I’ve enjoyed reading all the breaktime discussions over the years, but this is the first time I’ve joined in here, so here goes……………
I’m building a house for some people on the Oregon coast on a hillside, and there is a lot of water moving through the dirt, both from the sides of the excavation and from the bottom. When the dirt was first scraped off at the bottom of the hole, there were mini-geysers shooting about 6″ up from what look like worm holes. Darndest thing; never seen that before. Anyway, I’ll be installing a sub-slab drain system with a lot of gravel and perforated pipe which will be attached to solid pipe outside the foundation and drain to daylight. So, I’m not too worried about that part of the water issue.
But, for the foundation walls, I plan on using a liquid-applied polyurethane coating for the outside of the walls, and then installing a drainage mat over that, which will drain into a perforated perimeter drain pipe. What do you all think? Is this overkill, is it not enough? Any products you would or would not use?
Replies
Where on the Oregon coast? (filling out your profile is helpful).
I've had the spray on coating done on two backfilled daylight basement walls....the applicator came out of Eugene. Both applications came out well and I was impressed with the stuff. It's somewhat expensive, about $1.50 sq. ft. as I recall, but with the situation you've got would be a good investment.
If I understand you correctly, it sounds like you're on the right path. We've had a lot of rain lately and I imagine you've got a layer of sandstone that's carrying the excessive groundwater under the overburden.
In the worst case, you might have to have french drains dug around the house. We had one down here near Coos Bay a few years ago that had to be trenched 14' deep.
Hey, from Lincoln City. Profile? I'll have to figure out how to do that.
Could you give me the name of the Contractor who did your work? I don't imagine it would be much, if any more expensive for him to come up thisaway.
We moved back to Oregon (orig. from Beaverton) 3 years ago after living in Colorado for 21 years (north of Denver), and there, it doesn't rain quite as much as here, so spraying on asphalt dampproofing was all anyone did, and it was maybe $150-200 for a whole basement. Quite a change.
Thanks!
Use enough rebar in the foundation to prevent shrinklage cracks from opening.
Sounds like you've got a bad enough site (excess water) that you may want to consult a civil engineer for insurance. Let him design and be reponsible for the drainage, soil compaction and maybe rebar, if knowledgable.
With other things taken care of, the spray on (we used to use an "elastomeric" product) plus the drainage mat plus draining backfill should be enough.
From the experience of one house I worked on: The young couple were building for the sweat equity and not to have the regular problems they were hearing about. They dampproofed the basement walls themselves (3 coats), installed 2 runs of perforated drain pipe at the footings and 1+1/2 ft of crushed stone over that- all way beyond code!! I had been given the key to install an ERV on my own time since this was a long build. Walked in on a late November cold Saturady morning to find a humid building but no water installed yet! In basement found a wet slab, a hole broken into the slab at the front corner and a sump pump installed and run to drain out the rim joist.
They were at the bottom of a long gentle downhill slope and it was a wet fall- a spring had developed inside the footings. The soils were pure clay and the footings were acting like a dam so the water had no place to go but up through any slab shrinkage cracks and at the inner wall/floor/footing joints. The owner had been out the night before to find 1+" water on the floor and took the corrective action- sump pump. The way to stop this (and on your site, you can't do too much) is to put sections of drain pipe through the footings every 8" to join the inner drainage stone under the slab to the exterior drainage pipe (if your laying footings on native soils and not on designed drainage bed).
Thanks for the input; I think I will add more pipes under the center footings under the floor, based on what you say. I'm using 4" pipe for all the drains under the floor, so one evey 4' should do it. I plan on filling the spaces between footings and grade beams with1-1/2" crushed rock up to the bottom of the floor, so water should flow pretty freely thru that.
"When the dirt was first scraped off at the bottom of the hole, there were mini-geysers shooting about 6" up from what look like worm holes."
With a water situation that bad, it may be worth considering a secondary 'diversion' scheme on the uphill side. It would be better if your foundation/slab drainage system were not the primary defense for a constant flow situation.
