Types of Roofs by Shape: Gable, Hip, Gambrel, Mansard, Shed, and Flat

Residential roofs come in six basic shapes: gable, hip, gambrel, mansard, shed and flat, and a single house can combine several. The shape tells you where to look for trouble: gable ends and roof edges in wind, low sections where water lingers, and every joint where two roof planes or a roof and a wall meet.

Use this page to name your roof and list its weak points; the map of roof decisions shows where each of the other decisions is covered.

How to Identify Your Roof Shape From the Street

Stand across the street and look at the ends of the house first, then the sides.

• Gable: two slopes meet at a ridge, and each end of the house shows a triangular wall, the gable, rising to the peak.
• Hip: slopes rise from all four sides to a ridge or a point. There is no triangular end wall; every lower edge is a level eave.
• Gambrel: two slopes on each side of the ridge, a steep lower one and a shallower upper one, with gable walls at the ends. It is the classic barn profile.
• Mansard: two slopes on all four sides, a very steep lower slope that reads almost like a wall and a much shallower upper section that can be nearly flat.
• Shed: a single plane sloping one way. When it leans against a taller wall, its high edge meets that wall.
• Flat: a roof that looks level from the street. In practice it has a slight slope toward drains, gutters or scuppers, and it is covered with a membrane rather than shingles.

Additions, porches, garages and dormers can carry their own shape, so describe each section. The table compares the six shapes on geometry alone.

Material choice comes after shape and slope; it is covered in roofing materials compared.

Gable vs. Hip: Wind Exposure and Attic Space

The difference is at the ends. A gable roof leaves two tall triangular walls facing whatever direction the wind blows from, and its sloped rake edges are long, exposed roof edges. A hip roof has no gable walls; it turns those ends into sloped roof planes, so every lower edge is a level eave and the ends are covered by hips instead of rakes.

Whether either shape keeps its roof on in a storm depends on how it is built, not on the shape alone. FEMA’s Wind Retrofit Guide for Residential Buildings (P-804, second edition, April 2023) covers improving the wind resistance of existing one- and two-family homes and states that a continuous load path is an important part of a building’s ability to resist wind loads. The same guide reports that in Hurricane Ida, light-framed wood trusses were lifted off exterior walls, a connection failure that can happen under any roof shape. The construction details are covered in hurricane-resistant roofing.

Gable ends carry one more exposure in wildfire country. Gable end vents appear on the list of ember and flame entry points in a Firewise fact sheet on roofing materials prepared with the Insurance Institute for Business and Home Safety.

Attic space follows the geometry. Under a gable roof, the full ridge height runs the length of the house, so the attic keeps its height out to both end walls. Under a hip roof, the slopes rise from all four sides, so headroom shrinks toward the ends as well as the sides. The hip framing also has more angled cuts where hip rafters meet the ridge, which means more pieces to frame and more cap shingles to install.

Gambrel and Mansard: Two Slopes on Each Side

Both shapes break the roof into a steep lower section and a shallow upper section. That break is the first weak point: the line where the slope changes is a joint, and the layers above it must lap over the layers below so water running off the upper section lands on top of the steep lower one, not behind it.

The upper section is the second weak point. If it is shallow, it can fall into the band where shingles need extra underlayment, or below the point where shingles are allowed at all. Between 2 in 12 and 4 in 12, federal Building America guidance on asphalt shingle roofs calls for two layers of underlayment, and the code text summarized in the next section does not permit shingles below 2:12. Measure the upper section separately using the methods in measuring roof pitch, and check that the quote treats it under the rules for its actual slope.

Where a mansard has dormers set into its steep lower slope, each dormer brings its own sidewalls, valleys and flashing, covered under complex roofs below.

Shed and Flat Roofs: Where Drainage Is the Main Risk

A shed roof sheds all its water off one edge, so its weak points are at the extremes: the high side, where the roof meets a wall and needs flashing, and the slope itself if it is shallow.

Minimum slopes decide which covering a shed or flat roof can take. They come from the International Residential Code (IRC) in whatever edition, and with whatever amendments, your building department enforces; the 2021 Seattle Residential Code, Chapter 9, one city’s adoption of that text, allows asphalt shingles only at 2:12 or steeper and standing-seam metal down to 1/4:12. A shed roof below 2:12 needs a metal panel system within its own minimum or a membrane.

Flat roofs are not truly flat; they are low-slope roofs that depend on drains, scuppers and gutters to move water. When water stays after rain, it adds weight and sits on every seam it covers. How long water may sit and what to do about it are covered in ponding water on flat roofs.

Why Complex Roofs Have More Leak Points

Every place a roof changes direction or meets a wall is a joint that has to be lapped and flashed by hand. A plain gable has four rake edges, two eaves and a ridge. Add an L-shaped wing and you add a valley. Add a gable dormer and you add two sidewalls, a front wall and two more valleys. Add a second-story wall above a porch roof and you add a roof-wall intersection.

Hypothetical count: a house starts as a plain gable, then gains an L-shaped wing, one gable dormer and a porch roof against a second-story wall. Using the counts above, the wing adds 1 valley, the dormer adds 2 valleys plus 2 sidewalls and a front wall, and the porch adds 1 roof-wall intersection. That is 3 valleys and 4 wall joints, 7 hand-flashed junctions that the plain gable did not have, each one a place to look on every inspection and a line to price on every re-roof quote.

These are the places inspectors look: HUD’s Residential Rehabilitation Inspection Guide has them check the flashing for deterioration or looseness. Where a roof edge dies into a wall, a federal guide to step and kick-out flashing calls for a kickout at the bottom of the intersection, so the runoff ends up in the gutter instead of against the wall; see kickout flashing.

Valleys deserve special attention on a cut-up roof, because they collect water from two planes and debris from both. The valley methods are compared in roof valleys.

What Your Roof Shape Means for Your Next Inspection

The sections above reduce to one comparison. It lists where each shape is exposed, not which shape performs best, because construction details decide that.

Name each section of your roof by shape, then write down the weak points that come with it:

1. Gable sections: rake edges, gable end walls and gable vents.
2. Hip sections: hip and ridge caps and the joints where hips meet the ridge.
3. Gambrel or mansard sections: the slope break and the measured pitch of the upper section.
4. Shed or flat sections: the high-side wall flashing, the slope against the covering’s minimum, and any standing water.
5. Every junction: each valley, each dormer wall and each roof-wall intersection, including a kickout at the bottom of each.

Give the list to the inspector or roofer before the visit and ask for a written finding on each item, with a photo. A report that addresses your shape’s weak points one by one is worth more than a general “roof in fair condition.”

This guide is general information for U.S. homeowners, not legal, insurance, tax, or engineering advice. Codes, laws, and policy terms vary by location and change over time; confirm details with your local building department, your insurer, or a licensed professional.

Sources

• FEMA P-804 Wind Retrofit Guide for Residential Buildings, Second Edition, Federal Emergency Management Agency
• Reduce Your Roof’s Vulnerability to Wildfire, Insurance Institute for Business & Home Safety with USDA Forest Service and partners, hosted by Texas A&M Forest Service
• Asphalt Shingle Roofs, U.S. Department of Energy Building America Solution Center
• 2021 Seattle Residential Code, Chapter 9: Roof Assemblies, City of Seattle Department of Construction and Inspections
• Residential Rehabilitation Inspection Guide, U.S. Department of Housing and Urban Development
• Step and Kick-Out Flashing at Roof-Wall Intersections, U.S. Department of Energy Building America Solution Center