FAQs

If my roof has an existing lumber sheathing deck (1x6, 1x8, etc.), do I have to re-deck my roof with OSB or plywood when replacing the asphalt/composition roofing?: It depends, as this requirement comes from a change in shingle manufacturers’ installation instructions. Some, not all, shingle manufacturers now state (in their instructions) that their product cannot be installed on solid lumber sheathing wider than a 1x6. This is due to the possibility for expansion/contraction of the deck boards wider than a 1x6. The code does state that new roof covering material (shingles) must be installed in accordance with the manufacturers’ installation instructions. These instructions may also address the gap between boards and may require an overlay of OSB or plywood if the gaps are too wide.

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Storm / Re-Roof Information

1. If my roof has an existing lumber sheathing deck (1x6, 1x8, etc.), do I have to re-deck my roof with OSB or plywood when replacing the asphalt/composition roofing?: It depends, as this requirement comes from a change in shingle manufacturers’ installation instructions. Some, not all, shingle manufacturers now state (in their instructions) that their product cannot be installed on solid lumber sheathing wider than a 1x6. This is due to the possibility for expansion/contraction of the deck boards wider than a 1x6. The code does state that new roof covering material (shingles) must be installed in accordance with the manufacturers’ installation instructions. These instructions may also address the gap between boards and may require an overlay of OSB or plywood if the gaps are too wide.

2. If my shingle manufacturer does not allow my existing (1x8, 1x10 etc.) deck to be used as a base for their product, do I have to remove the old decking or can new OSB or plywood sheathing be installed: The 2018 International Residential Code (IRC) does not require you to remove the existing deck material prior to installation of a new sheathing substrate except in very unusual circumstances where the existing roof framing is inadequate. Roof replacements do require the removal of all existing layers of roof covering (shingles).

3. Is Drip edge required by code?: Yes, per IRC section R905.2.8.5 drip edge is required for asphalt shingle installations. Drip edge must be installed in accordance with the manufacturers’ installation instructions.

4. My roofing contractor told me I need to add a cricket to my existing fireplace chimney. Is this correct?: If the chimney measures more than 30 inches wide, perpendicular to the slope, then a cricket is required per the IRC section R903.2.2.

5. If a permit or inspection are not required, do I still have to meet code?: All requirements of the code are enforced and in effect even if a specific permit or inspection are not required.

6. Is an ice and water shield required?: No, currently it is not specifically required by code unless mandated by a shingle manufacturers’ installation instructions for certain applications.

7. Is valley flashing/lining required?: Yes, multiple code approved options are available per IRC section R905 for asphalt installations.