Hardwood floors have been in high demand lately. Unfortunately, there are some types of subfloors that make installing traditional hardwood difficult, or even impossible. For people that have concrete basements or subfloors, like slab houses, traditional solid hardwood will not work. However, you can still get the same look like solid wood by using engineered flooring. Because it doesn’t require nails and is less sensitive to changes in humidity than solid wood, engineered wood can be installed at any grade level. If there isn’t excessive moisture, you can even install engineered hardwood below grade, like in a basement or room below ground.
Before you can put anything on top of your concrete, you need to make sure that the surface is flat. Over time concrete can chip and crack. If you don’t fill in these cracks and chips, your engineered floor won’t lay correctly on top of the concrete. You can use a cementitious patch or a self-leveling underlayment. Also, if you have radiant heated subfloors make sure to turn off the heat for 24 hours before, during, and after installation is complete.
The next step when installing engineered flooring on top of the concrete is to check the subfloor’s moisture level. More than likely, there will be moisture present. Because of the pores nature of concrete, most slab floors contain excess moisture. If left unchecked, the moisture can break down the adhesive used between the concrete and engineered wood floor.
Because of the moisture issues, manufacturers have developed products that can mitigate the moisture in the concrete. Most of these products are topical treatments that are applied to the surface of the concrete. When applying these topical treatments, it is important to use the right amount of coating. If enough coating is not applied, the permeability of the treatment can be compromised. In this case, permeability is referring to the degree to which moisture can pass through the coating. If the permeability of the coating is greater than that of the overlying floor, moisture can pass through the coating and get trapped beneath the engineered wood flooring. The trapped moisture can then break down the adhesive bond between the engineered wood and the concrete.
After the moisture mitigating coating is dry, it is time to apply the adhesive. The adhesive needs to be strong enough to bind with concrete and wood, but also should have the flexibility to allow for slight movement when the engineered wood floor is stepped upon. Make sure to use an adhesive that doesn’t contain water. You don’t want the moisture in the adhesive to damage the engineered wood.
As you begin to lay down your engineered wood, leave expansion gaps between the floor and the wall. The manufacturer should supply the necessary recommendations for the size of your gaps. To make it easier, place small pieces of wood in the gaps between the floor and the wall. They will prevent your floor from shifting towards the wall during the installation process.
After it is applied to the subfloor, use a notched trowel to evenly spread the adhesive. The glue manufacturer should give you specific instructions on what size trowel to use. Immediately after the adhesive is spread, install the engineered wood flooring.
When you lay the flooring, leave the tongue side of the board facing the center of the room. Don’t move onto the next flooring row until you have completely installed the first row. The initial row will provide support and limit the movement of each subsequent row.
Once you have finished installing your engineered wood, use a 100-150 lb. roller to make sure that the adhesive fully transfers to the engineered wood floor and the concrete. Foot traffic should be restricted on the newly installed floor for 16-24 hours.
Installing engineered flooring on top of concrete requires time and patience. Before you start it is important to prep the existing concrete floor to prevent issues from developing after installation is completed. Follow the steps in this guide to ensure that you install a beautiful wood floor that will last for years.