Moisture will then be able to migrate through the concrete and cause hydrostatic pressure (vapor) at the interface where the paint film meets the concrete. The tough hard finish of deck coatings will not allow this moisture (vapor) to pass through the paint film, and thus the pressure will force the paint away from the surface, causing loss of adhesion and peeling. When multiply coats of paint have been applied over the years the problem is accentuated.
When evaluating decks for repainting if any areas of peeling paint is pre-existing one can predict that the next coat of paint will cause the deck paint to peel even more.
In addition, if there are areas of ponding water accumulating on the slab, floor coatings are not formulated to be submerge under water. Floor coatings are not “swimming pool” paints andin areas where the water does not evaporate within a 24-hour period the paint may start to peel.
There comes a point in time with multiple coats of paint have been applied, the decks will need to be stripped down to original substrate. There are various types of processes that can be used to strip off the coating from a surface. Typically, wet sandblasting, or shot blasting will be the best and fastest method. An additional advantage to sand or shot blasting is that it will also give the concrete substrate a profile (rough surface).