Basement moisture issue..

[tropics surfer]

Probably been discussed a zillion times...concrete block construction, blocks filled with cement, and now a year or so after finishing, moisture is lifting the paint off the walls, where the basement is in the hillside.
At first, it was only in a small area and I thought it was residual moisture inside the blocks left over during construction. It rained "a little" during construction.
We get about 6 feet of rain a year here.
So, now it's breaking out like ebola, lifting the paint, primer, etc., and I have no idea how to treat it. The wall exteriors are now buried in the hillside and backfilled with a rock/sand-like mixture that supposedly drains well, and the soil in the hillside, everywhere around us actually, has a high clay content that when dry season is here, is like concrete.
So, I've read about stripping the walls and using barrier paints, and understand that epoxy paints are good, but would we need to sandblast all the latex off the walls first? That would be a monumental task. My hope is that there is a water based barrier paint that would work.
This is what my wife calls "charms and challenges", living in the tropics--you get both.
And, we're limited by what HD, Sears, etc. carries in stock, and newer products you find in the States take a long time to reach us.
Thanks for any ideas, Buzz

[johnfrwhipple]

Do you have a perimeter drainage system in place? Perhaps it was broken or became clogged. Many time the drainage pipes are not covered properly with landscape cloth and drainage rocks.

Any ideas on this. If this is the root of the problem you might be able to snake the drain lines clean or find the break or plug in the system.

If opening up the backside of the home is not an option you might need to install an interior perimeter drainage system. There is no easy option - sad to say.

JW

[tropics surfer]

thanks John. No perimeter drainage system in place, but there is a concrete walkway and a patio surrounding the back wall. I trusted the builders knew what they were doing; turns out they were likely guessing. The basement wall is set forward from the upstairs by 3 feet and has the mentioned walkway and patio above...This is most likely moisture coming in from below ground due to the amount of rainfall we get.
I'm looking at the only solution I can find and that is strip the existing paint and dry to dry the walls somewhat, then recoat with something like Zinsser Water-tite, repaint and hope for the best.

[Dana]

If you have real bulk water issues to deal with there is no such thing as an interior side paint-on solution.

If it's water wicking up from a poorly drained footing it's possible to trench in a perimeter drain on the interior below the slab that could relieve much of it. If the walls were not waterproofed, yet backfilled with a sandy mix much of it could be coming through the walls from the side, no matter how well the backfill drains. (Gravel such as 1/2-3/4" screenings, with a minimum of sand "fines" works a lot better.)

If your roof overhangs are minimal and rainwater isn't ducted well away (as is the case for many concrete & tile roofs) you may get some relief out of a buried perimeter drain comprising of 3-4' of EPDM roofing attached to the foundation about a foot below grade that slopes at least an inch per foot going away from the foundation, with a perforated drain at the outer edge of your EPDM skirting to direct the water elsewhere. See the details on p.6 (.pdf pagination) of this document.

It's sometimes hard to diagnose the true water pathways even WITH a site visit. I'm not sure if you'll be able to nail it with a web-forum approach. Most moisture problems are bulk-water related, but capillary draw through soils and concrete are quite powerful. Unless the footings are well drained (6" of compacted gravel, no fines) or a capillary break is inserted between the footing & foundation wall it's quite possible that the moisture coming through the wall is being slurped up from the footing.

[tropics surfer]

Thanks Dana, much to think about..

[Windows on Washington]

Is this Dana from Green Building Talk....?

If you have real bulk water issues to deal with there is no such thing as an interior side paint-on solution.

If it's water wicking up from a poorly drained footing it's possible to trench in a perimeter drain on the interior below the slab that could relieve much of it. If the walls were not waterproofed, yet backfilled with a sandy mix much of it could be coming through the walls from the side, no matter how well the backfill drains. (Gravel such as 1/2-3/4" screenings, with a minimum of sand "fines" works a lot better.)

If your roof overhangs are minimal and rainwater isn't ducted well away (as is the case for many concrete & tile roofs) you may get some relief out of a buried perimeter drain comprising of 3-4' of EPDM roofing attached to the foundation about a foot below grade that slopes at least an inch per foot going away from the foundation, with a perforated drain at the outer edge of your EPDM skirting to direct the water elsewhere. See the details on p.6 (.pdf pagination) of this document.

It's sometimes hard to diagnose the true water pathways even WITH a site visit. I'm not sure if you'll be able to nail it with a web-forum approach. Most moisture problems are bulk-water related, but capillary draw through soils and concrete are quite powerful. Unless the footings are well drained (6" of compacted gravel, no fines) or a capillary break is inserted between the footing & foundation wall it's quite possible that the moisture coming through the wall is being slurped up from the footing.

[Dana]

Been there more than once...