Sealing concrete block retaining wall

Originally Posted By: jhugenroth
This post was automatically imported from our archived forum.

I had a question from a Realtor concerning a moisture problem in her house. The house is built against a hillside, with a concrete block retaining wall up to the soil. This area usually only gets 10 inches of rain a year, but this year we have had 14, with more on the way. She said she had a cardboard box in a closet that she used for filing, so it never got moved. Well, she moved it the other day, and the back and underside were wet and moldy. I let her borrow my moisture meter, and she said the sheetrock was wet up to about four feet. How would they seal the wall against moisture penetration? I know the wall should be sealed on the soil side, but they don’t have that option now. Is there some kind of sealant or vapor barrier that can go on the inside of the block wall? Any other recommendations, thoughts, comments?

I haven’t seen the house, so I’m just going on what the Realtor told me.

She said they have no idea where the moisture is coming from.

Originally Posted By: dvalley
This post was automatically imported from our archived forum.


There is no lasting permanent solution to keeping this closet area permanently dry from the inside. Wall anti-leaking barriers do not affect water penetration due to massive water accumulation at the exterior footer and foundation area. The water accumulation next this wall (from the exterior) is the problem. This exterior hillside water must be diverted away from the rear of the house in order to keep the inside dry.

The ideal solution to this problem lies in directing the accumulation of water away from the foundation or into a some sort of drainage or pumping system. Being on a hillside, an exterior diversion is needed in order to handle surface runoff flowing next to the exterior foundation from the upslope of the hill.

I would recommend directing hillside water to a safe outlet -- never directly onto the downstream slope itself. And never direct water onto adjoining property without consulting the owners. A french drain system is another good option.

Another solution would be to install some sort of culvert to direct this rain water around the house. Always consult a qualified engineer to design water diversion measures in this situation.

David Valley
MAB Member

Massachusetts Certified Home Inspections

"Some cause happiness wherever they go; others, whenever they go."

Originally Posted By: jhugenroth
This post was automatically imported from our archived forum.

Thanks, David

I haven't seen it, but from what she tells me the soil is right up to the block wall, with a hill behind. Sounds to me like they have a very bad problem with no real solution. The water from all the rain is percolating through the soil, and seeping into the wall. Besides diverting the runoff, the block wall should have been sealed on the soil side. Maybe it was, and it cracked. I'm just glad I'm on the outside looking in.