The parts of a roof system, what each one does, and what every RISE quote includes.
The shingles or metal you see from the street are only the top layer of a roof. Roof system components are all the parts under and around that layer, from the wood deck to the vent along the ridge. Each one has a job, either keeping water out or letting heat and moisture escape from the attic.
When one part fails, the rest of the roof can be in good shape and still leak. A cracked pipe boot or a loose strip of flashing lets water in just as easily as a missing shingle. That is why we look at the whole system when we inspect a roof, and why we replace the whole system when we re-roof one.
Below are the 9 parts homeowners ask us about most, in roughly the order they go on: decking, underlayment, drip edge, starter, the field material, hip and ridge caps, ventilation, flashing and pipe boots. After them come what every RISE quote includes, how Texas windstorm rules touch each part, and the questions worth asking any roofer.
The deck is the layer of wood fastened across the rafters or trusses. Owens Corning's anatomy of a roof calls it the structural base of the roof system. On most homes it is plywood or oriented strand board (OSB), and some older houses still have board decking. Every other layer is nailed into it, so it has to be solid.
Decking rots when water gets through for a long time or when a poorly vented attic keeps it damp. Soft spots underfoot, sagging between rafters and dark stains on the underside are the usual signs. The Texas Department of Insurance, in its guidance on repairing a roof after a storm, says to have the deck inspected and to replace any deteriorated or damaged decking before a new roof covering goes on.
We check the deck after tear-off and replace the bad sheets. Because nobody can see them until the old roof is off, rotten sheets are priced per sheet, outside the signed price.
Underlayment is the sheet that covers the deck under the roof covering. It is the backup layer: if wind drives rain under a shingle or a panel, the underlayment is what keeps it off the wood. TDI lists No. 15 or No. 30 felt, synthetic underlayment and self-adhered polymer-modified bitumen as the accepted types. Owens Corning notes that synthetic underlayment has become a popular choice over felt because it repels moisture and lasts.
Ice and water barrier is a self-adhering membrane that sticks to the deck and seals around the nails driven through it. Despite the name, on the Gulf Coast its real work is against wind-driven rain. Owens Corning places it along eaves, in valleys, along side walls and around chimneys and skylights, the places where water collects or runs hardest.
Every RISE quote includes new underlayment. Ask which product your quote names and where the self-adhered membrane goes. Our roofing underlayment guide has more detail on the types.
Drip edge is a strip of metal bent in an L and fastened along the eaves and the rakes. Owens Corning describes it as noncorrosive metal that helps water run off so it doesn't creep back onto the fascia and the wall below. It also covers the raw edge of the deck and gives the first course of roofing a straight line to follow. New drip edge is part of every RISE quote.
Starter is the first course along the edges. On a shingle roof it is a row of starter shingles with a factory sealant strip, laid at the eaves and up the rakes so the first full course has something to bond to. Owens Corning says starter shingles give a straight edge and an effective seal along the eave and rake, areas it calls vulnerable to high winds. On a standing seam roof, the panels hook onto a metal cleat or starter strip at the eave instead.
The field is the main roof covering. It takes the sun, rain and wind first, and it decides how long the roof lasts and how the house looks. These are the field materials we install:
TDI's storm-repair guidance adds a few rules for shingle roofs. Asphalt shingles can only go on slopes of 2:12 or steeper. TDI recommends shingles tested to ASTM D3161 Class F or ASTM D7158 Class H, which the maker states on the wrapper. Roofing nails must be galvanized or stainless steel, at least 12-gauge, with a 0.105-inch shank and a 3/8-inch head, and the code does not allow staples. Our asphalt shingle roofing page covers the shingle lines in more depth.
Hips are the sloped edges where two roof planes meet, and the ridge is the level peak along the top. Both get cap pieces. A shingle roof uses hip and ridge shingles made to match the field, and a metal roof uses a formed metal ridge cap. Owens Corning's Total Protection Roofing System pages point out that hips and ridges, like eaves and rakes, are areas vulnerable to high winds.
Ventilation works in pairs. Intake vents under the eaves, often called soffit vents, let outside air into the attic. Exhaust vents near the top, usually a ridge vent hidden under the caps, let hot, humid air out. Owens Corning describes the goal as a balanced flow in which warm, humid air is continually replaced by cooler, drier air. If the intake is blocked or missing, the exhaust has nothing to pull through.
