What wood is 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.

Is OSB better than plywood for roofing?

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 thickness OSB should be used for roofing?

If you are using OSB for your roof deck, then ⅝” is the recommended thickness. For plywood, which is slightly stronger than strand board, ½” thick is appropriate.

What kind of wood is used for roof rafters?

Rafters are usually made of Pine or Cedar. For longer span rafters, building materials manufacturers have created LVL (Laminated veneer lumber) rafters that can be 2–5 times longer than typical wood rafter.

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What is the best plywood to use for roofing?

CDX is the grade of plywood most commonly used for roofing (CDX plywood means it is Construction Grade for exterior purposes). The wood is graded on each side from A to D, depending on the level of imperfections, (A being free of all imperfections and knots and D being un-sanded and considerably defected).

Which is stronger OSB or plywood?

Osb is stronger than plywood in shear. Shear values, through its thickness, are about 2 times greater than plywood. This is one of the reasons osb is used for webs of wooden I-joists.

Is 7/16 OSB OK for roofing?

…or a non-laminated panel, such as this OSB. Either one is acceptable. The typical thickness of roof sheathing is about 7/16-inch, which is just under 1/2-inch. … If you find 3/8-inch plywood installed as roof sheathing, it’s a good idea to make your client aware of its presence.

Can I use screws for roof sheathing?

Screws can be used for even greater withdrawal strength, but should be sized by the building designer. Staples are not recommended for roof sheathing attachment in high-wind areas. … Oriented strand board (OSB) is one of the most popular materials for roof sheathing.

What size nails should I use for roof sheathing?

Step 3: Fasten Roof Sheathing Panels Properly. Fasten panels with a minimum of 8d Common (0.131-inch by 2-1/2-inch) nails spaced a maximum of 6 inches on center at supported panel ends and edges. At intermediate supports, fasten panels 12 inches on center. In high-wind areas, more fasteners may be required.

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Do I need treated timber for roof?

The simple truth is that you do NOT need to treat timber. … The same goes for actual rot by fungus – timber is simply NOT going to rot if it is kept dry.

What size wood do you use for rafters?

Max. Live Load 20 lbs/ft2 (956 N/m2)

Maximum Span (ft – in)
Nominal Size (inches) Rafter Spacing, Center to Center, OC (inches) Lumber Grade
2 x 10 16 25′
24 20′ – 9”
2 x 12 12 33′ – 6”

Can I use pressure treated wood for roof rafters?

As long as the rafters are not directly exposed to the elements, no need to be treated. … Treated is generally for ground contact or exposed to the elements or high humidity areas.

Do you use treated plywood for roofs?

Contractors generally recommend treated plywood rather than regular plywood for roof decking because condensation can build up on the sheathing and cause rot. Roofers understand that when it comes to the roof deck, the amount of water that gets on the wood is a concern.

Can you put plywood over old shingles?

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.

Can CDX plywood be used for roofing?

Only use CDX plywood for the interior of a house, where water damage is far less likely. 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.

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Roofs and roofing