Back wall of downstairs is 3/4 underground, sheetrock was moldy at the bottom. We opened it up from floor to ceiling at SE corner and found saturated batt insulation, wet studs and a cold/seeping/damp foundation wall. The owner want to “watch” it over the winter (Washington coast) but expects some sort of fix next year.
What do you think it would take to fix it?
If I didn’t provide enough information, let me know and I will check periodically and fill in any blanks. Thank you.
Replies
Wall is probably not supporting anything but the sheetrock so I say, sure, go ahead and let the whole wall rot. It should be an interesting science lesson by this time next year.
The only effective method is to waterproof from the outside. There are a number of systems, but my favorite is the one consisting of gooey rubber sheets that are applied to the exterior. Grace is one brand.
Such a waterproofing membrane needs to be combined with drainage. There should be a drain about the level of the footing all around the building which drains by gravity downhill out into the open ("draining to daylight"). The drain should be buried in stone, then the dirt goes back on top. The first few feet from the house should have considerable slope, say 8 inches or more, away from the house.
Downspouts have to drain well away from the foundation. They can be drained in pipe underground also to daylight, but in piping not connected to footing drains.
Most complete solution is generally to dig down on the outside and install drain tile below the floor level, drained to daylight. But sometimes a little grading and some downspout extensions is all that's necessary.
Downspouts have been extended already, and the wall is still weeping (moist and sweaty, not soaking wet) from top to bottom.
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There be water back there. You can use one of the "waterproofing" paints on the inside, but there's no way to guarantee that they'll keep working, even if they seem to at the start.
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How old is the house?
Are there obvious cracks in the foundation wall?
If the wall is seeping then it sounds like the capillary breaks are not in place or are compromised. The drain tile, or raindrains could also be an issue.
Best fix is probably dig up the outside, fix drain tile if in need of fixing, fix rain drain if in need of fixing, fix grading if in need of fixing, rubber spray or tar outside of concrete wall for capillary break, install plenum around wall, use clean rock fill covered in fabric to allow easy flow of ground water to drain tile.
House is probably 20-30 yrs at the most.
No cracks except for the rods/dimples from the original concrete forms.
What is a capillary break?
There is probably no drain tile (what is a rain drain?).
Is "plenum" you mention, a rock/stone barrier? covered in fabric?
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Edited 11/2/2006 6:00 pm ET by RRooster
Concrete has the property of wicking water much in the same way a tree does - such that a concrete wall that has its footer resting in a pool of water can wick water all the way to the top of the wall and rot out your top plate. The wicking is known as capillary action, in order to stop the process you put in a capillary break. Most of the time the break is tar on the exterior of your concrete wall. Rain drain is the pvc pipe that the downspouts connect into it is a seperate pipe from the train tile.Plenum is a plastic covering with dimples that surrounds the foundation, if ground water approaches the concrete wall it will hit the plenum and run down the dimple gaps in the plenum to the drain tile. If your foundation settles and cracks the plenum will prevent the water from getting to the crack, most builders do not install it but as fixing a foundation wall water leak like this is a very expensive operation I think you'd be mad not to install it.No drain tile? How much rain does your location get a year?There are some good free videos on foundation under bestpractices athttp://www.hgtvpro.comI've found them to be good. There are also articles that talk about the best practices to use.
> Concrete has the property of wicking water much in the same way a tree
> does - such that a concrete wall that has its footer resting in a pool
> of water can wick water all the way to the top of the wall and rot out
> your top plate. The wicking is known as capillary action, in order to
> stop the process you put in a capillary break. Most of the time the
> break is tar on the exterior of your concrete wall. Uh, er ... If water is wicking from the footer up THROUGH the concrete via capillary action, coating the outside of the wall above the footer will make no difference (and in fact could actually make matters worse by keeping the moisture from escaping back into the soil). In practice, however, I doubt that significant moisture wicks up more than a foot or so (through the concrete) above the wet soil area. You coat the concrete to prevent moisture from coming directly through from the soil.Certainly dampness sufficient to cause rot in the long-term can wick up farther, but that's different from what the OP describes, and is why mud sills are made of treated lumber with sill seal (a capillary break) between them and the concrete.
