Concrete pH test

What the test measures

The test reads how alkaline the surface of a concrete slab is. NWFA leaves the acceptable result to the adhesive maker, so the test matters most under a glued floor. NWFA’s installation guidelines name the method:

The current method for measuring the pH level of a concrete slab surface is described in ASTM F710 (Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring).

NWFA Installation Guidelines, Revised © 2025, p. 70 (PDF p. 74)¹

NWFA gives no pH figure of its own. The limit is in the installation document of the adhesive or the floor product, and the table under Red flags shows the ones the documents read publish.

What a valid report looks like

A complete report names, at minimum:

• the method, ASTM F710;
• the date of each reading;
• where on the slab each reading was taken;
• each reading;
• the adhesive or product document the readings were compared with.

On the acceptable result, NWFA defers to the adhesive maker:

Follow the adhesive manufacturer’s instructions on pH testing and acceptable results.

NWFA Installation Guidelines, Revised © 2025, p. 70 (PDF p. 74)¹

Some product documents put the check on the installer. COREtec’s guidelines say:

IT IS, HOWEVER, THE FLOOR COVERING INSTALLER'S RESPONSIBILITY TO MAKE SURE THESE TESTS HAVE BEEN CONDUCTED, AND THAT THE RESULTS ARE ACCEPTABLE PRIOR TO INSTALLING THE FLOOR COVERING.

COREtec Pro SPC Residential Installation Guidelines (Shaw/USFloors), Revision: 11052024, web page²

Red flags

Rigid core vinyl: the one company’s limit, from COREtec Pro SPC Residential Installation Guidelines (Shaw/USFloors).

pH level of concrete should be between 7-10.

COREtec Pro SPC Residential Installation Guidelines (Shaw/USFloors), Revision: 11052024, web page²

1. Any floor type: the report calls the pH acceptable without naming the adhesive or product document. NWFA gives no number to fall back on, so there is nothing else for the reading to be held against. The limit that binds you is in your product's installation document.

2. Any floor type: an acid rinse was used to bring the pH down. NWFA:

   Do not use acid rinses to “neutralize” a high-pH concrete surface.

   NWFA Installation Guidelines, Revised © 2025, p. 70 (PDF p. 74)¹

3. Glue-down LVT: the product’s document gives two bands. One glue-down document read, Shaw’s residential guide, prints different pH bands in two sections. In the section “1. Test Before Starting Installation, PH”:

   PH reading must not exceed 10.0. Readings below 7.0 and in excess of 10.0 affect resilient flooring and adhesives negatively.

   Shaw Resilient Residential Installation Guidelines, glue-down, Revision: 04012022, web page⁴

   and in the section “5. Installing Resilient Tile & Plank, General”:

   PH of concrete sub‐floor needs to be between 5&10.

   Shaw Resilient Residential Installation Guidelines, glue-down, Revision: 04012022, web page⁴

   The document conflicts with itself. A report that cites it should say which band it used.

Questions to ask the installer

1. Which adhesive or product document did you compare the pH with, and which band in it?
2. How were the readings taken, and where on the slab?
3. If the pH was high, what was done about it, and does the adhesive maker accept that fix?