Four Case Histories for Smart Specifying

Lumber Dimensions
Why You Can't Get 14-Inch Mouldings from a 24-Inch Diameter Tree
Nature pre-selects the color, grain pattern and character of each hardwood species. It also determines the available dimensions for North American hardwood lumber.

A hardwood tree may be 55 feet tall and 24 inches in diameter, but it will yield boards that are no more than 12 inches wide. Mouldings, then, will necessarily be narrower than that. Larger trees may yield wider lumber, yet wide boards are more difficult to work with because of hardwood's natural expansion and contraction characteristics. Since standard minimums are 5-inch widths for upper grade hardwood lumber, an alternative is to build a custom moulding from multiple stock profiles -- a process called stacking.

An intricate moulding design can be created by combining individual profiles through "stacking."

Stacked Mouldings
Through stacking, several complementary stock profiles are joined to create moulding with a custom look. More than 350 standard moulding profiles are produced in the United States and each typically costs $200 - $300 less than a custom profile. If that doesn't sound like much for a custom appearance, consider that an elaborate crown moulding can combine up to 10 separate profiles. Creating one-of-a-kind profiles can boost project costs by several thousand dollars -- and that's before the lumber in purchased.

With more than 350 stock profiles available, custom profiles often are an unnecessary expense.

Species Substitution
The Right Look at the Right Price
Another way to manage cost is to let the finish make the presentation over the natural grain or color. Some lighter-hued, close-grained hardwoods, such as poplar or basswood, often are stained to resemble other species.

Species substitution works especially well in decorative applications above eye-level -- crown mouldings and recessed ceiling panels, for instance. More functional millwork applications, such as railings, door and window trim, also present good opportunities to specify a lower-cost hardwood species.

Building Your Hardwood Knowledge
The Relative Abundance of North American Hardwoods

*Includes Sap Gum, Basswood, Cottonwood, Hackberry, Hickory, Pecan, Birch, Beech, Tupelo, Elm, Walnut and other Hardwoods. Source: United States Department of Agriculture (USDA) Forest Service

How Hard Are Hardwoods?
Each North American hardwood species has unique physical properties and there are wide variations in their relative hardness. The hardest species are well-suited for commercial and residential applications with high traffic and heavy wear.

Solid Advice
-- Specify hardwood lumber in widely available dimensions to control costs. Generally, in any species, hardwood lumber that exceeds 10 inches in width commands a premium.

-- Stack standard mouldings to create custom millwork while reducing material costs.

-- When budgets are tight, one hardwood can be stained to resemble another. Several abundant light-colored species can look like darker hardwoods.

-- The cost of hardwood products varies from region to region. Be creative with species that are abundant in your part of the country. This may significantly lower the price of a project.

There is a noticeable difference in grain patterns among plain-, quartered- and rift-sawn lumber.

What You Need To Know

Sawing Methods
Hardwood logs become lumber by one of several sawing methods. Each gives hardwood boards a distinct grain pattern, along with performance characteristics that must be considered when specifying. Sawing methods are plain sawing, quarter sawing and rift sawing.

Plain-Sawn Lumber
Plain-sawn hardwood boards are produced by cutting tangentially to a tree's growth rings, creating the familiar "flame-shaped" or "cathedral" grain found in most hardwood flooring and millwork. This method also produces the most lumber from each log, making plain-sawn lumber a cost-effective design choice.

Quarter-Sawn Lumber
Quarter sawing means cutting a log radially (90-degree angle) to the growth rings to produce "vertical" graining. This method yields fewer and narrower boards per log than plain sawing, boosting their cost significantly. Quarter-sawn boards are popular for decorative applications such as cabinet faces or wainscoting.

Rift-Sawn Lumber
Rift sawing at a 30-degree or greater angle to the growth rings produces narrow boards with accentuated vertical or "straight" grain patterns. Rift-sawn boards are often favored for fine furniture and other applications where matching grain is important. This type of lumber is available in limited quantities and species.

Sawing Methods, Moisture Content and Dimensional Change
A product of nature, hardwoods respond to changes in relative humidity by exchanging moisture with their environment. Plain-, quarter-, and rift-sawn boards react differently to these changes. Because hardwoods are more dimensionally stable across the grain, plain-sawn lumber expands and contracts more than quarter-sawn hardwood boards, which have a more vertical grain pattern. Likewise, quarter-sawn lumber, with its emphasized vertical grain, shrinks and swells less than rift-sawn hardwood boards.

With a 20 percent change in relative humidity, plain-sawn hardwood panels can expand or contract as much as 1/8 inch per foot of width, depending on the species. To accommodate these effects, it's important to know:

-- The recommended moisture content of hardwood products before installation.

-- How to acclimate hardwood products to their new home.

-- Installation techniques that take hardwood's natural expansion and contraction into account.

How Dry Should Hardwood Products Be?

How Much Dimensional Change Should You Expect?
These figures represent possible width change in 12 inches of lumber when moisture content is reduced from 10 percent to 5 percent. Figures are for plain-sawn unless indicated otherwise.

Check the Moisture Content
Moisture content is the amount of moisture in wood, expressed as a percentage of its oven-dry weight. The proper moisture content for kiln-dried hardwood products varies in different regions of the country. When receiving a shipment of hardwood paneling, flooring, millwork or cabinetry, pull out several sample boards and use a hand-held moisture meter to measure their moisture content. The figure should closely match the one recommended for your part of the country. If it doesn't, take the following precautions:

Let Hardwoods Adjust to Their Surroundings
Sawmills dry and condition hardwood lumber to the moisture content expected in service. During transport and storage, hardwoods can accumulate moisture or become too dry. To avoid problems, let hardwood products adjust to the site before installation. Here's how:

-- Have hardwood products delivered after all windows and doors are installed, and masonry and plastering are complete.

-- With the home's HVAC system operating at a normal level, unbundle and store hardwood paneling, flooring and millwork for three to five days in the room where it will be installed. If delivered before the HVAC system is operational, store the material in a dry environment until you can follow the instructions above.

Plan for Natural Expansion and Contraction
Here are a few important installation tips for minimizing expansion and contraction of hardwood paneling, flooring and millwork during seasonal changes in relative humidity:

-- Install hardwood paneling so it moves across the grain. Use narrow widths when possible.

-- For large areas, such as paneling, leave an expansion gap to accommodate the natural expansion and contraction, based on changes in humidity specific to your region. Conceal the edge with baseboards or mouldings.

Solid Advice
-- Specify hardwood sawing methods based on appearance and cost. You can effectively manage how much hardwoods shrink and swell by letting them adjust to a new environment. Control moisture content through proper storage and care of hardwoods at the work site.

-- Plain-sawn hardwoods of any species cost significantly less than a quarter-sawn counterpart. Rift-sawn hardwoods are very expensive and have limited species availability.