Inspiration2 min

How Fire-Rated OSB Outperforms FRT Plywood

Both fire-rated OSB and Fire Retardant Treated (FRT) plywood are commonly used in fire-rated wall sheathing and roof deck applications. Because these materials are always evolving, it’s good for architects and builders to know how they compare to each other.

An engineered wood product like LP® FlameBlock® Fire-Rated Sheathing combines a layer of ignition-resistant, cementitious coating with a layer of OSB. It carries an Exposure 1 classification, which means it can withstand normal exposure to moisture during construction. In contrast, some fire-retardant treatments are applied after the plywood is manufactured – and the treatment is sometimes water-soluble, requiring it to be protected from moisture during construction. 

A fire-rated OSB product like LP FlameBlock offers both flame-spread resistance and burn-through resistance in the same panel, as verified in tests like the 30-minute Class A Flame Spread Rating (ASTM E84, UL723) and 15-minute Thermal Barrier Protection test (UBC 26-2).  FRT plywood has a flame spread rating, but no rating for burn-through resistance. 

Fire-rated OSB sheathing has load/span and shear design values that are superior to FRT plywood at the same thickness. In addition, engineered wood sheathing reduces dead load and wall thickness versus FRT plywood. This gives architects more flexibility in designing wall openings, plus more options in framing and bracing to meet structural requirements.

When architects specify fire-rated OSB sheathing, it’s important for builders and subcontractors to “respect the spec” and stick with a material like LP FlameBlock that has so many advantages over FRT plywood.

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Industry Trends5 min

Solutions for the Starter Home Shortage

The supply of modestly priced starter homes continues to drop nationwide. A recent report by Realtor.com found that the number of homes priced above $750,000 grew 11 percent last year, while the number of starter homes priced under $200,000 fell by 8 percent.

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News & Stories6 min
The What’s & Why’s of the LP® SmartSide® 5/50 Limited Warranty

Any building professional will tell you that the quality of a building material is only as good as its warranty. This is why LP Building Solutions created an industry-leading limited warranty for our line of LP® SmartSide® siding products. One that aims to ensure peace-of-mind for builders and homeowners.

Business Advice6 min
Why It’s Important To “Respect the Spec”

While it’s perfectly alright for a jazz musician to improvise, that approach doesn’t always work as well in homebuilding. Architects, specifiers, engineers and product reps spend many hours collaboratively choosing the right materials for each job – and an abrupt substitution to save a few dollars can ironically be very costly in terms of callbacks, design underperformance and even code violations. “Ideally, all parties involved – the architect, builder and developer – have reviewed the spec before it’s final and have agreed on all the products being used,” says Karen Alves, LP Brand Marketing Associate. “That’s because finding an ‘equivalent’ for siding or fire-rated sheathing involves not just the substrate but the codes that the product meets as well.”