Crawlspace moisture problems

2333 Views 14 Replies 10 Participants Last post by Ronald Cruse, Sep 25, 2014

Waltwood

Discussion Starter · Dec 23, 2013

I have been dealing with this issue most of my Contracting career but I just don't know the best- less expensive and effective way to correct severe moisture problems in the crawlspace at my mothers house.

The house was built in 1957 and has a CMU foundation. The grade on the inside of the foundation is 18" lower than the outside. The foundation is only 8" high on the outside. There are working gutters on the house. There is no plastic sheeting on the ground on the inside. Water is pooling on the inside and the underside of the floor joists and subfloor is wet. I have determined there are no plumbing leaks or other source of water other than from the ground

This is the part I need you all to comprehend that the area were the house is located has sandy loam soils with no grade changes. Land is flat. This makes the french drain option on the outside not a solution as I see it and maybe even other solutions. The soils are well drained on the outside. I am thinking that it needs a crawlspace dehumidifier or a power venting of some sort. I hope you all can offer helpful solutions before Mother and other family members drive me crazy.

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griz

· #2 · Dec 23, 2013 (Edited)

Are you near a lake stream or aquifer?

Where does the general drainage in the area appear to go?

Know the depth of the water table?

Working gutters? What about downspouts, runoff directed away from house?

How well is the crawl space vented?

IMO, you have too much water for venting or a dehumidifier to work.

You will have to divert water away from the exterior of the house.

French Drains can "daylight" in to a pit.

Maybe also a sump in the crawl space.

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Waltwood

Discussion Starter · #3 · Dec 23, 2013

No ditch or place to go to but a pit is option that I thought of while I was describing the situation with no where to go with water.

Thanks for reply, battery is very low on laptop and don't have charger. Getting new one tomorrow and will check back in. Did not want you all to think I was ignoring responses.

Dave in Pa

· #4 · Dec 23, 2013 (Edited)

A bit confused here for me?? If the outside soil drains, the gutters work, the inside soil is lower than the outside, 8" outside of foundation, the joist are wet, subfloor wet as well, you have a indoor swimming pool! Things don't add up in my look at things here?? DO you have open vents to outside air? Does your crap vents feed into here? Does your dryer?

woodchuck2

· #5 · Dec 23, 2013 (Edited)

The more i read into this i think the foundation is pulling the water in and holding it. I say dig up around the foundation, seal it on the outside with block bond or a rubberized membrane, put in drainage pipe with a good stone base and pitch that away from the home in several directions. If possible put a pit in the floor with a sump pump, this will give the water a place to go and then can be pumped out.

If the land is that wet then i recommend lifting the house and putting in some big fans to help ventilate the area. I am currently working on a home sitting on piers next to a lake that the original floor joists litterly fell out from under it leaving the floors and walls hanging and sagging. When i am finished replacing all the floors and repairing sills i am lifting the home 2' for additional air flow. The home also used to have a skirting around it which will be removed. This home already sits 16-18" off the ground in the lowest area and it rotted out within yrs after the skirting was installed.

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Bob Vila

· #6 · Dec 24, 2013

I would say its a grading issue. I would bet the grade on the outside most likely does not slope away on ALL sides. When it rains next go find out where the water is coming in and create a swale to draw the water away from the CMU and to the drainage area. Digging a sump pit next to the foundation and pumping the water 20 feet or o away could help if its a high water table.

SLSTech

· #7 · Dec 24, 2013

It is called a sealed crawl - French drain inside to sump if need be, plastic on ground sealed properly & then run a dehumidifier for a week or more to dry everything out. If you have any ducts down there make sure they are sealed properly & check for plumbing leaks. Seal everything up properly & insulate the CMU walls & rim joist areas (Closed cell sprayed is best but can be done with foam board)

As others mentioned, check the grading & if need be / if possible increase the slope - you can always create a retention area away from the house to have everything run to

Adding more humid air into a basement is folly especially during the summer

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TimNJ

· #8 · Dec 24, 2013

I have been through your area a lot and it is low in the DelMarva.
You need a vapor barrier down on the ground in the crawl space. The ground moisture will just keep coming up through the soil no matter what you do.

