Hi everyone:
Just looking for any comments, thoughts, recommendations, etc., on a water intrusion issue.
I am in Toronto, Canada.
In particularly heavy rainstorms (a week ago we got 3.5” in 2 hours totalling to 5” in 24 hours) my drainage tile gets overwhelmed and water seeps into my basement, apparently in between the joint between the wall and the footing. I did not get more than about 3/4 of an inch, but clearly that is enough to destroy the laminate floor I had installed only four weeks ago. No damage to the walls or furniture. Normal rain (e.g., all of last year) I do not get any seepage.
To frame the issue – Walls are CMU, exterior waterproofed with hard plastic Delta product. Inside I have 2×4 framing and closed cell sprayfoam and paperless moldproof (Dens sheild) drywall. On the floor I laid the Delta-FL product, standard underpad and 12mm laminiate flooring.
The water only comes high enough to get over the Delta-FL product and inbetween it and the laminate, after which point, it is essentially trapped and will not evaporate (I just ripped up my floor, so I know this).
Water intrusion seems to be caused by the fact the exterior waterproofing does not continue down to the bottom of the footing – it stops at the top of the footing where the wall stops (I know this becasuse this is a 2 year old addition and I still have the blue-prints).
I think the only way to permanently fix this is to excavate, cove the joint between the wall and the footing with mortar and then extend the waterproofing to the bottom of the footing – looking at a big $20K+ price tag for that, which since it is really just a basement and I am not too keen on going into debt for this (I would rather leave the floor unfinished and just paint it).
Couple questions
a) I am considering just laying a nice ceramic tile, either right on the floor or maybe on top of Ditra. From what I understand, there is really no permanent damage if ceramic tile and concrete get wet once or twice a year and then dry out.
b) can you lay an electric underfloor heating system under ceramic tile directly, or do you need a subfloor?
c) would using some sort of heavy duty caulk (e.g., polyurethane used to seal sidewalk cracks) to the joint between the bottom of the 2×4 and the floor be effective long term? I am assuming the 2×4 framing will dry out through evaporation throught the drywall in the 363 or 364 days a year when water intrusion is not occuring.(there is no vapor barrier between the drywall and framing since the sray foam handlles that duty and it is right on the wall)
d) also considering adding a second floor drain near where the water comes in – which could prevent water from reaching high enough to cause damage and then just going with the same strategy – Delta FL and laminate.
Any thoughts or comments would be gladly accepted.
thanks.
Replies
Before you go digging up everything, survey your property for any spot within 10-15 feet of the foundation where water can stand. While sometimes the water comes from some distance away, most often it soaks in directly adjacent to the house, and changing the drainage around the house can work wonders.
Examine your drain tile system to make sure that it's not clogged where it exits. And don't drain the gutters into the same line as the drain tile, as that can easily backfire -- make sure the gutters drain separately.
And you can consider installing a sump pump to drain the tile system, vs relying on gravity.
RE: Water in the basement (post #208000)
Hey Mikeman,
Those are all great points Dan made. I will make a few suggestions on how we typically deal with water infiltration issues. 1). REDIRECT - You really don't want the water ever getting to the point of flooding underground at your footing. Stopping the water is a losing battle. You really want to redirect the water before it hits your foundation wall like a damn, ponds, and then finds it's way into your basement. Can you encourage the water to keep moving past your house with grading changes? Next time it's pouring go outside and see if it is apparent where the water wants to run. Sometimes there is an obvious "river" that runs right into a corner of the house. Create a swale to carry this water away. If this is not a viable option because maybe you don't have a big enough lot or are too close to neighbors etc., you'll have to move on to the next strategy.
2). COLLECTION - Think perimeter drain. The ideal location for this is different for every job. Most people would rely on perforated pipe just above the footing to protect the vulnerable joint where wall meets footing. Usually a two-tiered system works better and takes the bulk of the water before it gets to the footing drain keeping the material surrounding your home much drier overall. You will need to determine at what elevation the water is moving in. Sometimes there is a lot of ledge just below the topsoil where the water just flies along. Other times the water perculates through all the topsoil, then finds gravelly material then starts to move quickly below the surface. After determining where the water is moving, install a perimeter perforated drain pipe to collect this water and carry it to daylight (in solid pipe) somewhere downstream from your house. If you can't dump the water out somewhere far away from your house, you may have to install a drywell. Although, with rain like you have experienced even a large drywell would probably be quickly overwhelmed. The other place to collect water if you really can't keep it out is with an interior perimeter drain. This makes your finished basement a bit smaller as you now have to build your walls in front of your interior moat and sump pit.
My advice would be to do everything you can with your site first, then move on to "systems" to deal with water that can not be stopped. Good luck and let us know what you end up doing and get back to us after your first big rain storm. Oh yea, maybe live with an unfinished floor for a while to see just how wet everything is getting before deciding what material will tolerate your environment.
