A special grade of plywood called “CDX” is a popular choice for roof sheathing. No, the “X” in CDXplywood does not stand for “exterior.” Rather, it references the kind of glue used to bond the layers of veneer together. CDX plywood can withstand temporary exposure to rain and other moisture sources.
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.
What type of plywood is recommended for roofs?
Most Common Thickness
For rafters spaced 20 or more inches apart, 1/2- or 5/8-inch plywood is recommended. The most common rafter spacing is 24 inches, and 5/8-inch plywood is recommended for that. It will support roof loads for most situations and is the standard for most roof applications.
What does CDX plywood mean?
CDX is a type of plywood. Basically, plywoods are thin veneer sheets that are glued and held together with linking plies. … If so, it therefore, means CDX has the most number of knots and defects, making it a lower grade plywood. C in CDX means one side of the plywood is of grade C, and the other is of grade D.
Is CDX better than OSB?
CDX and OSB are used for almost similar things, but because they have different features, one is better applied in some tasks and the other one on other tasks. CDX is best for sub-flooring. … OSB also seems to be good for roof sheathing. But take care, it also requires that you use water-resistant coating at the edges.
Which is better for roofing OSB or plywood?
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 is the difference between ACX and CDX plywood?
ACX is a designation given to a traditional wood exterior plywood panel with one sanded face and one rough face. … CDX plywood is the lowest class of plywood and is often used in the construction industry or as a base for other materials. CDX plywood is much thicker and can be bought for low prices in large volumes.
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.
Do I need plywood on my roof?
Sometimes referred to as roof sheathing or a roof deck, this plywood acts as a foundation for the layers of underlay and the shingles on your roof and connects the roof to the frame of the house. Even though it isn’t visible, it is very important to the structure of your home.
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 weather resistant?
Homeowners considering using CDX plywood for their next project should recognize that, by no means is CDX plywood fit for extensive exposure to the elements, because it is not weatherproof. … With that said, CDX plywood is capable of withstanding limited exposure to moisture – including rain and snow.
How can I waterproof plywood?
Using an epoxy sealer is probably the most popular way to seal plywood against the elements. The epoxy is usually found in paint or spray forms. The advantage that epoxy provides is that it makes the plywood stronger, in addition to waterproof.
What is CDX plywood good 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.
Which lasts longer plywood or OSB?
Plywood and OSB are generally considered to have the same load strength. However, as plywood has been around longer, it has shown that it can last 50 or more years in an installation. OSB does not have the same track record because it has only been marketed for about 30 years.
Is OSB cheaper than plywood?
OSB is less expensive than plywood. To build a typical 2,400-square foot home, OSB may cost $700 less than plywood. OSB is considered by many to be a “green” building material because it can be made from smaller-diameter trees, such as poplars, that are often farmed.
Why is OSB price so high?
So what does this mean for prices? An oligopoly has few producers but many buyers. When industry production capacity exceeds demand, OSB pricing resembles a competitive market. The few producers will compete with each other for business in order to keep their enormous, expensive, manufacturing plants producing 24/7.