Do the other stuff; grading, sealing block, sump pit, foundation vents, and then vapor barrier on the ground and rat slab over top of it.

We Fix Houses

· #9 · Dec 24, 2013

Is it over a spring ?

I agree about digging a pit - see if it fills. Get a sump pump.

Had a customer with same issue. Now sump pump turns on every 10 - 15 min - throws out about 3 - 4 gal water.

Be vary careful about adding powered ventilation. Recent studies show they introduce moisture into the crawl - causing problems. See GreenBuildingAdvisor.com

Shellbuilder

· #10 · Dec 24, 2013 (Edited)

A little south of you but experience this often with crawl spaces built too low or excavated like yours. I do these in a stages. Stage one is to bring clay soil in and create a slope 10 feet from house and tamp the material. Wait a couple of rains and see if crawl is improving. If not, install sump pump. Ive had about a 75% success to not need the sump. Sometimes I install the plastic but only if soil is damp, not wet after sump has been installed for a few weeks. Your mother will just have to chock up the craw; space sump electrical use as the only way to fix a really dumb construction decision in the 50s. Good luck Glad they caught that serial arsonist up there.

Waltwood

Discussion Starter · #11 · Dec 25, 2013

Dave in Pa said:
A bit confused here for me?? If the outside soil drains, the gutters work, the inside soil is lower than the outside, 8" outside of foundation, the joist are wet, subfloor wet as well, you have a indoor swimming pool! Things don't add up in my look at things here?? DO you have open vents to outside air? Does your crap vents feed into here? Does your dryer?

Yes it is confusing, that is the reason I asked for help. I have been solving moisture problems for other people for more than 30 years and I can't solve this one yet. But I can tell you that the soil under the house is hard and packed down and quite unlike the outside making it poorly draining. I was born in this house and the grade on the outside has risen quite a bit over the years. None of the fans terminate under the house and they would not give off as much water as there is under there.

Waltwood

Discussion Starter · #12 · Dec 25, 2013

Shellbuilder said:
A little south of you but experience this often with crawl saves bullt too low or excavated like yours. I do these in a stages. Stage one is to bring clay soil in and create a slope 10 feet from house and tamp the material. Wait a couple of rains and see if crawl is improving. If not, install sump pump. Ive had about a 75% success to not need the sump. Sometimes I install the plastic but only if soil is damp, not wet after sump has been installed for a few weeks. Your mother will just have to chock up the craw; space sump electrical use as the only way to fix a really dumb construction decision in the 50s. Good luck Glad they caught that serial arsonist up there.

Thank you for the ideas but in some areas on the outside of the foundation the grade is 4 to 6 inches from the siding with no slope away from the house. If I add dirt it would touch the siding and cover the foundation vents. I guess the sump is the way to go.
The arsonist was the biggest thing ever happened around here and they have been charged with 47 fires! They were offering a large reward before they got caught and all the ******** were staking out abandoned houses at night trying to catch them- it was great!

Shellbuilder

· #13 · Dec 25, 2013

Sometimes even an inch and a half of soil will fix the problem and use a level to fix grade. That arson news was on every night on news here.

Waltwood

Discussion Starter · #14 · Jul 28, 2014

This problem is solved! House sewer line was leaking and I had sent 2 plumbers to look if that was part of the problem and they said all was fine. Sewer pipe was half buried in the dirt and rusted out on the bottom side. There was ground water issues also. I had a Co. called JES do a foundation encapsulation. It works very good but is expensive. They also put in a dehumidifier. There were 5 contractors involved including asbestoes removal.

Ronald Cruse

· #15 · Sep 25, 2014

Thanks for the tip Shell, sounds like a winner.

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