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

Affordable Housing | Jun 12, 2024

Studio Libeskind designs 190 affordable housing apartments for seniors

In Brooklyn, New York, the recently opened Atrium at Sumner offers 132,418 sf of affordable housing for seniors. The $132 million project includes 190 apartments—132 of them available to senior households earning below or at 50% of the area median income and 57 units available to formerly homeless seniors. 

Mass Timber | Jun 10, 2024

5 hidden benefits of mass timber design

Mass timber is a materials and design approach that holds immense potential to transform the future of the commercial building industry, as well as our environment. 

Lighting | Jun 10, 2024

LEDs were nearly half of the installed base of lighting products in the U.S. in 2020

Federal government research shows a huge leap in the penetration of LEDs in the lighting market from 2010 to 2020. In 2010 and 2015, LED installations represented 1% and 8% of overall lighting inventory, respectively. 

Education Facilities | Jun 6, 2024

Studio Gang designs agricultural education center for the New York City Housing Authority

Earlier this month, the City of New York broke ground on the new $18.2 million Marlboro Agricultural Education Center (MAEC) at the New York City Housing Authority’s Marlboro Houses in Brooklyn. In line with the mission of its nonprofit operator, The Campaign Against Hunger, MAEC aims to strengthen food autonomy and security in underserved neighborhoods. MAEC will provide Marlboro Houses with diverse, community-oriented programs.

Office Buildings | Jun 6, 2024

HOK presents neurodiversity research and design guidelines at SXSW 2024

Workplace experts share insights on designing inclusive spaces that cater to diverse sensory processing needs.

Architects | Jun 4, 2024

HED and Larson Incitti Architects merge, combine Denver staff

HED, a leading national architecture and engineering firm, today announced a merger with award-winning, Denver-based Larson Incitti Architects (LIA). The merger combines LIA's staff with HED's Denver office, significantly expanding the local team and leveraging community relationships to create new opportunities across multiple market sectors.

Airports | Jun 3, 2024

SOM unveils ‘branching’ structural design for new Satellite Concourse 1 at O’Hare Airport

The Chicago Department of Aviation has revealed the design for Satellite Concourse 1 at O’Hare International Airport, one of the nation’s business airports. Designed by Skidmore, Owings & Merrill (SOM), with Ross Barney Architects, Juan Gabriel Moreno Architects (JGMA), and Arup, the concourse will be the first new building in the Terminal Area Program, the largest concourse area expansion and revitalization in the airport’s almost seven-decade history. 

Office Buildings | Jun 3, 2024

Insights for working well in a hybrid world

GBBN Principal and Interior Designer Beth Latto, NCIDQ, LEED AP, ID+C, WELL AP, share a few takeaways, insights, and lessons learned from a recent Post Occupancy Evaluation of the firm's Cincinnati, Ohio, office.

Multifamily Housing | Jun 3, 2024

Grassroots groups becoming a force in housing advocacy

A growing movement of grassroots organizing to support new housing construction is having an impact in city halls across the country. Fed up with high housing costs and the commonly hostile reception to new housing proposals, advocacy groups have sprung up in many communities to attend public meetings to speak in support of developments.

MFPRO+ News | Jun 3, 2024

New York’s office to residential conversion program draws interest from 64 owners

New York City’s Office Conversion Accelerator Program has been contacted by the owners of 64 commercial buildings interested in converting their properties to residential use.

boombox1
boombox2
native1

More In Category




Education Facilities

Studio Gang designs agricultural education center for the New York City Housing Authority

Earlier this month, the City of New York broke ground on the new $18.2 million Marlboro Agricultural Education Center (MAEC) at the New York City Housing Authority’s Marlboro Houses in Brooklyn. In line with the mission of its nonprofit operator, The Campaign Against Hunger, MAEC aims to strengthen food autonomy and security in underserved neighborhoods. MAEC will provide Marlboro Houses with diverse, community-oriented programs.

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