Solutions for Water in Crawlspace?

[mmhouse]

Again not exactly garage related but I trust you folks for advice so here goes...

I have water in my crawlspace during the rainy season. My gutters and downspouts drain into a piped system which dumps into a pond well away from the house and is working well. The surface grading for runoff around the house is good. For these reasons and because I am fairly low I'm sure the problem is a high water table that is migrating up into the crawlspace as it rises. Since the footing drains are at the top of the footers they are apparently just a bit too high to prevent an inch or two of water from accumulating in the crawlspace.

I have two bids that I am comfortable with for installing a drainage and sump pump system but each take a little different approach and I'm not sure which is best.

The first would put a trench around the perimeter of the footing and one down the middle all leading to the sump pump. These trenches would have perf pipe and be filled with pea gravel with a vapor barrier over the entire crawlspace.

The second would put an open trench around the entire perimeter leading to the sump pump with no central trench. There would be no pipe or gravel because the bidder says the gravel can impede water flow and that the pipe can silt up over time.

My question is, which is the best approach?

I don't know why the first bidder would go to the expense of putting in the pipe and gravel if it is not necessary and could cause problems and callbacks down the road. On the other hand the impeded flow and silting does sound feasible.

Do any of you have experience or expertise in this area? If so, what is the best approach?

 

[NUTTSGT]

I'd do it myself first of all, it's not technically hard, just some physical labor.

I'd trench around the inside of the walls, along with one down the center. Dig a hole on one end for a sump pit. Make sure all the tile run down hill to the sump pit. I'd also use a larger stone than a pea gravel, I've used #57s in my basement. The larger stone allows more gaps for the water to run.

After that is done, put your sump pump in the pit and plumb it to the outside and away from your house.

 

[mmhouse]

Thanks Eric. I could certainly do it myself but I'm willing to pay someone to take care of some of those less enjoyable tasks. For some reason digging around in my crawlspace just doesn't sound that interesting.

It sounds like you prefer solution #1 with the perf pipe and gravel though.

 

[hayfarmer]

Is your crawl space concrete?

I would just install a sump pump in the plastic sump pump pit that you buy at Lowes or Home Depot. If you have the pump remove water well below the surface of your crawl space the water shouldn't come through the floor. This is very easy to do.

 

[mmhouse]

Is your crawl space concrete?

I would just install a sump pump in the plastic sump pump pit that you buy at Lowes or Home Depot. If you have the pump remove water well below the surface of your crawl space the water shouldn't come through the floor. This is very easy to do.

No, the crawlspace is native soil with a 6 or 8 mil plastic sheet laying over it.

 

[e-tek]

Thanks Eric. I could certainly do it myself but I'm willing to pay someone to take care of some of those less enjoyable tasks. For some reason digging around in my crawlspace just doesn't sound that interesting.

BEST ANSWER TO THE: "I'd Do it Myself" mantra we hear on the forum all the time!! Sometimes we "Don't Wanna Do It Ourselves"!!!

It sounds like you prefer solution #1 with the perf pipe and gravel though.

I did too as that's what I've seen before, but then I've also seen the silting and clogging happen. The pea gravel method will likely work best - before it silts up.....so I'm on the fence! But I know for sure I'd hire it out too!!

 

[blue dog]

Solution number 1 is the way to go, as far as the silt build up goes, if it ever becomes an issue, you can all way's snake the drain line. It would take a lot of silt to clog up a 4" or 6" line. I all so feel that the pipe will aid in disposing of silt as opposed to having it build up at the bottom of the gravel. Good luck

 

[Torque1st]

Use the drain pipe with a fabric cover.

Put a clean-out access at the high point of the system.

 

[robertlynk]

PROVIDE RETAINING WALL DRAINAGE SYSTEM AS FOLLOWSROVIDE 1CF/FT OF CLEAN COARSE GRAVEL WITH 4" DIAMETER PERFORATED PVC DRAINAGE PIPE WITH 1% GRADIENT TO DRAIN .6) OPTIONAL: INSTALLATION OF A MOISTURE BARRIER ON THE FILL SIDE OF THE WALL WILL HELP TO PREVENT MOISTURE FROM PENETRATING THE WALL, RESULTING IN migration of water through wall

 

[boo coo tracks]

I would use a sock tile to avoid silt build up.
Trust me on this one.
Tracks

 

[cowboyjosh]

I like solution 1 the best with the suggestion of using the drain pipe with a fabric cover, and putting a clean-out access at the high point of the system, if the possibility of silt keeps you up at night.

