Brandi Henson 
Plywood is an economical and effective material for roof sheathing due to its cheap cost and ability to evenly distribute weight distribution. Furthermore, plywood handles moisture well and dries quickly after exposure.
OSB boards expand more than plywood boards when wet and take longer to dry off completely, creating visible ridges around their edges.
Grade A
Plywood with moisture resistant properties makes a great material for roofing sheathing, and can withstand extreme temperature variations without suffering damage from moisture exposure. Furthermore, this plywood type can withstand moisture exposure without cracking under pressure – making it an excellent choice when combined with metal, stone-coated steel or rubber slate roofing systems.
This plywood offers the highest level of quality available. With few visual imperfections and water resistance properties, it makes an excellent choice for durable roofs that will stand the test of time.
Plywood can be made of various kinds of wood, but when selecting plywood for use on roofs it’s recommended that fir plywood be chosen due to its harder grain than pine plywood and increased moisture-resistant properties that prevent warping or warping of this type of roof material. Furthermore, use moisture-proof adhesive when attaching this type of plywood for roof use.
Grade B
Plywood roofing material is an increasingly popular choice because of its strength, water-resistance and cost effectiveness compared to other options. Furthermore, plywood contains low levels of formaldehyde which helps lower risks associated with occupational asthma.
Grade B plywood is another great choice for roofing purposes. It boasts an undamaged, smooth surface that’s paintable. Furthermore, Grade B plywood is less costly than Grade A; although not as strong as OSB it still makes for excellent sheathing or other construction projects.
Grade C
Plywood comes in various thicknesses and types; selecting an optimal plywood type for roofing will depend on the load requirements for that roof; for instance, flat roofs require thicker plywood than pitched ones.
Lower grades of plywood will contain more flaws in their wood grain, yet still provide strong water-resistant layers with budget-friendly pricing for construction projects.
Look for CDX plywood when searching for exterior sheathing materials, as this plywood has three ratings – C on the front, D on the back, and X for exposure – which indicate its suitability to outdoor use. However, such plywood shouldn’t remain exposed – usually it will be concealed behind bricks or shingles on roofs, storage bins or garages to avoid exposure to elements such as rain.
Grade D
Plywood roofing material boasts high water resistance, making it an attractive option. Furthermore, plywood offers structural stability at an economical cost and costs less than many alternatives. However, Oriented Strand Board (OSB) sheathing material has recently gained in popularity for roof sheathing due to its greater shear strength than plywood.
Grade D plywood features numerous visual imperfections that make it less suitable for projects in which its wood grain will be visible. While still strong enough for roofing applications, Grade D may require paint application on its surface before use in other projects.
CDX plywood is a hybrid variety frequently utilized for building projects. The name refers to its C and D grades used on both sides, while its moisture-resistant glue provides stability to hold all layers together.
CDX
CDX plywood is an economical and enduring roofing material option, made up of two grades of wood bonded together with water-resistant glue for ease of installation. Though not ideal for projects where moisture exposure will occur on an ongoing basis, CDX can handle short bursts of rain with minimal adverse affect.
However, if your CDX will be subjected to frequent rain or other severe weather conditions, pressure-treated CDX should be the superior choice compared with generic varieties which could eventually succumb to moisture damage over time.
