De Realtà Mapei n.° 36 - 1/11/2023
Work on an unventilated jobsite in the middle of summer in the Caribbean, or on an equally unheated one in Detroit in mid-January, and you will soon realize that the setting materials are affected by climate. How do temperature and humidity affect setting materials, grouts and membranes? Maybe more then you think. Read on and find out.
When the weather turns cold and you have a tile project that needs to be completed, what should you be aware of? Tile installations are incredibly durable and can stand up to some of the most extreme climates and conditions, but during the installation process, you have to pay attention to the weather.
When temperatures are falling, you need to consider multiple factors. On a cooler-weather jobsite, you must consider not only the ambient temperature, but also the temperature of the substrate. Once temperatures drop below 50ºF (10ºC), the curing process of setting materials and grouts starts to slow down, and this slowing process becomes more dramatic as the temperature drops closer to freezing. This is true for both cementitious and reactive materials, and it is why 50ºF (10ºC) is the minimum recommended installation temperature, unless otherwise stated on the product’s Technical Data Sheet (TDS).
If there is a possibility that the installation will be exposed to freezing temperatures after completion, make sure you check the TDS for every component of the installation system regarding the timeframe in which it can be exposed to freezing conditions. This is very important because cementitious products contain water immediately after installation and, if that water freezes, it will expand and can weaken the strength of the installation while also preventing proper curing.
Always take extra precautions to ensure a successful installation. Be aware of the forecasted temperatures and make plans to create suitable, consistent conditions for the installation and curing of the project. This may require temporary shelter and temporary heating. Also, be certain to vent the exhaust if the heating element burns fossil fuels. So, while it is possible to install tile once temperatures begin to drop, you will need to plan to ensure success.
A common question that accompanies temperature considerations is one that MAPEI Technical Services often hears concerning our waterproofing membrane Mapelastic AquaDefense… specifically “How long does it take to dry?”
This seems like a simple question, but the answer is not quite as straightforward as you may think. There are a couple of factors to consider with this question. Are you asking when it is dry enough to set tile over? Or are you asking when it is dry enough for a flood test? Flood-testing always requires a minimum of 12 hours’ drying time prior to beginning the test.
If the membrane needs to be dry to move forward with a tile installation, that window is typically 30 to 50 minutes after applying the final coat. If that answer sounds like I am hedging, I suppose I am. When it is first applied, Mapelastic AquaDefense is essentially liquid rubber. The water that makes it liquid and, therefore, easy to apply needs to evacuate either into the substrate or into the atmosphere. This leaves behind a cohesive, continuous rubber – waterproof – sheet.
The substrate conditions and the environment around the membrane will greatly affect the drying time. Imagine a damp towel hanging on a rack with warm, dry air moving around it. This towel will dry much faster than if we took the same towel, laid it on top of another damp towel, and tossed them both into a dark, cool room.
If you are applying Mapelastic AquaDefense over dry, porous concrete or cement backer board, that first coat will typically dry fast because the substrate is pulling moisture out of the membrane, while moisture is also evaporating into the air. Our instructions call for a second coat, which will dry much differently than the first. Think about it: You have a dry, first coat of a waterproofing membrane, so now the substrate will not be able to pull moisture out of the second coat. This second coat will have to dry almost exclusively by evaporation into the air, which takes additional time.
Another common scenario is applying Mapelastic AquaDefense over green or fresh mud beds. We see this in fast-track shower installations, where a mud bed was installed the day before the crew tried to install the waterproofing. This scenario is much like the towel example. Moisture from the mud bed is still trying to evaporate and is keeping the Mapelastic AquaDefense from drying correctly.
Ambient temperature, substrate temperature, ambient humidity, substrate moisture – all these conditions are large factors in the success of your installations and should play a part in the selection of the right products for the project. Understanding how the different conditions will affect your drying time is a start. Remember, you can always call us at 1-800-992-6273 in the U.S. and Puerto Rico or 1-800-361-9309 in Canada, or visit our Website at www.mapei.com, regarding any questions.
About the author
Logan Reavis is the Manager of Technical Services at MAPEI. He is responsible for the Product Support Department, Architectural Support Department and regional field representatives. Logan grew up around floor-covering businesses and, shortly after completing his B.B.A. from the University of Texas at Arlington, began his career in the industry. He brings over 15 years of experience in floor covering after spending time in distribution and on the flooring contractor side of the business.