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- 22 Mar 2010
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Hi. This is a first post, and I'm in a bit of a quandary about membranes on timber frame builds.
This is not a 'conventional' timber frame build - at least not initially. I do not have planning permission for a house, so I am following an unusual precedent set by a neighbour.
A bit of background ....
I currently live on a large (several acres) plot, in a large residential mobile home. I have full planning permission for this. The legal term for this is 'caravan', and the legal definition of a 'caravan' in a nutshell amounts to a transportable modular type structure (not necessarily on wheels), made up of no more than two modules/parts, up to about 65 feet long and 23 feet wide. There's obviously a lot more to it than that, but that's the basics.
My neighbour (with the same permission) has got around this by effectively building the inside of a 1,000sq.ft timber framed bungalow, on discrete columns of concrete blocks, with a full slate tiled roof, and a suspended timber floor, but without the masonry skin, theoretically qualifying as a 'caravan'. He then applied for planning permission to turn it into a permanent dwelling by adding a blockwork skin, on the basis that there was 'no material change' and there would be no additional vehicle movements. [We also have an unrelated bargaining chip which helps]. The permission was approved.
The council have advised me that although I cannot build a house outright, I can follow his precedent as a route to getting a permanent dwelling.
I am doing the same. Last year I discreetly buried a full set of house foundations under a portion of my land and covered them over. On this I am building columns of concrete blocks which will support a timber frame on a suspended timber floor with a slate tiled roof. Initially I will only build the timber frame, then I'll apply for the same planning permission, wave my bargaining chip and hopefully get the masonry skin/permanent dwelling approval, on the same grounds as my neighbour PLUS the precedent set by him.
Problem.
For a year or so, it's going to have to survive as just a timber frame with no masonry skin, and look half decent. I know this is possible, as my neighbour managed it. My initial plan was to build the frame as (starting from the inside) Plaster, Plasterboard, Vapour check membrane, 140mm timber frame with 140mm frametherm insulation, followed by 11mm OSB skin to which I was going to apply a temporary coating of primer followed by some kind of textured masonry paint. The paint protects the OSB for the year it has to spend un-clad. At the end of the year, if I get permission to turn it into a dwelling, I add a breather membrane and the masonry skin. If for some reason I don't get permission and it has to stay a 'caravan', I then add a membrane, battens and cedar cladding.
BUT. Is the temporary coating of primer+textured masonry paint going to form effectively an external vapour check membrane and ruin the outward path of condensation?
AND. For the year it spends un-clad, do I need to consider a breathable membrane BEHIND the OSB?
Thanks. I'm due to commence the timber frame just after Easter, the timber goes on order tomorrow!
This is not a 'conventional' timber frame build - at least not initially. I do not have planning permission for a house, so I am following an unusual precedent set by a neighbour.
A bit of background ....
I currently live on a large (several acres) plot, in a large residential mobile home. I have full planning permission for this. The legal term for this is 'caravan', and the legal definition of a 'caravan' in a nutshell amounts to a transportable modular type structure (not necessarily on wheels), made up of no more than two modules/parts, up to about 65 feet long and 23 feet wide. There's obviously a lot more to it than that, but that's the basics.
My neighbour (with the same permission) has got around this by effectively building the inside of a 1,000sq.ft timber framed bungalow, on discrete columns of concrete blocks, with a full slate tiled roof, and a suspended timber floor, but without the masonry skin, theoretically qualifying as a 'caravan'. He then applied for planning permission to turn it into a permanent dwelling by adding a blockwork skin, on the basis that there was 'no material change' and there would be no additional vehicle movements. [We also have an unrelated bargaining chip which helps]. The permission was approved.
The council have advised me that although I cannot build a house outright, I can follow his precedent as a route to getting a permanent dwelling.
I am doing the same. Last year I discreetly buried a full set of house foundations under a portion of my land and covered them over. On this I am building columns of concrete blocks which will support a timber frame on a suspended timber floor with a slate tiled roof. Initially I will only build the timber frame, then I'll apply for the same planning permission, wave my bargaining chip and hopefully get the masonry skin/permanent dwelling approval, on the same grounds as my neighbour PLUS the precedent set by him.
Problem.
For a year or so, it's going to have to survive as just a timber frame with no masonry skin, and look half decent. I know this is possible, as my neighbour managed it. My initial plan was to build the frame as (starting from the inside) Plaster, Plasterboard, Vapour check membrane, 140mm timber frame with 140mm frametherm insulation, followed by 11mm OSB skin to which I was going to apply a temporary coating of primer followed by some kind of textured masonry paint. The paint protects the OSB for the year it has to spend un-clad. At the end of the year, if I get permission to turn it into a dwelling, I add a breather membrane and the masonry skin. If for some reason I don't get permission and it has to stay a 'caravan', I then add a membrane, battens and cedar cladding.
BUT. Is the temporary coating of primer+textured masonry paint going to form effectively an external vapour check membrane and ruin the outward path of condensation?
AND. For the year it spends un-clad, do I need to consider a breathable membrane BEHIND the OSB?
Thanks. I'm due to commence the timber frame just after Easter, the timber goes on order tomorrow!