How to Dry Concrete Floors

by Kristy Robinson, Demand Media Use a propane torch to dry garage or patio floors quickly. Concrete slab floors take up to 90 days to fully cure, or harden and dry. Unfortunately, that means waiting to install a new, more attractive floor, which is not what most builders or homeowners want. Moisture in the floor, even if there’s no standing water, interferes with the adhesion of glue and mortar products. Luckily, there are things you can do to speed up the process. These same techniques work well if you’ve had a flood or moisture seeping into a basement and want to prevent mold from developing. 1. Sweep the floor to remove all dust and debris where no standing water is present. Scrape up excess adhesive or other matter on the floor that can hold moisture or catch fire. 2. Vacuum up standing water from the floor with a wet vac. Empty the wet vac before it becomes full to prevent the water from coming back out or the machine becoming too heavy to lift. Dump the water away from the foundation of your home so that it doesn’t seep back in. 3. Raise the temperature in the room as high as possible. A temperature of 90 degrees is preferred to add energy to the excess water in the slab enabling faster curing. Place a humidifier in the room and set it to lower the humidity to 10 percent. 4. Tape a piece of plastic sheeting to the floor tightly. Leave the room closed off for three days, and then come back and test underneath the plastic with a dew point hygrometer. This tool tells you the humidity level of the concrete. Compare the humidity level with the tile or carpet adhesive manufacturers’ guidelines to determine if the moisture level is low enough for installation of the product. 5. Put on long pants, a long sleeve shirt and heat-resistant gloves. Remove all flammable obstacles from the room. 6. Assemble the propane torch parts, inspecting each to make sure there is no damage and no o-rings are missing. Connect the torch assembly to a 20-pound propane tank according to manufacturers’ directions. Place the propane tank in the center of the room for maximum mobility. 7. Test the torch for any leaks by shutting off the torch adjustment valve and opening the supply valve on the tank. Tighten or replace any parts of the torch assembly where there is a leak. Close the shut-off valve on the tank and open the torch adjustment valve after testing to release any gas in the torch. 8. Close the torch adjustment valve and leave it for 30 seconds. Open the shut-off valve on the tank slowly. Point the torch away from the tank and turn the adjustment valve just until you hear gas escaping. Hold the igniter near the end of the torch and strike it to light the torch. 9. Hold the torch so that the flame is 6-inches off the concrete floor. Wave the torch from left to right slowly over a small area. Keep the torch moving and walk slowly to a new area as you complete one portion of the floor. 10. Shut off the tank supply valve. Disconnect the torch assembly from the tank and leave it to cool before storing. Things You Will Need Broom Scraper Wet vac Humidifier Long pants Long sleeve shirt Heat-resistant gloves Propane torch 20-pound propane tank Tips Only use a propane torch approved for indoor operation. Warnings Propane torches provide up to 3000 degrees of instant heat. Use extreme caution when working with the torch and follow all manufacturers’ safety guidelines to avoid injury. Propane torches are not recommended for use in enclosed spaces due to the inability of the propane tank to withstand temperatures above 120. The heat from the torch raises the temperature in the room above that level quickly.