Two Roof Quotes Can Hide Different Valley Systems

A roofing quote can say "replace valleys" without telling you what will actually carry water through them. One contractor may install an exposed metal channel. Another may run shingles across the valley and cut the top layer along the center. Those are different assemblies, with different materials, labor, appearance, and maintenance concerns. Before you compare the totals, find the valley method in each written scope.

A valley is the inside angle where two roof slopes meet. Water from both slopes is concentrated into that narrow path. On a complicated St. Louis roof, one valley may collect runoff from a large upper section before sending it toward a short gutter below. Leaves, oak catkins, maple seeds, granules, and winter ice can also collect there. That makes the valley more than a cosmetic detail.

Roofer comparison

The two common choices on an asphalt shingle roof are an open metal valley and a closed-cut valley. A woven valley is another method, but it is not suitable for every shingle type or roof layout. If a proposal simply says "valley treatment," ask the bidder to name the exact assembly.

Open metal valley

An open valley has visible metal running down the center. Shingles stop on both sides, leaving a clear metal channel for water. The metal should be identified in the quote, including its type, finish, width, and how it will be formed. "Metal valley" alone does not answer those questions.

The opening must be laid out consistently. The shingle cuts should be straight, and their upper corners should be trimmed so water does not catch and track sideways. Fasteners should stay out of the central water path. The underlayment beneath the metal also matters because the visible channel is only one part of the assembly.

An open valley gives water, granules, and small debris a defined route off the roof. It can also make later inspection easier because the primary drainage surface remains visible. The tradeoff is appearance. Some homeowners like the crisp metal line. Others do not want a contrasting strip visible from the street. Metal with a finish selected to work with the roof color can reduce that contrast, but the finish needs to be chosen before materials are ordered.

Closed-cut valley

In a closed-cut valley, shingles from one roof slope continue through the valley. Shingles from the adjoining slope overlap them and are cut along a line near the center. The result looks like a continuous shingle roof because no broad metal channel is exposed.

The direction of the cut matters. A contractor should consider which roof plane carries more water and how the slopes meet. The cut line should not be treated as an arbitrary choice made after both sides are installed. The upper corners of cut shingles need attention so they do not direct water under the overlapping course.

A closed-cut valley still needs a sound layer beneath it. The shingles are the visible drainage surface, not the entire water-control system. Ask what underlayment will run through the valley, how wide it will be, and how it will connect with the underlayment on both roof planes.

Closed-cut valleys avoid the exposed-metal look, but they place more shingle material in a part of the roof that already sees concentrated water. Heavy debris can sit against the cut line. Repeated freeze and thaw cycles can make a poorly laid valley show its weaknesses, especially where a shaded roof holds snow or ice longer than the sunny side.

Woven valley

A woven valley alternates shingle courses from the two slopes across the center. It can produce a continuous appearance, but it creates a thicker stack of material in the valley. That stack can become pronounced with heavier laminated shingles or where the two roof slopes meet at an awkward angle.

Do not accept a woven valley merely because it is described as traditional. The shingle instructions, roof geometry, and contractor's planned installation all have to agree. If one bid proposes weaving and another proposes a closed cut, ask each roofer why that method fits your particular shingles and valley angle.

Compare what is underneath

Two bids can name the same visible valley method and still describe different work. Put these items side by side:

• The valley method: open metal, closed cut, or woven.
• The underlayment used through the valley.
• The width and material of exposed metal, if applicable.
• Whether old valley metal will be removed.
• How damaged decking discovered in the valley will be priced.
• How the valley ends at the eave, gutter, wall, or lower roof.
• Whether nearby siding, chimney flashing, or skylight flashing must be disturbed.

The last several feet often reveal the real difference between proposals. A valley that ends cleanly into an open gutter is straightforward. A valley that empties beside a wall, over a lower roof, or behind a short gutter can require additional flashing and careful water direction. A satellite measurement may show the valley length, but it will not always show how that termination was built.

What it costs

An open metal valley often carries additional material and fabrication cost. The crew has to fit the metal, keep the channel straight, cut the shingles on both sides, and finish the lower end correctly. A painted or otherwise finished metal can cost more than a basic valley lining. Long valleys may require more than one piece, making the laps and fastening plan part of the work.

A closed-cut valley may use less visible metal, but that does not mean it should be priced as a shortcut. It still requires valley underlayment, careful course placement, straight cutting, and proper treatment at the top and bottom. A low number that omits the underlayment or leaves the existing valley assembly in place is not directly comparable with a full tear-off and rebuild.

Decking repairs are common enough around leaking valleys that the proposal should state a unit rate or another clear pricing method before work begins. Water can travel beneath an old valley and damage wood outside the stain visible in the attic. The crew may not know the full area until the shingles and old lining are removed.

Access changes the labor too. A short, walkable valley over a driveway is different from a steep valley above landscaping, a finished patio, or a lower roof. Multiple intersecting valleys create more cutting and more opportunities for one drainage path to affect another. Ask bidders to separate the valley upgrade or special fabrication from the base roof price. That lets you see whether the price difference comes from the valley system or from another part of the roof.

Repairing only a valley can make sense when the surrounding shingles remain flexible, compatible material is available, and the leak is confined to the valley assembly. It becomes harder to justify when removal will break brittle shingles on both sides. On a three-tab roof approaching roughly 15 to 20 years, repairability often matters more than the apparent size of the leak. Sun exposure, ventilation, prior repairs, and freeze-thaw wear can move that point earlier or later.

What to ask

Start with one direct question: "Which valley system is included in this price?" Then keep going until the answer is specific enough to place beside the other bids.

1. Will the old valley be removed? A full tear-off exposes the decking and the lower edges of nearby flashing. Covering an unknown assembly leaves conditions beneath it unseen.
2. What goes directly over the decking? Ask for the valley underlayment by product type and width, not just the word "membrane."
3. If the valley is open, what metal is included? The written answer should identify the material, finish, approximate width, and whether the metal will be formed for the valley.
4. If the valley is closed, which side runs through? The contractor should be able to explain the drainage choice using the size and pitch of the two roof planes.
5. Where will fasteners be placed? Nails should not be driven casually into the main water channel. The answer should reflect the selected system and its installation instructions.
6. How will the valley terminate? Ask where the water goes at the eave and whether it will enter the gutter without shooting past the end or running behind it.
7. What happens if the decking is soft? Get the pricing method and the approval process in writing before tear-off.
8. Will the valley appearance change? If exposed metal will be visible from the street, select its finish with the shingle color before the order is authorized.

Photos help settle this comparison. Ask each bidder for one wide photo showing the whole valley and close photos of its upper and lower terminations. If the roof has several valleys, label them on a simple sketch. "Front garage valley" is easier to verify later than a general note saying "repair valleys."

Also ask whether the selected Atlas or Malarkey shingle has installation instructions that affect the proposed method. The contractor should build the written scope around the actual product being installed, not a generic detail remembered from another shingle.

Permit requirements differ among the municipal permit desks across St. Louis County. A permit review may address the overall reroofing project, but it does not replace a precise agreement about valley material, layout, and termination. Those details belong in your proposal even if the permit form never asks for them.

If you want Keys Roofing to inspect the valleys and put the proposed assembly in writing, call (314) 220-2333. Have the other quotes nearby. The useful comparison is the method, what sits beneath it, and where the concentrated water goes when it reaches the bottom.