Breathable walls

My Shabbihaus eco retrofit project part 4 living wall insulation

Dry air in the house is a good achievement but I have also been worrying about the pollution levels. Two of the three air intakes are located above the back garden and the front one has some good tree coverage between it and the road but it is still a busy traffic area. This made me look at some alternative ways of cleaning the air, I did some googling and came across the NASA research project on houseplants and their impact on air quality. Now before I go any further I do realise that these were controlled tests and we would also need a very large number of plants to get a big impact but I figure it can’t hurt and what I made looks great.

I have been keen to do something with reclaimed wood and also to add some extra insulation to the flank wall in the kids bedroom so I got a bit carried away here and produced this wall made from old pallets with 50mm of woodfibre insulation behind it. I was a bit nervous about this project as it has a bit more of a design impact than some of the other projects, it’s been in a while now though and I am so pleased with the outcome visually.

The first thing we did was tour the streets collecting abandoned pallets. I found that ones that were slightly broken already were better as they are easier to dismantle than really well built ones. The kids really enjoyed the collection process and I also got them to stain some of the planks we extracted to add some variety to the wall.

Next step was to get hold of some wood fibre insulation, not so easy for small quantities but thanks to https://phstore.co.uk/ for arranging it for me, delivery costs almost the same as the insulation in small quantities but cheaper than elsewhere and charming service too. I then fixed some 50mm battens to the wall at 600mm and push fitted the insulation between.

The next bit involved a nail gun so was great fun managed to charm the lady at Travis Perkins into giving me a discount and I was off. I fixed them in an offset pattern and tried to group similar widths of board together so it wasn’t too bumpy.

Then we had to make shelves for the plants to grow on. I used the ‘dice’ from the pallets (technical term for the square bits that go in between the pallets) screwed into the wall to support shelves made from more pallet boards. These dice are pretty tough and tricky to drill through, one of them still has half a drill bit in it where it snapped.

Once it was all up we put in the plants, I used Chinese evergreen, peace lily, some snake plants and a cutting from an old spider plant. I also put in a watering system! Well, I bought some globes that you fill up and they drip out over a couple of weeks, they are a bit inconsistent but a lot cheaper than some automated system. I top them up with waste water from kids water bottles and they are still growing nearly a year later.

I have spent the last couple of days on a lime plastering course in Bedford. I am learning this skill so I can deliver more retrofit services to the customers of www.ecoalex.com. One of the key ways to improve the energy performance of older houses is to add internal insulation to walls. There are lots of people offering this service with celotex and other oil based insulation materials. These are very efficient and applicable in many more modern homes, however they do require careful installation of vapour barriers in the walls and have a risk of condensation. I want to be able to offer my customers something a little different, Natural Insulation. This will enable be breathable and allow moisture to pass through it naturally rather than gathering hidden inside the construction of the wall. After talking with a vegan customer I have been looking at wood fibre insulation in batts and boards. To get all this finished properly it needs plastering, modern plaster sets solid and isn’t breathable so I have been learning to work with lime.

There is a resurgence of interest in lime plaster at the moment, partly because of heritage projects like St Pancras station and partly because of a renewed interested in it’s flexibility and breath ability. This meant there was a choice of a few courses, however a lot of them were quite rural and a good distance from London so I chose DIY plastering in Bedford and I am very pleased I did. The course was one to one so I got plenty of help from Paul and could have it tailored to my requirements.

When I got there Paul had prepared two walls, one typical brick one and a second much flatter one to simulate the type of wall I am building using wood fibre insulation. After checking my fitness we agreed to try and plaster both walls so I could tackle any different lime issues. I started with the masonry wall applying two guides across the wall that would cover all the bumps and undulations and produce a flat surface. I then filled in with plaster and used a straight edge to get the plaster flat and even.

Then we left this to dry and I moved on to the flatter surface set up to simulate wood fibre board. Here I applied a much thinner coat of plaster, embedded some mesh in it and then a second thin coat. This was then flattened using the straight edge. Only 10-15mm of plaster are needed as the base wall is so much flatter than an older brick wall. Once these two walls had dried a little I went over them with a float, flattening the surface and adding some roughness for the skim coat. That was day one completed.

Day two was all about getting things smooth, very satisfying it was too. After drying overnight both walls had developed some cracks, especially the masonry one where we had a much thicker covering of plaster. Many of these could be sealed again with the floats but the larger ones needed a bit more compression from the trowel and some extra plaster adding. Next we added the top coat of plaster, this had more lime and less sand to make it smoother, but went on the same way using a trowel. Once the wall was covered with an even layer of topcoat we left it to dry. During this time Paul gave me a quick tutorial in filling holes in walls, very useful for my bathroom wall. Then I went over the wall with a float to even out the plaster further.

After this and some more drying I went over it with a trowel to get it even flatter and remove the air bubbles. It was all very pleasing to produce such a flat surface. At this point you can keep going making it flatter and smoother gradually using the trowel and the float. Looking forward to using the skills on an insulation project next month in Hertfordshire, get in touch if you would like me to help you with your house. I am based in Central London but can travel. There are lots more photos on my Google+ page.