Logs 'n Dogs
Floors
"Um...I think that concrete guy had beer for breakfast."
We wanted a concrete slab floor in our home because we had decided on radiant floor heat. (Warm water was piped through tubing in the concrete slab. It provides wonderful, even heat, but it cost a little more than other heating methods at the time.)
For our upper level, we constructed a wood floor using standard wood joists and plywood sheeting. The wood flooring system is described too and could have been used in place of a concrete main floor.
Radiant Slab on the Main Floor
Our continuous concrete foundation, while not necessary for the house’s structural integrity, made construction of our radiant floor slab quite simple. No forming was required for the floor. We just poured the concrete floor inside the concrete foundation walls. First, however, some preparatory work was required.
Since there would be no crawlspace under our floor, we had to construct all the rough plumbing needed for the house before pouring our floor slab. Because a concrete floor is such a permanent feature, there would be no opportunity later to correct errors in the location of our plumbing lines, so we carefully checked their locations. Also, we ran water through all of the supply lines and waste pipes, to make sure there were no leaks before pouring the floor.
All the rough plumbing needed to be done before pouring the concrete slab.
After all of the rough plumbing checked out, we filled the area underneath our floor with gravel to about 8-inches below the floor surface and compacted it well. Next, we placed a plastic sheeting over the compacted crushed rock, followed by a layer of 2-inch-thick rigid insulation board. The insulation was important, because we wanted to be sure that heat from our floor would rise into the house, and not be transmitted into the ground below the house.
On top of the rigid insulation, we laid a sheet of wire mesh, with a 4-inch grid pattern. Then, we laid down polyethylene tubing for radiant heating systems. We looped the tubing in a pattern that made sure all areas of our floor would be heated, with no cold areas. The tubing was tied to the wire mesh below, to hold it in place.
Although we designed the radiant system to have each room of the house on a separate heating zone, we realized after we were using the system that this was really unnecessary and a single zone would have worked fine.
Rigid insulation, 4-inch wire mesh, and plastic (PEX) tubing in place.
Each room of the house was a separate heating zone. Supply and return pipes for each room were brought to a central location where control valves would be installed. In hindsight, this was overkill and a single zone would have been just fine.
Now we were ready to pour concrete for the floor. We ordered concrete to be delivered in a pump truck and hired a concrete finisher to help. Concrete was pumped though a hose from the truck that extended through our door and window openings. Our concrete guy worked the concrete around the wire and tubing, leveled off the surface with a concrete float, and troweled it smooth. After curing for three weeks, the floor was finished and ready for tile.
Loft Floor
A wood floor could have been constructed less expensively. We constructed a wood floor for our upper loft, and the same method could have been used for our main floor.
To construct our wood floor upstairs, we first attached 2x10 girders to our vertical support logs with large lag bolts. Next, we nailed 2x8 floor joists perpendicularly on top of the girders. We used commercial joist hangers to attach the ends of our floor joists to our perimeter wall logs.
Atop of the floor joists, we screwed two layers of ¾ inch plywood. Except for carpeting, the floor was finished.
Upper floor attached to vertical support logs.
If we had used a wood floor as the main floor of the house, we would have insulated it, with a plastic sheeting vapor barrier placed on the warm side of the insulation.
Example wood floor detail.