flexiblefullpage
billboard
interstitial1
catfish1
Currently Reading

8 Tips for Designing Wood Trusses

8 Tips for Designing Wood Trusses

Successful metal-plate-connected wood truss projects require careful attention to detail from Building Team members.


By By Kate Cline, Associate Editor | May 18, 2011
Wood truss ceiling in a salt storage building
Wood truss ceiling in a salt storage building
This article first appeared in the May 2011 issue of BD+C.

Wood truss construction surged in popularity in the 1960s and ’70s, but back then most buildings that used metal-plate-connected wood trusses had flat ceilings. With today’s CAD and BIM technology, however, manufacturers can create trusses for much more intricate and complicated architectural designs.

Archie Landreman, a technical director with WoodWorks, an initiative of the Wood Products Council, offers eight tips for working with metal-plate-connected wood trusses.

 

1. Sweat the details.

Creating a complete set of construction documents is the first no-brainer step for any wood truss project. “The more information the team has, the better job they’re going to do,” Landreman says. “You need a complete set of blueprints—architectural, structural, mechanical.”

Detailed sections, including design loads, spacing, building codes, and special shapes, are crucial for a manufacturer to properly design trusses for your project. Providing these details up front will save time and money, and the approval process will go more smoothly.

Landreman’s advice: Make sure the truss heel height isn’t overlooked during the blueprint stage. “A lot of times, plans are drawn in such a way that that particular section of the building is generic—it doesn’t necessarily show details to scale,” he says. To accurately calculate heel height, the manufacturer needs detailed information—including a drawing of a typical wall section—on wall height, height at the bottom of the header, length of the overhang, and dimensions for the soffit and fascia materials.

 

2. Specifications are as important as blueprints.

To design trusses properly, you must supply the manufacturer with a specification book. Such documentation may include specific carpentry information on trusses that does not appear on the project blueprints. Without a spec book, the truss manufacturer could do a complete set of truss layouts and profiles for approval, Landreman says, only to have the architect or structural engineer come back with a whole new set of drawings and specifications. “It could add a lot of time and expense for the manufacturer to have to redo something that was done without complete information,” Landreman says.

Landreman’s advice: Provide the truss manufacturer with the spec book at the time of the bid. “In some cases, it can provide a lot more detail than the blueprint itself.”

 

3. Get close to your manufacturer.

Before beginning a truss project, do your research on several truss manufacturers. Don’t be afraid to ask tough questions; for example, “Have you done big commercial jobs with spans in excess of 60 feet before?”

Ask truss manufacturers for their annual business volume, which can be an indicator of experience. “If someone’s manufacturing $10 million worth of trusses a year, you would think that they should have more experience and probably be able to do a better job than a manufacturer that’s doing $500,000 a year,” he says. Business volume may not always be a perfect indicator, but it’s a factor you should take into consideration.

Landreman’s advice: Ask manufacturers for references on projects similar to yours to get a sense of their experience in that area. “Not everybody has done the kind of job you’re working on,” he says.

 

4. Keep in touch with your manufacturer as the job progresses.

Developing a solid relationship with your truss manufacturer is important, since a good manufacturer can assist your Building Team during the early stages of the design process. If, for example, you’re designing a building with a 26-foot span for a floor truss, get the specifications details to the manufacturer, request a preliminary drawing, and work with the manufacturer’s drawing to develop a better sense of what the truss would look like and whether the manufacturer’s concept can become a reality.

Landreman’s advice: Work with the truss manufacturer to get details on span and truss height before starting any drawings to make sure the basic design concept will work before it is put on paper.

 

5. Make your manufacturer part of your Building Team.

When your manufacturer completes shop drawings for the placement diagrams of the trusses, getting input from all parties involved in the project should provide added perspective before final approval of these documents.

Landreman’s advice: Share manufacturer drawings with all the members of your Building Team, so that “you’re getting viewpoints from different angles.”

 

6. Schedule the wood truss work carefully.

The approval process can take time. To keep on schedule, leave ample time for placing the order, completing the layout and profile designs, and approving the drawings. According to Landreman, this process usually takes about two weeks, but it can vary depending on the manufacturer, the time of year, and the size and complexity of the project.

Landreman’s advice: Ask the manufacturer how long to expect the drawings to take once the purchase order or contract is placed. 

 

7. Follow the manufacturer’s directions carefully.

The truss manufacturer should provide detailed guidelines on truss storage and installation during the approval process and upon delivery to the job site. The guidelines should include instructions on storage, lifting installation, bracing, cutting, and notching. Follow the manufacturer’s guidelines to the letter, since problems can occur if trusses are mishandled.

The chief problem is damage during delivery to the job site, as trusses are being rolled off the truck and dropped to the ground. “If they put them on a really rough part of the job site, some of the trusses could be broken or there could be damage to the connector plates when they hit the ground,” Landreman says.

Some trusses cannot be repaired once they’re put in place, so damage that goes unnoticed until after the trusses and roof sheeting are installed could result in extra time and expense to remove the sheeting and put in a new truss.

To avoid any confusion during installation, the manufacturer’s instructions should include the latest set of truss drawings showing the proper placement of all of the trusses. “Many times through the approval process some of the details in the drawings may change,” Landreman says. “If the contractor in the field doesn’t have the last revised set of truss drawings, some of those numbers and placements might have changed, and the truss could wind up in the wrong location.”

