Thursday, September 17, 2009

Dealing with Control Joints

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Hello Kent,

Q.-  I am getting ready to stain the concrete slab in a sun porch using products from Concrete Camouflage. The slab is divided into 4 pieces by grooves cut in the floor to control cracking. These cuts are about 3/16 inch wide by 2 inches deep. The slab is 5-6 inches thick.
   I plan on cutting some more grooves of the same width and using these with the crack control grooves to create a pattern.  These new grooves will be just deep enough to grout. 1/4 inch or so.
   My question is, what do I use to fill crack control cuts? I assume there will be movement which would cause grout to crack. Can I use a sanded caulk that matches the grout to fill these grooves? I would use backer rod under the caulk.
I understand that the grouting should be done after the first layer of sealer. Would this be the same for the caulk? This implies that I should use a paintable caulk.
A.- You may want to consider using a "Deco-Seal" type product. It is a two part caulk/epoxy type material that goes between a pool deck and its coping at the edge of the pool. It is usually colored to your specification and then finished with a light sanding for texture and appearance. It looks great, stands up well, and is fairly inexpensive. You can fill the deep joints with the same sand that you are going to hand sift on top of the deco-seal before it dries. The only real negative to deco seal is that it may have to be redone every few years or so in open exterior cases.
   You can find it at your local "Contractor" Supply Store(not Home Improvement Store - they won't have it), perhaps through a "Pool Company or Pool Supply Company", or You can check for an Installer to do it for you. They can be found in "The Blue Book" at or in your local directories or papers.
You will finish all your grouting and all sealing. Then you will deco seal very last.
You may also want to consider just filling the deep joints with sand and then grouting them as well. It may work or not depending on how much movement you get in the ground under the concrete. If you don't get much movement, then all the joints will be filled with the same material and they all match. If you get alot of ground movement, then the grout will break out of the control joints and you can then go ahead and deco seal at that time if need be. But you must decide for yourself.
I hope this helps.