Flatness article

​Three types of flatness measurements
By George Bell, CTC, CTEF, CSMT, FCITS, IFCII, IICRC, NTCA, CFIU
CSI Flooring Expert, LLC
 
Out of Plane (OP)
The measurement taken when a six or ten foot level is set on the top of a ridge on the concrete and is level to the bubble (a plane) and measurements are taken on each side to determine the measurement on each side of the ridge.
Out of flat (OF)
An end of the six- or ten-foot level is placed flat on the subfloor and a measurement is taken at the end of the six- or ten-foot area.
Low spots (LS)
Placing a six- or ten-foot level on the subfloor identifying areas that have a dip in the subfloor and measuring both the depth of the dip and the distance between the areas flat on the surface of the subfloor. (Example: the floor had a measurement of 1/16” or .0625” in a two-foot span)
What are we trying to accomplish?
 
If installing over an OP, OF or LS subfloor area you are asking the product to bend to conform to the subfloor.  This will cause deflection and a failure in the product.  As we have transitions from glue down to floating floors floor preparation has become even more important.
Yes, we all know a flat floor can be sloped and still be flat, but the concern is that the subfloor low spots and high spots are too great that the locking mechanisms of the installed floor can come apart when stepped on.
I have read advertisements saying that some floors are stronger or using a pad will reduce the amount of subfloor preparation required for a successful installation.  When you read the installation instructions the manufacture still requires the floors to be flat within 3/16” in 10’ or 1/8” in 6’.
Why is this problem so prevalent now and not so much earlier?
This is explained by both the products and the installation systems.
At one time all LVP was glued down.  This had the product following the contours of the floor, but it did not separate or bounce.
Laminates were used we would get calls that the floor felt like a trampoline when walked on.
This was a sub floor issue, but the tongue and groove construction were solid enough to hold the planks together and bridge over the LS and OF areas.
Today with LVP the locking mechanisms are good when put together on a flat surface any deflection can cause the floor over time to uncouple and start to either gap, peak or become damaged.
Installation crews and businesses continue to treat floor prep as a “necessary evil” instead of explaining that it is only a required to have a successful installation.  Some types of flooring require more preparation than others. 
A carpeted area with padding can be OP, OF, and have LS but the padding and carpet disguise the concerns.
When you mention floor prep to a consumer most assume that it is cleaning of the floor before installation.  We should consider using a new term for this that better explains what needs to be done prior to the installation.  Consider using the term “floor flattening” as a line item on the estimate.
Each product needs to be sold with both features, benefits, and installation knowledge so a consumer can get the product and installation they are expecting.  Unreal expectations only lead to concerns and hard feelings in the future.
First published in The Inspector’s Review, April 2022 Issue 5, IICRC