Posted in Builders
The Callback Cure
The full weight of a home’s interior ultimately rests on the sub-flooring. That includes walls, ceilings, cabinets, appliances, furniture, and people. It’s a heavy job, and not all structural sub-flooring panels are created equally.
Some sub-flooring will sag or separate—resulting in unlevel surfaces, squeaky floors, and even annoying vibrations. Any of these problems could result in a callback and lead to costly repairs.
To prevent callbacks, homebuilders and designers need to understand the pros and cons of each sub-flooring material.
The modern era of sub-flooring began around 1920 with the use of standard planks nailed at a right angle to the floor joists. Planks are cut from natural wood (typically pine) and contain all the imperfections that come with it, including knots, bows, and splits.
After WWII, plywood began to replace planks in new home construction. Plywood is an engineered product created from thin veneers (or plies) of wood—typically pine, spruce, and/or fir. The veneers are glued and hot-pressed together and then cut into 4’ by 8’ panels. Plywood panels are quicker to install than planks, and they provide a stronger, flatter surface.
Next came oriented strand board, or OSB, which is manufactured from small strands of wood rather than plies. That’s why OSB does not contain core voids, knotholes, and other defects commonly found in plywood. These strands are then bonded together with water-resistant resins and wax under heat and extreme pressure. Like plywood, OSB sub-flooring panels are typically 4’ by 8’ in size.
Since 1990, OSB has become the nation’s most popular material for sub-flooring. And the technology behind OSB sub-flooring continues to evolve. LP Building Products and other manufacturers have introduced “enhanced” OSB sub-flooring panels with more powerful resins and edge seals.
In some regions of the country, plywood remains the most commonly used sub-flooring material because of pricing, availability, and building traditions. Throughout most of the United States, however, OSB is typically the less expensive option.
Getting beyond price, how does OSB compare to plywood in performance? Independent studies rank OSB equal to plywood in strength and stiffness. But, since OSB does not contain the natural defects found in plywood, the OSB sub-flooring panels also provide superior resistance to splitting, warping, delamination, and buckling. The most advanced OSB products also feature strategically placed notches to drain standing water. This notch system allows water to quickly drain with minimal absorption and edge swelling.
Perhaps best of all, OSB manufacturers are able to offer a 50-year transferable limited warranty on the most advanced sub-flooring products. Some manufacturers also offer up to a 200-day “No Sand” warranty, which states that if builders have to sand the panels due to moisture, they will be reimbursed for the cost of the sanding. These warranties give peace of mind to designers, builders, dealers, and homeowners that callbacks will not be an issue.
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