Roof Trusses

Trusses Make a Stronger, Straighter Roof and They Go Up Quickly

Bird's eye view

Assembled at the factory, trusses reduce labor and material costs

Trusses can be ordered for just about any roof configuration and are made from smaller lumber sizes than dimensional rafter stock. They are assembled by the manufacturer in jigs using pieces engineered specifically for the application, which translates into consistency and precision, and they can be boomed into place quickly once they’re on the job site.

Key Materials

Trusses can be made from stock that might not work in other applications

Trusses are manufactured in a variety of standard configurations and can be fashioned into just about any type of roof. Builders can special order trusses to fit the job.

Design Notes

Strongly consider raised-heel trusses to permit more insulation

Roof trusses made from 2x4s can span distances up to 34 ft. on a roof with a pitch of 5 in 12 or greater. When made from 2x6s, trusses can span up to 56 ft. without any intermediate supports.

Like engineered rafters, roof trusses permit longer clear spans than conventional sawn rafters, giving the designer more latitude in homes with large rooms. But last-minute design changes are much more difficult to implement than they would be for a conventionally framed roof.

In all but the mildest climates, it makes sense to order raised-heel trusses, which provides extra depth at the eaves for insulation.

Builder Tips

Handle with care until they're in place

Although trusses are very strong, they are unwieldy. They don’t have much strength until they are set in place vertically and they can be stressed or damaged if they’re handled carelessly on site. Large trusses should be placed with a crane. Smaller trusses can be tipped into place with one or more long poles. In all cases, they must be braced to prevent tipping or even collapsing until roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. is applied.

Trusses are engineered. Manufacturers design trusses for specific applications. They can’t be modified in the field if something doesn’t fit. If a truss is damaged on site, the manufacturer should be contacted for help in devising a fix.

The Code

The code

Roof connectorsClick for slide show

Section 802.10 of the International Residential Code covers engineered roof trusses. The code prohibits drilling, notching, or modifying trusses. It's important to adequately plan for mechanical equipment so as not to exceed the design load [802.10.4]

Illustration: from Code Check Building 2nd Edition. click to buy .


The price of trusses is competitive with a conventionally framed roof once labor costs are considered. Roof trusses must be ordered ahead, so some lead time has to be built into the schedule.


LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. -H Roof trusses do not earn credit, unless they are made from FSCNonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.-certified lumber. If spaced greater than 16 inches on center, they can contribute to MR1 (Materials & Resources).

NAHBNational Association of Home Builders, which awards a Model Green Home Certification.:
NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions.
Bronze: 222 points minimum
Silver: 406 points minimum
Gold: 558 points minimum
Emerald: 697 points minimum
Total points available: 1300 - 1500 Number of mandatory requirements (varying based on project specifics and level of rating): 40 /ICC-700: Meeting Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. requirements is mandatory; up to 12 points for windows with enhanced performance (703.3.1).


Roof trusses are increasingly common in residential construction, accounting for roughly two-thirds of the U.S. market for new houses built in the U.S.

Trusses reduce labor as well as materials costs, as a 1996 study by the Wood Truss Council of America and the Building Systems Council of NAHBNational Association of Home Builders, which awards a Model Green Home Certification. discovered. “Framing the American Dream” presented a comparison of labor and materials costs in two identical 2,600-sq. ft. houses, one built with engineered components and the other framed conventionally. Using roof trusses saved a total of 156 hours of labor and 4,190 board feet of lumber.

Another advantage: Some manufacturers are making roof trusses from lumber that is certified by the Forest Stewardship Council(FSC) Nonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.. The Hayward Corporation of Monterey, Calif., is one firm that makes trusses from 100% certified wood. TrusPro Inc., of Guadalupe, Calif., is another.

Drywall, Wood, and Truss Uplift

Image Credits:

  1. Donald Blum/Fine Homebuilding #168
  2. Courtesy Wood Structures, Inc./Fine Homebuilding #89
  3. Christopher Clapp/Fine Homebuilding #89
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Sep 13, 2010 10:28 AM ET

LEED for Homes & trusses
by Ann Edminster

Martin is spot-on, as usual! That was exactly the logic -- LEED is designed to reward leadership, not widespread common practice, which the use of roof trusses certainly is. Floor trusses, on the other hand, aren't so common and have a number of under-appreciated (and under-utilitized) benefits: longer spans facilitate later interior remodeling; they help eliminate soffits and their associated complications, materials, and expense; and they make it easy to run wiring and pipes through floor spaces. Not to mention saving wood.

Sep 11, 2010 8:51 PM ET

Leed Points for Engineered Roofs
by Jennings Ward

Engineered roofs do fall under Leed requirements for points. Builders can earn up to 2 points for using engineered roof trusses instead of stick-framed applications. Please clarify if there is a difference. - Jennings Ward, Builders First Source

Mar 18, 2010 11:51 AM ET

Wood roof trusses
by Martin Holladay

I imagine that wood roof trusses are now so common — in residential new construction, they dominate the market — that green rating programs decided that awarding points for their use would be a giveaway available to almost any builder who follows routine building methods.

Mar 18, 2010 11:40 AM ET

Truss? under engineered wood points?
by Steve Kennedy

Why wouldn't roof trusses fall under the requirment for engineered wood when floor trusses do? They both save on using larger lumber.

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