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Australia Storm Book
After The Storm - 21
Roof Repairs: Basic Materials
General
A common roof covering consists of three layers of material attached to
rafters on trusses: sheathing, roofing felt, and shingles.
In replacing a roof, make certain that all three layers have at least minimum
standard materials applied and installed correctly on a sound structural system of
rafters and trusses.
Some minimum standards follow:
- The minimum standard for asphalt shingles, which is printed on each
package, is "ASTM D 312-78."
- Building felt (tar paper) should be Number 15 for roofing.
- Sheathing may be plywood, particle board, or 1 x 6 T&G sheathing as
follows:
- Plywood CD, CC Structural I and II Exterior grade or interior type
bonded with exterior glue of a thickness ranging from 5/16 to 7/8
inch. Span ratings (distance from the center of one rafter to the
center of the next rafter) are stamped on each piece. The numerator
of a span number represents allowable spans for roofs. Buy a
thickness of the proper grade of plywood that will span the space
between the rafters -- or a thicker, not thinner, substitute.
- Particle Board Type 2-M-F or 2-M-W identified by grade mark or
inspection certificate.
- T&G 1 x 6 Boards Construction grade lumber Number 2 or Number 3
minimum. Sheathing should be the same material as the rest of the
roof and, in all cases, the same thickness of material when repairing
only an area of roof.
- Fasteners from CABO One- and Two-Family Dwelling Code.
Licensed builders are preferred for roof repairs. However, with pressure to
get the job done, this may become a "do it yourself" job. Avoid hiring someone
with limited ability, knowledge, or less-than-honorable purpose.
Adequate materials may be in short supply at a given moment.
Substitution should be made only after checking with the nearest code inspector,
architect, or engineer. Rather than accepting less than minimum standards of
material, it would be better to tolerate patching until minimum materials and
procedures are available.
A good repair job is required now to keep from having trouble at a future
date and to avoid depreciating the value of your property.
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