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Damp on Garage Wall Cavity and What Possible Fixes are There?

Postby BiggusDickus » Thu Jun 15, 2017 2:57 pm

Can anyone help with ideas, solutions or products for my problem below please?

Basically I have a detached single garage. It's ground level is lower than my neighbours ground level, so the lower half of this one wall is below their garden level (soil against my wall). Strangely this wall is a cavity wall. The roof has recently been replaced with one piece rubber (EPDM) and is sound, but the issue was present before this was replaced (I didn't know if the old corrugated roofing was causing the issue or not before it was replaced). Anyhoo, hours after heavy rainfall, or periods of continued rainfall, the lower 3/4 courses of bricks along this wall become saturated and water pools on the floor - enough to make a splash with your hand. Also, during this last winter I noticed that the OSB3 roof decking going above the cavity was also showing signs of water/damp - I guess where the cavity is pooling water that then evaporates, the moisture comes upto those boards and soaks in? The inner cavity wall is bone dry above the bottom 3/4 courses that get saturated.

The true fix would be to knock the garage down and rebuild, but this would be a huge cost - money I haven't got anytime soon.

Is there any solutions that people know of that can help me out? I have not yet had any damp proofing contractors in to survey, thought I would put the question out there first. I'm hoping that there could be some kind of waterproofing foam that could be injected through the inner wall into the cavity to prevent to the water ingress into the cavity from the outer wall? Simply rendering the inner wall with a damp proofing mix would not stop the cavity water moisture in the air rising up and getting into the roofing deck boards above the cavity.

Thanks in advance, Richard.
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Simply Build It

Postby collectors » Sat Jun 17, 2017 8:45 pm

Any soil against the garage wants to be removed by digging a trench along the area & at worst put a perforated land pipe in & then soil pipe to a soak away. Then back fill with 10mm pea shingle.
But would be better with no soil against the wall.
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