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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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?
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
3. Is Drip edge required by code?
4. My roofing contractor told me I need to add a cricket to my existing fireplace chimney. Is this correct?
5. If a permit or inspection are not required, do I still have to meet code?
6. Is an ice and water shield required?
7. Is valley flashing/lining required?