The rules a wood floor is actually held to
Acclimation is a number, not a waiting period
Most wood floors that cup, gap or crown were installed at the wrong moisture content, not with the wrong technique. The National Wood Flooring Association sets the tolerance as a difference between two measurements: the moisture content of the flooring and the moisture content of the subfloor it is going onto. For solid strip flooring under three inches wide that difference must be no more than four percentage points. For boards three inches and wider it tightens to two.
- Source
- NWFA Installation Guidelines
- Solid strip, under 3 inches wide
- No more than 4 percentage points difference between flooring and subfloor
- Solid plank, 3 inches and wider
- No more than 2 percentage points
- Reading density
- A minimum of 20 readings per 1,000 square feet, averaged
- What acclimation actually means
- Matching the wood to the conditions the room will live in, not leaving boxes in a room for a set number of days
Why the wide board rule is stricter
A wider board moves more across its width for the same change in moisture, so the same error shows up as a bigger gap.
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Twenty readings, not one
A single meter reading tells you about one spot, and one wet spot is the one that ruins the floor.
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Leaving the boxes in the house for a week is not acclimation
Acclimation is reached when the numbers match, and unopened boxes in an unconditioned room may never reach it.
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Questions about The Moisture Rule Behind Every Wood Floor That Stayed Flat
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Sources and references
- NWFA Installation Guidelines. https://www.nwfa.org/
Related work
Send a photo and we will tell you what you are looking at
The Moisture Rule Behind Every Wood Floor That Stayed Flat starts with someone reading the house. We quote every job ourselves, with no salesperson in between, and a photo of the floor gets you a straight answer faster than a form does.
