Replace Plywood Roof Cost Calculator

Get the per-sheet decking rate written into the contract before anyone touches your shingles.

That single line is worth more than everything else on this page. Once the roof is open you can't walk away, can't collect a second bid, and can't delay.

Whatever number the contractor names in that moment is the number you pay. A rate agreed in writing beforehand turns that phone call into simple arithmetic.

Ten minutes at the end of the job protects you for years.

Wide shots of each plane. This is your only record of the nailing pattern and panel layout, and it's invisible forever after.

Stacked by the dumpster, in one frame, countable.

Sistered members, one close shot and one wide.

Ice and water shield or flashing at chimneys, vents, and valleys, before shingles cover them.

Paper, photographed, filed with everything else.

Keep those with the contractor invoice and the shingle warranty registration. A warranty claim on a fifty-year shingle asks for evidence the decking was sound and correctly fastened. Photos are that evidence.

Then check the attic once, six months later, after a heavy rain. New sheathing shouldn't show a single stain in its first five years. If it does, the problem is flashing or ventilation, not the panels you just bought.

Before you price anything, find out whether you have a decking problem or a shingle problem. They look identical from the driveway and differ by thousands of dollars.

Go into the attic on a bright day with the lights off. Daylight through the sheathing means holes. Dark streaks running down a rafter mean water has been tracking there for seasons.

Press a screwdriver handle against the underside of the panel near any stain. Firm is fine. Spongy means the wood fibers have already let go.

Then look at the roof from across the street at a low sun angle. A healthy deck reads as flat planes. Waves, dips between rafters, or a sag near a plumbing vent mean panels have lost stiffness underneath.

Do this before the first bid, not after. A homeowner who has already been in the attic asks better questions and gets quoted differently.

Decking, sheathing, and "the plywood" are three words for one layer: the flat skin of panels nailed across your rafters that everything else sits on. Shingles are waterproofing. Decking is structure.

It fails from underneath more often than from above. Warm indoor air carrying moisture rises into the attic, hits the cold underside of the panels in winter, and condenses.

That cycle runs every night of the heating season. Panels that never saw a drop of rain can still rot along the north slope where the sun never dries them.

That's why sheathing failure clusters. It concentrates near bathroom vents, over blocked soffits, and in valleys where two roof planes dump water into one path. Crews pulling a deck routinely find a tight patch of ruined panels surrounded by wood that's still perfect.

Fix the cause when you fix the deck. New panels over the same bad ventilation start the same clock again.

Not every warning sign means replacement. The order of seriousness.

The middle three rows are where money gets wasted in both directions. Homeowners ignore backing-out nails for years, then get talked into a whole new deck. The right response to those rows is a targeted inspection, not a full quote.

The decision, following NRCA threshold guidance, with explicit branches.

If any one of those three fails, price the full deck and compare.

The mechanism is crew time, not material. A crew replacing scattered panels spends its day moving staging, cutting odd openings, and matching thickness to what's already there.

A crew stripping a whole plane works in a straight line and nails panels as fast as it can. Past roughly a third of the deck, working around the good panels runs more than replacing them.

TA second reason. Old and new panels sit at different thicknesses after decades of compression and moisture. A patchwork deck telegraphs every seam through the shingles once the sun softens them.

Ask directly: "Are the bad panels in one area, or scattered across the roof?" Scattered damage on an older roof is the honest case for going full.

Installed decking replacement runs $3.50 to $6.00 per square foot. That covers material, labor, fasteners, and tear-out of the old panel. Treat it as an estimate to check against local bids, not as federal data.

The wage inputs behind it are solid. Plywood PPI tracks the material index. The finished price range is a market estimate.

Convert it to the unit contractors actually bill in. A 4x8 panel covers 32 square feet.

32 sq ft x $3.50 = $112 per sheet
32 sq ft x $6.00 = $192 per sheet

Where you land in that spread isn't random. Low end: simple gable, walkable pitch under 6/12, single story, panels already exposed during a full reroof.

