We have existing concrete walls, only gravel on the floor. How do we go about building a wooden floor. We want to install hot water heating underneath the floor. Any help or suggestions appreciated.

[Edited by Diane Lorenz on 12-16-00 at 04:39]

 

I hate to tell you this, but I think you should re think very carefully your basement floor plans. The heating in the floor is very expensive, not a DIY project, and will not work very well with a wooden floor. A wooden floor in the basement is not a very good idea. As you know wood will draw moisture, and will warp, never be float, and will rot. If you are intent on heating in the floor, you will have to have a concrete floor. The pipes or hoses run through the concrete. I think a concrete floor with other means of heat will work alot better and be much less inexpensive.

 

First off use preserved lumber which is treated and meant for below grade application. Level the gravel, lay 2x4's flat (sleepers) at 48" on center across the gravel. Cover the entire area with a poly vapour barrier. Run the poly up the wall a bit so you can tie it into the wall vapour barrier. At 16" O.C. at right angles to the sleepers use 2x4's on their edge as floor joists and rim joists. Sheath with 5/8" treated plywood.
Polystyrene insulation under the floor is your option but not necessary. If this is a walk out basement, put insulation between the joists at the walk out and back from it about ten feet before sheathing. Mechanical heating under the floor would be expensive and like the insulation not required. I have a preserved wood foundation with a sleeper floor and the floor is warm & dry without insulation or a heat source.

 

There are a lot of homes with wooden floors in the basement of course, but you need to consider a lot of factors specific to your climate and lot. As Jack points out, moisture is your biggest consideration. An alternative to that suggested by Allan is to suspend this floor above the dirt by installing ledgers and joists and probably new footings. The construction of this would be very similar to a deck. This of course sacrifices a lot of headroom, but I don't know how much you have now.

Sounds like a quite ambitious project! Good luck.

 

John & Allen:

Good input. Have a good day.

 

We live on a farm in Southern Alberta (just on the Northeast
side of Calgary). I have had a wooden basement floor before, (with 12" centers) but my husband has not. I know it was much warmer than concrete, and we never had a moisture problem.
We have moved a doublewide mobile home onto the concrete basement walls, I believe there is at least 9' or more headroom. We actually went a little deeper with the hole than we had planned. My husband has installed hot water heating under concrete floors before, circulating through a hot water tank, but has never experienced a wooden floor, so, we are counting on your help to help us decide. Also, how deep should the layer of gravel be? Thanks.

 

Howdy Diane. The gravel base should be six to eight inches. Don't forget to install a sump pit. This can be lined with preserved lumber frame & plywood, or made of concrete if you go with that option. How much of the nine foot walls of your foundation are below grade, and what is the depth of frost penetration in your area? If there is more backfill than frost depth, the ground below the floor will stay at approx 8-10 degrees celcius. A concrete floor will absorb heat from the basement and via conduction will pass that heat into the ground. By laying down a couple of inches of polystyrene insulation (R10) before you pour the floor you will prevent the heat loss into the ground, and the concrete will be much warmer. The insulation is a must if you do run heating pipes through the floor. With the wood sleeper floor I described, a 4" air space is created under the plywood which gives some what of an insulating factor and wood is a poor conductor. Therefore the need for insulation is minimal. To maximize the effectivness of water heat under the floor you would want to insulate as described earlier & have the pipes in contact with the plywood floor. Future floor covering like carpet would insulate you from the heat source & it would be money wasted for the limited gain. Wood foundations in Canada started in Loydminster in 1967 and are used quite frequently in the west & northern regions. Good luck.