Many manufacturers of wood flooring require that the variation in floor flatness be no more than 3/16" in 10' and 1/8" in 6'. the installation of wood flooring also requires that the floor be dry.
Most experts agree that the maximum tolerance for a subfloor is 3/16” over a ten-foot span. Any dips or mounds exceeding this measurement need to be addressed before installation.
No subfloor is perfectly level, but any signs of unevenness and high or low spots must be remedied. Please follow these requirements: Subfloor unevenness cannot be greater than 3/16 of an inch over a 10-foot span or 1/8 inch over a 6-foot span. Subfloors must not slope more than ½ inch per 6 feet (25 mm per 1.8 m)
If hardwood flooring is installed over an unlevel subfloor, it can lead to creaking and squeaking whenever someone walks across it. It can also cause structural damage over time, leading to warping and denting of the hardwood planks, and affect the longevity of the floor.
Generally speaking, gaps in a wood floor are normal for boards up to 2¼ inches wide if the gaps close during more humid times of the year. Normal gaps can vary in width, ranging from hairline gaps to the thickness of a quarter.
Tolerances are 1/8” within a 6' radius, or 3/16” within a 10' radius.
If you install hardwood flooring directly over an uneven subfloor, your new floor will also be uneven. But when you first cover this subfloor with a self-levelling compound, then your new floor will be level and smooth.
The Standard simply defines the required flatness of a concrete subfloor. The subfloor, or 'underfloor' as I like to call it, “shall not deviate more than 3/16 of an inch in ten feet.” Photo 1 shows a ten straight edge being used to gauge the undulation of the floor.
Bathrooms and laundry rooms are rooms where you should not install hardwood floors. Separately stands the basement, where it is not recommended to install hardwood flooring under almost any conditions. Humidity, the possibility of spills, and floods make these rooms dangerous for hardwood flooring.
Ambient temperature and humidity along with subfloor moisture content must be in synch with the moisture content of the wood. Flatness required as follows- 3/16" in 10' or 1/8" in 6'. Floating floors requirements are more stringent, see section 4.4 for more details.
Just like ceramic tile, wood and resilient flooring require a high degree of flatness that can easily be achieved using a cementitious SLu. Many manufacturers of wood flooring require that the variation in floor flatness be no more than 3/16" in 10' and 1/8" in 6'.
Floor Flatness is measured by tracking the difference in elevation between two points 1 foot apart and comparing them with every other 1-foot elevation change across a measured distance or “run.” Floor Levelness on the other hand compares the change in elevation over a distance of 10 feet, by determining the net change ...
By dividing the span of the joist in inches by 360, you can calculate the maximum acceptable deflection. For example, if a joist spans 10 feet, dividing 120 by 360 results in approximately 5/16″ of allowable sag in 10 feet.
In general, if a floor slopes ½ inch to 1 inch for every 20 feet of the floor, it may require you to watch the situation, but it may not be a big concern. Sloping or sagging floors of more than 2 inches will indicate a problem. Sometimes, original builders slope the floor to allow for drainage.
Most engineered flooring can be installed using staples, full spread adhesive or a floating method over an approved subfloor. Make sure you have a sturdy subfloor: 3/4-inch CDX plywood is preferred and 3/4-inch OSB is acceptable.
Flat: All wood and concrete subfloors must be flat within 1/8” over a 6' span, or 3/16” over a 10' span. All areas of the subfloor must be checked prior to installation. High spots can be sanded or grinded down and low spots filled with appropriate patching compounds.
The underlayment acts as a barrier between your subfloor and hardwood, potentially saving your investment from damage caused by moisture. This is particularly important in humid climates or homes with moisture-emitting concrete subfloors.
With dry concrete and the right subfloors and vapor retarders, solid hardwood floors can be installed on slabs that are either on-grade (at ground level) or above-grade (above ground level).
Do Termites Eat Solid, Laminate & Engineered Hardwood Floors? Termites will damage solid wood floors as well as laminate and engineered wood floors. However, hardwood floors most frequently fall victim to termite damage.
For parts under 36” in both width and length, flatness should not exceed ¼”. For parts whose length is between 36” and 72”, the flatness variation should not exceed 75% of the flatness of a 10' sheet for that given width.
The level tolerance is 1/8 + or - over 10'. This tolerance applies to nail down, floating and direct glue down applications. Installing hardwood flooring over uneven sub-floors can lead to excessive movement, squeaks and gapping between boards.
MZ Flatness Definition
Flatness can also be analysed by a minimum zone calculation, defined as two parallel planes that totally enclose the data and are kept to a minimum separation. The flatness error can be defined as the separation of the two planes.
During the hotter and more humid months of the year, hardwood flooring will absorb moisture from the air, which causes it to expand and swell. The expansion of the boards can cause them to warp. Floor planks can create excess pressure when they absorb humidity, forcing boards to adjust to relieve the pressure.
Vinyl and Laminate flooring:
Both vinyl and laminate floors are versatile and durable options that can be installed over slightly uneven surfaces. They are relatively inexpensive, easy to clean and maintain, and come in a wide range of patterns and colors so you don't have to sacrifice style for function.
To treat low spots on concrete and mortar subfloors, use a leveling compound and a trowel. Wood subfloors need to be solid and free of rot or damage. If some of the plywood or wood is damaged, you might need to replace the entire piece. If your floor has any low spots, use a self-leveler.