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Engineered Wood Components

The scope of Engineered Wood Products is immense. Engineered wood products are a high-performance, consistent, reliable and environmentally responsible choice for everything from construction to materials handling applications to home projects. New building systems and high-tech products are changing the way builders build and homeowners live. Leading the change into tomorrow are high performance glued engineered wood products and systems that provide builders with cost-effective and labor-saving alternatives in construction applications behind the walls.

Glued engineered wood is manufactured by bonding together wood strands, veneers, lumber or other forms of wood fiber to produce a larger and integral composite unit that is stronger and stiffer than the sum of its parts. The phenomenal growth in the use and acceptance of engineered wood is proof that a new era is dawning in residential building.

We spoke with Tom Williamson, Executive Vice President of Engineered Wood Systems, a Tacoma, Washington-based affiliate of the APA.

Williamson explained why these products have become so popular: "Glued engineered wood products provide designers with greater flexibility to create the open spans desired by today's home owners. And they result in stronger and more durable floors, walls and roofs. They are carpenter-friendly and lightweight, making them easier to use by the builder."

Prefabricated I-Joists

Williamson brought up the benefits to the environment: "Manufactured wood products use less wood fiber than traditional wood products to achieve the same or better performance. They make use of wood elements that might otherwise not be suitable for use as a structural product. In addition, these products make efficient use of faster-growing trees from managed forests and farms and previously under-utilized species which helps preserve old-growth forests. Also, engineered wood compares very favorably to non-wood products with regard to pollutants and emissions during manufacturing."

To promote high quality building practices using engineered wood products, the APA instituted the Code Plus Program. It requires participating builders to go one step above minimum code requirements. For example, most areas require some sort of let-in bracing or corner bracing using OSB or plywood on the corners. A Code-Plus home would have fully sheathed walls using OSB or plywood. The APA provides materials such as brochures, window decals and a certificate suitable for framing for builders to promote the fact that their homes are built according to Code Plus criteria.

Overview of APA Engineered Wood Products

Sheathing
Structural wood panel wall sheathing, whether plywood or oriented strand board (OSB), is a major element in a high-quality, engineered wood home.

OSB consists of wood strands bonded with waterproof adhesives to form a mat which is then pressed under high pressure and temperature to create the finished product. Like the veneers in plywood, these mats are layered and cross-oriented for maximum strength, stiffness and stability.

OSB is widely used as construction sheathing and as the web material for wood I-joists. A house with walls sheathed with OSB or plywood will provide much greater resistance to high wind and seismic conditions and will be four times stronger than one with only foam sheathing - providing a shear capacity of 350 lbs/foot.

Glulam

Glulam is an engineered stress-rated product created by bonding together individual pieces of lumber having a thickness of two inches or less, which are then end-joined together to create long lengths referred to as laminations. These laminations are then face-bonded together to create the finished product. G

lulam is the most cost competitive engineered wood product on the market today for beams and headers. It can be shaped into forms ranging from straight beams to complex curved members and is used in a wide variety of residential building construction applications including headers, floor beams, ridge beams, purlins, cantilever beams systems and arches. It is especially ideal for floor beams because it is stronger and allows longer clear spans than traditional sawn dimensional lumber. Because it is manufactured from kiln-dried lumber, it has less shrinkage and warping - which means less squeaks and bumps - than lumber. Providing the appearance of wood, it is also appropriate for exposed headers and beams and can be stained and varnished.

Local distributors generally inventory beams in lengths up to 56 feet. Stock beams are cut to specified length and delivered with the framing package which reduces waste. Because it's a manufactured product, the quality is consistent - eliminating the need for callbacks. Custom orders, when required, are routinely supplied in one to two weeks.

Laminated Veneer Lumber (LVL)

Laminated Veneer Lumber

Laminated Veneer Lumber (LVL) is the most widely used of the structural composite lumber products. It is produced by bonding thin wood veneers together in a large billet with the grain of all veneers parallel to the long direction. It is then sawn to the desired dimensions depending on the construction application.

Some of the product's many uses are headers and beams, hip and valley rafters, and a flange material for prefabricated wood I-joists.

Rim Board

Rim board is the wood component that fills the space between the sill plate and bottom plate of a wall, or in second-floor construction, between the top plate and bottom plate of two wall sections. It not only supports the wall loads, but also ties the floor joists together and transmits lateral loads between framing elements. An engineered wood flooring system typically consists of I-joists, glulam or LVL beams, rim board and Sturd-I-Floor panels.

Due to differing performance characteristics, manufacturers of wood I-joists universally recommend against the use of sawn dimensional lumber as a rim board with an I-joist floor system. Instead, it is recommended that a glued engineered wood product be used as a rim board for these systems.

Prefabricated wood I-joists

Prefabricated Wood I-joists

Prefabricated wood I-joists are structural, load-carrying members. "Wood I-joists have become a popular substitute for solid lumber framing in floor systems," says Williamson, "because they can span longer distances and provide greater design flexibility. They are often delivered cut-to-length, reducing job site waste and framing labor."Their "I" configuration provides high bending strength and stiffness characteristics. The top and bottom flange material is sawn lumber or laminated veneer lumber; the web material is typically OSB. Prefabricated wood I-joists are used extensively in residential construction for floors and framing and can be used in roof framing where long-length rafters are required.

They have pre-scored knockouts which allow contractors to easily create holes in the webs to run small wiring or plumbing lines. Larger holes can also be cut in the webs for other mechanical systems. Wood I-joists are stable, consistent, easy to work with, lightweight and easy to handle. Home buyers benefit from open floor plans and quieter floors.

Engineered Wood Components applied to a common situaltion - structural beams and the supporting polls

Figure A	Figure B

These two figures show a finished basement example with and without an engineered wood floor system.

In Figure A (with steel beams and dimensional lumber), furniture must be arranges around the pole on the right. The poles on the left break up the wall and make it appear smaller and cluttered.

A soffit on the right side (covering a steel beam) divides the area. Figure B illustrates the room with an engineered wood system. The elimination of poles and the soffit provide a flat ceiling, more flexibility to arrange furniture and a sense of openness.

Sturd-I-Floor

Sturd-I-Floor is a tongue and groove, single-floor system which requires less time and labor to install than a traditional glue and nail system and provides a stronger, stiffer floor. According to Wachtler, Sturd-I-Floor is now used in the majority of home construction in the U .S.

Designs Adapted for Engineered Wood Products

Glulam	Rim board	Sheathing
Laminated Veneer Lumber	Prefabricated Wood I-joists	Sturd-I-Floor

52 of our designs have been modified to use these APA Engineered Wood Components. Look for the APA Logo to identify a design adapted for these products.

Build A Better Home
Designed to provide builders and homeowners the construction guidelines they need to protect their homes against damaging moisture infiltration, the Build a Better Home program from APA - The Engineered Wood Association encourages better building practices for the key elements of a residential structure - roof, walls and foundation.
		Design Basics Design 1019, the Hazelton

Updated: Thursday, May 10, 2012 12:06 PM