High end: steep pitch needing roof jacks, two or three stories, a cut-up hip roof, or a standalone repair where the crew mobilizes just for you.

Adjust that national range for where you live. BEA Regional Price Parity data shows two clear tiers: the Northeast and coastal metros run 20-30% above this range; the Southeast and South-Central run 10-15% below (BEA RPP).

If a bid comes in above $192 a sheet, the extra is buying something specific. Make the contractor name it.

Do this math yourself before anyone quotes you. It takes two minutes, and it's the number that catches a padded change order.

Roof area is not house footprint. A 1,200 square foot one-story house with a 6/12 pitch carries roughly 1,340 square feet of roof surface, because the slope stretches it.

Waste factor is 10% for a simple gable, 15 to 20% for a hip roof (NAHB residential construction standards). Every panel meeting a hip gets cut on an angle, and the offcut is scrap.

Worked example, using the calculator's default: 1,200 square feet of roof area, 10% waste (NAHB standard).

1,200 x 1.10 = 1,320 sq ft
1,320 / 32 = 41.25, round up to 42 sheets

Fast sanity check by house: a 1,200 square foot ranch runs about 42 to 47 sheets. A 1,600 to 2,000 square foot colonial runs 60 to 75. A 2,400 to 3,000 square foot hip roof runs 90 to 110. An attached two-car garage runs about 22.

If a roofer's sheet count sits more than 15% above NAHB typical estimates, ask what's driving it before you ask what it costs.

The decking portion of a quote written out in full. Pattern-match your own paperwork against it.

Look at that bottom row. The implied per-sheet number sits below the standalone $112 to $192 range, and that gap is real.

When the shingles are off and the crew is already up there, panels get cheaper per unit. A contractor quoting standalone repair pricing mid-reroof is charging you twice for the same mobilization.

Everything below the decking line on your quote is a separate conversation: underlayment, drip edge, disposal, permit, flashing. Those swing too hard by county to put a national number on honestly. Demand each one as its own line.

OSB is wood strands pressed with resin. CDX plywood is thin veneers cross-laminated in alternating grain, where the C and D are face grades and the X means exterior glue. Both are code-legal. They fail differently.

Those sheet prices are 2025 retail estimates, not federal data, so price both at your local yard before signing. On a 42-sheet deck the gap is roughly $700 to $1,500 in material alone, which is the number the plywood upgrade has to earn back.

Look at the two wetting rows. That's the entire argument. OSB doesn't fail because it's weaker. It fails because one slow leak around a plumbing boot swells the panel edges permanently.

In a dry climate with good attic ventilation, OSB is genuinely fine and the savings are real. That sounds like something a budget contractor would tell you, and it is.

It also happens to be true. The trade has moved toward OSB in new construction for years for exactly that reason. In a humid or coastal climate, the plywood premium buys a deck that survives its first leak.

Whichever you pick, write material and thickness into the contract. Swapping in OSB where plywood was quoted is one of the easiest silent downgrades in the trade.

You don't get to pick thickness freely. Rafter spacing decides it, and the residential code sets the floor.

Measure it yourself in the attic: from the center of one rafter to the center of the next. Most houses read 16 or 24 inches on center.

H-clips are small metal clips set between panels at unsupported edges. They stop adjacent sheets from deflecting independently under load. On 24-inch spacing they're standard practice, and a crew that skips them on a thin panel leaves you a springy roof.

When you're patching, match the new panel to the existing thickness. A 1/2-inch panel dropped into a 5/8-inch deck leaves a step that shows through the shingles for the life of the roof.

Measure the existing deck thickness yourself before the crew orders panels, then write that number into the contract.

The full walk from a federal wage number to the labor line on your invoice. Every step is a multiplier somebody has to cover.

