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What grade of plywood is used for roof sheathing?
1/2 or 3/4-inch Plywood for Roof Sheathing? – Traditionally, 1/2-in CDX plywood was common choice with 24-in rafter spacing. However, heavier roof loads may require the use of 3/4-in CDX plywood for roof sheathing. Roofs with less pitch often carry heavier loads, including snow and ice accumulations in the winter.
What type of plywood should be used for roofing?
CDX is the grade of plywood most commonly used for roofing (CDX plywood means it is Construction Grade for exterior purposes).
Is OSB or plywood better for roof sheathing?
Plywood Holds the Moisture Advantage Over OSB When plywood gets wet, it tends to swell. OSB takes longer than plywood to get saturated, but also takes much longer to dry out. When used as roof sheathing, this tendency to hold moisture means it will degrade faster than plywood when exposed to chronic leaks.
What plywood is best for sheathing?
3. Structural Fiberboard. Plywood and OSB are largely considered the best wall sheathing choices because of their overall abilities to hold fasteners well, create a strong bond between studs, and provide some thermal advantages.
How thick should roofing plywood be?
Most roofs will be sheathed in plywood at least 3/8 inch thick. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. Loads will vary with the pitch of the roof; the flatter the roof, the greater the load on any one section. Steeper roofs will have lighter loads per square foot.
Is 7/16 OSB OK for roofing?
Standard types of wood designed for roof sheathing are oriented strand board, known as OSB, and plywood, the most popular being OSB. Sheets of 7/16-inch thick, without edge support, can be used in an area where the snow load is 30 pounds per square foot.
Is 3 ply or 4 ply plywood better?
So what is the difference between 3-ply and 4-ply plywood? 3-ply plywood is the standard for internal-use plywood, featuring 3 layers of wood. While 4-ply plywood is available, it is very rare, and 5-ply plywood would be a better choice if you’re looking for increased structural ability compared to a 3-ply.
What can I use for roof sheathing?
Oriented Strand Board (OSB) or plywood can be used, although plywood will provide higher nail head pull-through resistance. Use panels rated as “Exposure 1” or better. Install sheathing panels according to the recommendations of the Engineered Wood Association (APA). Use panels no smaller than 4 feet long.
Can you put plywood over plywood on roof?
The new plywood will have to be nailed to the rafters or roof trusses. But, with the old plywood left in place, it will be considerably more difficult to locate the rafters to ensure proper nail placement.
Is CDX plywood good for roofing?
Moisture Differences In reality, CDX plywood can only withstand water for a short period of time. Do not use CDX for roofing, sheds, or other places that are exposed to moisture consistently. The sole exception to this is pressure treated CDX, which can survive for decades without even a protective coating.
How thick should sheathing be?
The U.S. Department of Energy has determined that 7/16-inch sheathing is the minimum appropriate thickness for structural wall sheathing with an exception for gable end walls, where the minimum thickness is 3/8 inch.
What is RTD plywood used for?
Exterior panels sometimes referred to as RTD sheathing, are designed to hold up to constant moisture. They are completely waterproof and are great for installing in places where you expect consistent exposure to moisture. This RTD sheathing is great for roofs and other outdoor applications.
What is the difference between sheathing and sanded plywood?
Sheathing: Standard construction plywood used for wall sheathing, roof decking, floor structures (subflooring) and general rough construction where looks and surface imperfections aren’t important. Sanded plywood: General-purpose “project” plywood with decent-looking face veneers that have been sanded smooth.
What is CDX plywood used for?
CDX Plywood is used primarily by contractors to build exterior walls and roofs. CDX plywood has one side veneer grade “C” and one side veneer grade “D”. The two are bonded together with glue which can withstand a little moisture. The APA would recognize CDX Grade Plywood as C-D Exposure 1 plywood.
Can plywood roof sheathing wet?
A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the steam finally escapes.
Should you use tongue and groove OSB for roof sheathing?
Tongue & Groove Boards T&G roof decking, however, looks classy and rich. In fact, T&G boards are most frequently used when the sheathing is visible from the inside such as in cathedral ceilings or in some cabin-style homes, especially if the span of the rafters is greater than 2 feet.
What type of wood should be used for roofing?
Oriented strand board (OSB) – OSB is the most common type of material used for roof decking. It’s durable and readily available, and has relatively low costs. OSB is made of interwoven strands of wood bonded with adhesive.
How thick should plywood be for a shed roof?
Plywood thicknesses for roofs start at 3/8” in areas with light load requirements on rafters at 16” centers. Thicknesses of 1/2 to 5/8 inch are common with rafters spaced at 24” centers. For heavy load rated areas, 3/4-inch-thick plywood is recommended, regardless of rafter spacing.
