Specification:Wood properties and appropriate lumber

__NUMBEREDHEADINGS__ =GENERAL=

DESCRIPTION
 This specification provides guidance for determining wood properties and appropriate lumber selection. This specification has been developed for use on historic properties (defined as any district, site, building, structure, or object that is listed in or eligible for listing in the National Register of Historic Places) and provides an overview of accepted practices. Site-specific specifications will be provided by the Architect when appropriate. All work described herein and related work must conform to the Secretary of Interior’s Standards for the Treatment of Historic Properties. The Contractor shall provide all labor, materials, equipment, and operations required to complete the rehabilitation work indicated herein. All work described herein and related work must have the approval of a Cultural Resources Manager, Conservator, Historic Architect, or other professional who meets the standards outlined in the Secretary of the Interior’s Standards – Professional Qualifications Standards pursuant to 36 CFR 61. Such person is referred to in this document as the Architect. 

SECTION INCLUDES
 Wood Properties Criteria for Lumber Selection</li> </ol>

RELATED SECTIONS
<ol type="A"> Section 06200.01 – Fasteners</li> Section 06220.01 – Replication of Profiles </li> Section 06220.02 – Replication of Objects </li> </ol>

SUBMITTALS
<ol type="A"> Detail Drawings: The Contractor shall submit detail drawings showing fabricated items and all custom millwork items. Extent and type of replacements shall be subject to Architect approval. Drawings shall indicate materials and details of construction, methods of fastening, erection, and installation.</li> Certificates: Provide certificates of grade from the grading agency on graded but unmarked lumber or plywood attesting that materials meet the grade requirements specified herein. Provide certificates of compliance unless materials bear certification markings or statements.</li> Samples: Wood product and lumber samples shall be submitted as requested by the Architect. Samples shall be of sufficient size to show patterns, color ranges, and types, as applicable, of the material proposed to be used. Submit one 12-inch section of each molding profile required for the work.</li> </ol>

QUALITY ASSURANCE
<ol type="A"> Work Experience: The Contractor performing the work described in this Section shall have a minimum of seven (7) years experience with finish and restoration carpentry and shall have successfully completed at least three projects of similar scope within the previous five years. He/she shall demonstrate a working knowledge of The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring &amp; Reconstructing Historic Buildings.</li> Warranty: Installer shall provide a warranty, in writing, against defects in material and installation for a period of five years.</li> </ol>

DELIVERY, STORAGE AND HANDLING
<ol type="A"> Deliver lumber, plywood, trim, and millwork to job site in an undamaged condition. Stack materials off the ground to ensure ventilation and drainage. Protect against dampness before and after delivery. Do not store products in a building until wet trade materials are dry.</li> Store materials under cover in a well-ventilated enclosure and protect against extreme changes in temperature and humidity. Allow new millwork to acclimate to ambient humidity levels for a minimum of seven days prior to installation.</li> </ol>

PROJECT / SITE CONDITIONS
<ol type="A"> The Contractor is responsible for protecting existing adjacent materials and surfaces during the execution of the work. Provide all necessary protection and work procedures to avoid damage to existing material assemblies not a part of the work in the Section.</li> Provide visible barriers and/or warning tape around the perimeter of the work area for visitor protection. Protect nearby vehicles and adjacent structures from damage during the course of the work.</li> The Contractor shall coordinate wood selection and repairs with the other trades involved in exterior and interior restoration work including, but not limited to roofing, rough carpentry, sealants, painting, plastering, roof and gutter repairs.</li> The Contractor shall dispose of all packaging, waste and debris in accordance with federal, state and local environmental laws. All wood scrap shall be kept separate for recycling. </li> </ol> =PRODUCTS=

MOISTURE CONTENT
<ol type="A"> Generally recommended maximum moisture content for exterior wood applications are 25 percent for framing/rough exterior carpentry and 12-15 percent for finish carpentry / joinery. Most generally accepted design values are for applications where the moisture content of the wood does not exceed 19 percent. Consult the appropriate lumber grading rules (see also 1.04, REFERENCES, above) for specified kiln-dried moisture content for various woods.</li> </ol>

LUMBER TYPES
<ol type="A"> Graded Lumber: Identify each piece or each bundle of lumber, stock trim and millwork, and siding/cladding by the grade mark of a recognized association or independent inspection agency that is certified by the Board of Review, American Lumber Standards Committee, to grade the species. Custom millwork or custom siding / cladding should separately tagged and identified with the same relevant information including species and grade.</li> <li>Plywood: Each sheet of plywood shall bear the mark of a recognized association or independent inspection agency that maintains continuing control over quality of the plywood. The mark shall identify plywood by species group or span rating, and shall show exposure durability classification, grade, and compliance with APA/Engineered Wood Association   PS 1.</li> <li>Hardboard and Particleboard: Materials shall bear a marking or statement identifying the producer and the applicable standard.</li> <li>Pressure-Treated Lumber and Plywood: Each treated piece shall be inspected in accordance with AWPA (American Wood Protection Association) M2.</li> <li>Nonpressure-Treated Woodwork and Millwork: Mark, stamp, or label, indicating compliance with WDMA (Window &amp; Door Manufacturers Association) I.S. 4.</li> </ol>

