Need Help: Fixing a leaking foundation
I have a potential client who needs to remedy the situation of water getting into her basement at the stemwall-footing joint. The foundation is not damp proofed and there is no perimeter drain at the footing. The first obvious fix is to correct some poor grading and get better positive drainage away from the house. An excavator gaver her a bid for about 20k to trench around the entire building, intall a perimeter drain, and correct the grading problems. This price may sound high, but the house is on a steep slope and doing the work would be pretty involved. She doesn’t want to spend that much money and is looking for a less expensive approach.
I think I remember reading in FHB somewhere years ago about using EPDM pond liner/roofing membrane as a skirt just below grade to direct water away from the building. This underground flashing so to speak is fastened to the foundation wall using flat aluminum bar as a cleat which is shot to the wall effectively pinching the EPDM to the foundation. The joint is sealed with a suitable sealant.
I’m thinking that a less expensive solution would be to excavate another 8″ – 12″ down when correcting the grading, install this skirt, thoroughly seal the foundation wall above the skirt, and backfill over the skirt. The soil is very sandy, so it drains well. If water can be kept from penetrating the soil for the first 6′ – 10′ away from the house, and there’s good drainage after that, I think this will solve the problem.
So my question is whether this less-than-ideal solution is worth the effort and an effective long-term fix, or whether it’s just a big band aid. Any thoughts/suggestions would be greatly appreciated.
Thanks
Replies
I'm not a pro, so take this for what it's worth. It has been my experience that band aids for water entering basements are a waste of time. Do it right!!
One possible solution is to correct the grade so it slopes away from the house(like you said) and then install a curtain drain at the lowest elevation of that grade...8-10' from the house. Most likely the curtain drain would not have to be installed around the entire house, just in the problem area. Then you wouldn't haven't have to excavate the entire perimeter of the foundation.
20K is alot of $$$, but excavating to the foundation footing is alot of work...
I'm sure others will offer their advice, so sit tight
Nine times out of ten, just correcting the grade so that no water can stand within 15-20 feet of the house (10 foot absolute minimum) will solve the problem, or at least reduce it to a minor irritation. Pay special attention to driveways, patios, and walks, as they tend to tilt towards the house over time. A few hundred to a mud jacker might be all that's really needed.
Another thing that can help is removing the (sandy) soil down to a depth of about 18-24 inches and putting in 6-8 inches of clay. Near to the house overlay this with a plastic membrane that is brought to daylight against the foundation.
Since you're saying potential client I assume you're a contractor. If you tell the owner that it won't take 20K and you can get it fixed, you better be right, since I'm sure she doesn't want a partial solution and I'm really sure you don't want to go back later and dig it up again for no more money. Usual approach for us is to trench the full depth of the foundation, remove the soil, install perf pipe and drain rock wrapped in filter fabric, slope out to daylight, and backfill with drain rock to about 6" of grade, a bit of soil on top of that. You may also need tight line for the downspouts.
I'm thinking that a less expensive solution would be to excavate another 8" - 12" down when correcting the grading, install this skirt, thoroughly seal the foundation wall above the skirt, and backfill over the skirt. The soil is very sandy, so it drains well. If water can be kept from penetrating the soil for the first 6' - 10' away from the house, and there's good drainage after that, I think this will solve the problem.
You're going the right direction. No need for EPDM expense.
For our underground houses we use 6 mil poly, preferably 3 thicknesses. While you're down there, does the house have enough basement to merit placing insulation between the poly layers as we do? That's the basis of passive annual heat storage (PAHS). We go out 20' from the perimeter, but that's for heat storage. The dry walls/floor/ceiling just happen when we keep the dirt outside dry. Enough dirt on top of the "umbrella" to grow whatever to avoid erosion.
I certainly wouldn't call it a " less-than-ideal solution". Works great for us.
PAHS Designer/Builder- Bury it!
If the home is on a steep slope... I am to surmise that the water is coming in from the high-side slope... correct?
If this is the case, I did a house that had a similar situation. The slope into the front of the house was relatively steep... and all water from the front yard flowed right over the surface and pooled next to the foundation.
We did a tiered front yard using landscaping block... with drain tile behind each block wall. Directed these tiles to a larger tile that ran beside the house to daylight in the back. We were lucky... there was storm sewer in the rear swail, so we didn't have to worry about ponding in the back.
This slowed the water flow from a rather large front yard and allowed the water to settle in the drain. We did have one place that we had to install a yard drain.
From there... we dug the loamy soil out from the foundation and replaced with clay (3 ft) We lowered the grade directly in front of the house to create another swail.. and buried tile beneath it. Tied that tile into the larger one on the side of the house.
Just to be "more safe", we created several ponding areas to serve as holding areas during an especially hard rainfall. Tile can handle the water... but it has to have time to settle before it gets to the tile in the first place. By creating these ponding areas... hard sheeting rains would create puddles in these areas... but wouldn't surface-flow to the foundation of the house.
We installed perimeter drainage under the floor of the basement. Not easy... but easier than digging up the exterior. Run to newly installed sump... out to tile.
Sealed the basement with 2 coats of Drylok.
No issues with water so far... it seems we cut off the flow causing the problem in the first place...as the owner reports that her sump rarely runs. In hindsight, we might have waited before digging up the basement floor for the sump and tile.
Which leads me to this... any of this could be done in phases. Do the front yard retaining walls first with tile... etc, etc. Keep going until you isolate the water and direct it somewhere else.
Water will follow the path of least resistance. If you simply direct it away from the foundation... and do nothing with it once you get it directed away... it will seep under whatever fix you have installed and be leaking as soon as it reaches a saturation level.
Best wishes.
Very difficult to say without actually seeing the place and knowing the climate and age of the house.
Most important in my opinion is good downspout extensions - 10' - well past the overdig area and routing the water off the roof away from the house. (40 gallons comes off a 30x40 house per inch of rain: concentrate that through 4 downs, say, and that's a lot of water to dump in one spot.)
I believe it is not uncommon for water to travel a distance along the top of footers before getting through the foundation, based on having seen leaks with no obvious nearby source but with a distant down spout on the same wall.
Can't prove it, though.
"It is as hard for the good to suspect evil, as it is for the bad to suspect good."
-- Marcus Tullius Cicero, statesman, orator, writer (106-43 BCE)
but the house is on a steep slope
You have sandy soil.........and a steep slope. I think you could come up with a good fix without digging to the foundation and spending all that money..
Last house I built on a steep slope I put two 6 inch fench drains that caught the water in front and directed it under the basement floor. Watr came down the hill flowed through the drains and out the other side.........Worked real good.
Here I'd do the same thing but route the water to either side of the house and down to the (hopefully creek).