In-Floor Radiant Heat Installation

Note: Warranty coverage may be lost due to failure to strictly follow all installation instructions and recommendations or the use of improper materials or tools.


Note: Hickory and Maple expand and contract more than other species of wood. Thus, there is a greater risk of gaps appearing in the floor. This is NOT a manufacturing defect but should be taken into consideration when choosing these types of species for your radiant heat floor.


A. The surface of the subfloor must be level to within 1/8” in an 8 ft. radius.

B. The subfloor must be clean and dry.

C. Relative humidity at the job site should reflect normal living conditions. Temperature settings at the time of installation should be within 15 degrees F of these normal living conditions.


Before installing Lighthouse’s Engineered Plank over radiant heat subfloor, inspect the job site thoroughly. The heating system must be installed correctly according to the manufacturer’s specifications. Before installing Lighthouse’s Engineered Plank over a Radiant Heat system, the following conditions must be met:

A. Concrete slabs must be dry. To determine if a concrete slab is dry and suitable for hardwood flooring, follow the NWFA guidelines and procedures for performing a Calcium Chloride test. If excessive moisture is present, do not lay flooring.

B. The concrete must have been installed and cured at least 6 weeks with no heat transfer.

C. The heating system should then be run at 2/3 of maximum output for a minimum of 2 weeks to allow any remaining moisture to evaporate, attaining its final moisture content without causing damage. Three or four days before installation, the heating system must be reduced to a suitable temperature (about 18c/64f).

D. The sub floor level should not vary more than 1/8” in an area of 8ft. Check this by using the edge of a plank to find any high or low spots.


  • Concrete: To prepare a concrete subfloor for installation, scrape any high spots and fill low areas.
  • Plywood: To prepare a plywood sub floor, re-nail any loose areas or areas with squeaks. Sand and/or plane any high spots; fill any low areas. Be careful not to damage the radiant heating system.


Lighthouse’s Engineered Plank can be glued directly to concrete or nailed/stapled to a wood subfloor. Please refer to the previous sections for installation methods, the NWFA Technical Manual or your Lighthouse Custom Wood Co’s Distributor for installation support.


Approximately 2 days after installation is complete, gradually (over a period of 1 week) raise the temperature of the heating system to its desired operating level. Surface Temperature of flooring should never exceed 81 degrees F/27 degrees C. Exceeding this temperature will void any warranty.





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