These are my notes on creating nice residential concrete floors. In my primary residence, I put in about 1500 sq-ft of concrete floors in the lower level. I used a 6-inch slab on crushed stone with 1/2 inch PEX tubing for hydronic heating. I’m pretty happy with these floors, although not wild about the results I got in finishing/sealing them. I am in the process of building a second home in which all three levels will have concrete floors. In principle concrete is (a) very inexpensive, (b) a wonderful means of installing hydronic heating, and (c) attractive. But, I’ve found that there is all kinds of confusing information about how to achieve these aims. Here is what I’ve learned based on experience, research, talking to concrete contractors, and my own experiments.
Posts Tagged ‘concrete floors’
I have finished concrete floors in my lower level. I like them quite a lot. However, the area under my chair at my desk had developed some spalling. The spalling is a crumbling of the top surface of the concrete. I believe this is caused by a failure of the surface layer, which is comprised of the concrete “fines” which float to the top during troweling. I suspect that some gritty material gets on the caster of the office chair and with repeated rolling causes some little compression cracks, which then spread. The spalling was not deep, but I suspected it would get worse if I did not deal with it.
The flatwork guy (Gough Concrete) poured the lower-level slab on Thursday and saw-cut the control joints on Friday. I stopped by on Saturday to take a look. We used a 2% mix of Solomon liquid color, which they call “smoke.” It’s just right. The tint is significantly darker than natural concrete, but still comes across as gray, not black. This color in this concentration costs $39 per cubic yard of concrete. Given that the mud itself only costs $110 per yard, that’s pretty significant. However, given that for this I get a finished floor, I consider the tinted concrete a bargain. This floor cost $5.40 per square foot for everything (#4 rebar, pump truck, concrete, tinting, placing the concrete, finishing the concrete, coating with an acrylic sealer, and saw cuts). This did not include the 15 mil vapor barrier and the under-slab insulation, which my plumbing and heating guy did.