Crawl space water problem 1

[dannyypk]

I have just did a crawl space inspection for a house with water problem. There was standing water in the crawl space. When I was there, the insulation were all wet, joists are moisted, and the soil are wet. The owner had installed a french drain around the foundation wall in the interior. They reported that no major standing water after the drain. I would like to seek as more solution as I could to help this home owner. I believe the water problem is from the sloping grade from the outside of the house. Air circulation were all blocked by the HVAC and the duct works.
If rock trench is needed how can I get information to design the drain, like the dimension ?

 

[CESSNA1]

DANNYYPK: Obviously water is getting in somehow. It sounds like the floor of the crawl space is below the water table or at least sometimes, maybe after a rain, the water table rises to above the level of the crawlspace floor, maybe as high as the floor joists. Also was the french drain installed properly and sloped correctly? To where does it drain? You may want to check with the city to see if they have information on water table heights; or you may wnat to run a few test bores to see if you hit water. Also, how about a perc test to make sure the the soil is percable.

Regards
Dave

 

[bimr]

You do not say whether this is a new or existing house.

http://www.wafrc.com/WAFRC_IndStd.asp

1. CONDITION: Wet walls / No leakage on floor (NO DISPLACEMENT)

Characteristics:

Water spots on walls, wet walls, walls periodically dry up usually leaving scale stains, efflorescence, or mildew. Damp spots either high or low on wall. No major cracks or bowing. No significant block deterioration or displacement. No leaning of walls. No movement in footing.

Testing:


Check palmer valve or sump pump for correct operation. Check with local jurisdiction if palmer valve is permitted (per local requirements).
Break open floor, test interior drain tile for correct flow to palmer valve, or sump pump.
Use water spud pipe, inserted along outside wall to exterior drain tile, to introduce water to check exterior drain tile operation.
Check for proper grade away from exterior walls and adequate gutters & downspouts.
Standard Repairs:

Extend downspouts, improve grade by increasing pitch away from buildings to the greatest extent possible.
Install, replace, or repair sump pump. Sump pump must meet State and local Plumbing and Electrical Code.
Replace some or all of interior drain tile as necessary, drain first block into interior drain tile using an approved one-piece wall drainage board that provides water passage and lateral support to first course of block. Wall drainage board to be 1" minimum higher than floor. Use a wall drainage board that can be caulked for retarding radon migration. Install to manufactures specifications. See Appendix B & C.
In some cases it may be necessary to excavate to footing, seal wall, clean out bleeders, replace exterior drain tile, backfill to within 12-18" of grade with clear stone backfill. See Appendix A.

Maintenance After Repair:

Keep downspouts extended.
Maintain positive pitch of grade away from house.

http://www.ibacos.com/pubs/BestPrac/0104 Best Practice.pdf

http://www.cdm-mich.com/AA-SSO/Public/FinalReport_6_01/Appendix D.pdf

 

[RCEJD]

I disagree the previous posts in the sense that it may not be as simple as high groundwater.

Numerous factors come into play which include: broken pipes, sloping ground diverting irrigation, a permeable soil layer, over irrigation, improper subdrain design, too thick of sand below the slab, and/or any number of other factors or combinations thereof may be occuring.

Bimr has god recommendations for the downspout is good and is fundamental in the approach. ALthough you may be require to install a sump pump, this creates long term maintenance issues for homeowners who tend to forget about the pumps, which rust and fail with time.

Consult an experienced geotech who will know the exact approach. Good luck.

 

[dirtguy4]

I agree with RCEJD. This is a geotechnical problem. You may want to post this thread on Foundation engineering site, either way hiring an experienced geotechnical engineer is probably your safest approach.