Our house is old – and cold. We use gas central heating that never quite succeeds in heating the place properly. The reason for this has been clear for years: the cavity walls have no internal insulation.
Yesterday, two young men arrived in a truck and filled the walls with bonded insulation beads. These are small, light, grey beads coated with glue that are injected into the cavity walls where they fill every nook and cranny. Within 3 days they stick together and provide an insulation barrier against the cold.
The first part of the process involved fitting sleeves inside all the air vents in the walls. There were 5 of these. The sleeves turned out to be hedgehogs – wire and nylon contraptions that I use to keep the gutters clear and to discourage the birds from invading the attic during the nesting season.
While the first worker used a heavy drill with a 1-inch bit to drill holes in the walls spaced about a metre apart all around the house, the second worker followed him and injected the beads using a long tube attached to a compressor.
The whole job took the best part of a day, which was pretty good considering that they lost about an hour when disaster struck:
The first injection had begun under the kitchen window when I noticed a creepy miasma in the kitchen, growing thicker by the second, and asked about it.
They stopped the injector immediately and opened the cabinet under the sink. Beads had filled every space in and around all our cleaning products. It transpired that there was a gaping hole in the kitchen wall – a plumbing relic from an earlier kitchen.
As I said, it took about an hour to dismantle the cabinet, scoop out all those beads, and remove them. They filled 3 plastic bags.
Once the injection process was complete they filled the holes with a putty-like substance, painted over the patches, rebuilt the kitchen cabinet and left.
I got to thinking: how many beads had they injected into the walls? If I knew the number of beads per cubic metre I could work it out. The quote for the job specified the number of square metres (140) of wall space, and I knew that the cavity was 10cm wide. That gave me a total internal cavity space of 14 cubic metres.
This morning I found a few beads in my study. In fact quite a few had escaped from the vent in the wall and invaded my workspace. I used a dust-buster to gather them up and placed them in a measuring cup. I had about 120ml of beads. If I knew how many beads I had collected I could work out the number of beads per cubic metre and estimate the number of beads in the walls.
So I counted the beads I had collected. That took most of the day (yes, I know I need to get a life). I had 2,302 beads. I reckoned 20,000 beads would fill 1 litre = 1,000 ml = 1,000 cc.
The rest of the calculation was simple: 1 cubic metre = 1 million cc = 20 million beads.
14 cubic metres = 280 million beads!
I put the heating on. It could be my imagination, but the house feels a lot warmer than it ever did before. I reckon I’ll never have to buy another tank of heating oil.