After a Disaster Roof Repairs 2: Basic Materials

Publication Number 490-323, August 1996

General

In replacing a roof, be sure all three layers have at least minimum standard materials applied and installed correctly on a sound structural system of rafters or trusses. Some minimum standards follow:

1. The minimum standard for asphalt shingles, which is printed on each package, is "ASTM D 312-78."

2. Building felt (tar paper) should be #15 for roofing.

3. Sheathing may be plywood, particle board, or 1 x 6 T&G sheathing as follows:
   1. 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, (top number), 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.

   2. Particle Board -- Type 2-M-F or 2-M-W identified by grade mark or inspection certificate.

   3. T&G 1x6 Boards -- Construction grade lumber #2 or #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.

4. Fasteners -- from CABO One- and Two-Family Dwelling Code. See Table 1, Fastener Specfications.

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 people with limited ability, knowledge, or less-than-honorable purpose. One test of their ability, if not their intent, might be to ask them to explain the terms used here.

Adequate materials may be in short supply at a given moment. Substitution should be made only after checking with local or 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 can be obtained.

A good repair job is required now to prevent trouble later and to avoid reducing the value of your property.

Table 1

Fastener Specifications

* Shingles attached to roof sheathing having the underside of the sheathing exposed to visual view as a finished interior ceiling may be attached in these locations with shorter nails and staples than specified so as not to penetrate the exposed side of the sheathing.

** All nails and staples shall be corrosion resistant.

*** Nails or staples shall be long enough to penetrate into the sheathing 3/4 inch or through the thickness of the sheathing, whichever is less.

**** Annular threaded nails with minimum 1-inch-diameter heads shall be used for plywood decks.

Based on information developed by Clemson Cooperative Extension following Hurricane Hugo. Revised for Virginia audiences by Virginia Cooperative Extension.

For more information, contact your local office of Virginia Cooperative Extension.

Return to "After a Disaster Roof Repairs 1: The Rafters ."

Return to "After a Disaster Roof Repairs 3: Sheathing Applications ."

Return to "After a Disaster Roof Repairs 5: Building Felt & Asphalt Shingles ."

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View a list of publications in this series.