Composite siding is a building material used on the exterior of homes, referred to as cladding or plainly, siding, these products help to protect the framing, structural sheathing and interior of a home from water and other exterior elements. As any cladding material should, it also serves an aesthetic role and is available in a number of types to suit various home designs.
Composite siding began hitting the mainstream market in the early 90’s. The pioneer of composite wood products in the US is the Louisiana-Pacific Corporation (LP), launching the production of Oriented Strand Board panels, more commonly known as “OSB” in the 1970s. The product came about as LP needed a new product because Southern Pine and Douglas Fir timber were in short supply. The answer was fast growing, less expensive Cottonwood and Aspen. By the late 1970s, the production of OSB began by chipping logs into wafers, adding resin and pressing into sheets, then called Waferwood, later renamed Inner-Seal. It was a cheaper alternative and stronger than plywood sheathing and existing sub-flooring products. LP called this new Inner-Seal product, “the smart man’s plywood”.
Like any new manufacturing process, the expansion of sheet products turned into other products including, but not limited to, exterior cladding materials. As adoption of these more affordable materials grew, so did the problems surrounding all of the products. Without a significant level of maintenance, moisture would easily penetrate this highly absorbent material, expand and damage the integrity of the product. As the siding materials absorbed moisture, soon followed mold and sometimes fungal growth.
The most problematic areas for the siding materials were around windows, doors and the bottom drip edge. Improperly flashed openings would trap moisture, while poorly applied paint along the bottom edges would allow absorption to occur, leading to expansion damage, which would then exacerbate the problem. Class action lawsuits soon emerged, and there was a period of time where homeowners could file claims. Most claims were regarding the LP Siding products. After these problems emerged, the Louisiana-Pacific Corporation redesigned their products, along with changing the installation requirements.
After the changes, LP renamed this product “LP SmartSide” and since the late 90s, has sold billions of square feet with no warranty claims for fungal decay to date. With improved installation methods, product design and proper flashing techniques, LP siding is now truly a quality siding option that can be utilized in most climate zones.
Although, some homes are still found today clad with recalled LP siding, it doesn’t necessarily mean that the siding needs to be replaced. The original siding products required more maintenance than most homeowners were aware of, which led to many of its failures. Homes that were maintained, had large overhangs or were not subject to weather extremes, may have perfectly intact siding components. Because these siding components can have damage that is not visible on the exterior surfaces, any home clad with these siding materials should be evaluated by a qualified contractor to ensure hidden damage does not exist.