We’ve now completely re-plastered our house internally using lime and a three coat system. It’s a 3 story house and on the top floor, we used steico woodfibre and NHL2. On the 1st floor, we used an insulating lime plaster as the middle layer on the external walls. For a few reasons, we didn’t continue with the wood fibre on this floor. My query relates to the subfloor. How do we now prevent cold air coming in through the subfloor wall and coming up through our footboards? They are all lifted currently which gives us the opportunity to do something, but we’re under time pressure and need a relatively fast and cost effective solution. Suggestions appreciated.
- Thread starter Maria D
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There have been many posts here in recent times concerning materials and methods to insulate suspended wooden floors. A search of the site using that term will produce many of the them for your examination and consideration.
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Sorry, I may have misunderstood. Could you clarify please? Do you feel that cold air is rising first 'through' a subfloor wall before then emerging into the room via gaps between the floorboards? Is this a cavity wall of some kind or a solid wall sitting on a foundation?
Apologies I may have used incorrect terms. Solid wall redbrick. Replastered with insulating lime on 1st floor and with woodfibre on 2nd floor. Underneath the floorboard is bare brick. I’m concerned that when we relay the floorboards, the cold air will come in through the brick and up through the boards. I want to mitigate this issue while allowing some airflow around the joists. Is it possible?
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As I understand it yes, but I haven't used the materials and technique myself. This consists of installing two membranes, the first is draped over the top of and between the joists with the trough then used to carry an insulating material and a further membrane above over which the floorboards are then re-laid. The lower membrane is breathable to allow air circulation around the joist timbers.
That said, please do not trust this guidance as I could be mistaken. It may be an idea to look up a recent thread posted by @lizziecupcakes, and others to which she refers, that I think will provide more reliable information.
That said, please do not trust this guidance as I could be mistaken. It may be an idea to look up a recent thread posted by @lizziecupcakes, and others to which she refers, that I think will provide more reliable information.
I’ve actually used this system on the ground floor. I got a comment in to do it and I’m very happy with it. I don’t think I need to go to this level on the first floor (& it’s very expensive to get done). I’m hoping for a cheaper, quicker solution. Maybe wood fibre board up against the wall between the joists?
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Frankly speaking the amount of cold that would be transmitted vertically through a masonry wall to then be transferred by air movement through the voids of upper floors would be nigh on zero. Particularly as some most of that cold would have been neutralised by your heating systems. Sorry Maria, but bluntly put I think you are over-engineering a solution for no real need.
Thanks Paul. So, should I even bother laying mineral wool flat between the joists before I relay the floorboards? I was going to do this to reduce noise from TV and kitchen room below. Might be another unnecessary step that won't have much effect, although I did read posts where others did it.