Coastal Shingle Re-Roof Over Skip Sheathing

The contractor should not nail architectural shingles directly to spaced skip sheathing. Shingle manufacturers require a solid, smooth, flat deck, and the building code requires roof covering attachment to a substrate that provides the intended withdrawal resistance. Skip sheathing leaves unsupported spans, so nails cannot be reliably placed in the shingle nail line, and the roof will be vulnerable to wind uplift and foot traffic. The soft spots near the chimney also indicate possible decay or inadequate framing that must be investigated.

The correct approach is to strip the existing shingles, inspect and repair the skip sheathing and framing, then install a solid deck such as 7/16-inch or thicker OSB or plywood rated for the application, fastened to the framing per code and manufacturer requirements. The new deck should be gapped as required and should not be installed over rotten or loose boards. The existing drip edge should be removed and replaced with new corrosion-resistant drip edge at eaves and gables. This is not optional cost cutting; it is a substrate and wind-resistance requirement.

The contractor should follow the code and shingle manufacturer's underlayment requirements for the slope and location, including any high-wind or coastal requirements. A 15-pound felt may not be acceptable under the manufacturer's warranty or the code if a higher-grade underlayment is required. The underlayment should be installed over the solid deck with proper laps and fastening, and at valleys the contractor should use the manufacturer's approved method, typically a metal valley flashing or an open valley with the underlayment carried through.

The two valleys and chimney require careful sequencing. The chimney should have new flashing, counterflashing, and a cricket if the roof-to-chimney width requires it, rather than relying on sealant. Because rain is due in two days, the crew should not strip more roof than it can dry in the same day, and it should have temporary underlayment and tie-in details ready. A dry-in with felt is not a permanent roof; the contractor should stage the work, protect open valleys and penetrations, and avoid leaving the skip sheathing exposed. The schedule should be communicated to the homeowner in writing.

The contractor should verify the required roof covering approval for the wind-borne debris region and the design wind speed, then confirm that the selected shingle is listed for that use. The installation must follow the manufacturer's high-wind detail and the code, which usually means a minimum number of fasteners per shingle, fasteners placed in the manufacturer's nail line and not above or below it, and correct starter strip and hip and ridge attachment. In many high-wind installations, six nails per shingle are required instead of four, and the nail head must be flush with the shingle surface without cutting into it.

The contractor should also confirm the fastener length is sufficient to penetrate the new solid deck and, where required, the framing. The existing drip edge and rake details should be replaced with wind-rated edge metal. The crew should be trained on the specific pattern, and the contractor should inspect the first few squares before production nailing begins. Reusing the old drip edge or nailing through skip sheathing would undermine both the code approval and the manufacturer's warranty.