Basement moisture

[Eric29]

I’m not sure that this is an appropriate question for this section of the forums so I apologize in advance if it’s not. It does concern flooring, but maybe not in the context that is usually discussed here.

My son is considering buying a home in Pittsburgh that was built in the 1850s. The basement is very damp, partially because in the very front of the house, there is a room with a dirt floor. If he buys the house, I’d like to cover the floor up to reduce moisture in the basement.

Other than pouring concrete, would there be a good way to do this? I was thinking of putting plastic down and adhering it to the walls. The problem is that the room would then really become unusable because no one could really walk on the plastic. I thought about the possibility of building a frame over the plastic and putting on some sort of decking boards but I’m afraid that since the plastic will not completely stop the moisture, the bottom of anything I put on would just become moldy.

There is a way to pour concrete. The room has a coal chute facing the street and I think that I could get a concrete chute down there and we could pour. I was hoping to avoid that though because I think it would be pretty time-consuming. On the other hand, if it’s the only way to really stop moisture, I guess I would suggest that we do it.

I wonder if anyone had any suggestions or thoughts? I’m sure that many of you are more experienced at dealing with moisture on floors than I am.

Thanks

 

[ConCretin]

I would suggest placing a good vapor barrier under a concrete slab. A properly installed 15 mil product like Stegowrap will stop any water vapor transmission into the space. Tape the seams and any penetrations and run the membrane up the wall around the perimeter and tie it into a barrier on the walls. This is a pretty typical installation for your situation.

You'd be surprised how much concrete a few guys can move with a chute and a couple wheelbarrows. You might want to get a professional finisher if the space will be finished but otherwise the concrete is just there to provide a walking surface and protect the vapor barrier from damage.

 

[Eric29]

Thank you.

 

[zak77]

I've come across a person who owned an old farm house and put plastic down on the dirt floor, then put crushed stone on top of it. They sealed the edges as best they could. I'd be a little leary of doing this if you're going to be walking on it often, since you could puncture it with the rocks. But if it's almost never going to be used, stone may be a better option. Otherwise, concrete.

 

[Eric29]

After looking at the place again, I think it’s likely that I’m not going to get able to get access to deliver concrete or crushed stone. So I think my only option would be to put a moisture barrier down, and then maybe just put some rubber pads on top of the moisture barrier so that people can walk across the room.

So again, I’m back to my idea of whether building some sort of deck (2x4 or 2x6 frame sitting on the floor) over the moisture barrier would be OK, or if the bottom of the deck boards, even if they are spaced, would just turn into a mold farm.

I’m not sure how effective moisture barriers are. If they let a lot of moisture thru, then I think moisture will collect on the bottom of the deck boards. If they are super efficient, and I put spaces between the boards and put a dehumidifier in the room, then it might work. I just don’t have any experience with this.

 

[captain14]

One of the members here just completed a project like that in his home.
NuttsGT hand mixed cement and poured a portion of his basement.
Look at his garage thread and he describes his work. I don’t remember if it was a delayed thread or part of his continuing thread about his garage.

 

[b-boy]

Whatever you do, you need to be careful. The last thing you want to do is create a worse situation than already exists.

Maybe hit some of the building science websites out there? There is some really good information on insulation/moisture in basements available. I used it when I redid my basement.

I think anything you decide to do should probably include a vapor barrier and maybe some insulation.

 

[8pack]

I have lived in several very old homes, 1890's. I run a Santa Fe dehumidifier in my basements. It removes an amazing amount of moisture and my humididty levels went from the high 50s to the mid 30's in just a few days and consistently stay there. Sometimes after a heavy rain there is some catch up but very rarely does the humidity ever get over 45%. There is no musty smell or odors in the basement with it running.

I also recommend running over all the walls and concrete floors 2x with a bleach mixture when you get the dehumidifier in place. We got nailed in hurricane sandy and our basement was full of sewage tainted water. The bleach treatment took care of it and there is no odor or mildew etc. at all.

Good luck.

 

[johnnyradiant]

Have you done any Radon research? You may be wise to look into that aspect and get that floor dealt with as a top priority.

 

[Eric29]

The radon test came back ok. I’ll take a look at the Santa Fe dehumidifiers. If possible, I would like to reduce the moisture is much as I can so that the electric bills aren’t through the roof, but we have to do what we have to do to keep the moisture down and if running a dehumidifier is it, that’s what we’ll do. I was really hoping though to get the moisture within normal bounds.

Have you done any Radon research? You may be wise to look into that aspect and get that floor dealt with as a top priority.

 

[CombatNinja]

Do a search on crawlspace encapsulation. The basement here is just a bigger crawlspace. One thing I would caution on is if there is going to be people walking on the floor, you need to use a heavy (expensive) floor membrane or it will be ripped up in no time. If it were me, I would try to seal the dirt floor but probably leave the walls alone. If you think about it, if you put a vapor barrier on the walls, they then can't dry at all since they can't dry to the outside since they are underground. Then you might end up with a really wet foundation that might start to rot out the framing on top. My approach would be to seal the floor with a membrane and get a dehumidifier installed. Not the cheap plug-in type you can buy for $100 and you have to empty a drain pan every day but a hard-wired one that has the capacity to properly deal with the space.