This could be anything from some additional uphill drain tile runs to a below grade concrete 'dam', depending upon severity. At least you have someplace to direct the drain water with gravity.
Sounds like you could dig yourself a great well.
I used a product like this stuff:
http://www.cosella-dorken.com/products/foundation_residential/products/MS.php?navid=10
Someone here on BT recommended it to me, and I was really impressed with it. If I ever build a house again, I'm using this stuff - No question about it.
I think the cost for the material was about $850 back in 2001. That was for a 1,200 square foor house.
Rockwood,
You've got some real water issues there.
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I would take several steps to control this amount of water. First, I would create drain swales and curtain drains above the house as in the above sketch. Be sure to wrap the gravel in the curtain drains with Geo Filter fabric. Run the curtain drains to open air any place outside the 45* radial lines and make sure the drain swales extend outside them too.
Second, I would use Xypex in the slab and on the outsides of the basement walls. I would over-excavate the footings 18", place a compacted 6" layer of straight run gravel under a 12" layer of 3/4" clean, all of which was at least 12" outside the footings. I believe that the crushed gravel is better and cheaper than geo filter for this. I would also put 4" drains 10' OC with a perimeter drain pipe on the crushed and under the clean gravel with drainage to open air.
Third, I would use a two layer drain plane system on the walls. The first layer would be Cosella Dorken like Boss Hogg reccomends. Finally I would place a 1' thick layer of 3/4" Clean next to the walls from the gravel base to about a foot from the surface.
When I repaired and waterproofed my FFIL's hoouse I made two forms to place the gravel.
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The end cleats should be about 1' from the ends. The Breaking Braces are 10 1/2" overall for a 1' thick layer of gravel, and the break in their middles is about in their middles. As shown here they lasted for 2 sides of the walkout that I excavated. I will be rebuliding them with heavier hinges and thru-bolting the hinges. I will also soak the Breaking Braces in a penetrating oil finish for durability.
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Here you can see my supervisor checking out the work. It is just after compacting a 1' lift of backfill up to the forms. The next step will be to whack the hinge side of the Breaking Braces with a 16# sledge so I can remove the forms. The heavier the sledge, the easier you can whack them, making them last longer. After the forms are removed, they will be set at the end of the trench left by the backfill, kinda like a sliding form. Then I will fill the trench with gravel up to the re-set forms, then backfill against them again. When I get to the end of the wall, I will come back and set the forms over the gravel at the start and repeat as needed.
If I do this against Cosella Dorken I will put a 1'x1'x3/4" plywood pad between it and the Breaking Braces.
I had two hands doing all the grunt work, and, except during compaction, I was hard pressed to keep up with them with the bucked loader.
SamT
Hey, thanks for all the work you put into your helpful reply! All the photos and drawings were especially helpful.
I plan on using the Cosella-Dorken (Delta-Drain)material that you and Boss Hogg recommended, or possibly Miradrain 6000. It's a polystyrene material, rather than a polyethylene mat.
Rockwood
Hi Rockwood, We have installed many basements in similar conditions to yours and have no problems at all if you can get all of the drains flowing to free air. Sam T. does almost exactly what we normally do and gave you good advice.
If you are using a poured concrete basement, pay close attention to your initial coating over the concrete. If you take a close up look at the small pores on the outside of the wall, you will often see that they are covered over from the top with a little concrete "hood". This happens when the concrete is worked or vibrated and the slurry runs down against the form. If the person applying or spraying the water proofer doesn't get under those little hoods, it leaves tiny uncovered spots that are just bare concrete. This is a very common problem with somebody just standing on the top edge of the hole and spraying down on to the wall.
The most important thing you should do is use a LOT of washed rock around and under your basement. This will take the hydraulic pressure off of the walls and floor and the water will run out of your tile without ever getting into the floor or wall. We built a home on a steep side hill where the water was actually flowing at times and disappearing down the stone drains on the up hill side of the house. You could see it pouring out the tile outlets down the hill. That was five years ago and the basement has been as dry as a bone since we built it. It has absolutely no moisture or dampness on any of the walls or floor.