Yes you can put an electric floor directly in the mortar under the tiles. It's easy to install and if you follow a few precautions is relatively low - risk to install and get to work correctly. I don't know if it works with ditra, but if you don't have any moving cracks I don't see how the extra cost of ditra could be justified over a slab.
As for your leak - redirecting the moisture away from the foundation wall is what I am most in favor of. This is mostly done with a simple dirt grade that slopes away from your house - NO flower beds, gutter drains, or driveways that allow water to soak the ground next to the house. That's the price you have to pay for corners that are cut that allow poor drainage away from a house.
if that's just not working there are ways to essentially add a roof overhang under the ground surface. It is quite litterally like a waterproof roof - a membrane or water resistant layer of bentonite (powder available just for stuff like this) is put down in an even layer sloping away from the foundation. As water percolates down through the soil, especially directly along the foundation walls, it hits this underground "roof" and is forced away from the foundation. How deep it needs to be depends on your situation - a foot near the foundation with a 1' in 10' slope is a safe bet. Of course extending 10' away from the foundation would be ideal, half that would solve many problems.
As an interesting side note, if your footer/foundation wall joint had a water resistant seal installed when it was poured it would most likely be a rubbery/asphalt 'ish material in a 1"x2" cross section that has bentonite mixed into it - as water contacts it the bentonite swells forcing the black gooey stuff tighter and tighter against both concrete surfaces. First a primer is painted on one surface so the water blocking strip will stick solidly to it and remain there through the concrete pour for the walls. Then....that's it! It simply does it's job as needed hidden in the middle of a bunch of concrete :)
I honestly don't think you'd gain anything by putting caulking of any kind along the bottom of the studs - it may keep water out from one direction, but it also keeps free water in, not what you want to have happen.
I'd spend 90% of the effort on the exterior of the foundation wall to keep the water away from the foundation in the first place.
Reply
Thank-you, all, for the comments.
In fact I have my downspouts going into pipes and leading to a makeshift drywell about 30 feet away; BUT, the outlet on the gutter was clogged and most of the rain spilled over and fell right beside my house onto a patio. While the patio is slightly sloped (like 1/4'' per foot) the sheer amount of rain probably led to a good amount going backwards and down the foundation wall.
On that note - anyone have any experience with the gutter guards or other contraptions that prevent leaves from filling the gutters? Part of me wonders if they might actually restrict water flow too much in the event of another downpour.
Thanks again.
Re gutter guards, we have the cheap ones -- the 4-foot plastic screen sections -- and they seem to work pretty well. Have never noticed a tendency to overflow in a downpour.
Do leave an area open directly above the downspout, though, so that you can remove any trash that does happen to get in.
It bothers me that you refer to your drywell as "makeshift". What does that mean exactly?
Since you obviously have a drain line from your footing drains to your "makeshift" drywell, the water should be running that way rather than backing up under the slab. I'm thinking one of 2 things.
Your drain line from the footing drains to the drywell is collapsed or plugged. Or the drywell can't handle that much water. Once it got full the water simply backed up into the footing drains and them came up into the basement.
Addimg a sump pump or a drain to daylight (if possible) would probably cure the problem.
The makeshift description is because it might not qualify as a well designed dry well, but essentially is it a 24'' layer of 3/4'' crushed stone, about 12'' under the surface. Also, it is about 30 feet behind the back of the house, where the natural slope means the surface is already about 18'' below the surface at the edge of the house.
The footing drains go to a sump and the gutter drains go to this "drywell".
But your point is a valid one and one I am worried about - the 4'' PVC line that goes to the drywell was put down before some other landscaping - it may well have been crused during the subsequent work. I think the only way to check though it to get and plumber or rent one of those plumbing inspection cameras -
"The footing drains go to a
"The footing drains go to a sump..."
Is the sump pump running full time? If not, the water under the slab isn't getting to the pump. Or maybe the pump is too small.
They make some really large sump pumps for situations where they have to deal with a lot of water.
At the peak of the storm the pump ran every 4 to 5 minutes. the pump and the basin had no trouble keeping up. I think the constraint is the flow into the basin, which may just be a caused by the relatively flat slope of the footing drain - since the footings are level the drain can only be sloped so much before it is way to high at the far end.
The constraint is the slope of the water table inside the soil. The water table adjacent to the tile is even with the tile, but 5 feet from the house it's maybe 1 foot below the surface. A line drawn between the two points will intersect the edge of the basement, if the tile is only on the inside of the footing (which is "normal" for older homes).
If the sump pump was running but you were still getting water up through the slab then I'd guess the footing drains are inadequate or installed wrong. No way to fix that without taking up the floor. And that's not easy or inexpensive.
Attacking the ground water problem outside is your best bet.