Drainage solutions – mission impossible?
I have a problem to solve for a customer. Their house was built on ledge and apparently at least some of the foundation walls for the full basement were perched directly on the ledge. Then, a slab was poured within to provide something other than mud to walk on.
House vintage is early 1970s and the contractor who built it did state of the art work considering the time and place. There is a daylight perimeter drain. Where ledge is exposed in a portion of the cellar, it is parge coated, sound, and dry. The problem lies in a larger 2/3s portion of this cellar.
Apparently, the ledge was weeping water under the foundation wall, so at some point in the past ( ten or twelve years past, I hear) another contractor built an interior curb to channel water to an interior perimeter drain. But that was unsucessful since mortar for those concrete blocks is not watrerproof, so they then built up a wooden floor with PT sleepers, a plastic moisture barrier, and (here’s the big boo-boo) particle baord decking.
From the surface the only thing apparent was a heavy mildew smell and sagging (no big surprise there) between the sleepers.
We have now removed about half of the flooring amterial – enough to expose all these conditions and the toxic smells of partially digested PBoard. The slab is good except for where the sleepers were nailed down. There was water running across the slab.
Landscaping worth more than the house makes digging around unacceptable and the perimeter drain functions anyway, just not well enough.
There are several cellar windows for light and ventilation but only one facing the driveway so concrete may be a difficult solution. I’m wondering about pumped gypcrete/grout type floor leveling to raise above the water flow. Would a drainage sheet be desireable and what product will work?
re-doing this with more PT would still allow moisture and mold spores to find a happy home between plywood and concrete.
My job is “Just fix it, Please.” But there is a limit to the budget.
Your mission, should you decide to accept it, is to comment from the depths of your knowledge.
Excellence is its own reward!
Replies
Good morning Mr Piffin...
Dig out the foundation..
Establish a new working to day light drain. Perhaps at a lower elevation than the exsisting drain.
Grace membrain for new water proofing.
Put it all back together.
Pull the built up flooring and sanitize.
Consider that...
The current drain and water proofing have failed all or in part.
That there is currently a substancial increase of water seepage / flow from intial installation.
Plan "B's"
Series of well points / sumps up hill from the foundation.
Interior sump pits.
Interior sumps will remove the water but then you have the possibility of foundation erosion to consider.
This message will self destruct in 5 minets or be hijacked.
Who ever invented work didn't know how to fish....
Need more info on potential source of water, topo, soils, and region. I'm a geotech so my attack is typically to head off the water before it gets inside.
If water is shallow ground water 'floating' on the hardpan then you may be able to install a french drain upslope of the home at outside of the landscaping (i.e. property line).
If no outside work then...Saw cut the slab perimeter just inside the footing and install RIGID PVC (don't you dare use that black flexible ADS pipe or my head will explode). Drain pipe holes down, sloped to drain 1/4" per foot towards interior sump(s). Trench should extend a few inches below footing. Expose the top of the footing. Install plastic drain mat/geotextile on footing to allow water to pass under stem wall to the drain pipe. Install bentonite adhesive waterstop material on the stem wall above the drain mat and within the slab elev. Place new concrete to cover top of trench and footing to match ex. slab. Check slab for moisture through the wet season. If still wet then you must solve from the outside. If not, then install PT subfloor with knotches in the sleepers to allow air/H20 movement and have the owners sign a waiver that you are not responsible for mold growth.
Gotta run before my dog attacks me cause it is almost 5 minutes past feeding time
Joe
Both of you guys - thanks.
One thing I may not have been clear on is that at point of entry, there is no footing. The triangle in my schematic represents solid rock ledge and the blue arrows represent path of water as it percs thru soil to the ledge and then it follows gravity in under the wall and onto the slab. Elevating the slab by pouring over it while providing another interior path at perimeter will probably do it. The idea of adding a sump pump had not fully formed in my mind but sounds like a good backup plan.
There is a perim drain outside but since it sits on ledge that is higher than the floor at the uphill side, and the ledge is undoubtably irregular, then much water runs under it.
I suppose I should have taken a photo but I may not be back theere before i leave town for a few days.
Names for plastic drain mat to lead to it is one thing I am seeking - this is the northeast.
And suggestions for product to use for the elevated slab. Wheeling ten yards of crete in wheelbarows way around the side of a house doesn't appeal to me. Must be getting old - besides, that would make me as cantankerous as a hungry dog..
Excellence is its own reward!
Edited 11/4/2003 7:44:24 PM ET by piffin
Here is a link to manufacturer for plastic drain mat. You could use the G-series drain mat installed with the dimples down to allow water movement. http://www.mirafi.com/products/products_index.html
A concrete material/supplier would likely be a local distributor to you in the NE (I'm in the NW).
No footing. Just pretend there is a footing. Use the drain mat around the interior perimeter to allow water to pass under stem wall and into interior perimeter drain. You may not need a sump if you can daylight it out under the foundation (but then you are on rock so that may not be feasible). Sump it is. Plan for battery backup if power outages occur.
A topping slab would likely be the best. If possible try to use barrier between the two. What you want is a self leveling pumpable topping mix. These are usually pumped through small dia. hose (1-1/2 to 2-inch). You might be able to use a latex modified concrete overlay product but the overlays are typically thin (1/8 inch to 1 inch) and may start to break the bank as you get thicker. It might be a good idea to talk to some concrete boys to sub out the work.
Good luck. Joe
Thanks more.