Rockwood
I'm just finishing my house up North of you in Manzanita.....and just think, had you built in this area, you wouldn't have this problem....for Manzanita is a giant sand spit. Heck, you don't even have to put in a foundation drain in this area!
Are you sure the small water spouts aren't mud clams?
On a more serious note.....you may know this already, but BE SURE you work with an experience local contractor on issues of weather (read water) sealing. I discovered many, many local tips on how to ensure your siding/windows/doors and roof penetrations are absolutely sealed. Builders who come over from the valley and employ their normal building techniques, more times than not, learn the hard way how penetrating the water can be on the coast!
Good luck!
BruceM
I build a lot of houses stuck in the side of limestone ridges. I,ve seen the water skeetin up thru the full footing ditch thing. looks kind of neat till you remember thqat these people want carpet in the basement. I over-dig the hole and put in 3or4 ft of what we call #3 rock, some people call it cat head rock 'cause it's about that size. put 'bout twice as many drains in it as you think it needs. form your footings on top of the rock. seems weird,your BI will fidget nervously wondering if he needs to dial 911. run this past an engineer first and be prepared with your can of truth spray before the white suits get there. about the waterproofing on the basement walls, I've had a guy do mine for years w/o a single failore. don't know what its its called but its like a thick vinyl sheet w/ a1/8 inch layer of clay bonded to it. if,[when] the clay gets wet it blows up to nearly an inth thick and is absolutly water proof. again,weird but seems to work. good luck. jim
don't know what its its called but its like a thick vinyl sheet w/ a1/8 inch layer of clay bonded to it. if,[when] the clay gets wet it blows up to nearly an inth thick and is absolutly water proof. again,weird but seems to work.
Those are rolls of bentonite. Easy to install, extremely effective. Requires adequate backfill pressure. For my money the best waterproofing there is. Same material (bentonite) is what our health dept urges well drillers to use for casing sealing.PAHS Designer/Builder- Bury it!
Don't have any bentonite products here but read about it 20+ years ago. Apparently, for small shrinkage cracks that develop into nuisance water leaks (not floods), they can drive a small pipe down along the exterior foundation in the vicinity of the crack/s and pump a bentonite slurry down and saturate the area, resulting in a sealed crack. Sounds like a wonderful fix, rather than digging to seal or ripping out interior basement walls to do an epoxy injection.
I'm surprised nobody uses bentonite there. Uncommon here, but so is any kind of waterproofing. The first I bought (rolls) I couldn't find, tracked down the factory in N. Dakota (IIRC) and asked them who they sold to. Turned out my formwork supplier had a large dusty pile in the warehouse that nobody remembered was there. Got a fantastic price to clear them out. The sales force wasn't promoting it and nobody but me had ever asked for it. Often spec. for gov't buildings. Already an aged product, so you don't have to worry about it deteriorating.
Slurry? Not sure how that'd work. Bentonite seals by expanding to fill the void, preventing water flow. I suppose if not all the slurry's bentonite was saturated, it would still expand sufficiently with the ground water.
Maybe a little like the bentonite ropes we put in the bottom of forms to totally seal between footing and wall. We clearly wet them down pretty well with the concrete, but they still do an excellent job of sealing the seam. Much simpler than traditional gasketing. Keeps the water in some swimming pools. Rope is sized according to wall thickness so you don't risk subsequent blowout.
One misconception I've encountered is a belief that you had to keep the bentonite wet for it to work. Not at all. It will swell and shrink very nicely as long as there's some pressure. Another form of bentonite wall waterproofing is panels, usually with something like cardboard to hold it in place. Installation is considerably more difficult than the rolls, often with less than great results.