I've been a home builder and electrical contractor for quite some time now and before I was on my own worked for a couple "old timer" builders, and have always done what your solution 1 contractor suggest and I have never had a "silt" issue nor have I heard of any from foundation contractors or excavators, so I wouldn't worry too much about that, then again I don't know specifics about the soil your house sits on, so do whatever works best for you and your checkbook.
On all new builds, I now I do a Certainteed footer / drainage system, see link. http://www.certainteed.com/resources/PBFForms.pdf

Also how about some cross ventilation in that craw to help keep it dry? do you have any mechanical ventilation? http://www.tjernlund.com/retail/underaire.htm

 

[mmhouse]

Thanks for the link cowboy, that's an intriguing forming/drainage system. Looks like a real win-win for the builder and the homeowner.

I was leaning toward solution #1 and think I just needed a little shove in that direction. From the replies so far I think I have it.

I don't have any mechanical ventilation but lots of foundation vents that I keep clear. Up to this point when I've gotten some water down there the poly vapor barrier has remained on top of the water (preventing too much evaporation) and with the vents there has been no evidence of mold or other moisture related damage. I do have some squeaks in my floor that I am fixing and I want to prevent them from returning by getting the moisture level down further.

Thanks for all the info.

 

[lawfarm]

Solution #1, with coarse gravel or pea gravel (no fines), and a silt sock over the tile is the way to go.

 

[mrpowderkeg]

Solution number 1 is the correct way. It will be working long after you are gone from this earth if it is installed properly.

 

[Mike83]

I had the same problem...water would come up from under the foundation wall into the crawl space.

I actually built a french drain outside my house (about 4' away). I dug 18" deep, placed 2" of 3/4" stone, place the perforated drain tile with sock, and sloped it down for about 50' away from my house to drain at the edge of my property line. I backfilled the trench along the house with the 3/4" stone. It has worked like a charm so far (I used to get many inches of water down there, now only a small amount even after a heavy rain). All the water that did go down to the crawlspace gets sucked up by the drain tile.

That said, go with the drain tile option with coarse stone and a sock on the tile. The water that comes through clay (which is what I have) is clear enough to drink, so do not fret about silt assuming you have clay too. The sock will be extra insurance.

 

[shotgunfatcat]

One word, Shamwow.

 

[scott37300]

Another vote for option 1. I have had to do this in my last two houses, except I had full basement and dug from the outside. I used perferated drain tile with the fabric over it and 3/4" clear stone. I did a lot of reading and everything recommended the 3/4" clear stone.

What ever do, do not hire contractor #2. If he doesn't know about fabric covered drain tile to stop silt than he doesn't seem to know a lot about this. Also if he thinks that just digging a trench and leaving it will last he sounds shaddy to me. I would bet the dirt would collapse over time and you would be back at where you are now. From your post I get a feeling this guy is just trying to get in do as little as possible and get paid.

What kind of garuanty do either of these compainies offer?

 

[SL6RAM]

Just had option #1 done in my house and it has worked very well. They guy has done this type of system before and hasn't had any problems.

 

[mmhouse]

Thanks all. I committed to contractor #1 and he will be doing the job within the next month or so.

Contractor #2 called me after I sent him an e-mail to let him know I was going with the #1 due to his recommended method. He then offered to do the job with tile and gravel at his original bid price (which was very close to #1). I said thanks, but no thanks. Although he seemed to know what he was doing I was not impressed that he recommended a far cheaper method but bid a price that would cover doing it right. I had asked him about doing it the correct way when he was working out his bid and he said nothing about that being an option for him. I guess he took his chances and lost on this one.

At any rate, I think I'm on track to getting the problem solved correctly.

 

[rockchucker]

Your whole issue could just be Hydrostatic Pressure. This is where there is so much water saturating the earth that it will find an empty place to come up or through. As the Curtain Drain (Option #1) will take care of the standing water there still will be a considerable amount of moisture. Especially under the Vapor Barrier. In the rainy Season you may just want to throw a box fan under your House to promote air Flow in the Crawl Space.

Just my .o2

 

[NUTTSGT]

The box fan is not a bad idea. I have one in my basement blowing into the crawlspace. It's been there for about 3 1/2 years.

 

[mmhouse]

Your whole issue could just be Hydrostatic Pressure. This is where there is so much water saturating the earth that it will find an empty place to come up or through. As the Curtain Drain (Option #1) will take care of the standing water there still will be a considerable amount of moisture. Especially under the Vapor Barrier. In the rainy Season you may just want to throw a box fan under your House to promote air Flow in the Crawl Space.

Just my .o2

You are correct, the problem is hydrostatic pressure. The water migrates up through the soil when the water table is high. My surface drainage is good and all downspouts lead to a solid perimeter drain (external) which daylights to a pond. I have confirmed that they drain as they should.

The install is scheduled for 9/22. We are installing a full perimeter drain plus one down the center with a couple of branches in order to catch as much of the water as possible (within reason). There will be perf pipe with gravel in the trenches leading to a pit with liner. I'm also replacing the vapor barrier on the ground with 8mil poly and will tape all the seams with duct tape.