WLFI Moisture Testing & Subfloor Preparation 2

Question 1

What is the acceptable moisture content range for a wood subfloor before installing solid hardwood flooring in most US climates?

Accepted Answer

6–9%

Answer

Wood subfloors should be between 6–9% MC to be within acceptable range for solid hardwood installation in most US climates.

Question 2

When using a calcium chloride test (ASTM F1869) on a concrete slab, results are expressed as:

Accepted Answer

Pounds of moisture per 1,000 sq ft per 24 hours (lbs/1000 sf/24h)

Answer

ASTM F1869 calcium chloride tests report moisture vapor emission rate (MVER) in pounds per 1,000 square feet per 24 hours.

Question 3

A concrete slab shows an in-situ RH reading of 82% at a depth of 40% of the slab thickness. What is the inspector's recommended action?

Accepted Answer

Apply a moisture mitigation system before flooring installation

Answer

An RH reading above 80% (ASTM F2170 threshold for most adhesives) requires a moisture mitigation system before flooring is installed.

Question 4

Which of the following subfloor conditions would MOST likely cause laminate flooring panels to buckle after installation?

Accepted Answer

Excess moisture in the subfloor exceeding manufacturer limits

Answer

Excess moisture causes laminate core materials to swell, leading to buckling or peaking at panel joints.

Question 5

Before installing a floating laminate floor over a concrete slab, the inspector discovers multiple hairline cracks. What is the primary concern?

Accepted Answer

Cracks allow moisture vapor to migrate upward from below the slab

Answer

Hairline cracks in slabs act as pathways for moisture vapor to migrate upward, potentially damaging the flooring above.

(WLFI) Wood and Laminate Flooring Inspector Practice Test