Been a long time since we lived in Denver, but it was a particular problem there, occurring naturally in the soil. One friend bought a new house, had the basement collapse. The GC had to raise the house and replace the basement, with better ground water control. I've seen basement stairs stop 4" short of the floor, with the assumption that the floor would rise to the stairs. An 11 acre apartment complex I worked on had piers under the stem walls. Between the piers we had to shovel out 4" of dirt so there was expansion room without displacing the walls.
Bentonite's powerful stuff. Also the key ingredient in rock breaking powders that you add to a drilled hole.PAHS Designer/Builder- Bury it!
Just moved to Oregon from Denver area about 3 years ago; I did a lot of expansive soil damage mitigation. Depends on the area; some are much worse than others. One floor had raised about 5" - the house was 2 or 3 years old. So when I hear about actually incorporating this material into a project, it makes me cringe, although I understand it's good for this use.
So when I hear about actually incorporating this material into a project, it makes me cringe, although I understand it's good for this use.
Yup. We lived 44th&Zuni, brick basement, no problem except for the spring down there. Oh, and when the dimwit next door left his sprinkler going for hours. Wet, but the foundation was stable.
Bentonite's powerful stuff, the reason it excells as waterproofing. You notice I mentioned multiple rope sizes for different wall thicknesses. Not good if you blow your wall apart. The rolls first mentioned here have about 1/8" of (dry) bentonite on the back side of the plastic. Not enough to damage anything. But you have to backfill before it gets wet. Backfill pressure is the other half of the equation, absolutely necessary.
PAHS Designer/Builder- Bury it!
Edited 12/27/2005 6:40 pm ET by VaTom
After some research via buildingscience.com and the foundation book (by Pros for Pros series) I settled on using Dowfoam and Rub-R-Wall. The rub-r-wall is sprayed on and allows the dowfoam to be "glued" to the wall. You get several benefits: the wall is insulated, the water stays outside (waterproof, will stretch 15x its thickness to cover cracks), and the thermal mass is inside the basement.
We're on a hill with lots of clay and the previous foundation was destroyed by it. Despite 1.5 cold joints, we have never had a leak in the basement (or even a moist concrete wall) despite deep puddles lapping up to the concrete on the outside. The rebar probably helped keep the concrete together though...
For you situation, I would supplement the Dowfoam/rub-r-wall with a 12"+ wide ring of crushed gravel on the uphill side with a geotex-wrapped drainpipe draining to daylight below. Building a swale to carry the surface water away from the house is another effective technique of reducing the amount of water that your foundation has to deal with.
The local builders went thru a phase with that stuff here a few years back.seemed like if you didn' use it you weren't keeping up with the latest and greatest. I was giver all the samples and promo stuff,tend to be conservative, if it aint broke, don't fix it. saw a lot of basements dug out. I guess I'm just old fashionad. jim
You are getting a lot of good advice with your potential problem. However pay special attention to the foundation wall where it sits on the footing. When building my own new home 3 years ago I put 4 in. drain pipe covered with filter cloth with drain rock under and over to code and ran the pipe to a sump which then pumps to a field a considerable distance away and which is below my foundation grade. Had the foundation wall (which in places is as much as 24 feet below grade because of the hillside I am built into) sprayed with a standard foundation coating used here in the B.C. Interior where generally the climate is quite dry (less than 30 in/yr. I then put 2 heavy coats on the inside. My problem is now with water forcing itself between the footing & the foundation wall during the wet springtime. I have used a couple of highly recommended products including one suggested on this forum with no success. Next summer I am having a excavator dig back down to footing level and redo everything paying extra attention to this junction and the drainage plane to grade. Good-luck!
Suggestion: bentonite comes in (dry) pourable granules too. Ideal for the footing/wall joint as you didn't get waterproofing in the joint originally. Requires backfill pressure prior to getting wet.
This is where a bentonite rope in the middle of the wall (on top of the footing) would have saved you a whole lot of grief, and money. Even better, plan for dry dirt on the outside of the wall, but sometimes that gets very difficult.PAHS Designer/Builder- Bury it!
