I am going to be placing a heated concrete slab floor in a custom home and the finished flooring will be the polished and dyed slab. I would anticipate some cracking in the concrete, and would like to minimize its effect. The heating will be plastic tubing placed into clips in the rigid foam insulation, and I plan to lay a 6 inch welded wire mesh over the tubing. The surface will be cut on a 3ft by 3ft grid to simulate large tiles. The slab is to be 4 inches thick, and the tile cuts will be about 1/4 to 3/8″ deep. Trowelling control strips into the slab would not look very good and they never seem to end up straight or in the right place. My flooring contractor does not want to cut the grid lines any deeper, and they would probably just fill up with dirt anyway. I will be trying to keep the water content as low as possible, and probably could make up for this with some plasticizer, or other admixtures. I just hate the thought of a big crack arcing across the living room floor! Any tips?
Replies
In addition to (or instead of?) the 6" mesh, make a separate rebar reinforcement in the shape of a cross or a tic-tac-toe pattern with a square around it for each "tile". Tedious, but it increases the integrity of each square.
Use a hexagonal pattern instead of squares. Much less likely to have a crack run across a corner. Harder to saw the lines though.
How about fibermat along with the rebar.
We've done a few of these floors, you don't want cracks. I'd try to get some rebar in the slab as well. Cutting a little deeper would help, I realize you have tubing in the slab and don't want dirt traps but I think the sealer on the slab will fill some of the cut.
Good joice on floor, looks great and very affordable.
Why not hand-tool (so you don't cut the radiant tubing) every third one of those joints a little deeper, (the 1" that gives you a true control joint) so they land every 9', then grout the whole pattern so it looks like tile? You can use colored grout after the stain is down. It works fine. Just go with a fortified grout and use a little bonding agent in the joints.
What shape is the slab? How big? Any re-entrant corners?
Slabs don't have to crack. Gabe Martel wrote an article on this some time ago, and everything he put in that article has proved useful on my jobs. I poured a 500 square foot slab back in December and still have no cracks at all. Of course time will tell, but so far so good.
Careful subgrade prep, good quality mixture, skilled finishers, careful curing, and you'll probably be fine.
DRC
I just happened to go back to one of our jobs with a finished concrete floor. We had cut the floor in every doorway, and everywhere else possible. There were a few small cracks that didn't look to bad. Just try to prevent as many as possible, make sure you use some small rebar as well. The acid itched designs look great also.
Edited 3/5/2003 10:32:25 PM ET by RICKSHORT
Thanks for the attached photos. The floors look great. I am hoping for a similar look. I have added lots of 3/8 inch re-bar to my list. Hopefully a liberal spread of rods combined with the 6 x 6 mesh will do the job. I am wondering of polypropelene fibremesh is compatable with this type of floor finish as well.
Cheers.
I'd check with the concrete company, but fiber mesh is usually visible. Good luck