Do I Need New Roof Decking When I Replace My Roof in Boise?
Sometimes, yes. Roof decking is the wood layer under your shingles, and when it is soft, rotted, or too thin to hold nails, a roof replacement is not finished until that wood is fixed. At Dodd Roofing and Exteriors, we cannot see the decking until the old shingles come off, so we write a clear per-sheet rule into the contract for any boards that need replacing, and we show you photos of every problem we find.
What is roof decking and why does it matter?
Decking, also called sheathing, is the plywood or oriented strand board that sits on top of your rafters. Your underlayment, flashing, and shingles all attach to it. If the deck is weak, nails do not hold, shingles lift in the first big windstorm, and the new roof will not last as long as it should. Newer homes in Meridian, Star, and Eagle usually have sheet decking. Many older homes in the Boise North End and Bench have 1x6 or 1x8 plank boards instead, sometimes with gaps between them, and those often need a layer of plywood or OSB before new shingles go on.
How can you tell if decking is damaged before the tear off?
You can spot some warning signs without a ladder. From the yard, look for a roof surface that dips or looks wavy between rafters, or a spot that feels spongy when a roofer walks it. In the attic, shine a flashlight on the underside of the deck. Dark stains, flaking or layered plywood, mold, rusty nail tips, or daylight coming through are all reasons to ask for a closer look. Decking damage hides well, so an attic check tells you where to look, but it cannot promise what the tear off will show.
What damages roof decking in the Treasure Valley?
Moisture is almost always the cause. A slow leak at a chimney, vent pipe, or valley soaks the wood a little at a time. Bathroom and kitchen fans that vent into the attic instead of outside add humidity. During winter inversions, warm indoor air can condense on the cold underside of the deck, which we explain in our post on attic moisture and frost in winter. Hot summer attics bake poorly ventilated roofs and leave the wood dry and brittle. Older ranch homes around Nampa and Caldwell with limited ventilation are the likeliest to show damage along the ridge and eaves.
What does building code say about decking?
Idaho residential code is based on the International Residential Code, and it calls for asphalt shingles to be installed over solid, sound sheathing. Shingle manufacturers say the same in their installation instructions, because a deck that will not hold a nail cannot support a warranty. That is why we replace damaged sections instead of roofing over them. Boise, Meridian, and Nampa each handle their own permits, so your installer should confirm local requirements before work starts.
How is decking replacement priced?
Nobody knows the true condition until the old roof is off, so honest contractors price decking as an add-on per sheet, with the rate written into your contract before work begins. The total depends on how many sheets are bad, which depends on roof age, leak history, and attic ventilation. Ask how many sheets are included in the base price and what happens past that number. Our guide on what to expect during a roof replacement walks through the full tear off day by day.
What should you do next?
Book a free inspection and ask for an attic check, not only a roof walk. If you plan to replace this fall, look at financing options ahead of time so a decking surprise does not stall the job. You can find more answers in our homeowner guide library, and details on our roofing services. Call Dodd Roofing and Exteriors at (208) 295-9421 and we will tell you plainly what your roof needs.
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