Damp-proofing (?) an existing wall

Katymac · 4 Nov 2006

My barn again

Could we paint 4 coats of bitumen on the walls of the barn, before putting insulation in (& then either a stud wall or a block wall) to act as a bit of damp-proofing?

How much of a gap can we leave to put cavity wall insulation in?
Is there any benefit in putting an extra thickness of insulation?

Will this cause problems when fitting the windows if the cavity is extra wide?

Thanks
KMc

noseall · 4 Nov 2006

Katymac said:
My barn again

Could we paint 4 coats of bitumen on the walls of the barn, before putting insulation in (& then either a stud wall or a block wall) to act as a bit of damp-proofing?

How much of a gap can we leave to put cavity wall insulation in?
Is there any benefit in putting an extra thickness of insulation?

Will this cause problems when fitting the windows if the cavity is extra wide?

Thanks
KMc

a vapour barrier in the form of a breathable membrane would be more suitable than a painted on version.

there shouldn't be a problem with the windows and thicker walls, as all you need to do is fit deeper window boards. you can buy 300mm wide pre-primed mdf window boards off the shelf.

75-100mm full fill cavities are normal, though insulation plus a 25mm air gap would be ideal.
an ideal wall would be 100mm brick work, 25mm air gap 50 mm rigid celotex (pinned back), lightweight blockwork, dot'n'dab or light weight plaster.

Katymac · 4 Nov 2006

I have 9 inch block wall atm....how does that fit into your scheme?

markthebuilder · 5 Nov 2006

go for 75mm full fill insulation and a 4" inner block wall
you are going to have to consider the detail around window and door oppenings as 9"" external will bridge past windows and doors

Tozzy · 6 Nov 2006

Could we paint 4 coats of bitumen on the walls of the barn

External, internal walls or both? Does anyone know if DPC actually exists in internal walls, other than external walls?

Katymac · 6 Nov 2006

External walls for the bitumen (maybe?) & are 9 inch block work
Internal walls don't exist yet but will have a dpc & as yet there construction has not been decided on

ops

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Damp-proofing (?) an existing wall

Katymac

noseall

Katymac

markthebuilder

Tozzy

Katymac

DIYnot Local

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