Unit 36

Structural part of the building Two good types of sheathing Lumber Lumber or laminated roof decking is sometimes used in homes with exposed ceilings Laid horizontally or diagonally Nailed to each rafter with two 8d common nails Boards should be laid so they lay on at least two rafters Softwoods are the wood species used for sheathing Sheathing covered with asphalt shingles must be seasoned

Two good types of sheathing (continued) Plywood Provides a smooth base Provides a minimum number of joints Costs less by cutting waste to a minimum Offers flexibility in design Very durable Takes less time to install than lumber sheathing Face grain should run the opposite direction of rafters Non-exterior type plywood should not be exposed to the weather

 3/8”  Asphalt shingles and rafter spacing of 24”  ½”  Slate or tile and rafter spacing of 16”  5/16”  Asphalt shingles and rafter spacing of 16”  5/8”  Slate or tile and rafter spacing of 24”

 Can be adapted to exposed ceiling applications  Has an advantage of strength and isulation  Weather-proof  Ideal for shingles on all types of buildings

 Can be purchased with tongue and groove edges  Widths of 4” to 12”  **Check manufacturers recommendations for correct thickness for the span of all types of decking  Excellent base for any roof material  Makes a ready to finish interior ceiling

 Provides a solid, permanent roof deck  Strong enough to use as a floor deck  Comes in many grades, patterns, and sizes  Select grade decking is the best choice when appearance is important  Commercial grade decking when appearance and strength are not as important

 Should be installed……  With each plank bearing on two supports  With a 2 degree angle cut in the butting pieces  In a controlled, random lying pattern for best economy  Should be fastened with common nails twice as long as the thickness of the plank  Galvanized nails have better holding power than bright common nails

 Metal splines are recommended on decking end joints of 3” and 4” material for better alignment, appearance, and strength  Closed sheathing  Laid with no spacing of boards

 Roof boards should give solid and continuous support for roofs….  Where snow and wind-driven conditions prevail  Made of asphalt shingles  Made in cold climates  Roof platform  Constructed to help apply plywood sheathing  Any sheathing should clear the chimney brick by ¾”

A measure of the size of nails, at least as early as the fifteeenth century – 21st century. Symbol, d. The symbol comes from the Latin denarius through the French denier, and is also the symbol for the monetary penny. There are 240 pennies to the pound sterling. In current usage in the United States, a 2d nail is 1 inch long. Each 1d increase is a ¼ inch increase in length up to 12d. A sixteen-penny nail is a ¼ inch longer than 12d, and the remaining sizes, beginning with 20d, are multiples of 10 and are each ½ inch longer than the preceding size.

In England before about 1488 the penny size was the price in pennies of 100 nails of that size

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