A shingle roof is built in layers: the wood deck, drip edge at the edges, ice and water shield at the eaves and valleys, underlayment over the rest, then the shingles, with flashing wherever the roof meets a wall, chimney or pipe, and vents to let the attic breathe. The shingles are the part you see. Most leaks start at the parts you don't.
The layers, in the order they go on.
Decking
The wood the roof is built on, also called sheathing: plywood or OSB on most houses, boards on many older ones. Everything else is nailed to it. Soft spots get replaced at tear-off; ours are priced per sheet before we start.
Drip edge
Metal trim along the eaves and rakes that kicks water off the edge, into the gutter and away from the fascia. Code requires it on shingle roofs.
Ice and water shield
Self-sealing membrane at the eaves, the valleys and around chimneys, skylights and pipes, where water is most likely to back up. Required at the eaves in Connecticut. More in our ice and water shield guide.
Underlayment
A water-resistant layer over the rest of the deck, synthetic on our roofs. It's the backup under the shingles, and it keeps the house dry between tear-off and shingles.
Starter strip
A row of starter shingles along the eaves and rakes. Its seal strip locks down the edge of the first course against wind.
Shingles
The field of the roof, laid from the eave up, each course nailed to the maker's pattern. See types of roof shingles.
Flashing
Metal that turns water wherever the roof meets something else: step flashing along walls and chimney sides, counter flashing over it, valley flashing, and pipe boots around plumbing vents.
Ridge vent and caps
The exhaust vent along the peak, covered by the cap shingles that finish every hip and ridge.
Edges and airflow.
Soffit vents and the ridge vent work as a pair: cool air in low, warm, damp air out high. One without the other doesn't work. We check both on every roof we replace and fix what's wrong as part of the quote.
Around the chimney.
A chimney is one of the most common places for a roof to leak, because it's a hole through the roof that moves separately from it. Step flashing runs up the sides, one piece per shingle course. Counter flashing is set into the mortar joints and laps over it, so the roof and the chimney can move without opening a gap.
Behind any chimney wider than 30 inches across the slope, code calls for a cricket: a small peaked roof that splits the water around the chimney instead of letting it pool. Chimney repairs and rebuilds.
See it built.
Our roofing page takes a roof apart layer by layer as you scroll. And every job on our work shows the deck, membrane, flashing and finished roof on a real Connecticut house.
Code references are general information, checked November 2, 2026. Your town's building department has the final word on your house.
LET’S CLEAR A FEW THINGS UP.
What is roof decking?
The wood layer the roof is built on, usually plywood or OSB, or boards on older houses. The underlayment and shingles are nailed into it, and rotten decking has to be replaced before a new roof goes on.
What is drip edge, and is it required?
Metal trim along the roof edges that directs water off the roof and into the gutter. Code requires it at the eaves and rakes of shingle roofs.
What is a chimney cricket?
A small peaked section of roof built behind a chimney to split the water around it. Code requires one when the chimney is wider than 30 inches across the slope and doesn't sit on the ridge.
What's the difference between step flashing and counter flashing?
Step flashing is woven in with each course of shingles where the roof meets a wall or chimney. Counter flashing is set into the chimney or wall and laps over the step flashing, so water can't get behind it.
What does a ridge vent do?
It lets warm, damp air out of the attic at the peak, while soffit vents let cool air in at the eaves. Together they keep the attic dry and help prevent ice dams.