All,
I had the crete guy out today pouring my footers on another job and he took a look. Has done this before and sees easy passage for grout pump to place crete and finish new slab over old. Turns out that my local yard stocks a dimpled drainage mat to allow water passage.
The downhill/daylight side of this cellar does have escape to daylight below with gravity draining.
So the next hurdle is to finish removing all the old crud.
BTW, Here an updated drawing....
Excellence is its own reward!
I,m not really understand problem but I have had good result witl "Loc Tight" its a waterproofer paint that works on the inside.
That might be appropriate for some situations but here, the volumn of water is geat, and it comes in where, in the drawings, there is acurb only 4-5" away from the wall which would make it extremely hard to clean and dry well enough for a caulk or paint product to adhere or even to fit a hand and tool into for application.
I am following a theory here that it is best to divert the water and control where it flows than to try damming it up..
Excellence is its own reward!
Piff what are you going to do about the mineral deposit build up and the cultures that will more than likely begin growing in the chase ways?
What about sealing with epoxy where the foundation and bedrock connect on the exterior side. This also will give you a chance to repair the drains and foundation water proofing.
Who ever invented work didn't know how to fish....
An exterior solution like that would always be my first choice and the way I would detail it on a new house.
But there is a limited budget available, flinchingly ready to pay what is needed up to...
And since that budget would not begin to allow for diggin out and replacing all that landscaping, they will have to release me from future liability.
The chaseway cultures have still been bothering me. They have had 3/4" stone placed there and I am unsure if I want to suck it all out and leave it open for a hose to rinse down occasionally. Probably so.
But that still leaves the problem that any water running there contributes to the humidity level in the entire house. That implies that I should cap that drain channel over the top with a custom metal flashing.
Keep holding my feet to the fire here. Better to think it all through before I get committed all the way..
Excellence is its own reward!
the interior injection of epoxy out too then?bobl Volo, non valeo
Funny you should bring that back up. I was just sitting here thinking about contacting Abatron for getting supplies to do it myself instead of subbing it out.
I won't make any definite plans until I see the whole job demoed and cleaned up from what's ther now. The crew will have that done by time i get back from Boston. I'm on my way out the door now for a few days - so long guys.
And thanks - keep brewing up brainstorms for me..
Excellence is its own reward!
If the current drainage isn't doin squat in heading off much of the water now what happens to the water if you seal the interior. Where's the water gonna go? It more than likely find it's way in someplace else with a vengence. After all you can't see what's on the other side of the wall. Only speculate.
You must remember CO and all the bed rock / water combinations / issues. When "fixes" are done something else goes wrong some place else and some place else and...
A gut feeling says that place is going to continue to go rancid and some body is going to want to talk to you about it... After all it was already going there when you stepped in. Time to buy shares in lime.
Well points, at least, can be put in with a 2 man auger or hydro injection.
Turn the water water promblem into a covered fishing hole and call it unique.
Tell the HO you can't come up with a feasible working soulution because of so many variables / unknowns and walk. Here, when the "fixes" are asked for the jobs are passed up on because of the "problems" that come up latter. Too many sue happy folks out there. If not the current HO the next one that buys the place.
Who ever invented work didn't know how to fish....
I'm with the group advocating a proper solution rather than a certain temporary fix.
It seems counterproductive to insist upon placing renewable landscaping, surface items on the do not disturb list when the house is being carried away on the tide.
With the advances made in grouting, adhesive and waterproofing materials technology it would make more sense to excavate on the upstream side of the house right to the ledge and do something exterior to the foundation to divert the seepage and to apply or inject waterproofing materials to the ledge/wall interface and the backfilled wall.
What is being proposed is simply a bridge over troubled waters, hiding the problem from view and hoping it will either go away or not reach up with a big GOTCHA!
If you are truly stuck with moving the water out of the basement rather than preventing entry then I would go with the interior perimeter drain, to daylight if possible, and a thin pour over a raised drainage plane.
Something my brother and I discussed was increasing the ventilation under a sleepered basement floor by installing a forced air system, maybe a radon fan on a timer, to draw and exhaust moisture laden air to to the outside with the makeup air to be drawn from the room. Also included in the idea was requiring a dehumidifier running full time in the room. This might also work under a poured floor as long as the drainage plane would permit the airflow.
pif,
off the wall?
i am looking into have a crack in my foundation fixed by crack x. they pump an epoxy into the crack. give a ten year quarenty.
maybe this will work for that joint.
for a single floor to ceiling crack I was given a phone estimate of $595
their site says it is not for stone foundations, but this doesn't really sound like that, but stone is involved.
might be worth a phone call.bobl Volo, non valeo
If I'm understanding this, the water flows fine, it's just keeping out of the habitable space that's the problem. Like you said, an elevated slab would do the trick. Seems like a one-way ribbed slab would do it, but how do you cast the ribs?
What if you layed down galv. metal deck used for composite deck then cast a thin slab? Or maybe lay down a grid of concrete brick and put down those thick (2-3 in.) concrete pavers, kind of like a raised data floor?
just a take off from "seal tite" basement water ppl. in VA.
notch perimiter, install perf. pipe. Channel thru more pipe to sump. pour new floor over top of new drain pipe. kind of like a perimiter drain only inside.
Dig out the concrete floor and dirt. Pour pea gravel, and make sure it daylights at the other end. Cover with two mebranes, first that keeps the rocks from punching thru. Pump the slab in, it wont set for a while cause the water in the concrete has nowhere to go. Cover with glaze ceramic tile, leave the perimeter tile loose fo access to the trough that funnels the water under the slab.