The short answer: we replace bad roof decking at $55 per 4×8 sheet of 7/16" OSB, or $5 per linear foot where an older roof has plank boards. Both rates are written into the contract before we start, and you only pay for wood we actually replace, after you've seen photos of it. A roof that needs four sheets adds $220; one that needs none adds nothing.
Decking is the one part of a roof replacement nobody can price exactly in advance, because nobody can see it. That includes us, every other roofer, and the satellite measurement behind our instant quote. This guide explains what decking is, why older Downriver homes are the ones that turn it up, and how to make sure it never becomes a surprise on the final bill.
What is roof decking?
Decking, or sheathing, is the layer of wood nailed across the rafters that everything else sits on: the underlayment, the ice-and-water barrier and the shingles. Newer homes use 4×8 sheets of plywood or OSB. Many homes built before the 1960s were decked with individual boards, called plank or board decking, laid side by side across the rafters.
Why you can't know until tear-off
From the ground and even from the roof, the shingles hide the deck. Soft spots sometimes show as a sag or a spongy feel underfoot, and an attic inspection can show water stains on the underside of the boards. But most rot starts at the top surface, under a leak, and only shows once the old shingles and felt are stripped. That's why any honest quote treats decking as a unit price, not a guess.
What decking costs with us
| What we find | How it's priced | Example |
|---|---|---|
| Rotted or delaminated sheet decking | $55 per 4×8 sheet of 7/16" OSB, installed | 4 sheets = $220 |
| Rotted plank boards | $5 per linear foot of board, installed | 40 ft of board = $200 |
| Sound decking | Nothing | $0 |
Those rates cover the material, cutting it in and nailing it off. The examples are arithmetic, not a forecast for your roof: many tear-offs need no new wood at all, and an older roof that has leaked for a while can need more. Either way, you see each soft area in photos before it's replaced, and the count is on your final invoice.
See Your Roof Price in 60 Seconds
Older Downriver homes and plank decking
Most Downriver housing went up between the 1940s and 1960s, and a lot of those bungalows and ranches still have their original plank decking under one or two layers of shingles. Plank decking isn't automatically a problem; old-growth boards are often in better shape than you'd expect. What we look for is rot at the eaves and around chimneys and vents, boards that have split or cupped, and gaps wide enough that new shingles won't lie flat. Where individual boards are bad we replace those boards. If the whole deck is too gapped or uneven to hold a new roof properly, we'll show you and price re-sheeting over it with OSB at the same per-sheet rate before any work goes ahead.
A second layer of shingles makes it worse
A layover, a new roof nailed over the old one, is how a lot of Downriver roofs got their second layer. It saved money once, but it hides the deck for another twenty years and traps moisture against it. Tearing off two layers instead of one adds about $1,000 to $1,200 on a typical 1,600 sq ft roof, and two-layer roofs are where rotted decking most often hides. Michigan code allows at most two layers, so a third isn't an option anyway. We tear off to bare wood on every replacement.
How to protect yourself on any roofing quote
- Ask for the per-sheet and per-foot decking price in writing, on the contract, before you sign.
- Ask how you'll be told: you should see photos of every area before it's replaced, not a total at the end.
- Be wary of a quote that says "decking extra as needed" with no price, or one far below the others. That's often where the difference gets made up.
- Confirm it's a full tear-off, not a layover. Only a tear-off lets anyone see and fix the deck.
- No shingle manufacturer's warranty covers the deck itself, so the contract terms are what protect you here.
Frequently asked questions
Q: Is decking included in your instant quote?
No, and we say so on the quote. The online price covers a full tear-off, Owens Corning materials, installation, the permit and cleanup on a sound deck. Any wood we have to replace is billed at $55 a sheet or $5 a foot, only after you've seen it.
Q: Can I see the decking before you replace it?
Yes. We photograph every soft or rotted area once it's exposed and send the photos before we replace it. If you're home, we'll show you on the roof edge or in the attic.
Q: Does homeowners insurance pay for decking?
When a covered storm damages the roof, the decking under the damaged area is usually part of that claim. Rot from age or a long-term slow leak usually isn't covered. Our guide to whether insurance covers roof replacement in Michigan goes through how claims work.
For the full picture of a replacement budget, see our roof replacement cost guide. On a typical 1,600 sq ft roof with Owens Corning Duration shingles, the instant quote runs $10,100 to $12,300 before any decking. Guthix Roofing is a licensed and insured Michigan residential builder (License #262600716) based in Wyandotte, serving Downriver. Questions about your roof first? Call (734) 360-0805.
Want a roofer to look at yours?
See our roof replacement page, or how we work across Downriver from our shop in Wyandotte.
