BT5 - MODULE 1: WOOD CONSTRUCTION SYSTEM

Engineered Wood

carefully tested for strength, durability and resistance to moisture

Structural Composite Lumber

is a family of engineered wood products created by layering dried and graded wood veneers, strands or flakes with moisture-resistant adhesive into blocks of material known as billets, which are subsequently resawn into specified sizes.

Structural Composite Lumber

solid, highly predictable, and uniform engineered wood product that is sawn to consistent sizes and is virtually free from warping and splitting

Glulam

is a structural engineered wood product comprising a number of layers of dimensioned lumber bonded together with durable, moisture-resistant structural adhesives.

Lams

Glulam is manufactured by bonding together individual laminations of solid timber called _____, which produces members of rectangular cross-section that are larger and longer than may be obtained simply by sawing a normal log.

Machine Stress-Rated Lumber

is softwood dimension lumber that has had its strength predicted by mechanical means rather than by relying on visual indicators.

Machine Stress-Rated Lumber

has traditionally been used for producing engineered wood products such as roof trusses and is now commonly used in producing glulam beams, chords for wood. I-beams and webs in stressed skin panels.

Laminated Veneer Lumber

is a widely used structural composite lumber product. It is produced by bonding thin wood veneers together in a large billet so that the grain of all veneers is parallel to the long direction.

Applications include

• headers and beams,

• hip and valley rafters, scaffold planking and the

• flange material for prefabricated wood I-joists

Parallel Strand Lumber

is manufactured from veneers clipped into long strands laid in parallel formation and bonded together with an adhesive to form the finished structural section.

Laminated Strand Lumber

is made from flaked wood strands that have a length-to-thickness ratio of approximately 150.

Oriented Strand Lumber

Is also made from flaked wood strands.

• Strand geometry results in length-to-thickness ratios of approximately 75

• used in a variety of applications from studs to milwork components

Medium Density Fiber

is an engineered wood product formed by breaking down softwood into wood fibers, often in a defibrator, combining it with wax and resin, and forming panels by applying high temperature and pressure.

• denser than normal particle board

• also known as custom wood or craft wood

Advantages of MDF

• Some varieties are less expensive than many natural woods

• Isotropic (no grain), so no tendency to split

• Consistent in strength and size

Disadvantages of MDF

• Heavier (because of resin)

• Swells and breaks when waterlogged

• Warps or expands if not sealed

• Contains urea-formaldehyde which may cause eye and lung irritation when cutting and sanding

• Dulls blades more quickly than many woods

Engineered Wood Flooring

This is a material that features multi-ply or three-ply construction for enhanced structural stability. It is comprised of layers of natural wood.

Multi-ply Engineered Wood

• “As close as it gets to solid wood”

• Helps prevent over-expansion of the wood boards, while the plywood core provides extra strength and stability

Three-ply engineered wood

• Provides enhanced resistance to cupping and over-expansion

• Best used where the subfloor comprises joists with short spans between the supporting columns

• Core is not strong enough to provide adequate support on subfloors with larger joist spans

High Density Fiberboard

• Results in enhanced strength, stability and moisture resistance

• Made by combining recycled hardwood and resin, whereby the mixture is ground and then compressed for a hardy material

Advantages of Engineered Wood

1. Enhanced durability

2. Less maintenance requirements

3. Increased resistance to warping and bowing

1. Susceptible to fading

2. Dents and scratches easily

3. Poor moisture resistance

4. Poor quality core construction

5. High cost

6. Maintenance requirements (Regular cleaning required)

7. Poor wear resistance

8. Presence of toxic chemicals