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- 6 Oct 2010
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Hi,
I am converting the 10mx3m former garage beneath my house into a workshop. Having built a box garage elsewhere, the previous owner clad the inside of the garage with wooden panelling, which I removed earlier in the year, to find damp patches.
Walls are 20/30cm Ytong, AFAIK, none has been treated in any way to prevent moisture ingress. There is no damp in the house - only in the crawlspace, where humidity is always >85%, and the garage, where it's almost as high. No running water or condensation - just humidity. My target in my workshop-to-be is 55%, with minimal recourse to power-consuming devices.
Looking through the garage door, the long left-hand wall divides it from the crawlspace; a full-height door connects the two near the garage's back wall. Inside the crawlspace, along that wall it's high enough to stand, but under the majority of the house there is only 40-50cm clearance.
A single, 10x18cm grille provides the only ventilation to the crawlspace (total area ~60m2).
The back wall of the garage had damp problems due to a blocked drain - now fixed following camera inspection; with fans blowing on the area for a month now has visibly dried out. The right hand wall of the garage adjoins the garden, and is dry - ground level is around shoulder height from the garage floor - as are the exterior wall footings in the crawlspace.
View media item 38243
The attached photo (taken through the door) shows the footing height and the ventilation opening. That's not a crack on the right, BTW - a shift from 20 to 30cm Ytong where the footing drops (although I suspect it should have been 30cm everywhere).
I think that because the bulk of the volume of the crawlspace is below the footings and drains, there's no way of preventing moisture from seeping in through the soil and into the garage through the party wall.
Is that sound thinking?
My plan is to drywall the garage (40mm polystyrene, then 10 or 12mm fermacell), but I think that in addition to better ventilation of the crawlspace, the party wall also needs some treatment on the crawlspace side.
Am I on the right track?
Any advice appreciated.
I am converting the 10mx3m former garage beneath my house into a workshop. Having built a box garage elsewhere, the previous owner clad the inside of the garage with wooden panelling, which I removed earlier in the year, to find damp patches.
Walls are 20/30cm Ytong, AFAIK, none has been treated in any way to prevent moisture ingress. There is no damp in the house - only in the crawlspace, where humidity is always >85%, and the garage, where it's almost as high. No running water or condensation - just humidity. My target in my workshop-to-be is 55%, with minimal recourse to power-consuming devices.
Looking through the garage door, the long left-hand wall divides it from the crawlspace; a full-height door connects the two near the garage's back wall. Inside the crawlspace, along that wall it's high enough to stand, but under the majority of the house there is only 40-50cm clearance.
A single, 10x18cm grille provides the only ventilation to the crawlspace (total area ~60m2).
The back wall of the garage had damp problems due to a blocked drain - now fixed following camera inspection; with fans blowing on the area for a month now has visibly dried out. The right hand wall of the garage adjoins the garden, and is dry - ground level is around shoulder height from the garage floor - as are the exterior wall footings in the crawlspace.
View media item 38243
The attached photo (taken through the door) shows the footing height and the ventilation opening. That's not a crack on the right, BTW - a shift from 20 to 30cm Ytong where the footing drops (although I suspect it should have been 30cm everywhere).
I think that because the bulk of the volume of the crawlspace is below the footings and drains, there's no way of preventing moisture from seeping in through the soil and into the garage through the party wall.
Is that sound thinking?
My plan is to drywall the garage (40mm polystyrene, then 10 or 12mm fermacell), but I think that in addition to better ventilation of the crawlspace, the party wall also needs some treatment on the crawlspace side.
Am I on the right track?
Any advice appreciated.
