Honoring Concrete Floor Control Joints

Typical garage and basement concrete floors might not have “control joints.” However, in some cases, control joints will be present and must be dealt with accordingly.

If control joints are present, typically they usually look like a big plus sign (+) that divides your garage floor into what appears to be four separate concrete slabs. These joints can be deep 3/8” wide V-shaped grooves made during the pouring of the concrete, or joints can be saw cuts usually a minimum of 3/16” wide and 1” deep made 18-24 hours after the concrete is semi-cured.

Both types of control joints run from one end of your garage floor to the other. Simply put, “control joints” are in a concrete floor to control the direction the concrete will crack in. The concrete WILL crack! Because concrete cracks with expansion and contraction, these joints create a weakened line in the concrete that encourages cracks to follow the line within the joint.

This helps by discouraging cracks from following a more resistant line across the surface of your concrete floor. Thus, eliminating spider web cracks creating an unsightly new concrete floor. Control joints also help prevent adjoining slabs from damaging each other when they expand and contract.

The bottom line here is that concrete control joints are needed and should be honored. Meaning, not tampered with prior to an epoxy floor coating.

Flake floor control joint handling

Concrete floor control joints should be cleaned out from dirt and debris as well as chipped edges patched with our crack filler. Repaired edges should be ground straight in-line with the control joint using an angle grinder for joint width uniformity.

 A typical epoxy flake floor or decorative metallic epoxy floor installation allows for the epoxy, and optional color flakes, and clear coating to flow over the edges of the control joint and possibly into the bottom of the joint. How neatly this is done is dependent upon the actual joint and the installer.

Once the flakes have been broadcasted and cured, the control joint should be cleaned and over laying flakes removed. Use a floor scraper or putty knife to cut into the joint and cleanly remove flakes over the joint. Once all excess flakes have been removed, the garage flake floor top-coat can be applied.

For a completely smooth concrete floor, whereas the control joints are to be hidden, we do not recommend it. However, filling and leveling the control joint with our 100% solids Crack Filler will create a smooth surface over the control joint.

NOTE: Do this at your own risk! As per, the natural contraction and expansion of the concrete can also crack the base-coat epoxy, flake chips, and top-coat over the filled control joint.