So my week has been filled with homeowners who have to deal with OSB (oriented strand board) as their substrate or flooring underlayment. This normally wouldn’t be a problem for a floating floor install (click together type of flooring), but the same homeowners have requested a glue down cork tile as their final floor. Ohhhh dear! Things can go wrong in a HURRY on a job site. And this is one SNAFU that could have been avoided – but it takes forethought by everyone involved – including the homeowner.
Sigh. This is where my job gets REALLY intense. I mean dealing with swearing homeowners already up to their eyeballs in cost over-runs and delays. Boy oh boy does it get intense around here when OSB is the substrate for glue down tiles. Why all the fuss you ask? It starts with how OSB is created.
OSB is a manufactured product that uses tremendous amounts of adhesives (to keep all the wood chips together). It is pressed together and often finished with “wax” of some description. The wax helps keep the OSB moisture and rot resistant (doesn’t always work). Both the adhesives and the wax cause problems with permanent glue down floors. They are considered “contaminants” in the world of chemistry (in the flooring industry the chemistry component of the job can never be stressed enough). And cork is only one of many glue down or permanent floors that CANNOT use OSB as a substrate. It is an issue with so many floors. Not to mention it is problematic with nail down hardwood and bamboo as well.
“So why use OSB it if has so many problems?” Simple. Economics. OSB is CHEAP. And CHEAP is what helps sell homeowners on a project or wins a General Contractor (GC) the bid. The builder who puts in the lowest bid often wins the job. Part of that bid includes cheap surfaces. OSB is one of them. This gets everyone into trouble when the flooring has yet to be chosen (ahem…homeowners don’t have enough information about their build to be able to offer a floor cover), leaving the GC alone in “guessing” at what to use as underlay. When the floor is chosen (in this case a glue down cork tile) Builders are on the hook for a more expensive surface and homeowners are on the hook for a change order (that they didn’t even know existed). Tempers flare at this point.
The builders (either at the time the house was built or at the time of bidding the renovation) will use their best guess when it comes to bidding a project. They will use their own history to price out a job. Part of a flooring job includes underlayment – which means 90% of the time to be OSB (unless specifically stated as something else). That’s how they make money. They use “good enough” materials instead of the better or best materials. Most of the time they can get away with it. But in some cases, like a glue down cork floor, they are bitten by the “good enough” bug. And it bites HARD!
The problem with OSB and glue down materials comes from chemical incompatibility between the adhesives/wax in the OSB and the adhesive required to install these floors. The contaminants in the OSB means it is useless to even try to glue to it. Floor failure can be expected inside of a few weeks. In many cases it shows up the next day. By that time, it is too late. The cork cannot be salvaged, the adhesives cannot be salvaged and the whole thing is a redo. It is better to take the time to remove the OSB or cover it up and then start the glue down process once fresh, subfloor grade plywood has been installed and properly prepared. And properly prepared means the same sort of prep as sheet vinyl or linoleum. That’s a lot of prep. Especially if the OSB has to be removed or resurfaced with something else. The price of the project will climb – steeply.
The moral of the story is: Make sure you know what type of flooring you want before allowing your contractor cartier love bracelet knock off
to lay underlayment. If in doubt, specify subfloor grade plywood – be prepared to pay the extra. Subfloor grade plywood is acceptable in all but a few situations.
Cancork Floor Inc.
185-1991 Savage Road.
Richmond BC, V6V 0A4
Toll Free: 1-866-998-1198