Did the Deck Dry Out Before the New Shingles Went On?

Most homeowners picture a roof as the shingles on top. Underneath them sits the deck, usually plywood or oriented strand board in newer houses and boards in older ones, and that deck is what holds every nail. When a storm, an ice dam, or a long leak has soaked it, the wood can swell and soften. If the new shingles go on before the deck has dried, the nails can work loose later, and the damage may not show until the first hard rain of the next season. Asking how the crew checks moisture before the felt goes down is a practical question, and it is one of the few you can ask while the roof is still open.

Why a wet deck is a different job

St. Louis roofs go through freeze and thaw cycles every winter. Water gets into a small gap at a valley or a pipe boot, sits in the sheathing through a cold week, and then refreezes. The wood does not need to rot to become a problem. Plywood that has taken on water can delaminate at the edges, and OSB can lose stiffness where it has swelled. A nail that holds well in dry wood may pull through wood that has been wet for weeks. Once the felt and shingles cover the deck, the crew cannot see the boards anymore, so the time to look is before they go on.

Dryness is not a single reading. A deck can look dry on the surface and still hold moisture in the middle of a sheet, especially after a wet spring when the attic stayed humid. A roofer who glances at the top surface has not checked the deck. Ask what instrument will be used, where the readings will be taken, and whether the crew will record the numbers in the job file.

What a moisture check looks like

A pin-type or pinless moisture meter gives a rough reading of how much water is in the wood. Readings are taken across several sheets, including the spots nearest the leak, the eave, and the valley, and compared with a sheet from a drier part of the roof. The purpose is not a laboratory number. The purpose is to find sheets that are noticeably wetter than the rest, or sheets that feel soft when pressed with a screwdriver or a fingertip from the attic side.

Ask whether the attic will be checked from below at the same time. A dark stain on the underside of the sheathing, a sag between rafters, or a fresh tide line on the rafter tails tells the crew where to look on the roof. A thorough inspection uses both sides of the deck. If the roof is being opened in sections, the check should happen on each section before it is covered, not once at the end of the day.

Ask also what happens after the check. Dry is a threshold, not a feeling. If the sheathing reads wet, the crew should wait, dry the deck with fans or time, and take the readings again before felt goes down. Hearing that they will reread the deck is useful, but a written note that they will reread it is more useful.

Soft boards and what they mean for the nails

A soft sheet is not automatically a sheet that must be torn off, but it does need a decision. Some crews replace individual sheets that fail a screwdriver test. Others will say that a few soft spots can be cut out and patched with a fresh piece. A sheet that has been wet long enough to delaminate should be replaced rather than screwed down again, because new nails will not hold well in damaged layers. Ask the crew to show you one of the sheets they replaced, and ask where the replacements came from. If the answer is that sheets are always reused, ask why.

Nail pull is part of this. Shingle manufacturers publish nail length and placement in their installation instructions, and those instructions assume solid, dry sheathing. Ask which installation spec the crew is following for the nails, and whether it matches the instructions printed on the bundle wrapper. A roofer who writes a nail pattern into the scope and then drives it into soft plywood has not followed the spec in any useful sense.

Insurance claim

If the wet deck came from a storm or a sudden leak, whether the sheathing is covered belongs to your policy and to your insurer. Missouri law bars a roofing contractor from representing or negotiating your insurance claim, so a roofer is forbidden from arguing for the deck to be paid and cannot tell you what the insurer will decide. What a contractor can do is document what it finds. Keys documents damage, puts a written scope with photos and measurements in your hands, and attends as the contractor while you deal with your own insurer. Keep the moisture readings, the attic-side photos, and any replaced sheet with a date on it. Those records belong to you.

If the moisture check shows damage that predates the storm, say so in writing on the scope. A dated note that the deck was wet at the start of the job lets you describe the condition accurately to whoever reviews the claim. It does not decide the claim, but it means you are not relying on memory.

What it costs

Deck replacement is usually priced per sheet or per square foot of sheathing, and the price should appear as its own line rather than inside a general repairs figure. Ask what the unit price is, whether it includes labor and removal, and whether the crew bills for removed sheets only after they have checked them. Some quotes carry an allowance for decking, which is a number that is not yet a price until the crew counts what they actually find. An allowance can be reasonable, but the quote should say how the final figure gets settled and who signs off on it.

Drying time can cost money too. If the crew has to wait a day for the deck to dry, ask whether that day is in the schedule and whether the open section is covered overnight. Ask who pays if weather turns and the deck has to be dried again. These are not trick questions. They are questions that deserve written answers, and a written answer is what keeps the number on the page.

What to ask

Before the felt goes down, ask the crew these questions and write down the answers.

1. How will you measure moisture in the deck, and which instrument will you use?
2. Where on the roof will the readings be taken, and will the attic side be checked too?
3. What reading or condition means the deck is dry enough to cover?
4. Who decides whether a soft sheet is replaced or repaired, and will I see it before that decision is made?
5. Will the readings and the replaced sheets be recorded in the job file I receive?
6. If the deck needs to dry overnight or longer, is that time in the schedule, and is the open section covered?
7. How is decking priced, as a unit price, an allowance, or a fixed line?

If the answers are vague, ask for them in writing before the crew starts. Keys Roofing can be reached at (314) 220-2333 to talk through how a deck check would be handled on a specific roof. The check takes a short time, and the record it leaves is what you will want if a sheet ever needs to be looked at again.