Roof Water Protection: Eaves, Valleys, Drip Edge, Starter

An asphalt-shingle proposal describes more than the visible field shingles. Underlayment, leak-barrier membrane, edge metal, starter, valleys, and penetration details work together to manage water. If those components are not stated, two bids with similar shingles and totals may still describe different roof systems.

This guide helps organize proposal language. It does not decide which assembly is required for a specific house. Local adopted code, climate designation, roof slope, existing construction, and the selected manufacturer’s instructions control.

Separate the components

Create individual comparison rows for:

• General underlayment
• Ice-barrier or self-adhering membrane at eaves
• Membrane at valleys and penetrations
• Drip edge at eaves and rakes
• Starter course
• Valley method
• Hip and ridge caps
• Low-slope roof sections
• Plumbing, skylight, chimney, and wall intersections

Avoid one row called “waterproofing.” No steep-slope roof proposal should promise that the entire assembly is literally waterproof, and a single label hides the locations that matter.

Underlayment

Look for the product or material type, installation area, and treatment at laps and penetrations. If synthetic underlayment is proposed, the product name makes the comparison more reliable than the word “synthetic.”

Ask whether the underlayment covers the full shingle roof deck and how it interfaces with eave protection, valleys, walls, and penetrations. Installation details belong to the selected product instructions rather than a generic checklist.

Ice barrier at the eaves

The model International Residential Code contains an ice-barrier provision for designated areas prone to ice formation. The local jurisdiction determines whether and how that provision has been adopted. The model language describes a barrier extending from the lowest roof edge to a point inside the exterior wall line, so a proposal should use a meaningful location or coverage description instead of “code minimum.”

Ask:

• Which eaves receive membrane?
• How is the coverage distance determined for this wall and roof geometry?
• Are valleys, penetrations, or other locations included separately?
• What product is proposed?

Do not turn a model-code dimension into a universal requirement. Verify the adopted code and manufacturer instructions for the project address.

Drip edge and starter are different scope rows

Drip edge is edge metal. Starter is the first shingle-system course that helps establish the eave or rake edge and the seal pattern. A proposal should identify both rather than treating one as proof of the other.

For drip edge, ask which edges are included, whether existing edge metal is removed, the material or finish, and how gutters affect the work. For starter, ask whether a manufacturer-designated starter product or another allowed method is included and where it will be installed.

Valley language

“Valleys included” does not identify the assembly. Ask whether the proposal uses an open or closed valley method, what lining or membrane is included, and how the method follows the selected shingle instructions. Existing woven, metal-lined, or other valley conditions may affect tear-off and replacement scope.

If a valley meets a wall, chimney, or low-slope section, keep that transition as a separate comparison row.

Low-slope sections can change the system

Porches, additions, and transitions may have a lower slope than the main roof. The proposal should identify those areas and the roof-covering method. Do not assume the same shingle installation applies everywhere merely because the sections connect.

Ask the contractor to name the product and installation basis for each low-slope area, and to identify any excluded structural or drainage work.

A clean proposal matrix

For every component, record:

1. Product or material
2. Exact roof locations
3. New, reused, separately priced, allowance, or excluded
4. Related removal and disposal
5. Manufacturer-instruction reference where useful
6. Exact proposal page and wording

This method surfaces real differences without declaring one contractor or system correct from the proposal alone.

Pair this guide with the flashing guide and proposal checklist. View the synthetic sample record or start a private comparison.

Sources

• International Code Council: 2024 IRC Section R905.1.2, Ice Barriers
• International Code Council: 2024 IRC, Chapter 9 Roof Assemblies
• GAF: Timberline LayerLock installation instructions

Local adopted code, permit requirements, product instructions, and the signed contract control the actual project.