The gap between those last two rows is the honest part, and it's where most pricing articles quietly cheat. Bare nailing labor is cheap. Everything around it is not: prying the old panel off, hauling it down a ladder, disposal, staging, the truck.

Burden of 1.43 means the employer pays $1.43 in total compensation for every dollar of straight wage, using federal employer compensation data. The 21% markup (NAHB 2024) on top reflects typical residential builder gross margin.

Confidence labels, stated plainly. The $26.65 wage and the 1.43 burden are federal data, solid.

The 300 square feet per crew-hour and the 21% markup (NAHB 2024) are industry production figures, medium confidence. The $3.50 to $6.00 installed range is a market estimate, so check it against two local bids.

You can verify the wage yourself in the BLS OES May 2025 wage tables, and the margin figure against the NAHB 2024 Cost of Constructing a Home study.

This is the moment the page exists for. Shingles are off, the crew is on your roof, and the foreman calls to say twelve sheets are bad. You have about ninety seconds to respond well.

Say these, in order.

1. "Send me photos of every panel you're calling bad, with something in frame for scale." A crew with a phone can do that in five minutes. A refusal is itself the answer.

2. "Is that twelve sheets at the per-sheet rate in our contract?" If the rate is in the contract, this ends the negotiation in one sentence. If it isn't, you've just learned an expensive lesson for next time.

3. "Text me the revised total before anyone installs anything." Verbal change orders turn into invoice lines you never agreed to.

4. "Stack the bad panels by the dumpster and leave them until I've seen them." Nobody stacks rotten wood for a homeowner who isn't checking. The request alone changes behavior.

Never say "just do whatever it needs." Those five words are worth more to a dishonest contractor than anything else you can offer.

Your position is weaker than it feels, but it isn't zero. The crew wants the roof dried in tonight as badly as you do. Twenty minutes for photos costs them almost nothing.

Sheathing that has been nailed through three times is compromised even when it's dry and solid.

Each reroof drives thousands of new nails into the same panels. Old nails get pulled or driven flush, leaving holes behind. The panel keeps its shape but loses withdrawal strength, which is the exact property that keeps shingles from peeling off in a wind event.

If your house is on its third layer of shingles and the deck is original, budget for decking replacement even if nobody finds rot. A contractor who raises this without being asked is telling you something true that costs them nothing to hide.

Ask: "How many roofs has this deck carried?" A roofer standing on your tear-off can count the nail generations.

Above $3,000 on the decking line alone, get three bids. Below it, one good local contractor is fine, and the extra bids buy you delay, not savings.

The reasoning is proportional. On a 42-sheet full deck, the spread between the low and high installed rate is $4,200 against $7,200, a $3,000 swing on identical work. That's worth two more phone calls.

On an eight-sheet patch, the same percentage spread is a couple hundred dollars, and the delay risks a second rain event through an open roof.

One caveat that outranks the threshold: if the roof is already open or actively leaking, take the competent bid in front of you. Shopping a wet roof costs more than any bid spread.

The clean line is height and pitch, not skill.

a detached garage or shed, single slope, pitch under 6/12, roughly 22 sheets. You can walk it, you can hand panels up, and a fall is survivable.

The labor walk above says you're saving about $0.46 per square foot in billed labor, plus whatever tear-out and mobilization would have run. On a garage, that's real money for a weekend.

two stories or more, pitch above 6/12, any hip roof, and any job over an occupied room. Also any job you can't dry in the same day. A homeowner who loses daylight halfway through a deck has just built a swimming pool over the ceiling.

If you do go DIY, three things decide whether it holds. Stagger the panel seams so four corners never meet. Leave a gap at panel edges for expansion.

Follow the code nailing schedule, IRC Table R803.2: 8d nails at 6 inches on center at panel edges, 12 inches in the field. Under-nailed sheathing survives every calm day and fails in the one windstorm that matters.

Pricing other parts of the project? The concrete calculator runs the same sourced-rate approach for slabs and footings, and the firewood cost calculator does it for heating fuel.