Find Qualified Carpentry Professionals in Your Area. Document Library. Plywood is a common construction material which consists of multiple thinner sheets of wood. I have seen hundreds of houses where the roofing plywood has been installed improperly. Prime plywood deck with ½ gallon per 100 sq. It is true as the price of every OSB board is around $15 – $20 per sheet (4×8 sizes). Depth. Exterior plywood sheets typically have several veneers glued together, classifying them as multi-ply. If your roof has triangles and other shapes you’ll need to use a calculator to find the square footage. timber . Each material has its similarities and differences. Note, that when you buy in bulk, the price drops to $24.18 per sheet. Replacing rotten wood is critical because dry rot will spread. Then install another center row of nails along the roof felt, also spaced at 18-inch intervals. Talking about plywood or OSB for roofing, you cannot miss the information of the cost. Underlayment – is usually felt or fiberglass paper, that covers the entire roof deck. If you know you’ll be using 4-foot by 8-foot sheets of plywood, use the total roof area to find the set number of sheets you’ll need. You’ll need to ensure the line is square and the sheet finishes 10 – 30mm from the fascia. Here are some things to consider when choosing your decking material to install on a roof. Step 5 Measure the length of the roof edge with a tape measure. Poor water resistance. Structural Plywood Sheets (2) Rated. Depending upon the time of day, the angle of the sun in the sky and the pitch of a roof surface, sunlight will expose minor imperfections in either the shingles or the plywood beneath the shingles. This comes out to about 94 sheets of 4 x 8 plywood. I am using a 7/16" OSB Sheathing that I got from Lowe's. To secure it, measure it, roll it out over the plywood, cut it to the dimensions of the roof with a roofing or utility knife and finally hammer it securely to the plywood with 1/2-inch roofing nails. Square Edge (3) Tongue & Groove (3) Nominal Length (ft.) 8 (6) Nominal Width (in.) Hard to paint, but possible! 3.60 mm (2) 5.50 mm (3) 9 mm (3) 12 mm (4) 18 mm (4) Width. There’s no equivalent of the weak spots that can be left in plywood when knotholes in adjacent plies overlap. STEP 3 Installing Edge Flashing • Install Edge Flashing… at all eave and rake edges in a 1/8" (3.1 mm) bed of roofing cement and fasten with two rows of roofing nails staggered 3" (76.2 mm) o.c. This is the BEST product to use, because its very sturdy and high quality. The square footage of a Hip roof area is identical to the square footage of a Gable roof of the same measurements. Cons. Roof decks on homes built before 1970 are often 1×8 fir pre-plywood shiplap. Follow theses guidelines for a closer estimation. Since the boards used for shiplap were manufactured here in the Pacific Northwest, it was still cheaper than plywood up through the 1960s. For heavy load rated areas, 3/4-inch-thick plywood is recommended, regardless of rafter spacing. Generally, an OSB sheathing or wood panels are water-resistant. While a sheet of plywood might be 5 to 7 plies thick, a sheet of OSB is made from as many as 50 strand layers packed and compressed into the same thickness. The calculation is based on that the Plywood or OSB (Oriented Strand Board) sheets are of a 4' x 8' size. A layer of plywood also offers an additional layer of soundproofing from rain landing on the roof, though the air pocket between the roof and the interior drywall plays a larger part in keeping noise down. Estimate the amount of plywood or OSB needed for sheathing a roof. Roofing And Plywood Sheet. For example, if your roof is 3,000 square feet, divide 3,000 by 32. If there is water damage it will preform significantly better than the 1/2 plywood. Multi-ply. Using a string line, mark a line to guide the first row at the eaves. Planed Timber Mouldings Skirting Cladding & Wood Flooring Window Boards. It can also be used under hardwood, laminate, and carpet, but this is much less common these days because subflooring is typically smooth enough for these materials, many of which are installed with a different type of underlayment or pad. Standard spruce plywood manufactured with waterproof glue resist expansion and shrinkage. Roof Trusses Roofing Timber Roof Sheets Flat Roofing Roof Windows Roof Window Blinds Fascia & Soffit Guttering Flashings & Fixings Chimney Pots & Cowls Roofing Ventilation. This basically calculates the number of sheets needed for a Gable roof. Roof sheathing products like GP's Thermostat OSB roofing boards and Plytanium plywood roof sheathing provide heat and moisture resistant properties. Divide the roof’s area by 32 (32 is the total area of one sheet of plywood) to find this figure. Secure the felt to the plywood using a hammer and 1/2-inch roofing nails. Unroll new roofing felt over the new plywood and extend it at least 3 inches over each edge of the new plywood. Now, let’s have a look at some of the main differences between CDX and OSB as roofing plywood. Preparing Your Plywood Sheets. Use it to create strong walls, roofs, and floors. Differences Between OSB and CDX For Roofing Plywood. Tough to paint on. For a shape like a triangle (gables and hips), trapezoid (hip side with the ridge), or trapezium (gable roof with a valley); find the average length by measuring at the center of the width. Some locations that experience unusually harsh seasons may fair better with wood like oak, which can resist mildew and mold from damp conditions. Install gutters in valleys as needed. Most Western Washington residential homes during this time were built with shiplap roof decks rather than plywood. Until the 1940s, exterior grade plywood was not available. Here is approximately how much different options cost: 5/8 inch – $26.87 per sheet. Solving for the number of sheets of plywood necessary for more complicated shapes requires at least some estimating. This can be labor-intensive, and you may be tempted to cover those areas, but you will be dramatically reducing the life of your metal roofing if you do.