While I waited for the mortar to go off on the wall repair, I started to secure wall panel frames to the frame. I started by marking the amount I needed to take off the first wall panel frame to allow expanding foam to fit between this frame and the green oak frame. The green oak is going to shrink across its width so the expanding foam’s function is to fill the gaps that will emerge between the softwood frames and the green oak in this process.
I planed the frames to this line using an electric plane.
I then created recessed holes in the top of the frame to take 100mm stainless steel screws to secure the top of the frame to the green oak wall plate.
I have two sizes of expanding foam tape. Both are 15mm wide. One creates a weather-proof seal across 1 to 4mm but will ‘gap fill’ up to 9mm. This is perfect for the sides of the frames. These joints will not be exposed to weather so it’s just gap filling I want to stop drafts.
The second tape creates a weather-proof seal across 5 to 12mm but will ‘gap fill’ up to 28mm. I’m using this across the top of the frame.
First I stuck the tape to the sides and top of the frame.
I put strips of polythene sheeting on the sides of the posts to allow the tape to slide in. This worked brilliantly and I could easily pull out the polythene once the frame was in place.
In most places the gap looked like this.
Initially, I could see light through the junction at the top right of the frame. This was the only place.
But after a couple of hours the foam had expanded to completely fill the gap.
I used 15mm spacers to keep the frame the correct distance from the braces and secured the top of the wall panel frame to the green oak wall plate. My logic here is that when the wall plate shrinks the bottom face won’t move upwards, but instead the top face will move downwards. So, fixing the frame at the top won’t be a problem. Note, however, there are no fixings down the side of the frames as I think this would pull the frame out of shape when the posts shrink.
I used another 40mm ‘spacer’ to tap the frame into the right position to allow for the featherboards to fit against the posts without protruding beyond the face of the posts.
Once in the correct position, I hammered in wedges to lift the frame up as much as possible and compress the foam tape along the top edge. I then injected a sealant adhesive – CT1. This will form a seal and secure the frame to the brick plinth.
I was a bit apprehensive about all of this but the method worked really well. Using polythene sheet to insert the taped frame was a brainwave!
Onwards and upwards.