Crawl Space with Water Pump/condensation
I have a crawl space, 1/3 of which is below grade. (Steep slope on mountain in Southern Appachians.) I bring spring water into the crawl space then use a shallow well jet pump to supply the house. Condensation and moisture have always been a problem. (The pump and line are always covered with condensation in the warm months.) I have 5 vents in the crawlspace. Finally took the insulation out from between the joists because water would bead on the bats and stay damp all the time. I have a vapor barrier (3 mil) on the dirt floor. The back wall (block) is usually damp, but there doesn’t seem to be much in-migration of water. How can I keep the crawlspace dry and safely insulate between the joists. I’m afraid to seal off the vents and create that poly bubble that seems to be gaining favor but maybe that’s the right strategy …. All advice is welcome.
Replies
bringing the spring water into the crawl space.. how do you do that.. do you have a sump in your crawl space ?
if you do , you have a water /moisture source that is pretty hard to control.. why don't you move your sump outside the founcdation and cap it and supply your water need from ther instead of inside your house ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
The spring is 100 yards uphill and to the north of the house. (None of the spring water flows near to the house ....) I have a spring box at the source, then pipe the water down and across the hill and into the crawl space, where it passes through the shallow well pump. It then carries on out an overflow well below the house. It's under the house so it won't freeze, and for water pressure considerations. I believe that if I enclose it/tent it? under the house that will cut down on the condensation? I'll still have the problem of having the crawl space set into a cold hard slope in Appalachia, which I think is going to keep things damp without other mitigation measures.
can't you form and pour a concrete cap on it with a vapor barrier ?.. that is onw bad dude source of moisture vapor constantly flowing into your house..
Mike Smith Rhode Island : Design / Build / Repair / Restore
I guess I could build some kind of structure around the pump and air tank. Concrete might be overkill. The pump is only about as big as a bread box and the air tank is about as big as .... a bread box. There's no well of water, no standing water. Except for the inlet and outlet pipes right around the pump, all the pipe is under the existing vapor barrier (on the dirt) so they don't create much of a problem. Thanks for sticking with me on this. I think I need to contain any moisture from leaving the pump then consider insulating between each joist with rigid foam. Just came up from under house and now I see some of my block is uncapped with the sill improperly done, and this must be letting in lots of cold damp air too. Was thinking of filling those cavities with great stuff. Ideas?
No surprise that cold spring water is below your summer-time ambient air dewpoint. You're not going to get the crawl-space air less humid than the outside air, so the only solution I see is to box up the pump.
I always look for something off-the-shelf. A larger tupperware container, for instance. Drill holes through the sides for the wiring and piping penetrations but leave the lid area unused. Then you can simply snap the regular lid over the equipment and have it all pretty air-tight. If you can undersize the penetrations a bit, then the wires (like round SJ cord) and pipe (consider reinforced rubber hosing) can be squeezed into the holes pretty tightly. But for inspection or maintenance, the tupperware lid pops right off.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
I like this kind of thinking. Shape is a little too awkward for a tupperware container, but something along those lines. I'd love to have the snap lid for access!
My suggestion would be to seal off the vents. As it stands now, you're bringing warm moist air into the cooler crawlspace. No way is that going to prevent condensation.
But if you seal off the vents, and open a duct from your HVAC system into the crawlspace, you more or less make the crawlspace contitioned space. This will dramatically cut down on excess moisture.
I tries something with my basement once which convinced me of this. For about a week, I left 2 windows open so I had plenty of airflow. There was constantly water dripping off the ductork and water pipes. And the air felt musty.
Then I closed the windows and opened up one vent in the ductwork. Within 2 days, virtually all the condensation and dripping stopped.
You may also need to put some sort of vapor barrier on the crawlspace walls, as you're probably getting some moisture through them.
Q: How do you turn a fox into an elephant?
A: Marry her.
I could close off the vents, but I don't have the type of air system that could vent into the space. No need for air conditioning up here in the Appalachians! I'm at 5000 feet elevation. (I use a monitor heater for winter. Love it.) I don't get any mold/mildew in the house unless I have the windows open when the fog rolls through, so I'm not sure I've got a big problem. (Plus, I used pressure treated wood for all the floor joists.) But I would like to keep the floors a little warmer. That's why I'm thinking of foam board insulation between joists rather than fiberglass bats ....
Can you set up a dehumidifier down there, and pipe the condensate outside? (Assuming you close off the vents. Otherwise, you're trying to dehumidify the USA, in which case you'll need a bigger dehumidifier.) I have one in my basement and it runs all summer. It drains to my waste stack (via condensate pump.) Several considerations with a dehumidifier: They don't work in the cold (ice up), and they cost some money to run (like a small A/C unit.) But they do suck out the H2O. A client flooded her kitchen (spray hose split.) I took the hehumidifier from my basement, placed it against the sink and sealed it with duct tape and plastic to the counters, within a day it was as dry as parchment.
I'm going to consider that. Did I mention that I am a fanatic about energy consumption? I'd love to solve the problem using ingenuity rather than a machine, but solving the problem is a top priority whatever it takes ....
Do it in stages. Stage one: Block your vents. If that doesn't solve your problem, check to be sure the poly on the floor is in good shape -- if the 3 mil is torn up or in bad shape, install 6 mil, with plywood laid down on top in the areas where you walk. Stage 3: If necessary, install a dehumidifier to run during the summer months. You may cringe at the thought of the extra electricity required to operate a dehumidifier, but it's a lot better to pay a little more for electricity than to watch your floor joists rot slowly.
Very sound approach. Thanks for thinking on it. Luckily as I approach the problem I do so with the satisfaction of having laid 22 new pressure treated joists along the old ones a couple of years ago, so I'm not too worried about rot at the moment, just smell, mold, etc. And, if I can get it real nice and dry, I may reinsulate ....
Where in the Appalacians??? Near Mt. Rogers by chance? I am in Roanoke.