Malarkey strongly recommends overlaying or replacing older board decking with suitable sheathing because gaps, cracks and movement can damage the roof above. Board decking may be acceptable when it meets the stated conditions, but unsuitable or deteriorated sections need correction
Malarkey technical bulletin: Wood Board Decks as a Substrate for Steep Slope Roofing.
What this means for your roof
Malarkey strongly recommends overlaying or replacing older board decking with suitable sheathing because gaps, cracks and movement can damage the roof above. Board decking may be acceptable when it meets the stated conditions, but unsuitable or deteriorated sections need correction. New shingles cannot compensate for a weak fastening base.
A useful question for your contractor
Ask for a deck-condition allowance and photographs after tear-off, including gaps and damaged boards.
Ask for the answer to be tied to the actual roof condition and the exact product being installed. Keep the agreed repair or installation detail with your estimate and project photos.
Bulletin edition: April 2023. The date shown identifies the manufacturer document used for this summary.
Read Malarkey: Wood Board Decks as a Substrate for Steep Slope Roofing
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.