WOOD PROPERTIES
<ol type="A"> <li>Softwoods <ol> <li>Softwoods generally come from coniferous species such as pines, firs and spruces, all common in building applications. All hardwoods are broad-leafed species. The vast majority of woods used in exterior applications are softwoods such as spruce, fir, pine, redwood, or cedar. Redwood and western red cedar in particular have excellent natural decay resistance. Other softwoods can also be extremely durable: In pines and Douglas fir, occasional pieces of timber are very resinous or pitchy. Wood saturated with pitch or resin is exceptionally resistant to decay and has very long life in contact with the ground or in other places where conditions favor decay (The Encyclopedia of Wood 2). </li> <li>Softwood lumber and plywood are used for forms, scaffolding, framing, sheathing, siding, flooring, molding, paneling, cabinets, poles and piles, and many other building components. Softwoods may also appear in the form of shingles, sashes, doors, and other millwork, in addition to some rough products such as timber and round posts. Softwoods are available directly from the sawmill, wholesale and retail yards, or lumber brokers (The Encyclopedia of Wood 2). </li> </ol> </li> <li>Hardwoods: Hardwoods are typically used for interior applications such as flooring, architectural woodwork, interior woodwork, and paneling. Hardwoods may also be used for exterior applications where exceptional durability is required. These items are usually available from lumberyards and building supply dealers (The Encyclopedia of Wood 2). </li> <li>Durability / Resistance to Decay and Infestation <ol> <li>General: <li>When dealing with historic wood in particular it is especially important to understand how different species behave, as this impacts both their durability and the range of applications for which they may be used. In the United States, the earliest structures were frequently built using materials available locally. Typically the wood used would have been from local trees. The common species of wood grown in the United States vary widely in their ability to resist decay, from the highly resistant Osage orange or black locust to nonresistant willow and aspen. </li> <li>The decay resistance of lumber from any tree species is impacted by both how old the tree is and how quickly it has grown. Generally speaking, the timber from a quickly grown tree will not be as strong as that from a slowly grown tree of the same species. Most of today’s commercially available lumber comes from quickly grown trees, and is weaker and less resistant to decay than the wood found in many historic buildings.</li> </ol> </li> <li>Heartwood versus Sapwood: Two distinct zones can often be seen in the cross-section of a cut log. The inner darker zone is the heartwood, which provides structural strength. The outer zone is the sapwood, which provides for the tree's nutrient storage and sap flow. As the tree grows and the trunk expands, the inner sapwood cells are gradually converted to thicker-walled heartwood. Seasoned sapwood is not as dense as heartwood and the nutrients contained make it more prone to insect attack. Generally speaking, resistance of common species to decay rests only in the heartwood. The table below lists common U.S. tree species and the resistance of their heartwood to decay. </li> </ol> </li> </ol>

=EXECUTION=

CRITERIA FOR LUMBER SELECTION
<ol type="A"> <li>Historical Accuracy: Where possible, existing historic wood elements should be retained and repaired. Where replacement is required due to the nature or extent of deterioration, replacement material should match the original to the greatest extent possible. Factors to take into consideration include species, color, grain and grain orientation, age/tree ring density, and method of conversion (e.g. circular sawn, reciprocating sawn, hewn, etc.). The overall objective should be to use replacement lumber that maintains the building’s or structure’s important defining historic characteristics. </li> <li> Use <ol> <li>Historically, different woods have consistently been chosen for specific applications because of their particular properties. Cedar, cypress, mahogany, redwood, and teak are all commonly utilized in exposed exterior applications because they contain natural extractives that make them resistant to decay and attack. Cedar and redwood, for example, provide durability as a siding material even without an applied finish which will extend the life of the wood even further.</li> <li>Some of the more commonly used woods and their exterior applications are listed below. </li> </ol> </li> <li>Durability: Decay resistance should be important in the choice of species only when the wood is to be used under conditions that favor decay— e.g. high temperature combined with high humidity. When long life is desired of untreated wood under conditions favoring decay, all sapwood should be excluded - regardless of species. See 2.03 C 2 above, “Durability/Resistance to Decay and Infestation - Heartwood versus Sapwood”</li> <li>Structural Requirements: Design values for strength of wood in the U.S. are generally taken from the National Design Specifications for Wood Construction.</li> <li>Paint Grade versus Stain Grade: The grade of lumber selected should be appropriate for its intended finish (e.g. untreated, painted or stained). Consult the appropriate sources of grading rules as necessary, some of which are listed in 1.04 REFERENCES. </li> <li>Other Criteria <ol> <li>A variety of other factors may affect the selection of appropriate woods for use in the context of repairing or restoring historic exterior wood. The following table compares the general attributes of three softwoods commonly used in exterior building applications:

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FINAL REPORT
<ol type="A"> <li>The Contractor shall provide a final report of completed work including all approved submittals and photographs of the repaired areas taken before, during and after the work. Wood species and grade selections should also be thoroughly documented. </li> </ol>