How to fix my damp house

I had a really enjoyed my course on how to build a wind turbine at the Centre of Alternative technologies (CAT) in Machynlleth. I was up for doing more things along that line! Especially now that I could travel there without causing emissions. So I kept an eye on the website. And then I noticed a course titled "How to fix my damp house" and I thought that might be my next adventure! So I registered.

I was glad that by the time the date came up, I had access to the electric vehicle again. This time, though, I drove up on the day. It's not even that far!

When I got there I checked into my room; this one even had a better view than the previous one. And then it was time to meet the tutor and my fellow students. Nathan, the tutor, was a Welshman with a long history in building and conservation. Most people on the course, unsurprisingly, were living in a house with a damp problem. Not all; the one with the best timing had just bought one, but from the sounds of it I figured he was not going to move into it for a while, and could solve the damp problem first. And we ranged from London to the Isle of Harris. 

Nathan started showing us some pictures of situations with damp he had encountered during his career. He spoke a bit about what the problem was in each of them, how to read the signs, and what you could possibly do about it. But generally, doing something about it seemed like a lot of work. Not always; a blocked drain can do a lot of damage, and not all drains are particularly high above the ground.

He also showed a few diagrams of situations. The one I found most striking was an ideal house on the left, and pretty much an accurate diagram of my house on the right. Everything was wrong with it! Oh dear. He basically explained that a house should be able to breathe. If you coat it with waterproof layers on either the inside or the outside, you trap water inside the wall. And that can have two unpleasant effects: firstly, the wall is very wet and absorbs any heat you might throw at it. It will stay cold! And secondly, any wood floor joists do you have in that wall will stay wet and will rot. And that was what I was afraid of in my house.

To my surprise, in the afternoon we went outside to chisel the lime mortar out of the joints of a slate building. And then we mixed some new, and re-pointed the wall. I hadn't quite seen that coming! But it was clear why we were doing this; Nathan has been warning us against cement, which is way too waterproof. So chiselling that out and replacing it with lime mortar might be something any of us might have to do it at some point. 

Re-pointing with lime mortar

After the pointing we went for a short walk on the terrain of CAT; it has plenty of old buildings associated with the slate quarry the centre was built in. And plenty of these have a damp problem! Clearly, a lot of experimenting had been done with them, and not all experiments had been successful. So he had a lot to point out. Not only bad things, though!

Nathan points at issues of a row of quarrymen’s cottages

After that walk he was done for the day. And I figured I still had time to go for a run before dinner! I didn't think running after dinner would be a good idea; the days are just too short. And I wanted to get to the farm track I had run on the previous time, but now get onto it in the more civilised way. My Footpath app suggested there was a path I could take, and one of the CAT employees thought he pointed me in the right direction. The path turned out to be too overgrown to run on, so I had to stick with the road. So be it! Not wanting to be late for dinner I just ran to where I had joined the track the previous time and turned around. If I go to CAT again, and I find that likely, I will know where to go.

Scenic path on spoil tip

The quarry

Run selfie

After dinner we just chatted a bit. There were two courses going on: hours, and another one about managing building your own house. There was quite some mutual fascination between the two courses! But I spent most time with my own course mates; mainly Rebecca from the Marches, and Heather from Beddgelert. We clicked!

The next day I found Nathan before we officially started. I asked him about the wall of my office. He basically said I would have to remove everything my house is coated in, including the render I just had done this year. But also everything else. That is such a massive job! That will be a long-term plan. I decided that what I will do is just strip the problem wall from the inside. When the painter back in the day suggested sealing it in I had been skeptical; would that improve things or make everything worse? But you have to do something so I went along with it. But the gnawing doubt had been the main reason for me to sign up to this course. 

Taking it all off again will be messy, and will take the whole room out of action for a fair while! But then at least the water in it will have somewhere to go. I think this needs to be done. And once that's done I will start thinking about the rest! I had no other big damp problems, so I think that even though all that sealing in of the house isn't good, I seem to be getting away with it. I will keep a close eye on everything!

When the class officially restarted we did a bit more theory, and a house clinic. I basically had my questions answered already. But some unrelated things came up as well; I did learn about removing the paint from slate windowsills. And I want to do that one day!

We then did another walk over the terrain; this time a bigger one. There were very illustrative experimental houses, for instance with three different roof coverings; by the amount of moss and ferns that were growing on the various roofing materials, you good see quite clearly which ones were performing well.

Wood pellet boiler

Air source heat pump

He also showed us unrelated, but interesting things, such as a building with various environmentally friendly heating systems in. There was a heat pump system (I don’t know if it worked, but at least it showed the setup), and a (clearly working) wood pellet boiler. Interesting!

Then we were done. Time to go home! We said our goodbyes, and I again used the EV to drop someone off at the railway station. And then I drove home! I had plenty to think about.

The previous time I basically learned that I should not put a wind turbine on my house. This time I had learned that pretty much since my house had been built, all the alterations that had been made to it were detrimental. I should stop going there! I only learn depressing things. But I still love the place, and the kind of people it attracts. So I will be back I think! Maybe next time for something a bit more constructive? Like building furniture out of recycled wood or something? That sounds like something that doesn't leave you feeling like everything about your house is wrong!