Replies

1. 
   Dinosaur | Jun 07, 2003 06:36am | #1

   BASIC RULE FOR MANAGING WATER: YOU CAN'T STOP WATER (not permanently, anyway); THE BEST YOU CAN DO IS TO RE-DIRECT IT SOMEWHERE IT WON'T BOTHER YOU. Water, like most of us, will take the path of least resistance. What you want to do is give it an easy way to go somewhere harmless--or even useful.

   This is what exterior perimeter drains are for: ground water flowing downhill toward the basement or crawlspace wall is slowed by the wall and its waterproofing; it then sinks down to the first new barrier it encounters, and also flows sideways through the ground to go around the house. If it can't do this fast enough, some will seep through the wall into the basement. And once it's in the basement, it will stay there unless it can get out again easily.

   To speak directly to your problem: Your first step should be to dig down on the outside of the wall and see what's there. If there's no drain, you need to install one (see below). If there is a drain, and it's properly installed and in good shape, you may just have too much water for it to handle. Your choices are to replace it with a bigger one (go from 4" to 6" or 6" to 8"); or to help it out with more drainage inside the basement/crawl space (see further below).

   By the way, while you've got the foundation dug out, pressure wash it and re-waterproof it. There are membranes now that are made for this if you want to go hi-tech hi-$$$; or you can roll on two or three coats of fresh black goo. Put roofing pitch in all form-pin pits and at the joint between the footing and the wall.

   If you have to put an exterior drain in, put in an appropriately sized perforated pipe or hose rated for the amount of ground water you're dealing with (check with local contractors to see what they recommend). The drain pipe or hose must run downhill around the house from the high point in both directions to the low point, where you put in a 'T' connection and run a non-perforated drain out to daylight or an acceptable sewer connection, ideally. If you can't do that, run it to a LARGE rock pit. You then dump anywhere from a foot to three feet of 3/4 net (washed gravel) on top of the drain, protect the gravel with geotextile or heavy brown paper or straw, and backfill.

   To help you decide if drainage inside the basement is what you want to do, try running a percolation test. Dig a hole in the crawl space about three or four feet deep--it doesn't have to be wide; a shovel width or two is sufficient. If  you've got a post-hole digger that'll be fine. Fill the hole with water. Now you have to time how fast the water drains down. Check with your local municipality to see what they consider very permeable; permeable; or not permeable. (On the last septic system we installed, my client just squeaked in under the line at 1.0 cm per minute, this being the lower limit of the 'very permeable' category, which he needed to be authorized to put in the type of system he wanted.)

   If the ground under the house isn't in or darn close to the 'very permeable' range, you're going to have to help it drain somehow. Your choices range from (a) digging out the entire crawlspace and shooting 3/4 net in to replace the fill and draining this out under the footing (rather a big job), to (b) digging a series of trenches from high side to low side, plus a trench all around the inside perimeter, into which you will install a drainage 'field' of perforated pipe or hose, covered with gravel, etc., etc., as above. (For the crawl space, you don't have to cover the gravel with earth; just lay a poly sheet on top.) This you must connect to a clear drain going outside the basement under the footing.

   Sometimes footings are poured directly onto the bedrock. When I pour footings on bedrock (which is very common in my area), I run at least one 4" sched. BNQ through the footing on the high side per 30' of footing. For each inlet pipe, I run two outlet pipes on the low side. Then I load up the basement with at least a foot of gravel before I pour the floor. This lets the water flow under the floor through the gravel and out the other side.

   If your builder didn't do this and you can't go under the footing without major trouble you'll need to install a sump tank with a sump pump in it, and then pipe the discharge from the pump up and out through a wall somewhere. If you're on municipal sewers, check with the municipality before dumping this water into their system; some will allow you to do so, but not all. If you're on a septic tank and field of your own, DON'T run this into your own system; septic systems have a limited life span determined in part by the volume put through them. Instead, make a separate perfed or solid drain line and run to daylight or a big rock pit.

   Hope this helped.

   Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?

1. 
   SupraDave | Jun 11, 2003 06:03am | #3

   Thanks for the response, I'm planning to dig up the exterior found drain and see what is there. Good tip to go ahead an be prepared to apply water proofing while it's exposed...

2. 
   tabriz | Aug 03, 2003 04:53pm | #4

   Thanks for your very thorough response about reducing water problems in a basement.  I will ultimately have to add an exterior drain and reseal the exterior basement walls but before I do that, can you suggest anything to remedy water seeping in through hairline cracks in the basement floor?  This is my plan:  marking all the cracks, chiseling them out a bit, and using some kind of hydro-cement to seal them.  Is it necessary to chisel the cracks or is it sufficient to "push" in the cement?  I've been putting it off because it is daunting and I'm not sure I know what I'm doing.

   I appreciate any suggestions.......

1. 
   Dinosaur | Aug 04, 2003 05:32pm | #5

   It depends on how long it will be from now until you 'ultimately' deal with the footing drain and exterior tarring. If you mean a few years, well, it might be worth pouring some money into stop-gap measures. If you're talking about a month of so, forget it: attack the source and then wait to see what the result it; you could save youself some big bucks.

   If you do want to seal floor/interior wall cracks right away, there are injectable hydraulic cement products available that you can force into fissures under pressure. They are expen$$ive (I think a 300ml cartridge set is about $75-80 here ($C, of course!). Alternatively, you can use Polyplug, a hydraulic cement that will set up even with water actively running through the crack. (Warning: do not mix more Polyplug than you can use in about 1min30sec--you'll lose it. It sets so friggin' fast you won't believe it the first two or three times it happens to you.) Use an angle grinder with a concrete wheel on it to prepare the crack as a V-shaped fissue; ideally the entry to the crack at surface level should be narrower than the bottom, so the plug can't pop out later (realistically, this is difficult to do without turning a small crack into a big one).

   Have fun, LOL--and wear a respirator and goggles while running that grinder. Wash your hands with vinegar afterwards and then rub em down with Bag Balm.

   Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?

1. 
   tabriz | Aug 04, 2003 06:49pm | #6

   Thanks again...the grinder will be tons easier than the chisel!  It will be at least a year before I can do the exterior work and I may be relocating before then so this stop-gap measure is the way to go for now.

   Tabriz

2. 
   Piffin | Jun 07, 2003 03:39pm | #2

   You are describing a house that I re-built on a sloping lot. It had a wet crawl.

   I dug in a perimeter drain on the uphill side and directed it to daylight.

   Dryed up so quick inside that I didn't even have to put down plastic. I had been uncertain how well I would do because it is on ledge so some water would naturally follow the rock bottom.

   .

   Excellence is its own reward!