Dry lining with thermafleece - why the VCL?

wildwords1 · 29-11-2015 11:36pm #1

Hello,

I'm looking into dry lining a solid stone wall in a mid 19Century house. I'd like to use 70mm - 90mm sheep wool product from 'thermafleece'. The recommendations are to use a breather membrane on the cold side and Vapor control layer on the warm side.

From other recommendations, things should be kept as breathable as possible,

I am looking for advice on why I should include these 'vapour controlling' layers made from synthetic fibers (no matter how breathable the manufacturers says they are).

why is it not recommended to just put 70-90mm battens on wall (possible insulation between batten and wall?) and put sheep wool in between? the sheep wool product preforms to spec. up to 33% moisture.

also could I then run my service ducting in the wall

any advice welcome.

Emo

BryanF · 30-11-2015 8:26pm

Intelligent Vapour barrier on warm side of insulation is essential

http://www.greenspec.co.uk/building-design/airtightness-membranes/

What type of plaster is on the inside and outside of the wall? Ie is the existing plaster lime or cement?
Is there dampness currently?
How is the house ventilated?

The Sidewards Man · 01-12-2015 3:13am

Outside of wall may be exposed stone Bryan, steady your compass.

wildwords1 · 01-12-2015 12:39pm

thanks for response, here is some more details

Lime plaster on inside and outside of walls - some plaster starting to fail (x3 6 inch patches) on outside gable end which gets most weather, does not sound hollow underneath in other areas.

There is dampness on the gable end which gets the weather on the ceiling joint downstairs and all the walls upstairs - from what I see (without destructive survey yet) this looks to be from driving rain and vegetation around base of wall.

On this end of the house, the ground floor was also dry lined in 1980's with 15mm of white polystyrene and foil backed plaster board. I have taken off a 6 inch by 6inch section at the bottom and the wall is dry, however there is damp on the ceiling where it meets the wall and I suspect it is from the timbers of the first floor joists - driving rain, moisture etc.

Im thinking of timber cladding the external gable which gets the weather and dry lining the whole house with 80mm thermafleece, but I am very reluctant to put in vapour barriers, I wear gore-tex (vapour control layers based on the same technology) a lot in work and hate the feeling of being in a plastic bag, it is not as breathable as people say and also looses breathability over time. I don't want to live in a plastic bag, I dont think it is healthy, I'm happy for the house not to be airtight and don't really believe the manufactures claims of breathability.

I would however like to be warm and dry though, hence thermafleese, isn't the claim of the sheeps wool insulation that it can absorb moisture and then dry out over and over again and that it retains its thermal properties when wet to 33%? why the vapour control barrier then? otherwise external insulation (something like diffutherm or steico protect - cant figure difference) looks on cards but I am reluctant to loose sight of the old sandstone sills and outside character, will be building new extension on gable end and external insulation would tie in better with that to create complete envelope over whole building at end but I'm very reluctant to mess with old building to much. any advice welcome.

Emo

BryanF · 01-12-2015 3:54pm

wildwords1 wrote: »

thanks for response, here is some more details

Lime plaster on inside and outside of walls - some plaster starting to fail (x3 6 inch patches) on outside gable end which gets most weather, does not sound hollow underneath in other areas.

There is dampness on the gable end which gets the weather on the ceiling joint downstairs and all the walls upstairs - from what I see (without destructive survey yet) this looks to be from driving rain and vegetation around base of wall.

On this end of the house, the ground floor was also dry lined in 1980's with 15mm of white polystyrene and foil backed plaster board. I have taken off a 6 inch by 6inch section at the bottom and the wall is dry, however there is damp on the ceiling where it meets the wall and I suspect it is from the timbers of the first floor joists - driving rain, moisture etc.

Im thinking of timber cladding the external gable which gets the weather and dry lining the whole house with 80mm thermafleece, but I am very reluctant to put in vapour barriers, I wear gore-tex (vapour control layers based on the same technology) a lot in work and hate the feeling of being in a plastic bag, it is not as breathable as people say and also looses breathability over time. I don't want to live in a plastic bag, I dont think it is healthy, I'm happy for the house not to be airtight and don't really believe the manufactures claims of breathability.

I would however like to be warm and dry though, hence thermafleese, isn't the claim of the sheeps wool insulation that it can absorb moisture and then dry out over and over again and that it retains its thermal properties when wet to 33%? why the vapour control barrier then? otherwise external insulation (something like diffutherm or steico protect - cant figure difference) looks on cards but I am reluctant to loose sight of the old sandstone sills and outside character, will be building new extension on gable end and external insulation would tie in better with that to create complete envelope over whole building at end but I'm very reluctant to mess with old building to much. any advice welcome.

Emo

there'sso many points/questions to answer there..

Research calcium silicate, hemplime, gutex, and use one of these or use intello or ea

Dry lining with thermafleece - why the VCL?

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