About a month ago I started removing the wallpaper from a wall in our bedroom with the idea to cover it with 10mm of cork for insulation. I thought this would be an inexpensive way of keeping our bedroom warm in winter and lowering our energy bills. This wall is an external wall that faces east and so likely the source of much heat loss. The two stains on the wallpaper which you can just make out in the middle of the next photo were what I thought were old water stains.
Upon removing the wallpaper it was clear the water damage was not old but rather a present problem. The plaster felt damp.
The wall is a 50-70cm thick granite wall with a cavity followed by lath and plaster which is how they finished walls a century ago when these houses were built. There’s also the remains of a fireplace which someone removed probably mid last century. It always breaks my heart to see old character features removed from homes. Why not just leave it but not use it? I bet it was a beautiful old thing. Now there’s just a hole with a chimney.
Over time the mortar between the granite crumbles away and fills the cavity restricting airflow and creating a conduit for water from the outside to the inside. The solution to the damp problem is therefore to remove the lath and plaster, clean out all the rubble filling the cavity, then put plasterboard back up. This removes the water conduit and allows the air to flow freely in the cavity again.
Here’s the room with the wall partly removed and the hole where a fireplace once stood.
We took the opportunity to insulate the wall with 100mm of sheep’s wool insulation before fresh plasterboard went up.
The builder wanted to use the foil insulation which although good is essentially just polypropylene wrapped in foil and thinking of Grenfell I didn’t want to be wrapped in plastic while sleeping. He was very accommodating and happy to use the wool insulation instead. Here it is all done and ready for the new plasterboard.
As soon as the wall went in we noticed a massive difference in temperature. It was noticeably warmer. Usually our bedroom feels like an ice box which I actually don’t mind too much as I like sleeping in the cold but I despaired at the thought of all the heat escaping so readily into the night air.
Today I painted the wall. I will eventually wallpaper it again but the builder told me it’s better to paint on plasterboard first otherwise the wallpaper glue will rip the plasterboard when it gets removed in the future. Plus I haven’t bought the wallpaper yet although I know what I’m going to use.
And here it is today after several coats of paint. A huge improvement!
I no longer need the cork roll for that wall but I’m sure I’ll find another use for it.
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