OSB vs plywood flooring.

[Celtlund]

We did a lot of research before we bought our house and I was under the impression that OSB was just about as good as plywood for a sub-floor. To make a long story short our front loading high efficiency washing machine leaked a few times. My wife got the water up as soon as she could when she discovered the leaks. Unfortunately not quickly enough as it turns out. The OSB obviously got "soft" where they front feet of the washer sat on the floor so the machine was out of level. The washer repairman discovered the problem with the floor. The MF home repairman will be coming over next week to replace a 4' to 5' section of the sub-floor with 3/4' pressure treated plywood. I guess the bottom line is if you can get plywood as a sub-floor in the laundry room, do it. I'm very thankful we don't have cresdeck (fiberboard) sub-floors or the washer would have ended up under the house.

[David Oxhandler]

Like plywood there are different grades of OSB

OSB that is stamped EXPOSURE 1 is bonded together with waterproof resins and glues. EXPOSURE 1 OSB is made to withstand repeated rainfall with little or no damage but not permanently exposed to weather. OSB is waterproof.... but if the surface is penetrated, it compromises the waterproofing.. The weight of your washers legs may have caused an indent that opened the decking to water damage.

OSB that can be permanently exposed to weather and rain will be stamped "EXTERIOR". We had the water line in my office, to the ice maker leak over a three day week end. When we opened the office there was ankle deep standing water. I expected the OSB sub-floor to fall apart. We vacumed out the water and brought in a commercial dehumidifier for 3 days. The decking was stamped "EXTERIOR". There was no swelling or irregularities to the OSB a month after it dried when we re-covered it with carpet.

[Celtlund]

David, thanks for clearing that up for us. In any case, the floor is fixed and the washer will have a new seal next week.

[abraham.a]

OSB is a really good alternative of plywood flooring . it also has many advantages over plywood .

[David Oxhandler]

OSB has proven to be an excellent building component but is unfortunately often confused with particle board, which failed miserably as a flooring due to disintegration from moisture contact.

It took years for quality builders and carpenters to embrace plywood when it was introduced. Many stayed with individual planks of lumber for decking for quiet some time.

Comments lifted from various sources online:

The passage of time and success stories from millions of installations have clearly shown plywood to be a proven performer. Production figures indicate that OSB has finally been accepted by builders, remodelers and homeowners.

OSB is equivalent to other structural panels in its strength and rigidity, panel size and thickness, fastener performance and paintability. As a performance-rated structural panel, it meets specific end use requirements in all major building codes.

Unlike steel or concrete, OSB is made from a completely renewable resource -- small-diameter, fast-growing trees.

[BigMack21]

I had a similar situation. Except we caught the water in time that it didn't do any real structural damage to the boards, just a horrible, ugly water stain. Can't afford new floors, think I'm just going to have to go with the good ol http://www.arearugs.com coverup!