9 roof types on American houses and how each is framed

The shape of a house dictates how it sheds water and stands up to wind. Builders frame nine common roof types on American houses using wooden rafters or factory trusses. Knowing what sits under the shingles helps you plan structural modifications and seasonal maintenance safely.

1. Gable and cross gable roofs

A gable roof has two sloping sides that meet at a top ridge, creating triangle walls at the ends. Builders frame them by securing matched pairs of common rafters to a central ridge board. The ridge board is often one size wider than the rafters, so 2x8 rafters often pair with a 2x10 ridge board.

Many modern homes use factory trusses instead of hand cut rafters. The sloped sides shed rain and snow. High winds can be a weak point for this shape. The Federal Alliance for Safe Homes says a hip roof withstands high winds better than a gable roof because the gable can act like a sail.

A cross gable joins two gable roofs at a right angle. This requires heavy valley rafters where the two roof planes meet. Gable and cross gable roofs are common across the United States.

2. Hip roofs

A hip roof slopes down to the walls on all four sides without flat vertical ends. The framing starts with a ridge board and four long hip rafters running to the outside corners. Builders then fill the open spaces with shorter jack rafters. These short boards require complex angled cuts to fit snug against the hip rafter.

This shape tends to resist high wind better than a gable. After Hurricane Michael in 2018, an IBHS team found hip roofs performed better than gable or combination gable and hip roofs. Water runs off every side.

The trade-off is inside space. The four sloping ceilings reduce the volume of the attic. There is less room for ductwork or tall storage. Understanding the difference between a hip vs gable roof helps when buying property in a storm zone.

3. Dutch gable roofs

A Dutch gable combines the benefits of a hip and a gable. The base is framed like a normal hip roof with slopes on all four sides. Near the top, builders frame a small gable. This acts as a vertical wall for an attic window or a louvered vent.

The lower hip section can help with wind resistance. The upper gable adds attic space and natural light. Framing this type is labor intensive. Carpenters must build the lower hip structure, install roof decking, and then set a gable roof on top of it.

A builder or engineer has to design the support for the upper gable, and the cuts must be precise. Water sheds easily down the primary slopes, but the junction between the upper gable and lower roof needs careful flashing to stop water leaks.

4. Gambrel roofs

A gambrel is a symmetrical two-sided roof with a shallow upper slope and a steep lower slope. This classic barn shape is framed using specialized trusses or by joining two sets of rafters. A horizontal board called a purlin supports the joint between the upper and lower rafters. The steep lower side sheds water fast, while the shallow top sheds snow more slowly.

The tall shape can provide a full extra story of living space under the roof without building full height masonry walls. The broad flat sides catch the wind. They appear on colonial style houses and barn style homes. You will need a licensed pro to design the bracing if you build one in a high wind zone.

5. Mansard roofs

A mansard roof has four sides, and each side has two distinct slopes. The lower slope is very steep, while the upper slope is shallow. Builders frame the steep lower section like an exterior wall and often set dormer windows into it. The top section is framed like a standard low slope roof.

This shape gives you a full living space on the top floor. Mansard roofs require complex framing and extensive weatherproofing. The steep sides shed water fast, but the shallow top drains more slowly and can hold snow.

You see them on historic French style homes and urban row houses. They can add interior space, though how a building department counts stories varies. The upper section needs a roof covering rated for its slope, and a licensed roofer picks the product for each section.

6. Shed roofs

A shed roof is a single flat plane set on a slope. Builders frame it with straight rafters spanning from one high wall to a parallel lower wall. There is no ridge board. The rafters must be thick enough to cross the span without sagging.

You see shed roofs on modern minimalist homes, porches and simple additions. They shed water strictly in one direction. A steep shed roof moves snow fast, but a shallow one can hold snow weight. Wind pushes against the tall wall, so an engineer or designer checks the bracing.

It is a simple roof to build. You can tie one into an existing structure without building a complex ridge. Knowing how an addition roof joins the main house helps you plan the drainage slope.

7. Saltbox roofs

A saltbox roof is an asymmetrical gable. One side has a short slope. The other side has a long slope that sweeps down to a single story height. Builders frame it using common rafters of two different lengths.

A load bearing wall or beam usually supports the ridge where the unequal rafters meet. Water and snow run off both sides. The framing is simple, but the uneven load needs proper center support, which a designer or engineer should size.

The design leaves a large attic space on the short side and a sloped ceiling on the long side. This roof type is often found on older homes.

8. Flat and low slope roofs

A flat roof appears horizontal but should have a slight pitch to drain water. Builders frame them with joists sized for the span. These double as the roof rafters. They sit flat across the exterior walls and interior load bearing walls.

A slight slope is created using tapered rigid insulation or slightly angled wood framing. Water sheds slowly, and heavy rain can pool if the roof drains clog. Wind uplift can pull the roof deck off if it is not tied down as the plans specify.

Roofing material matters here. The Asphalt Roofing Manufacturers Association says asphalt shingles should never be applied on roofs with a slope lower than 2 inches per foot. You need a different roof covering instead, chosen by a licensed roofer. These roofs are common on commercial buildings and modern urban homes.

9. A frame roofs

An A frame roof has two steep sides that begin near the foundation and meet at a top ridge. The roof acts as the exterior walls. Builders frame it using large rafters.

These rafters bolt directly to the floor joists or sill plates. The triangle shape carries roof loads well when it is sized by an engineer. A frame roofs tend to shed snow because the steep angle lets it slide off. They are common in mountain towns and heavy snow zones.

The main drawback is the interior space. The steep walls create deep triangular corners in the living areas. Framing requires lifting very long, heavy timbers into place. A crane may be needed to set the main A frame members.

How the roof framing ties into the walls

Every roof shape transfers weight down through the walls to the foundation. Builders land the rafters or trusses on the top plate of the exterior walls. They cut a small notch called a birdsmouth into the underside of the rafter. This lets the wood sit flat on the wall plate.

To stop the roof from blowing away, carpenters secure the rafters with metal hurricane ties. Heavy snow pushes down while high wind tries to lift the roof off. The framing must handle both forces simultaneously. Knowing exactly how a house is framed helps you spot structural limits before you start a remodel.

You cannot remove walls inside the house without knowing if they support the roof. A load bearing wall carries the weight of the ridge board or roof joists. If you want to change your roof line or open up a room, you must hire a structural engineer to check the load paths first. Structural roof work usually needs a permit from your building department, so check with yours before you start.