JohnnyB Posted September 9, 2024 Posted September 9, 2024 I'm looking for advice on sealing around the windows and doors in our hempcrete house. I was thinking I would use compriband tape and then airtight tape on the inside between window frame and studwork but the hempcrete doesn't have a smooth even finish and there are gaps under the timber spacers fixed to the timber frame. Does compriband expand into small gaps and holes to seal tight againest the weather or would I be better to use FM330 foam and then us something else in the gap between the frame and wall to insulate the gap? If I used the foam any ideas on options to insulate the gap if it doesn't have compriband tape in there? Compriband would seem a little expensive/overkill if I use FM330 to seal the outside. The outside is timber clad so I will have timber around the outside reveal and the inside will have woodwool board and then plastered. Also any thoughts on fixing plates? I was thinking of simple metal strips but are there other options? Thanks, Johnny
Nick Laslett Posted September 9, 2024 Posted September 9, 2024 @JohnnyB, I have some left over rolls of compriband, various expansion thickness if you want some to experiment with. TP651 https://www.illbruck.com/en-gb/products-systems/product-finder/tp651-trio/
Redbeard Posted September 9, 2024 Posted September 9, 2024 Perhaps a v 'tight' coat of plaster (I would use lime, as I like it) for the Compriband to 'bear' on?
JohnnyB Posted September 9, 2024 Author Posted September 9, 2024 4 hours ago, Nick Laslett said: @JohnnyB, I have some left over rolls of compriband, various expansion thickness if you want some to experiment with. TP651 https://www.illbruck.com/en-gb/products-systems/product-finder/tp651-trio/ Thank you Nick, that is very kind. cuold you send me your address please and I'll head round at some point very soon
JohnnyB Posted September 9, 2024 Author Posted September 9, 2024 4 hours ago, Redbeard said: Perhaps a v 'tight' coat of plaster (I would use lime, as I like it) for the Compriband to 'bear' on? Yes, that would work but I'm not sure I have the time. I would need to wait for the plasterer to come and put a thin coat on and then let it dry before I could fit the windows. The windows are arrive about the same time the plasterer is coming to start on the internal walls. My previous attempts at plastering have been terrible so I'm not going to try doing it myself.
ChrisInKent Posted November 22, 2024 Posted November 22, 2024 @JohnnyB I’m about to compriband tape my windows. Did you do the underside/ bottom of windows? All the videos I’ve seen just show top and sides taped.
Mr Punter Posted November 22, 2024 Posted November 22, 2024 3 hours ago, ChrisInKent said: @JohnnyB I’m about to compriband tape my windows. Did you do the underside/ bottom of windows? All the videos I’ve seen just show top and sides taped. I do all round. 1
Adaman Posted November 24, 2024 Posted November 24, 2024 (edited) Hi Jonny, you've probably already done the job, but I'd suggest burnt sand mastic to seal timber winders into a lime rendered masonry. It's hygroscopic and maleable throughout its life time to adapt to the expansion and contraction at differing rates of the materials around it. https://cornishlime.co.uk/products/associated-products/cornerstone-burnt-sand-mastic/ or https://www.lime.org.uk/burnt-sand-mastic.html Edited November 24, 2024 by Adaman
Adaman Posted November 24, 2024 Posted November 24, 2024 What width / thickness did you go for on those hempcrete walls?
JohnnyB Posted December 4, 2024 Author Posted December 4, 2024 On 22/11/2024 at 12:21, ChrisInKent said: @JohnnyB I’m about to compriband tape my windows. Did you do the underside/ bottom of windows? All the videos I’ve seen just show top and sides taped. Sorry for the slow reply, I've been rather busy trying to get enough finished in the house to be able to move in and haven't been on here for a while. I didn't use the compriband in the end as it needs a reasonably smooth/flat surface to work, and hempcrete isn't smooth. I ended up using the Illbruck FM330 expanding foam and that has worked well for my situation. I used it under the windows as well. On 24/11/2024 at 19:25, Adaman said: Hi Jonny, you've probably already done the job, but I'd suggest burnt sand mastic to seal timber winders into a lime rendered masonry. It's hygroscopic and maleable throughout its life time to adapt to the expansion and contraction at differing rates of the materials around it. https://cornishlime.co.uk/products/associated-products/cornerstone-burnt-sand-mastic/ or https://www.lime.org.uk/burnt-sand-mastic.html I have done it but still have the main house to do next year so I will look at that for next time. As mentioned above I used airtight foam which has worked well but doesn't feel quite the right thing to be using with hempcrete but at this stage there have been a lot of compromises that's very few things I regret yet. On 24/11/2024 at 19:25, Adaman said: What width / thickness did you go for on those hempcrete walls? It varies depending on the exterior finish and the wall build up needed to make the cladding longer up with the brickwork as we want it, but the thinnest sections are 380mm of hempcrete and 440 at the thickest.
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