About Bamboo Flooring Expansion and Contraction
Bamboo Flooring Acclimation. It is very important to acclimate all wood flooring prior to installation. High quality
bamboo floor brands can be acclimated in as little as 72 hours; lower quality brands may require weeks.
There is a lot of misinformation on the internet about bamboo flooring. Bamboo floors are a wonderful, safe and extremely durable
flooring product as you will see many home-owners rave about on the web - especially if you choose the right brand.
If you want to avoid problems with bamboo flooring in general - follow these rules:
1) When you nail or glue down tongue and groove bamboo flooring there is no limit to the length of a "run" of flooring.
2) When installing a floating engineered click lock bamboo floor the longest run you can have before installing a break (t-molding) is 30 feet
3) When installing a floating click lock OR tongue and groove solid (all-the-way-through) bamboo floor the longest run before installing a break (t-molding) is 15 feet
If you have long runs of flooring in your home you should be gluing or nailing the floors down. Keep in mind that the optimum moisture levels for bamboo in the U.S. are 8%-12%.
If you have click lock bamboo floors that are solid all the way through (not engineered), and your "runs" of flooring are shorter than 15 feet - you‘re probably safe.
You also might be safe if you live in a
geographic area with year-round stable humidity or your home has constant humidity levels (+/- 2%). However if you live in an area that experiences seasons you will need to take steps to
prevent gapping. One such need is to install a break in your floor every 15 feet and then install a t-molding, then begin a new section of floor after the t-molding. This cuts down on the radiating
effect on the outside edges of the floor installation and keeps your floors from pulling away and gapping. Why? Read on...
Ever wonder why you don‘t see many solid wood locking (floating) floors on the market,
in any species? Because of its hygroscopic properties, all wood and bamboo expands and contracts in response to humidity levels, even after its cut and turned into
flooring. In glue and nail down applications (tongue and groove) each individual plank expands and contracts while secured to the subfloor. This explains why in the winter you’ll see tiny
gaps develop between planks and in the summer they close up; this is normal and expected wood flooring behavior. Conversely, locking floating floors expand and contract as one entire element: thus
each individual plank expands and contracts but since no tiny gaps form between the planks the overall effect gets pushed outwards exponentially to the outer edges of the installation (it "radiates out").
Now imagine a row of 100 planks that are floated and clicked together (a "run" of flooring) - if each plank contracts by 1/32 and no tiny gaps form between the planks, the
contraction effect then radiates out exponentially to the edges of the installation. If each plank contracts just 1/32 and you multiply that by 100 planks, you get the idea. Just a few seasonal
cycles later this can cause floors to separate from outer walls and get "pinned" and separated at doorways. This usually requires that the entire floor be taken up and re-laid. Conversely, when
floors are glued or nailed down the contraction of the planks results in just the slightest gap between the planks rather than pulling en masse from the edges of the installation.
This is one of the main reasons why engineered click lock wood floors exist. Because of their multi-layered substrate and dimensional stability, engineered floors expand and
contract at a rate that is 3x less than solid wood floors. With a floating/locking engineered wood floor you still need a break in your run but the allowable distance of the run is
25 feet or more depending on the species. Presto, now you have a stable floor that doesn’t pull away from the walls after a few cold winters. don’t believe it? Ask your manufacturer for their
dimensional stability test results for their solid floors and compare them to any engineered floor for the same species, and see the difference yourself.
As with other durable goods do your homework before choosing a brand (via the BBB, online reviews, etc).
Unless you're installing an engineered bamboo floor, using a tongue and groove bamboo floor in a glue or nail down method is always your best option. And despite what anyone tells you never
install a solid wood floor below grade!