We Have a Slab

For the sake of simplicity, cost, and because they really like the look, Mom and Dad decided to go with polished concrete for the finished floor throughout the main level of the house. This meant that a little additional planning, and a lot of extra care needed to be taken to ensure that when the slab got poured during the first month of construction it would remain in good condition throughout the rest of the construction process. Construction is a dirty job and having the finished floor be the primary work surface throughout construction can be risky.

Piping stubs can be seen coming through the layer
of insulation below the floor slab. A footing runs
down the center of the house below a load bearing wall.

Plumbing (under the slab) and radiant heating (in the slab) were the two critical items to get done right, because once the slab goes in there is no going back to change anything. In a typical home with a basement the plumbing is done long after the basement floor slab goes in, but in our case the entire first floor plumbing layout had to be done with only the foundation walls for reference. The same goes for the radiant floor layout which had to be done without any reference to the interior partitions that were to come along later.

Once the floor slab was poured the contractor had to cut control joints in the concrete. Concrete will expand and contract with changes in temperature and humidity, especially with a heated slab, and when this happens the concrete can crack. These control joints will allow us to define where the cracking occurs, like in a perfectly straight line between to rooms, rather than at random through the middle of a room. There is always a chance that cracking will occur where you don't want it, but that's just the risk you take when going with a finished concrete floor.

For the floor finish we looked into several options and ultimately decided upon a process of polishing and staining the concrete after it had cured. This would allow the general contractor to proceed with framing the house, and hold off on really finishing the floor until the house was fully enclosed.The subcontractor who would do this was Jon Meade, a Portland-based "concete artisan" who specializes in countertops on floors.

View of the foundation prior to pouring the slab

The almost completed floor slab, you can see where control joints are being cut.

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