basement floor

DaveGateway

I am renovating my basement and have a question reguarding what to do about my basement floor. I live in the northeast and the basement floor is poured concrete slab. Three walls are also poured concrete. The 4th wall is 2x4 construction leading outside (walk out).The problem is the basement floor gets damp in the summer. There is never any standing water. The concrete gets darker and the surface "feels" moist. There is a full bath in the basement however it has not been used and dosen't contribute to the problem. I demoed all the shreetrock walls, exposing the 2x4 walls which are about 1" away from the concrete walls. The concrete walls are coated with a black tar type sealer. The wall plates are not pressure treated but appear to be in good shape. I would like to leave the plate and walls if I can. The house was built in 1973 and everything is original. I was thinking of using this as a sub floor http://www.subflor.com/floating-sys.html It is locking 2x2 squares with plastic niples that keep it above the concrete floor. Should I paint the floor with dry-lock and or put down a vapor barrier? should I treat the wall plate with something before I enclose? I was thinking of building a cabinet and putting a dehumidifier in it with access to the concrete walls and floor. I already have a perminate drain line through the walls from an old dehumidifier.

Any thoughts, Thanks

Jon_2

I had a problem similar to yours, my house was the same way, damp late spring, summer and early fall. Would you know if there is drain tile under the cellar floor? Sometimes they put drain tile around the perimeter of the house but none under the cellar floor unless the inspector was there at the time before the stone was being dumped. I picked a corner of the cellar next to a drain pipe and opened up a hole and cemented in a 30 gal. plastic drum with the top off. I did this in the winter, and the dirt and gravel removed from the hole was damp but not excessive. In the spring, I remembered the sump hole that I had not finished. I had the pump in and the drain run but had not put any holes in the sides of the barrel nor powered up the pump. I grabbed my trusty cordless drill with a 3/8" bit and proceeded to drill some holes in the barrel stating at the bottom. Did I get drenched for a second, a 3/8" stream of water hit me full in the face. The hydrostatic pressure of water under the slab caused a 3/8" stream of water to shoot 4' up and caught me full in the face. I proceeded to drill a pile of holes in the side of the barrel. Now my cellar floor is dry all the time, all year round but I have to have that sump pump to do it.
To see if you need install a sump pump, bore a 1/2" hole where you would put a sump pump, insure that it penetrates thru the concrete and into the ground below and watch it next summer... If there is standing water in the hole you need a sump pump. There is another way but that depends upon the grade your house is on and whether you can run a drain tile to atmosphere but you will need a backhoe and a deep purse. Jon

Mike T., Swampeast MO

The last thing I would do is install ANY sort of flooring that creates an air space between the concrete and the finished floor.

If it is moisture migrating through the floor you ain't gonna' stop it--thus the post about sump pumps...

Since you're not getting BULK water it sounds like you have a good "dry" basement and you probably shouldn't mess with things by opening holes...

If it's humidity condensing on the cold floor surface it may well start condensing in the airspace BETWEEN the floors.

Think HARD SURFACE and CONDUCTIVE flooring like heavy commercial "vinyl" squares or ceramic with rugs if desired to "temper" the cold/hard floor.

A dehumidifier can do true wonders for a basement. While humidity does tend to equalize itself I wouldn't go so far as to build it in to an enclosure--it really wants to be located in free air.

Jon_2

Mike, I didn't have any standing water in my basement, just a damp floor. By drilling a hole and watching it in spring will let you know for sure what is happening. A little epoxy and sand mix will patch that hole is a jiff if there is no water. The moisture that makes that floor damp has to come from somewhere. My basement is bone dry now and remains that way all summer due the the sump pump. Before I ran a humidifer, and the cost of that running 24/7 made for some interesting light bills, for here in Northern NY it's 14 1/2 cents per kw and all it did is eat out of my wallet and the floor was still damp. I would find the problem first before I would invest in any improvements that I was going to do to the basement.

Mike T., Swampeast MO

Is your basement finished living space?

LEAD PIPE

holes in the floor

I do have 2 holes drilled into the floor that are about 3/4" in dia. I'm not sure what they are for but they do go prity deep. I don't get any water coming out of them (in the 3 years I've owned the house) The condensing seems to make sense because in one small are I have vinyl tiles ontop of the concrete which also have a wet feel to them.

LEAD PIPE

living space

Yes, I want to turn it into a playroom for my kids its about 750 SF.