How to Replace Roof Sheathing

Sheathing may need to be replaced for several reasons, but the most common is water or storm damage. To replace roof sheathing you must create an access to the roof area with either an extension ladder or scaffolding. This article will relate how to replace sheathing on a low pitched roof, where you can walk from the edge of the roof to the place that is in need of repair.

Things You'll Need

• Extension ladder or scaffolding
• Flat pry bar
• Framing hammer
• Four foot pry bar
• Work gloves
• Safety glasses or goggles
• Saw horses
• Circular saw
• Reciprocating saw
• 3/4 inch exterior grade plywood
• Galvanized common nails (#6 or #8)
• Tape measure
• Chalk line
• #16 galvanized framing nails

Instructions

1. Create a pathway to the roof using either extension ladders or scaffolding. Extension ladders work best for a one story building, but for any building that is higher, you might consider hiring a professional roofer.

2. Walk to the edge of the area that you wish to remove and mark the boundaries with a chalk line. You will need an assistant to help you do this. Have your helper hold one end of the line, while you hold the chalk container and then snap the line so it leaves a chalk impression on top of the roof shingles. Do this on all four sides of the area, forming a rectangular shaped area with the four lines.

3. Remove the shingles with a flat pry bar and hammer. You can cut the boundary areas with a utility knife or old pair of tin snips. Remove all shingles and building paper until the bare wood of the roof sheathing is exposed. Make sure all roofing nails are removed along with the shingles.

4. Cut the old sheathing out with a reciprocating saw. Make sure you are wearing goggles and work gloves when you do this. Make your cuts with the electric saw along the perimeter of the exposed wood and then remove the wood with a long pry bar. Then discard all material to one location. Once this step is complete, the rafters of the building should be exposed.

5. Inspect the rafters for damage. Repair any rafter that is damaged. If this cannot be done by splicing, then you might have to tear off some more roof to access the whole rafter. This consequence is not an uncommon occurrence in roof repair and the possibility of this occurrence should be taken into account beforehand.

6. Block in the edge of the replacement area with framing members that are the same size as the original rafters. Use #16 galvanized framing nails to nail each piece into place. Be certain that the top of the block is flush with the top of the rafter. If you can place the blocks so they support part of the old sheathing, but still provide a nailing surface for the new, then this will be the ideal situation.

7. Cut the new 3/4 inch plywood to fit into the newly created opening. Cut the plywood to fit as tightly to the sides of the old sheathing as possible.

8. Nail the sheathing with #6 or #8 galvanized box nails. Place a nail about every six to eight inches and make sure each nail goes into a rafter or block.

9. Lay down a layer of heavy weight building paper and then cover the area with new roofing material that matches the old roof.

Tips & Warnings

• Set aside an area beforehand to place the material that you remove from the roof. It is best to place this material in a dumpster or right into the bed of a truck. As an alternative to Step 6, keep tearing off the roof until you come to a natural stopping point such as a rafter or the roof ridge.

• This project will require one to two assistants. Working on a steep roof is only recommended for a professional roofer.

References

• Replacing An Asphalt Shingle Roof