Landreman’s advice: If any instructions, warnings, or recommendations are missing, call the manufacturer immediately. “They are more than willing to get that information to you or send someone out to the site to help make sure everything’s going the way it’s supposed to.”

 

8. Treat floor trusses with special care.

Floor trusses can be trickier than roof trusses. “With roof trusses, there’s a tremendous amount of design flexibility, and usually you’re dealing with slope trusses,” Landreman says. With floor trusses, however, “the height of the floor truss can affect the design of the whole building, especially when you’re looking to accommodate mechanicals in those floor trusses,” he says.

For example, say you’re designing a three-story building using 24-foot floor trusses, and you expect the truss to be 12 inches deep. During the bidding process, however, the manufacturer determines that each truss needs to be 16 inches deep. “That would add a whole foot to the building height, and it’s probably not going to work,” says Landreman.

Landreman’s advice: Consult your manufacturer on truss depth and spacing when considering floor trusses for any large-scale project, rather than relying on a preprinted span table.

Related Stories

MFPRO+ News | Dec 11, 2023

U.S. poorly prepared to house growing number of older adults

The U.S. is ill-prepared to provide adequate housing for the growing ranks of older people, according to a report from Harvard University’s Joint Center for Housing Studies. Over the next decade, the U.S. population older than 75 will increase by 45%, growing from 17 million to nearly 25 million, with many expected to struggle financially.

Office Buildings | Dec 11, 2023

Believe it or not, there could be a shortage of office space in the years ahead

With work-from-home firmly established, many real estate analysts predict a dramatic reduction in office space leasing and plummeting property values. But the high-end of the office segment might actually be headed for a shortage, according to real estate intelligence company CoStar Group. 

University Buildings | Dec 8, 2023

Yale University breaks ground on nation's largest Living Building student housing complex

A groundbreaking on Oct. 11 kicked off a project aiming to construct the largest Living Building Challenge-certified residence on a university campus. The Living Village, a 45,000 sf home for Yale University Divinity School graduate students, “will make an ecological statement about the need to build in harmony with the natural world while training students to become ‘apostles of the environment’,” according to Bruner/Cott, which is leading the design team that includes Höweler + Yoon Architecture and Andropogon Associates.

University Buildings | Dec 5, 2023

The University of Cincinnati builds its largest classroom building to serve its largest college

The University of Cincinnati’s recently completed Clifton Court Hall unifies the school’s social science programs into a multidisciplinary research and education facility. The 185,400-sf structure is the university’s largest classroom building, serving its largest college, the College of Arts and Sciences.

MFPRO+ News | Dec 5, 2023

DOE's Zero Energy Ready Home Multifamily Version 2 released

The U.S. Department of Energy has released Zero Energy Ready Home Multifamily Version 2. The latest version of the certification program increases energy efficiency and performance levels, adds electric readiness, and makes compliance pathways and the certification process more consistent with the ENERGY STAR Multifamily New Construction (ESMFNC) program.

Architects | Dec 5, 2023

Populous celebrates its 40th anniversary with a photo exhibit of its works

The firm partnered with Getty Images to assemble more than 60 images, many capturing fan ardor.

Office Buildings | Dec 1, 2023

Amazon office building doubles as emergency housing for Seattle families

The unusual location for services of this kind serves over 300 people per day. Mary's Place spreads across eight of the office's floors—all designed by Graphite—testing the status quo for its experimental approach to homelessness support.

Mixed-Use | Nov 29, 2023

Mixed-use community benefits from city amenities and ‘micro units’

Salt Lake City, Utah, is home to a new mixed-use residential community that benefits from transit-oriented zoning and cleverly designed multifamily units.

Giants 400 | Nov 28, 2023

Top 100 Laboratory Design Firms for 2023

HDR, Flad Architects, DGA, Elkus Manfredi Architects, and Gensler top BD+C's ranking of the nation's largest laboratory architecture and architecture/engineering (AE) firms for 2023, as reported in Building Design+Construction's 2023 Giants 400 Report.

Engineers | Nov 27, 2023

Kimley-Horn eliminates the guesswork of electric vehicle charger site selection

Private businesses and governments can now choose their new electric vehicle (EV) charger locations with data-driven precision. Kimley-Horn, the national engineering, planning, and design consulting firm, today launched TREDLite EV, a cloud-based tool that helps organizations develop and optimize their EV charger deployment strategies based on the organization’s unique priorities.

boombox1
boombox2
native1

More In Category




Adaptive Reuse

Detroit’s Michigan Central Station, centerpiece of innovation hub, opens

The recently opened Michigan Central Station in Detroit is the centerpiece of a 30-acre technology and cultural hub that will include development of urban transportation solutions. The six-year adaptive reuse project of the 640,000 sf historic station, created by the same architect as New York’s Grand Central Station, is the latest sign of a reinvigorating Detroit.

halfpage1

Most Popular Content

  1. 2021 Giants 400 Report
  2. Top 150 Architecture Firms for 2019
  3. 13 projects that represent the future of affordable housing
  4. Sagrada Familia completion date pushed back due to coronavirus
  5. Top 160 Architecture Firms 2021