What are the layers of a roof?
From the wood up, an asphalt shingle roof is decking, ice and water shield, underlayment, edge metal, flashing, starter strip, shingles, and hip and ridge caps. Most of them are covered for good the day the roof goes on.
Roof decking
The deck is the wood the roof is fastened to. On newer homes it is plywood or OSB in sheets. Many older homes here, including a lot of Miamisburg and Kettering houses built in the fifties and sixties, have plank decking.
After tear-off we walk the bare deck, photograph it, and replace soft or delaminated decking with 7/16 inch OSB. New shingles cannot fix a deck that will not hold a nail.
Ice and water shield
Ice and water shield is a membrane that sticks directly to the deck. It goes where water is most likely to get under the shingles: the eaves, the valleys, and around anything that comes through the roof.
Ohio requires an ice barrier from the lowest edge of the roof to at least 24 inches inside the exterior wall line.
We install two rows at the eaves, one row in every valley, along every roof-to-wall transition and around everything that comes through the roof.
Roof underlayment
Underlayment covers the rest of the deck, under the shingles. On a normal slope, Ohio's minimum is one layer, lapped 2 inches.
We put down two layers of synthetic underlayment and overlap them 24 inches, so every square foot of the deck has two layers over it.
Gutter apron and drip edge
Metal covers the edges of the deck. We use gutter apron at the eaves, where the gutters hang, and drip edge at the rakes, the sloped edges at the gable ends. Gutter apron vs drip edge explains the difference.
Roof flashing
Flashing is the metal that seals the places where the roof meets something else: a wall, a chimney, a skylight, a pipe. In the leaks we investigate, the cause is usually one of these details, not the shingles. Why roofs leak goes through them.
Starter strip, shingles, and hip and ridge caps
Starter strip runs along the edges and gives the first row of shingles something to seal to. Shingles cover the field. Hip and ridge caps cover the peaks, where two slopes meet.
We install these three as one Owens Corning Duration system: Owens Corning starter strip, Duration shingles, and Owens Corning hip and ridge caps, installed to the manufacturer's specifications. We do not mix in parts from other brands.
Roof ventilation
Ventilation is not a layer, but the layers above depend on it. Air comes in at the soffit and leaves at the ridge. Before we install a ridge vent we confirm there is enough intake at the soffit to feed it. How attic ventilation works covers what Ohio requires.
Every one of these is part of a roof replacement from us, and each step is photographed before it is covered.