The 8 Layers of a Roof, and the Ones Your Roofer Is Skipping

Every roof bid you get is going to look roughly the same on paper. Tear off the old one, put on a new one, here is the number. What that number does not tell you is which of the eight layers of an actual roof system the crew is planning to install, and which ones they are quietly leaving out.

Here is the thing that makes this so easy to get away with: seven of those eight layers end up buried under the shingles. Once the job is done, you cannot see any of it from the ground. Neither can the next guy who bids your roof in fifteen years, when it fails early and nobody can tell you why.

The system, in order

• 1. Decking. The plywood your whole roof sits on. Every sheet gets walked. Anything soft or rotted comes out before another layer goes down.
• 2. Drip edge at the eaves. Metal along the bottom edge, installed UNDER the underlayment, so water leaves the roof instead of wicking back into your fascia.
• 3. Ice and water shield. Self-sealing membrane at the eaves, valleys, and penetrations. Ohio code requires an ice barrier at the eaves. When an ice dam backs water up under your shingles, this is the only thing between that water and your ceiling.
• 4. Synthetic underlayment. The field barrier over the rest of the deck, lapped so water always runs over a seam, never into it.
• 5. Starter shingles. A purpose-made first course with the adhesive strip in the right place. Cutting up field shingles for this puts the glue in the wrong spot and hands the wind an edge to lift.
• 6. Flashing. Step, valley, pipe boots, chimney. Almost every leak is a flashing leak.
• 7. Shingles. The part you see. Nailed in the manufacturer's nail zone.
• 8. Hip and ridge cap. Purpose-made cap plus real ridge ventilation.

Where the corners get cut

Reused flashing is the big one. New flashing costs very little and takes time to do right, so a crew working on volume will set the old stuff back down and caulk it. Caulk is not flashing. Caulk is a three-year fix on a thirty-year roof.

Skipped starter course is next. Then ice and water shield only in the valleys and not at the eaves, which is the exact spot Ohio ice dams attack. Then high nails, which look fine and void your warranty.

What to actually ask

When you collect quotes, ask one question: what is going under the shingles? Ask them to walk you through it. The roofer who lights up and starts talking about drip edge and ice barrier is the one who does it. The roofer who says the shingles are what matter just told you everything.