to do it properly and ours is full of boxes.

They measured the walls and depending on the total area, you pay a contribution to the total cost and the company claims the rest from the grant scheme.  They do this directly, so you don't have to fill out any forms or apply for it.  In our case, we had to pay £199 for the job.

A few days later, the van turned up with the gear to inject the mineral wool insulation into the wall.

There are other types of insulation that were used in the past.  Our previous apartment was a 1985 build and did have insulation in the form of polystyrene beads.  There were some early horror stories about using chemical expanding foam as the insulation where the curing fumes from the foam solvent made people ill, so now most installers use this rock wool with no glue or solvent or anything.

They have to drill lots of holes at regular spaces in the mortar (between the bricks) to get the tube in and then just pump the stuff in (well it's actually blown in with compressed air). 

Before injecting the stuff they fit a long brush thingy in the whole height of the front and back walls of the house to keep the insulation from spilling over into the next door house wall (we live in a semi-detached house).

They also check any holes in the wall for air bricks and the central heating boiler vent to make sure they are sleeved with tubes so that the insulation stays out of those holes.

All the preparation work took about a couple of hours and made a lot of drilling noise outside (they don't need to do anything indoors).

After pumping the insulation into the various holes, they made up some new mortar, matching the colour of the old stuff fairly well and plugged all the holes in the walls.
Once dried, it's very hard to tell where the holes were.  A good match.  You can see one hole circled in the photo and one of the air bricks they had to check for sleeving.

Hopefully, we'll save quite a bit on gas this winter.  We got this installed just in time!

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