With the introduction of engineered wood flooring, hardwood
floors can be used in virtually every room in the house,
even in basements. Water on or near the building site is
still a consideration, however. It cannot be ignored or
Wood Floors Below-grade and On-grade
Which Floor What Room?
Moisture comes from a variety
of sources-from the earth itself, from surface water (i.e.,
rain water runoff), as well as from the interior atmosphere.
Let's consider the various ways that moisture problems
originate, and how they can be controlled and prevented.
A room that is exposed to
excessive moisture would be prone to trouble if solid wood
flooring were installed in it. Basement floors are
particularly tricky installations. But some products, such
as laminated flooring, may be suitable in many of these
circumstances because of their dimensional stability.
The use of these alternative
materials is necessary when the installation is below-grade.
"Below grade" is defined as any part of the slab having four
inches or more of earth above it. Additionally, walk-out
basements are considered a below-grade application, even if
a portion of the basement is above ground.
Most engineered flooring
consists of two or more layers of wood glued together, with
the grain of each running at 90 degree angles to the layers
adjacent This tends to result in increased dimensional
Engineered Wood Flooring Products
Engineered Wood Floors-uses multiple layers of wood glued
together, with the grain of each running at 90-degree angles
to the layers adjacent. As the wood fibers absorb moisture
and want to expand, each layer is restrained by the other
and improved dimensional stability results.
Because it displays far less
expansion and contraction with moisture changes, laminated
flooring can be successfully installed in areas with wide
humidity variations. It usually does not require full
acclimation before installation. In on-grade or above-grade
installations, various flooring types can be used: solid or
laminated. Moisture is still a consideration, although it is
less likely to cause problems than in
Once the grade limitations are determined, it's time to look
at other potential sources of moisture.
Methods for Basement Installation of Wood Flooring Products
On top of the concrete slab and prior to
installation of the basement hardwood floor, another vapor
barrier should be installed. These vapor barriers can be:
- PVC applied over the slab with a
- 6 mil polyethylene sheets embedded
into a skim coat of asphalt mastic.
- 15 pound roofing felt embedded into a
skim coat of asphalt mastic.
NEW CONSTRUCTION:( see
JOB SITE CHECK LIST)
During the building of a new home, moisture can Moisture can enter the
house in a number of ways. When the frame is going up, the
2-by-4s and subfloor materials often get rained on. Because
builders usually work on tight, demanding schedules, homes
are sometimes built trapping moisture that needs time to
evaporate. The amount of moisture introduced by framing
lumber and the wet trades can be significant.
Moisture Detection Equipment
Sources of Moisture
US Moisture Map & EMC Chart)
Sometimes the level of the water
in the ground is raised above the bottom surface of the
foundation due to: