Treat ed Lumber-lts Uses and Economies

Excerpts hom U. S. Department of Commerce Bulletin

Wood preservation, without doubt, is the keystone of the arch supporting efficient wood-utilization practices. The annual loss of timber in service because of decay alone, amounts to about one-fifth of the annual cut of lumber.

Since in most ,cases timbers in service are attacked by termites from the inside, not from the outside, spraying with chemicals will not protect the wood. It has been definitely established, however, that wood treated with preservatives according to accepted standards, both as to process and chemicals, by which the preservative is forced into the interior of the wood, is effective against termite attack and should be used in any construction where termite damage may be feared.

Having definitely established the fact that wood can be made immune to atta,ck of decay and insects, two very important things must be kept in mind if the greatest success is to be attained in that direction: (1) The preservative itself must be an effective one; and (2) proper methods of injecting the preservative into the wood must be followed.

There are many preservative materials on the market today. Some have great value, some have little or none, and some are so recent we have not yet sufficient knowledge regarding their performance under service conditions to judge of their merits.

Scar'cely a year passes but some new material is launched and claimed by its promoter to possess all the desirable qualities of.previously tried materials, plus a goodly number ttfirtrxl""?"?"* oi these new compounds show promise of possessing valuable properties as wood preservatives they have not been in use long enough to demonstrate their effectiveness over long periods of time. ff maximum service from preserved lumber is to be obtained, several important points must be carefully considered. Assuming that the w,ood is first of all properly seasoned and free from decay, the preservative treatment best suited to the particular purpose must be determined upon. There are certain purposes for which treatment with either creosote or a good chemical salt will be satisfactory. There are other purposes for which one or the other is definitely recommended. The choice of preservative can be determined by a study of the nature of the two classes of preservatives and their effect upon the wood, already described.

Fluoride-phenol salt mixtures are represented by Wolman salts and are also being used for treating wood. They are patented products composed of sodium fluoride to which other chemicals have been added. The large percentage of sodium fluoride contained in these pr'oducts would indicate that they have preservative value. While they have not been in use for a great length of time in the United States, it is generally understood they have been used in Germany for some time, principally for the treatment of mine timber and to some exfent for ties, and have given good service.

The superiority of pressure-treated lumber as ,compared with non-pressure-treated lumber has been established definitely by experience covering a long period of years, and lumber for.construction purposes should be pressure treated to obtain maximum servi,ce against.decay and insect attack.

Dipping, brushing, and spraying methods are especially superfi,cial in their results, and are not to be relied ripon for long life.

A surprisingly small investment will provide all the treated lumber that is required for most buildings.

Because the use of Dreserved lumber bv the small consumer has been comparatively..limit"ed, h-owever, there. it :. considerable lack of understanding of its application to his special needs. The recommendation that treated lumber be used in residen,ce construction, has reference only to its use for those portions of the buildings that are iir greatest danger of destruction by decay or inse.cts and which ordinarily are destroyed and must be replaced long before the remainder of the building has begun to show signs of deterioration. These are the portions that are in contact with or near the ground, in damp, poorly ventilated basements, or in contact with other timbers or with masonry, girders, joists, stringers, subflooring, window frames, roof timbers, and shingles. In these locations decay is certain, if moisture accumulates in the wood.

Wood Preservation and the Home Owner

The acquisition of a home is in most instances the most important investment which the average citizen undertakes. Generally ho'me ownership depends on the securing of a loan, and the terms of this loan are based largely on the value represented by the house. It is therefore evident that the home owner must not only consider the question of good design, plan, and construction, but he must also check up on the quality of the building materials used, because the life of the house is in direct proportion to the life of the materials employed. The best construction methods will not prevent premature depreciation if good building materials have not been employed. There are certain yi+*h.parts of a wooden structure which are particularly subject to decav and insect attack. If the home owner will insist on prottcting his interests by using treated wood for the construction of such parts he will undoubtedly find this fact taken into consideration by the banker wh,o grants the loan. The use of preserved wood will therefore contribute to the increase in individual home ownership.

Certain trends 'of modern archite,cture favor setting the house as close to the ground as possible. In su,ch cases preserved wood may be used to advantage wherever wood is used in direct contact with the ground.

In many cases home owners are desirous of remodeling their houses and thus an opportunity for the use of treated. lumber may be offered. The aim of the National Committee on Wood Utilization is to interest the small consumer in the use of preserved wood to protect his investment. If larger consumers of preserved wood, su,ch as railroads and public utilities, have been able to effect appreciable economy through its use, it is reasonable to expect that proportionately greater savings will accrue to the smaller consumers, on whom the burden of repair and premature depreciation rests more heavily. For this reason the National Committee on Wood Utilization is sponsoring the retail distribution of treated lumber, to make it available to the average lumber consumer.

The Builders' Interest in Wood Preservation

Ar.chitects, engineers, and builders interested in furthering good construction practices will find that the use of preserved wood represents an appreciable economy. They should bear in mind that it is cheaper to prevent decay than to repair or replace decayed.lumber. In determining the life of a building or a structure, and their obsolescence, it will often be found that the cost of the use of preserved

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