Ridge ventilation is part of every RISE quote. On the inspection we look at the soffits and, when it is accessible, the attic, to see whether outside air can actually reach the ridge. Our guide to roof ventilation and ridge vents explains intake and exhaust in more depth.
Flashing is metal that seals the joints a roof covering can't seal on its own. Owens Corning lists joints, chimneys, dormers and skylights as the places it goes. The pieces you will hear about most:
Pipe boots are flashing for round pipes, such as plumbing vents. A boot has a flat base with a rubber collar that hugs the pipe. The base slides under the roofing above it and sits on top of the roofing below it, so water runs over it rather than under it. The rubber collar is the weak point. Years of hard sun dry it out until it cracks, and then rain runs down the outside of the pipe into the attic.
Every RISE quote includes new flashing. If a boot cracks on a roof that still has years left, replacing it is one of the small fixes a tune-up covers; see our roof maintenance plans.
The same roof system components show up on every roof type, with a few changes. A standing seam roof still sits on a solid deck with underlayment, but its edges get formed metal trim, the panels hook onto an eave cleat, and the ridge gets a metal cap. The flashing around pipes and along walls is formed to suit the panel.
Stone-coated steel from DECRA and Tilcor comes with matching hip, ridge and edge pieces made for each profile. We install it both ways, on battens or direct to the deck; most of our shake and shingle roofs go direct to deck. Tile adds a lot of weight, so the framing has to be up to it before anything else is decided.
These items are built into the price of every roof we quote:
We also pull the city permit and arrange the TDI windstorm inspections, and the installation carries our 10-year workmanship warranty. Rotten decking is the one exception to the signed price, for the reason above. The price locks when you sign, and proposals hold for about 15 days, so you have time to compare.
When you compare bids, line them up part by part. A lower number sometimes means reused flashing, no new drip edge or no ridge vent. Ask each roofer to put every one of these roof system components in writing.
Nueces County is one of 14 coastal counties in the catastrophe area designated by the Texas Department of Insurance. A roof replacement here is normally inspected while the work is under way, and TDI issues a WPI-8 certificate of compliance when it passes. Most homes need that certificate to buy a policy from the Texas Windstorm Insurance Association.
Several of the rules above come from TDI's windstorm guidance: the nail and underlayment requirements, the minimum slope for shingles, and the advice to replace damaged decking. TDI also notes that skylights, roof vents and turbines are vulnerable to high winds and hail, and it advises choosing products with a published wind resistance rating. Inside the catastrophe area we always tear off to the deck instead of covering an old roof, which is also what lets the decking be checked.
We schedule the inspections and handle the paperwork. Our Texas windstorm guide walks through the full process.
The parts of a roof age at different speeds. Rubber pipe boot collars and exposed sealant tend to go first because they sit in full sun. Flashing can work loose or rust at its fasteners. Shingles shed granules and lose their seal, and metal panels can show rust at scratches and cut edges. The deck lasts as long as it stays dry.
That is how a roof can leak at a pipe while the shingles still look fine, and why patching only the surface of a worn roof rarely holds for long. Our free roof inspection covers every component on this page and comes with photos, so you can see what we saw.
A good proposal answers each of these in writing. Our roof replacement page shows how all of these roof system components come together on a full re-roof.
Not on a RISE re-roof. Inside the TDI catastrophe area, which includes Nueces County, we tear off to the deck, and every quote includes new underlayment, drip edge, flashing and ridge ventilation.
It is priced per sheet, outside the signed price, because it can only be found once the old roof is off. Damaged sheets are replaced before the new roof goes on.
A pipe boot is the flashing around a plumbing vent pipe: a flat base with a rubber collar that hugs the pipe. Sun dries the rubber until it cracks, and rain then runs down the pipe into the attic.
Mostly. A metal roof still needs a solid deck, underlayment, edge metal, flashing, ventilation and ridge caps. The differences are the panels themselves, the eave cleat the panels hook onto, and formed metal trim at the edges and around penetrations.
Building code resources from the NRCA.
No waiting around for multiple contractors to come bid your roof. One quick call is all it takes.
Pick any slot that works for you — online and instant.
Free video or voice call. We answer your questions and gather what we need.
We email your price-locked quote — no pressure, no sales visit.
🔒 Free, no-obligation quote — Price-locked estimate in 24–48 hrs
Trace your roof on satellite imagery and get a real installed price in under 60 seconds.
Powered by satellite roof measurement technology. No obligation.
