We're just about finished framing our Project House, but before we go any
further, I want to show you the flooring system we built here for the upstairs.
I'm standing on the sub-floor - this is the part directly underneath your carpet
or hardwood floor, or whatever material you decide to use. When you walk on
this floor, you definitely don't want to feel the floor give at all, and you
don't want to hear any squeaks. We've built a sub-flooring system that virtually
eliminates any chance of this floor squeaking or sagging. Every town has minimum
code requirements for this kind of work, but we've built this sub-floor better
than the code requires to make sure this floor is safe, strong & quiet.
"Code Plus" Defined - Code Plus is a building concept defined by APA
- The Engineered Wood Association (formerly known as the American Plywood Association).
This language is taken from the APA web site: "Code Plus is a brand that says
your floors, walls and roofs are built to high quality standards which are one
step above building code requirements. Code Plus floors, walls, and roofs are
stronger, safer and provide a greater measure of security against high wind
and seismic activity. A Code Plus floor is up to 84% stiffer between joists
than typical built-to-code floors. All APA-rated floor panels are glued and
nailed for increased rigidity. And squeaks are virtually eliminated."
"Engineered Wood" Defined - Strength in this flooring system comes
from Engineered Wood. Engineered Wood products are designed to eliminate the
flaws that are common to conventional lumber. Engineered wood products are manufactured
by bonding together wood strands, to produce a larger and stronger composite
unit with structural performance characteristics superior to conventional lumber.
Performance is engineered into the products, so you don't have to rely on the
potential performance of a piece of raw lumber based on simple visual grading.
These products are engineered for high performance and to meet rigorous quality
standards. Engineered wood products are kiln-dried to remove moisture, so they
won't warp like conventional wood that may still hold a lot of moisture when
it's harvested.
 I-Joists Defined - Willamette Industries provided all the I-Joists
& Glu-Lam for the Project House.
I-Joists are the support members that span the distance between load-bearing
walls. They are specifically engineered to support the load of the sub-floor
system on the second floor of this house. The end of an I-Joist is shaped like
the letter "I".
Here are the main parts of an I-joist:
- Webs made of Oriented Strand Board or OSB - The web is the vertical part of
the "I"
- Flanges made of Laminated Veneer Lumber or LVL -Tthe flanges are the two horizontal
lines of the "I".
I-joists require 1/3 less wood fiber than lumber for similar applications.
I-Joists are conveniently designed so you can punch pre-cut holes out of the
web to run electric and plumbing conduit through them (not so easy to do with
2x12s).
Consumer Tip - In a house as big as the project house (6000 square feet),
with big rooms, large open spaces and large distances between load-bearing walls,
I-joists typically perform better than conventional lumber (usually 2x10s or
2x12s) in supporting a floor. They're engineered to be longer, stronger & straighter
(they won't warp, camber or bend to make the floor squeak like conventional
lumber can). It's hard to find conventional lumber that's long enough and thick
enough to support the weight of the flooring system that doesn't have at least
a little bit of warp or twist in it.
 Plywood Defined - Georgia Pacific provided (90) pieces of 1-1/8" tongue
& groove "Plus Plywood Sturdi-Floor" for the Project House.
Plywood is an engineered product produced from thin sheets of wood
veneer or plies, arranged in layers, oriented perpendicular to adjacent layers.
Plywood always has an odd number of layers, each consisting of one or more plies.
Sometimes a layer consists of two or more plies with the grain running in the
same direction. Since wood is strongest along the grain and shrinks and swells
most across the grain, plywood is constructed by alternating the direction of
the grain between adjacent layers. This process maximizes strength and stiffness
for the long panel axis (the 8' direction) while minimizing shrinking and swelling
in both directions. Then an adhesive is applied which produces a structural
bond between the plies that is as strong as or stronger than the wood itself.
The "tongue & groove" design of this plywood "locks" each piece of plywood into
the next.
Consumer Tip - We're featuring 1-1/8" thick plywood, which is a few steps
above code. It may cost a little more than ½" or ¾", but the extra thickness
adds rigidity and strength between support beams (I-Joists in the project house),
so you'll almost never have a problem with squeaking or sagging floors.
Silent Flooring Defined - The framing crew applies glue to the top of
the I-Joists, then they place the plywood on top of the I-Joists. The tongue
& groove design of the plywood "locks" each piece of plywood into place, creating
a single sturdy surface. Next, the plywood is nailed to the I-Joists for an even
stronger connection. The combination of thick plywood (interlocked by tongue
and groove) attached with glue and nails to an unbending span of I-Joists creates
the Silent Flooring system.
We've done our best here to insure a safe, strong & quiet floor. You can do
the same if you make sure your builder follows the APA's "Code Plus" guidelines
and uses wood products engineered to give you a more predictable performance
than wood in its natural state. That way you'll build it safe and you'll build
it quiet, so this should be the last you'll ever hear about the sub-flooring
system on your new house.
Contact Information:
APA - The Engineered Wood Association
(253) 565-6600
Georgia-Pacific Corp.
1-800-BUILD
Willamette Industries, Inc.
888-650-6332 |