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. --Mahatma Gandhi
True about the capillary action from the footer and coating the wall. The way I've seen that addressed is when the footer is poured seperate from the wall and the top of the footer is coated then the wall is formed within the v grove of the footer. Not sure how you address this when you use a single footer/wall pour though or what you do would have to do after the fact. I agree that the capillary action is probably minimial if from the footer though the sill gasket and treated plates are in place to deal with that issue.
Also I suppose that the drain tile is lower than the footer of your wall so the concrete is not supposed to be resting in ground water or else would be subjected to the condition you describe. Really a lot of the techniques are used as backup. If for some reason the drain tile allows the water to rise to the level of the footer than if your wall is a two part wall then the capillary break prevents water from wicking further up. If you don't have the capillary break then the sill gasket and pt wood help to resist potential rot. If the rubber or tar membrane are compromised then the plenem helps prevent water from getting to the foundation wall in the first place.
Water follows the course of least resistence.
Apparently that would be the concrete wall.
It's time to dig.
The curious thing is that the water is reported coming through all the way down, not just at the bottom. If this indeed is true (OP may simply be seeing weeping out of absorbed moisture due to the area having been closed up), then the hydraulic pressure is there all the way down, and there must be some regular source of water out there. Could be a broken water pipe or some such.
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. --Mahatma Gandhi
Could a poor quality concrete mix allow water takeup like this?Rusti
no, concrete will weep water no matter how good the mix is. That why you put waterproofing on the outside. Like DanH said, its time to dig. that is the only answer. It must be stop from the outside.
no, concrete will weep water no matter how good the mix is.
How do concrete boats work?PAHS Designer/Builder- Bury it!
sump pumps
sump pumps
None in the small boats I've seen. They still float.
And I think you do know that concrete can be waterproof. Just takes more portland than usually used. Also more care than a typical foundation gets.
For the thread: As BB knows, I've built concrete underground homes that have no leaks, and use no waterproofing. Just buried 6 mil poly to divert ground water from around the homes. Works like a champ, even with lower strength concrete.
Does not mean I'd have dry concrete here without dehumidification. Condensation is an equal issue. Don't believe it was mentioned if the condensation/seepage test was perfomed by this OP.
PAHS Designer/Builder- Bury it!
What's OP?
Condensation/seepage test?
After removing the drywall and the insulation, the insulation was soaked at the bottom, the remainder of the insulation was damp, the concrete was moist top to bottom. There is no wood rot, just discolored wood from moisture stains.
As for the amount of rain we get, YTD about 60" going into the wet season. That is why the HO wants to observe for the winter and fix next year.
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"Condensation/seepage test?"Cover the wall with a sq ft piece of plastic duct taped to the wall.In fact do two, one near the top and one near the bottom.If you get moisture between the concrete and plastic the mositure is moving through the foundation.If you get moisture on the outside of the plastic then it is condensation.But before running the test you need to get the wall dried out first.Run a fan across it for a while.
Bill got you squared away on the test. OP is original poster.
All you know is you've got water, whether condensing or seeping. In addition to a lot of rain, you live in an area of high humidity. That foundation wall is presumably uninsulated on the outside, ground temp. Have you passed dew point?
I'm not suggesting you don't have a leaky wall, don't know. But you should determine that before you start digging or worrying about the inside of the wall. Could very well be that you have both leaks and condensation. Then you'd need 2 solutions.
Your HO is on the right track, but it won't take that long to determine the cause(s).
My head building inspector always advised against concrete houses, particularly me, when he learned what I was building. Asked him why they were wet, condensation or leaks? He said he didn't know, just that they were always wet. Ours isn't. He no longer suggests avoiding concrete, but I've had several calls after he suggested asking what I did to have dry concrete. Rocket science it ain't. Nor is it expensive.
Good luck.PAHS Designer/Builder- Bury it!
The same way concrete swimming pools do. You coat either the inside or outside with some kind of membrane. Capillary action isn't necessarily fast either so it isn't like you'd have to bail out the boat very often you would have to increase the weight of the concrete in your calculation for archimedies law of bouyancy if you didn't seal the concrete.
Concrete needs no coating to be waterproof if you have the right mix. This capillary action you're talking about does not always exist. Certainly does not need to. All concrete pools need is no leaking cold joints and a strong enough mix. Yes, I've done that.
No bailing in the concrete boats. Do some Googling. "Ferrocement" is a good place to start. Not new, lots of practical apps.
In my houses, I didn't pay for the extra portland, didn't need to with dry dirt on the outside. Dry dirt is necessary for my heating/cooling system to work.PAHS Designer/Builder- Bury it!
I'll check that out. What is a strong enough mix? I've read that a 3:1 ratio is about the max you can do if you want to ensure that no microfractures occur due to shirinkage.
What is a strong enough mix?
I didn't spec it.
IIRC, 5000 psi, but it might have been a little more. The folks on the fc list have discussed this a lot. Very important to them 'cause they want to avoid Monolithic type skins. I've been absent awhile as their interest was solely above grade and I'm the opposite.PAHS Designer/Builder- Bury it!
You might try Zypex. I have had a lot of success sealing walls with it. I used it on a large concrete cistern that would empty in a couple of hours, and after two coats it held water perfectly.
Correct spelling is Xypex. It works great.
"Correct spelling is Xypex and it works great"Thanks Joe - Have you ever used it on a slab that has been power trowelled to a fine polish? I was wondering if it could penetrate the surface?
Edited 11/4/2006 11:28 pm ET by fingersandtoes
I've just looked at one of the application instructions and it does mention that if the slab surface is too smooth it should be either acid etched, water blasted, or sandblassted. It's best to get some direction from a rep.
It's hard to get some of the products mentioned to you already to stick to a dirty wall, but plastic dimple fabric doesn't care if the wall isn't prefectly clean and is easy and fast to install when you dig a trench to install perforated drain pipe (holes facingdown).
http://www.deltafl.com/bvf/ca-en/products/foundation_residential/index.php
when you dig a trench to install perforated drain pipe (holes facingdown).
Holes facing down? Holes up and the groundwater enters the pipe and is gone. Holes down and what the heck is going to happen? I'm confused! (but I confuse easily).
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the perferated collection pipe is holes down
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Is there an easy way to print out an entire thread?
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The pipe is put into the trench with the holes down so that fine particulate matter - silt - does not flow into the pipe and lead to a clog. The river rock under the drain tile and the fabric either over the pipe or a sock around the pipe also address this concern. The ground water will get to the bottom of the pipe and rise into it through the holes in the bottom and be carried away to either your sump well or whereever you are draining the ground water rather than continuing to rise up into the soil.
If you have a 6" pipe, say, and place holes down, the pipe will be able to maintain the water level 6" lower than with holes up. Bigger issue is what configuration minimizes clogging, silting up, etc.
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. --Mahatma Gandhi
Any water that gets into your perf pipe will take the course of least resistance, so having the holes down allows the water to get in to flow away, while keeping dirt out. Theoretically, 'socking' your pipe (i did this where i had very sandy soil and didn't need to use gravel for backfill), or wrapping filter fabric around both the gravel and pipe will keep the 'fines' out, but the holes facing down is one more piece of insurance.This "course of least resistance" principle is in play with the dimple fabric as well: the plastic material is extremely tough and should keep the water out, but the dimples space the material far enough away from the cooncrete wall that any moisture that gets behind the fabric has an easy path to the footer drain, instead of being pressed into the concrete wall.A bit more about the dimple fabric: I had a bit of problem with backfill pulling the dimpled fabric down on my first try. On the second house i used it (wood foundation), i used slip sheets of old paneling to keep that from happening, this worked very well. I have a large area of the roof draining to a valley on the uphill side of the basement and no gutters; i left it that way for a couple years to make sure my system would work before i finished the basement walls. It's remained perfectly dry. Incidentally, i'd retro-repaired another very problematic walk-out basement, set too deeply in the ground to fix entirely with re-grading, using dimple fabric and French drains to daylight. I used that unfinished space as my woodshop. The people who bought that house finished the basement for living space, then took out the drains' paths to daylight because they interfered with a retaining wall they wished to build. I saw them pumping the recently-remodeled basement afterward...There are some other systems using foam board with channel cut in it and/or mesh filter layers, but after a lot of research, i went with the dimple fabric for ease of installation on dirty or rough walls, near-seamless application, low cost, and because the foam was getting a reputation for attracting insects.