On Grade Concrete Flooring and Luan Plywood Underlayment

On-Grade Concrete Floors and Luan Plywood Underlayment

 a. The slab must be of good quality, standard density concrete with low water/cement ratios consistent with placing and finishing requirements, having a maximum slump of 4″, a minimum compressive strength of 3500 psi, and following the recommendations of ACI Standard 302.1R for class 2 or class 4 floors and the Portland Cement Association’s recommendations for slabs on ground.


b. The concrete slab must be dry, clean, smooth, structurally sound and free of foreign materials that might prevent adhesive bond as described in ASTM F-710, “Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring”. The cleaner the slab the better, the adhesion properties.


 c. The concrete slab must be protected from ground moisture with an effective and intact vapor retarder that conforms to the requirements of ASTM E-1745, “Standard Specification for Water Vapor Retarders Used in Contact with Soil or Granular Fill Under Concrete Slabs.”


d. The concrete slab must be placed directly on the vapor retarder.


e. The concrete must be wet cured with a moisture-retaining curing cover. Do not use spray-on curing compounds because these reduce the drying rate of concrete and can interfere with adhesive bond.


f. Before installation of the finished flooring, moisture, alkali and bond testing must be conducted.


 1) Moisture testing must be performed in accordance with ASTM F-2170 “Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes” (preferred method) or in accordance with ASTM F-1869, “Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride.” See the section on Moisture Testing for more details.

2) The surface of the concrete must have a pH of 9 or less. 3) Bond testing must be run to determine compatibility of the adhesives to the concrete slab.

Top Pick for Subfloors- Luan Wood

  The top material for underlayment among Home Renovators and Contractors is the 1/4 inch Luan plywood. It's quality is unsurpassed, and it is extremely durable and long-lasting. It is also among the Manufacturer's of Vinyl Flooring, Hardwood Flooring, Tile Flooring and Laminate Flooring. The choice is clear, and Luan has to be the top pick. Of course, before you proceed with any Home improvement product, you should check with your flooring Manufacturer before you proceed with any installation that needs to be confirmed.

Luan Wood Video Series
Bending Luan Wood Video
Installing Luan Wood Video
Cutting and Installing Vinyl Over Luan
Installing Luan Over Subfloor
Laying laminate over Subfloor
Making Tile Flush With Subfloor
Attaching Luan To Subfloor
Working With Luan For Do It Yourselfers

  There are 2 types of Luan:

Luan Type 1:  wood with an exterior glue is the more resistant to delamination, and should be installed under very durable flooring

Luan Type 2: wood with a water-resistant glue.

  The Type is normally indicated on the panel edge. Usually on the 4 foot edge, on the 4 x 8 sheet. There are 3 possible standards of Luan, which are:

BB -   Best Graded 

CC -   Medium Graded

OVL-  (Overlay)

APA’s installation guidelines and WARNING!!! : 

 When using 1/4 inch plywood, Instructions should be followed when installing Luan plywood, but Installers BEWARE: Luan is made under a wall-panel specification of the International Hardwood Products Association (IHPA). No manufacturing specifications support its use or gauge its performance as an underlayment.