6.2 Valleys, Hips, Ridges & Starter Courses

6.2 Valleys, Hips, Ridges & Starter Courses

Quick Answer: Water and wind enter asphalt roofs first at edges and transitions—starter courses, drip edge, valleys, hips, and ridges. Get those details right and the field shingles can do their job through Illinois winters.

Field courses alone do not make a steep-slope roof. Domain 3 questions frequently isolate the eave start, valley type, and hip/ridge cap fastening because those details decide whether meltwater and wind-driven rain stay outside the deck.

Starter Courses

The starter course is the first asphalt strip at the eave (and often at rakes). Its jobs are to:

• Provide a sealed adhesive band under the butts of the first full course
• Cover the joints in the first course so water cannot reach the underlayment at cutouts
• Establish straight alignment for subsequent courses

Common Illinois practices:

Overhang the eave enough to drip into the gutter, not behind it. Too little overhang lets water run behind fascia; too much can cause wind lift. Fasten starters with nails in the specified locations—never rely on adhesive alone for structural hold-down.

Drip Edge

Drip edge is corrosion-resistant metal that protects the deck edge and directs water off the roof.

Typical asphalt sequence taught for CTS / IRC-style practice:

1. Eaves: Install drip edge under the underlayment (and under the ice barrier where used) so water on the membrane drains onto the metal and into the gutter.
2. Rakes: Install drip edge over the underlayment so wind-driven rain at gables cannot get under the edge of the felt or synthetic.

Illinois freeze-thaw adds a practical note: ice dams push water upslope. Ice-and-water membrane should lap onto or integrate with the eave drip edge per manufacturer so water cannot sneak behind the metal. Replace dented or rusted drip edge on reroofs—reusing failed edge metal is a common leak source at fascias.

Valley Methods

Valleys concentrate runoff from two roof planes. Three asphalt methods appear on exams:

Closed-Cut (Closed) Valley

1. Run shingles from one plane through the valley onto the adjacent plane.
2. Snap a line 2 inches from the centerline on the side being cut.
3. Cut the overlying shingles to that line; do not cut the underlying valley shingles.
4. Embed cut edges in cement where required; never nail within the valley center channel.

Closed-cut valleys look clean and shed well when the underlayment or ice membrane in the valley is continuous and reverse laps are avoided.

Open (Metal) Valley

1. Line the valley with ice-and-water membrane.
2. Install a preformed metal valley flashing (W-valley or similar) centered in the valley.
3. Shingle up to chalk lines set back from the metal center, leaving the metal exposed.
4. Fasten shingles outside the metal; clip or cement edges as specified—do not nail through the open metal pan.

Open valleys handle heavy Illinois debris and ice movement well because the metal channel stays clear. Minimum metal width and gauge follow manufacturer and code; overlaps in the metal must shed water downslope.

Woven Valley

Alternate shingles from each plane weave across the valley center so each course crosses to the other side. Woven valleys require flexible shingles and careful nailing away from the center. They are less common on thick laminated products and can be harder to waterproof if weave is uneven—know them for the exam even if your crew prefers closed-cut or open metal.

Regardless of type, valley underlayment in Illinois should be self-adhered ice-and-water membrane for the full valley length whenever possible—valleys are ice-dam and debris collection zones.

Hips and Ridges

Ridge is the horizontal peak; hips are sloping external intersections. Both need cap shingles that shed water onto the field courses below.

Installation essentials:

• Install field shingles up to the hip/ridge so caps cover the tops of both planes
• Use hip-and-ridge cap products or properly cut three-tab caps sized to the exposure
• Fasten each cap with two nails, one on each side, within the covered area of the next cap
• Maintain the manufacturer’s exposure (often about 5–5⅝ inches for cut three-tabs; follow laminate ridge product marks)
• On high-wind Illinois sites, use manufacturer high-wind ridge fasteners or sealant as specified; some laminated ridge caps require six nails or special plates

Start hip caps at the eave and work toward the ridge so laps shed downslope. At the ridge, finish with a final cap that covers the last hip/ridge joint—often cemented and face-nailed then sealed, or finished with a preformed end cap.

Preformed ridge vents, if used, change the ridge detail: shingles stop short of the cut slot, the vent is centered, and ridge caps install over the vent flanges with nails long enough to penetrate the deck. Never block attic ventilation while “sealing” a ridge for weather—Illinois moisture control depends on balanced intake and exhaust.

Putting Edges Together

A weather-tight asphalt perimeter in Illinois looks like this:

1. Eave drip edge → ice barrier → underlayment upslope
2. Starter with adhesive at the eave overhang
3. First course aligned; subsequent courses offset
4. Valleys detailed before or as field courses arrive at the valley
5. Rake drip edge over underlayment; shingles trimmed with slight overhang
6. Hips and ridges capped after both adjoining planes are complete

Exam questions may show a detail drawn wrong (drip edge over underlayment at the eave, nails in the open valley pan, ridge caps started at the peak and lapped uphill). Spot the reverse lap or missing starter seal strip—those are classic Domain 3 distractors.

Illinois Climate Notes for Transitions

Freeze-thaw cycles pry at valley metals and ridge caps. Use compatible metals (avoid corrosive galvanic pairs with fasteners), keep fastener counts honest, and hand-seal where winter temperatures prevent factory seal strips from bonding quickly. After major wind events, inspect ridge caps first—they are often the first asphalt components to lift when nailing was short or exposure was excessive.