How to Find Ridge, Eave, Valley and Hip on Technical Drawings

A roof design is a document that must be understandable to both the architect and the investor making cost decisions. You’re not looking for ridge lines, eaves, valleys, and hips on the drawings out of curiosity—you need to locate them to estimate the actual scope of work, understand water drainage patterns, and assess where the design requires custom solutions. Each of these elements has specific implications for budget, feasibility, and roof durability.

The ability to read these lines on plan and section views is a control tool. It allows you to verify whether the design is complete, whether the contractor has priced all details, and whether the roof layout actually matches what you saw in the visualization. This is the first step toward taking responsibility for decisions before they become irreversible.

Reading Framework: From Plan to Section

A roof design consists of several types of drawings that describe the same structure from different viewpoints. Your task is to overlay these perspectives and understand how lines on paper translate to actual edges that will be constructed on site.

Roof Plan — Top View

This is the simplest document to start your analysis. The plan shows the roof outline as seen from above. On this drawing:

• Ridge lines indicate lines running along the highest edges of roof planes—typically shown as a solid line marked with “K” or “ridge”
• Eaves are the outer edges of the roof where the covering ends and the gutter begins—usually a bold perimeter line
• Valleys are lines where two planes meet at a concave angle, forming a water channel—often marked with a dashed line or letter “E”
• Hips are convex edges where two planes meet forming a side ridge—solid line, often marked “N” or without additional description

However, the plan doesn’t show heights or pitch angles. Therefore, you must always cross-reference it with sections.

Cross-Sections and Longitudinal Sections

A section is a side view, as if the building were cut by a vertical plane. Here you can see:

• The ridge height above ground level or floor level
• The roof pitch angle
• How the ridge, valleys, and hips connect to the load-bearing structure
• The relationship between the eaves and the wall — whether the eaves project significantly or end just at the wall edge

If you see a valley line on the plan but the section lacks information about its depth or water drainage method — that’s a signal the design needs clarification before pricing.

Elevations

Views from each side of the building show how the roof looks from the front, back, and sides. Here you check:

• Whether the eaves line is level or has breaks
• How the hips appear in context of the overall form
• Where roof windows, chimneys, and vents are located — elements that interrupt the roofing continuity

Elevations help verify whether the line arrangement on the plan matches the actual building form. This is especially important in multi-pitch roofs, where interpretation errors are common.

The Consequence Tree: What Each Element Means in Practice

Every line on the design isn’t just geometry — it’s a decision about technology, cost, and risk. Below I describe what happens when a given line appears on your project.

Ridge

The ridge is the roof’s highest point, where two slopes meet. In practice, this means:

• The need for special finishing elements (e.g., ceramic ridge tiles, ridge flashing)
• An area particularly exposed to wind and rain — requires watertight installation with attic ventilation
• A reference point for the entire structure — an error in ridge height means trouble for the whole roof

If the design includes multiple ridges at different heights, you must ensure the contractor has priced all transitions and connections between them.

Eaves

The eaves are the edge that determines how water flows off the roof and how far from the wall it’s discharged. Consequences:

• Too short an overhang means water flows close to the foundation — risk of dampness
• Too long an overhang requires structural reinforcement and may conflict with windows or terraces
• The eaves are where gutters mount — their geometry affects the drainage system layout

On the drawing, check whether the eaves overhang length is specified in centimeters and is consistent across all elevations.

Valley (Endowa)

A valley is where water from two roof slopes converges into a single drainage line. It’s the most critical point of the roof:

• Requires special flashing work, often welded
• Collects leaves, snow, and ice — must be cleaned regularly
• A poorly executed valley is the most common cause of leaks

In the plans, check whether the valley has a marked water drainage direction and is connected to the gutter system. If there’s no technical detail for the valley in the documentation — that’s a red flag.

Hip

A hip is a convex edge, less problematic than a valley, but requiring precision:

• Needs special hip trim or proper tile cutting
• Is visually exposed — execution errors are visible from afar
• On roofs with ceramic or concrete tiles, requires additional shaped elements

On the roof plan, a hip is a line running from the eaves toward the ridge. If you have multiple hips — count them and ensure they’re included in the estimate.

Control Tool: Project Checklist Questions

Before handing the project to a contractor, go through the following checklist. This tool helps detect gaps in documentation that will later become sources of disputes or additional costs.

Questions Regarding Roof Plan

• Are all ridges marked and dimensioned?
• Do valleys have marked water drainage direction?
• Are hips counted and described?
• Does the eave have specified overhang length on each elevation?
• Are all roof covering interruptions marked on the plan: chimneys, skylights, vents?

Questions Regarding Cross-Sections

• Is the ridge height consistent with the plan?
• Is the slope angle given in degrees or percentages?
• Is the method of eave attachment to the structure visible?
• Is the drainage gutter depth shown at the valley location?

Questions Regarding Details

• Does the project include a technical detail of the valley?
• Is there a specification of materials for metal flashings?
• Do hips have a described finishing method?
• Is the gutter installation method marked at the eave?

If the answer to any question is “no” — return to the designer with a request for completion. Lack of this information means the contractor will improvise on-site, and you’ll lose control over quality and cost.

How to Use This Information When Talking to a Contractor

Once you can locate all the key elements on the design, you can have a substantive conversation with your contractor. It’s not about pretending to be an expert—it’s about asking questions that reveal whether the contractor has actually analyzed the documentation.

Ask:

• “How many linear meters of ridge, valley, and hip did you calculate in the quote?”
• “What material will you use for valley flashing and how will it be fastened?”
• “Does the eave length require additional support brackets?”
• “Do you plan to use special shaped elements at the hips, or will you cut standard tiles?”

If the contractor answers vaguely or says “it depends, we’ll see on site”—that’s a signal the quote may be incomplete. A professional roofer can answer these questions based on the design, without ever stepping on the roof.

The Irreversibility Rule

The layout of ridges, valleys, hips, and eaves is determined at the design stage and cannot be changed without rebuilding the structure. That’s why any doubts about roof geometry must be clarified before work begins. Changing roof pitch, relocating a valley, or extending an eave isn’t cosmetic—it’s intervention into the roof’s structural integrity and water management.

Investor’s Summary

The ability to read ridges, eaves, valleys, and hips on technical drawings isn’t about construction knowledge—it’s a tool for controlling your project and quote. Each of these lines represents specific work, materials, and risk. If you can locate them, count them, and understand their implications, you gain confidence that you’re paying for what will actually be delivered.

Rooffers’ philosophy is based on the principle that an investor doesn’t need to be an expert—but must know what questions to ask and when to demand clarification. A roof design isn’t a formality. It’s a document that defines the durability, watertightness, and maintenance costs of your home for decades to come. That’s why it’s worth spending an hour understanding it before signing a contractor agreement.