How Does High Humidity Affect Laying Ceramic Tile?

Normal Thinset Mortar

• The average recommended drying time for thinset mortar (cement-based adhesive) that is installed in a normal situation between 45 degrees and 70 degrees is between 24 hours and 72 hours, depending on the temperature. However, humidity can add time to this calculation on both ends of the range. Whether colder and more humid or hotter and more humid, the added humidity with condensation from warm weather creates excess moisture that takes time to evaporate, meaning that the drying time increases.

PreMixed Thinset

• While you can use premixed thinset mortars in certain situations, you should never use them in a high-humidity setting. Premixed thinsets are a combination of polymers, additives and other chemical substances rather than the concrete in regular thinset. As a rule, premixed thinset usually takes four days to a week to cure, but in cases of high humidity, premixed thinsets may take up to two weeks to dry properly before you can use the installation area.

Grout

• Humidity will slow down the curing process of grout (concrete-based joint filler) just as much as it does for thinset mortar, due to the cement that is in the mixture. However, there are more concerns than just curing time for grout. If you live in an excessively humid area you can actually see the grout and the face of the tile sweating due to the excess heat and humidity. This can cause the grout to stain during the curing process as additional water is introduced during the curing phase, causing areas to cure at different rates.

Seepage

• The largest concern related to tile installations in humid scenarios is seepage from concrete slabs. This applies to floor settings where the tile is installed on top of a slab, such as in a basement. The humidity can create a situation where the slab isn’t breathing properly, leaving behind condensation and mineral deposits. This slows the curing of thinset, and the minerals in the ground water may seep up through the slab into your grout and leave behind milky discolorations from mineral buildup.