Radiant Heat FAQ

Q: What phase of construction does the Gypsum Concrete get installed?

A: Typically, the building should be dried in with windows and roof installed. Generally, the Gypsum Concrete is installed shortly after the radiant heat contractor finishes the tubing installation, which in most cases follows plumbing and electrical rough-in. However, you can elect to install the Gypsum Concrete after drywall as well. Depending on the municipality you are building in, you may be required to pour Gypsum Concrete before the drywall installation because the inspection and permit process can vary. Refer to your local building guidelines and ask your building inspector about construction phasing.

Q: What is the typical thickness for radiant heat installations?

A: As a rule of thumb, Gypsum Concrete should be installed at ¾” thick over the top of the radiant heat tubes. The industry standard for radiant heat tubing is 5/8” Pex tubing (O.D. of approx ¾”), therefore a 1-1/2” thick Gypsum Concrete topping is most typical.

Q: How much does a Gypsum Concrete weigh?

A: Gypsum Concrete weighs 13-15 lb/sf at 1-1/2” thick.

Q: What floor coverings can be installed over Gypsum Concrete

A: Gypsum Concrete accepts virtually any floor covering on the market today.

Q: Can tile be installed directly to Gypsum Concrete

A: Yes, tile can be installed directly over Gypsum Concrete with thinset, mortar or mastic.

Q: Will water damage Gypsum Concrete?

A: Independent testing has shown that Gypsum Concrete which has been saturated with water and dried completely does not lose any of its compressive strength. Gypsum Concrete is meant for interior use. Gypsum Concrete can be installed in shower pans provided a water proof membrane is installed over the Gypsum Concrete.

Q: Can mold grow in Gypsum Concrete?

A: No, Gypsum Concrete will not support mold growth of any type.

Q: Does Gypsum Concrete give off VOC or other gasses that may be harmful?

A: No, Gypsum Concrete is a GREEN BUILDING MATERIAL and does not emit any VOC’s.

Q: Does Gypsum Concrete need to be covered?

A: Yes & No, Gypsum Concrete is considered to be a floor underlayment and must be covered with flooring goods. Standard Gypsum concrete needs to be covered with flooring. High strength gypsum concrete can be used as a wear surface is an appropriate sealer is applied. Additionally, cementitious self-leveling toppings can be installed on top of gypsum concrete to provide a wear surface.

Q: How can I get the look of concrete?

A: Install a cementitious self-leveling wear surface at ¼” thick over the Gypsum Concrete underlayment. These toppings can also be stained, pigmented and polished.

Q: How long before I can walk on the Gypsum Concrete?

A: Depending on the humidity and temperature, Gypsum Concrete can be walked on in 3-4 hours. We ask that you keep other trades off of the Gypsum Concrete for 24 hours.

Q: Do I need to provide heat or fans after the pour?

A: Depending on the season, temporary heat and/or ventilation may be required. The building should be kept at a temperature of approximately 50+ F before and after the pour. In colder climates/seasons the radiant heat system may be used to help cure the Gypsum Concrete. In warmer climates/seasons, opening the widows will provide enough air circulation for proper drying. We will consult with you before the installation to figure out the best method for properly drying your floor.

Q: How long does a typical installation take?

A: A typical 4-bedroom house can be installed in 4-8 hours. Large houses over 10,000 sf may take slightly longer but most can be finished the same day.

Q: Should I protect the floor after it has been installed?

A: Gypsum Concrete can withstand daily construction activities. Drywall trades should use care and not overload stocking carts or stack all of their materials in one room. Gypsum Concrete is not flexible and can be damaged by concentrated point loads (wheels of overloaded stocking carts) and deflection of the floor from overloaded stocking piles. Ladders and scaffolding are generally not heavy enough to cause any damage.

Q: Can any Gypsum Concrete products be installed over radiant heat systems?

A: Yes, we have installed standard gypsum concrete underlayments over radiant heat applications for the last 30 years with great success.

Q: What is the correct staple spacing for my radiant heat tubing

A: Staples should be placed at a minimum of 16” on-center.