Can You Replace Sections of Sheathing on a Roof?

Teardown

• Storm damage, moisture and time may all play a part in severely damaging your roof. In order to properly replace the sheathing underneath all the shingles, the shingles covering this area must be completely removed. Pry the shingles up with a tear-off shovel, pry bar or similar tool. Dispose of all shingles and nails that you remove from the area before you remove the old sheathing you want to replace. Proper demolition and cleanup of the area will allow you to start with a clean slate.

Sheathing Thickness

• Always match the new sheathing to the existing materials that are already in place. The new sheathing must be of the same thickness as what is currently in use in the section you want to replace. Your roofing project is doomed to failure if your use sheathing with a thickness that's different from what is already in place; the shingles will never match up evenly and your roof will never be adequately constructed against the forces of nature and time. The strength of your roof is dependent upon its conformity; it must be of the same thickness all over to be most effective.

Materials

• Generally, one of three types of sheathing are used to build a roof: plywood, particleboard and tongue and groove (or T&G). When using plywood sheathing, position the boards so the grain is perpendicular to the rafters of the roof. Particleboard sheathing may be positioned either way, perpendicular or parallel to the rafters.

Sheathing Spacing

• Spacing is extremely important when placing new sheathing on the roof. Because the roof will expand and contract due to routine weather changes, the boards must have a little space to "breathe" between them. Place new sheathing so that cracks, approximately one-sixteenth to one-eight of an inch, are visible between the boards. Some sheathing is sold with these cracks already in place. Spacing clips may also be used to help you create an adequate amount of room between each board.