MY my waterproofing sub cleans the joint betweeb wall and footing extremely well,then pours a fillrt of bentonite into the angle and lays the first row of w'proofing so it laps onto the footing. he also uses roofing tar to seal the top of the application so if I don't get it backfilled right away, water doesn't get in the top. I build in an ares of Karst/ limestone formations and all the basements are walk-out/ the sub grade parts shot or broken down into the rock. water runs thru the limestone in pecuilar ways. we have to waterproof like wer'e building an inside- out swimming pool. You can get a lot prepped,hole all cut uot, no water. somebody starts on the lot just up the hill, water paths thru the rock change, you got niagara falls pouring out of the wall when it rains. bentonite works. jim
we have to waterproof like wer'e building an inside- out swimming pool
Good analogy. Sure glad I don't have your sites. <G>
I assume there's also termination bar at the top of your waterproofing, in addition to roofing tar? Wish I'd had your guy to show me a couple of tricks when I started. Not that I had much failure, but did have to replace a little.
Alternatively, the rope would be attached to your footing before the wall was poured. Attachment (glue or nail) to maintain the minimum 3" of concrete to outside of wall. Then pour the wall. The rope sits there, awaiting moisture. I learned about ropes when I was figuring out how to waterproof my swimming pool's bottom-to-wall joint.
We're dry enough here that I've learned how to use 6 mil poly in lieu of bentonite for our underground houses. No leaks, saves quite a bit of money.
PAHS Designer/Builder- Bury it!
wish I knew how to send a picture ,could probably get one of my kids to show me. Imagine 24 feet of fall across a footing over rock that looks like the surface of the moon ,can you say 60 steps? jim
HNY Jim, that I would like to see.
I've got one wall in my next house that uses a large rock for a footing, but not that long or that much fall. Moved the house 3 times one afternoon while excavating, finally gave up. My inspections are handled by the inspector supervisor, so as to not confuse the others who are not familiar with what I build.
He asked me what I thought, then immediately agreed that the rock/footing was reasonable with some rebar in it. My first house, which I certainly didn't know what I was doing, completely confused the inspectors. "What do you mean there's no framing to inspect?" And nobody pays any attention to whether I get rebar in the walls. Couple or 3 hundred tons of roof to support and I have yet to see anybody bother to climb up to look at the tag on the bar joists, or measure their centers.
So..... click Attach Files, with my browser I get a new window where I click Browse. Gotta get to My Documents, or wherever you store pix. Then click on the pic logo whose name will then appear in the Browse window. Click Upload, then Done (when it's finished). Be kind to us dialuppers in the sticks about file size. Irfanview is the preferred photo managing program here. Search for a thread about using it, if you aren't. Very friendly to use. Here's my first effort: PAHS Designer/Builder- Bury it!
Thanks for the tips! Can you tell me where or the type of supplier you get it from? Do you have recomendations as to thickness to apply and do you need to compact the bentonite or cover it with anything before the drain rock? Thanks again!
http://www.cetco.pl/e/swelltite.htm The product most available here is Volclay Swelltite. There are several others, but make sure it's sodium bentonite. No compaction. The way it works is to swell many times beyond its original thickness. If it's constrained (backfill pressure) it plugs any leaks. That's why I consider it superior to sheet membranes, which if punctured will allow water movement behind the membrane. Bentonite won't.
While I have no experience with the corrugated cardboard panel bentonite system, I've read about failures. Pretty sure it was from improper backfill, but the rolls (~3'x25') are very simple to nail to the wall.
Here's a spec sheet from American Colloid. If it's too small to read, yell. One of the drawings shows a typical installation with conventional footing drains. Notice they recommend hydrobar tubes at the footing wall joint, not as notascrename and I used, a pourable bentonite under the rolls which overlapped the footing. Several methods to success.
Good luck. PAHS Designer/Builder- Bury it!
Thanks immensely! I'll be checking it out as I am only digging this footing out once!!!
HNY. Don't forget to come back to post results. We're all learning. Good luck.PAHS Designer/Builder- Bury it!