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Building Design and Construction Handbook - Merritt - Ventech!

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BUILDING MATERIALS 4.49<br />

TABLE 4.15 Resistance to Decay of Heartwood of Domestic Woods<br />

Resistant or very resistant<br />

Baldcypress (old growth)*<br />

Catalpa<br />

Cedars<br />

Cherry, black<br />

Chestnut<br />

Cypress, Arizona<br />

Junipers<br />

Locust, black†<br />

Mesquite<br />

Mulbery, red†<br />

Oak:<br />

Bur<br />

Chesnut<br />

Gambel<br />

Orgeon white<br />

Post<br />

White<br />

Osage orange†<br />

Redwood<br />

Sassafras<br />

Walnut, black<br />

Yew, Pacific†<br />

Moderately<br />

resistant<br />

Baldcypress (young growth)*<br />

Douglas fir<br />

Honeylocust<br />

Larch, western<br />

Oak, swamp chestnut<br />

Pine, eastern white*<br />

Souther pine:<br />

Longleaf*<br />

Slash*<br />

Tamarack<br />

Slightly or<br />

nonresistant<br />

Alder<br />

Ashes<br />

Aspens<br />

Basswood<br />

Beech<br />

Birches<br />

Buckeye<br />

Butternut<br />

Cottonwood<br />

Elms<br />

Hackberry<br />

Hemlocks<br />

Hickories<br />

Magnolia<br />

Maples<br />

Oak (red <strong>and</strong> black species)<br />

Pines (other than longleaf,<br />

slash, <strong>and</strong> eastern white)<br />

Poplars<br />

Spruces<br />

Sweetgum<br />

True firs (western <strong>and</strong><br />

eastern)<br />

Willows<br />

Yellow poplar<br />

* The southern <strong>and</strong> eastern pines <strong>and</strong> baldcypress are now largely second growth with a large proportion<br />

of sapwood. Consequently, substantial quantities of heartwood lumber of these species are not available.<br />

† These woods have exceptionally high decay resistance.<br />

From U.S. Forest Products Laboratory.<br />

The most commonly employed water-soluble salts are acid copper chromate, chromated<br />

copper arsenate <strong>and</strong> arsenite, fluor chrome arsenate phenol, chromated zinc<br />

chloride, <strong>and</strong> other materials that are often sold under various proprietary names.<br />

The principal solvent-soluble organic materials are chlorinated phenols, such as<br />

pentachlorphenol, <strong>and</strong> copper naphthenate.<br />

Preservatives may be applied in a variety of ways, including brushing <strong>and</strong> dipping,<br />

but for maximum treatment, pressure is required to provide deep side-grain<br />

penetration. Butts of poles <strong>and</strong> other parts are sometimes placed in a hot boiling<br />

creosote or salt solution, <strong>and</strong> after the water in the wood has been converted to<br />

steam, they are quickly transferred to a cold vat of the same preservative. As the<br />

steam condenses, it produces a partial vacuum, which draws the preservative fairly<br />

deeply into the surface.<br />

Pressure treatments may be classified as full-cell <strong>and</strong> empty-cell. In the full-cell<br />

treatment, a partial vacuum is first drawn in the pressure-treating tank to withdraw<br />

most of the air in the cells of the wood. The preservative is then let in without<br />

breaking the vacuum, after which pressure is applied to the hot solution. After<br />

treatment is completed, the individual cells are presumably filled with preservative.<br />

In the empty-cell method, no initial vacuum is drawn, but the preservative is

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