How do I stop moisture between foundation and slab?
I have a homeowner who is having moisture issues in one of her bedrooms. Everything we build now has a capillary break and vapor barrier under the slab and a WRB on the exterior sheathing of the home, but this one, like hundreds we’ve built over the years and countless thousands in our market doesn’t have either. This home has a pier and grade beam foundation with a floating slab on about 16 inches of fill sand. We are getting some moisture at the base plate from the outside (I assume) and some coming up through the joint between the slab and the foundation and it’s causing a strong musty smell. I haven’t had this happen before.
After reading an article here, I think the water at the base plates could very well be from solar vapor drive as this room faces south and west. We’ve had a lot of rain and we also have strong winds from the south which blow water from the sprinklers on the brick keeping it wet frequently. I think I’ll have to take off the brick veneer, install a drainage plane on the wall sheathing and make sure the air gap (between the brick and wall sheathing) breathes. I’ll also seal it off well to form a good air barrier.
I’m not sure how to handle the water coming up between the foundation and the slab. We had caulked the joint, but the caulk is wet to the touch and coming out. I considered digging down and placing aggregate on the outside of the foundation for a capillary break, but I assume this will be ineffective as the moisture can still go under it and back up through capillary action. I also considered finding some kind of waterproofing membrane over the joint and a concrete sealer in the rest of the room. Any suggestions? There is pretty fair drainage away from the house. No standing water. Thanks.
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