Below Grade Waterproofing Challenge before Insulating/Finishing

[Rossn]

Hi,

What a great forum!

I'm near Denver, CO and bought a 1964 split-level home last year. During some demo for a lower level remodel, I've found some efflorescence and that the foundation wall varies from a couple inches above grade to a couple inches below grade. One 20' re-graded section is probably 18" below grade. All but that short section of foundation wall are about 42" high, with 2x4 construction above (to 8'). No sill gasket, maybe 1/8" fiber board with reflective surface behind studs, and then brick veneer

Some areas have minimal efflorescence for 54 years, and some have more. Pulled up the 12 year old conventional carpet and pad, and didn't find any moisture or mold, but the room adjoining the house and garage has some mold beneath 1/2" rubber gym flooring I installed last year. Not sure if that is from the foundation wicking, condensation (room can warm up quickly), or from mopping. Have smelled some mustiness in the main house in one corner, though think that smell may be coming up through a failed cove joint.

The house is set back about 100' (and slightly uphill) from a 1800's unlined irrigation ditch, which runs about 6' deep for 6 weeks during the summer. Top layer soil I've tested is about 60% Sand, 20% Clay, 20% silt and drains well. Prior owners said they've never had any flooding or water issues, though clearly the grade around the house is an issue.

With finishing and insulation in mind, what is my most reasonable option for addressing the potential moisture, when re-grading will be difficult? I imagine some combination of:

- Sealing exterior walls between the footer and slightly above grade with asphalt material or rubberized material
- Exterior drain
- Interior Drain
- Sump pump

Thanks in advance for your input!

Ross

 

[Dj2]

The most effective waterproofing has to be applied on the exterior. To do that you have to dig out and expose the exterior.
I have used ThoroSeal before that gave me excellent waterproofing. Check it out.

After that regrade correctly to let water flow away from the bldg.

 

[Sponsor]

 

[Atomic1]

Is tough without seeing views of the exterior grade, but I'm thinking and exterior drain tile and waterproofing the exterior face of the foundation would be the best bet. Interior drains will be useless unless you're trying to control water bubbling up from the floor.

Consider a trench drain upslope from the wall as well for additional water diversion, and of course, make sure the gutters are reliable.

 

[Rossn]

Thanks dj2 and Atomic1. That is the direction I'm currently leaning. There does seem to be some ground moisture coming through the floor, but only visible thus far where I put down rubber flooring

 

[Dana]

How much digging are you into?

An exterior French drain 2' deep of washed 3/4" screenings wrapped in landscaping fabric with a perforated PVC drain tile near the bottom, with or without an EPDM "ground roof" directing water away from the foundation can do a lot.