Wood trusses top the engineered wood market

NGINEERED wood quiz: What's the most widely produced engineered wood building component for home construction?

- I-joists?

- Laminated veneer lumber?

- Glued laminated beams?

The answer: none of the above. The correct response is prefabricated roof and floor trusses.

About 4.5 billion bd. ft. of lumber was used for trusses last year. And,60Vo of these trusses were built with southem pine lumber, because of its strength and durability.

Trusses have steadily increased their market share over

Fewer architects and owners

want low-pitch roofs these days.

the past two decades. It's estimated that 257o of all retail building material retailers provide trusses for their contractor customers.

Roof trusses provide reliable, factory-engineered wood building components that can usually be installed faster than conventional framine. Floor trusses offer the advantage of high-strength framing and open webs, which make it possible to run ductwork, plumbing and wiring throughout the structure without drilling holes.

Architects, engineers, retailers and builders report that roof and floor trusses have benefited from two relatively recent design trends-the more dramatic visual impact of taller profile roofs, and the increase in "bonus rooms" for extra living space in the area that was formerly the attic.

Taller, Steeper Ttusses

As architects reach for steeper profiles in custom and multifamily homes, roof elevations are becoming unique and distinctive. Many building designers are turning to taller, more complex southern pine trusses to create higher roofs that give structures a more visible signature or shape. This is particularly true in roofs with multiple dormers, hips and valleys.

In the past, trusses with a 4ll2 pitch were the norm on many jobs. Today, more designers are calling for 8/12 to

10/12 pitch trusses.

Truss experts report that fewer architects and owners want lowpitch roofs these days. With the computer engineering and hightech equipment in the truss plant, it's easier to specify the higher profile trusses.

According to Kirk Grundahl, executive director of the Wood Truss Council of America, "Owners and architects like the variety of interior ceiling profiles like coffered or tray ceilings that are achieved with steeper pitched trusses." He sees continued growth in the taller trusses, even though their height sometimes causes manufacturers to build trusses in two pieces to deal with shipping restrictions.

Attic Trusses Greate New SPace

Wood roof truss manufacturers are also capitalizing on the increasing popularity of the attic truss. It's like finding "bonus space" upstairs for bedrooms, storage, home offices or heating and air conditioning equipment.

Builders and designers note that the attic area is often wasted in new homes that are framed with conventional trusses or rafters. The solution is an attic truss that has a square, box-shaped opening down the center, between the top and bottom chords of the truss. This square opening typically receives a subfloor and wall board to become a finished room.

The amount of open attic space for a "bonus room" depends on the roof pitch and the truss span. For example, a 40-ft. attic truss with a 10/12 pitch provides more space than a 30-ft. truss with a 6112 pitch. Some of the larger trusses provide 7 to 8 ft. of headroom down the canter.

When the steeP attic trusses are used for a bonus room over the garage, the extra strength of the southern pine truss makes it possible to span the width of a two-car garage without any intermediate Posts or columns.