Roofing Glossary

Roof Decking (Sheathing)

Roof decking — also called sheathing — is the layer of wood panels nailed to your rafters or trusses that forms the flat surface everything else attaches to. Shingles, underlayment, and flashing all fasten into the decking, so its condition determines whether a roof replacement is straightforward or complicated.

Most modern homes use plywood or OSB (oriented strand board) panels, typically 7/16-inch or 1/2-inch thick. Older homes may have plank decking — individual boards with small gaps. During a tear-off, the crew inspects every panel; any rotted, delaminated, or spongy decking must be replaced before new roofing goes on.

Decking replacement is usually priced per sheet in a roofing quote. A roof that looks fine from outside can hide bad decking, which is why reputable contractors include a per-sheet replacement allowance rather than a surprise change order.

Why It Matters

No shingle, however premium, can perform on failing decking. Nails pull out of rotted wood, and soft spots telegraph through to the finished roof. Ask any contractor bidding your roof replacement how they handle decking replacement and what it costs per sheet.

What to Watch For

• A spongy or bouncy feeling when walking on the roof
• Visible sagging between rafters from inside the attic
• Nail pops pushing shingles upward

A Maryland Note

Maryland's humidity and occasional roof leaks mean decking rot is common on older homes here — budget for at least a few sheets on any replacement of a 20-plus-year-old roof.

Questions about your own roof? Request a free estimate or call Nucci Brothers Roofing at (301) 458-1003.