The title of this blog is a frequently asked question that tile installers have considered when a concrete or plywood substrate has dips or humps in the floor. Because mortar will stick to the concrete slab and the wood subfloor, and mortar will stick to mortar, then it would only make sense that mortar would work for leveling or patching, right? Well, the answer is actually no.
Mortars cannot be used to level or patch a floor – ever! The materials used in mortars render the product unstable once the thickness exceeds the manufacturers’ recommended maximum thickness.
Most thin-set mortars have a maximum thickness of 1/4" (6 mm) and medium-bed mortars have a maximum of 1/2" (12 mm). So of course, the next question is, “What if it is done in layers?” The answer again is no. Once the mortar is cured, each new layer becomes one with the previous layer; this makes the mortar unstable once curing has occurred.
Now that we have established that mortars won’t work for leveling and patching, what can be done with a dip or a hump in the substrate? We recommend choosing a self-leveler or patch product instead.
MAPEI makes several different levelers and patches to accommodate a variety of issues that an installer may encounter on a tile-installation project. The most versatile self-leveler is Novoplan 2 Plus, a high-strength, cement-based underlayment and repair mix for use over interior concrete, plywood and other approved floor surfaces.
For smaller issues that only require patching and not necessarily the need to level an entire area, MAPEI makes a product called Planipatch, an ultra fast-drying, self-curing, polymer-modified, cement-based patching compound that rapidly develops high compressive strength and can be used to fill minor voids, holes and cracks.
Novoplan 2 Plus and Planipatch are easy to use, work exactly as intended and are readily available at a local distributor in your area. Every installer should have both a leveler and patching products ready to go when he or she starts a new project for a customer.
Looking for more tips for tile installation, as well as other flooring solutions? Visit our System Solutions portal here. At MAPEI, we believe that preparation and execution go hand in hand to obtain the best possible solution to any situation.