Specifications for Glued-Laminated Wood Construction

1. Code and Reference Standards:

AITC Timber Construction Manual, latest edition. “National Design Specifications For Stress-Grade Lumber And Its Fastenings.” American Wood Preservers Association AITC standards reference this sheet.

2. Description of Work:

The extent of glued-laminated timber work is shown on drawings, either by terminology used in this specification or by the abbreviations as indicated. Glued-Laminated Timber is hereby defined to include wood members fabricated from 1" or 2" nominal thickness lumber glued face-to-face with the grain of all laminates approximately parallel longitudinally

3. Quality Assurance:

Standards.

To comply with the “Structural Glued-Laminated Timber” ANSI/AITC A190.1-latest edition.

Manufacturer.

Provide factory-glued timber units, produced by an AITC licensed firm, qualified to issue the AITC “Quality Inspected “ Mark. Factory mark each piece of glued-laminated timber with AITC Quality Inspected Mark. Place AITC Mark on timber surfaces that will not be exposed in completed work.

Manufacture of glued-laminated timber shall be by:

Unit Structures, LLC
P.O. Box 669
Magnolia, AR 71754

4. Submittals:

Product Data.

Submit certification, indicating glued-laminated timbers comply with requirements of ANSI/AITC A190.1-latest edition.

Shop Drawings:

Submit shop drawings showing full dimensions of each member. Indicate species and stress grade of lumber, type of glue, and other variables in required work. Unit Structurea shall furnish four (4) sets of shop drawings for approval by the buyers approving agency. The contractor shall verify dimensions and be responsible for coordinating same.

5. Materials:

Lumber:

Comply with ANSI/AITC A190.1 and applicable lumber association standards cited therein for grades required to achieve glued-laminated timber requirements for allowable stress appearance, fabrication limitations and species.

Preservative Treatment. (option)

Where preservative treatment is specified or shown on plans, pressure treat lumber prior to gluing with Pentachlorophenol in mineral spirits in accordance with AITC 109 “Standard for Preservative Treatment of Structural Glued-Laminated Timber.”

Lumber Species.

Southern Pine

Adhesive.

Adhesives shall be wet-use (waterproof) complying with ANSI/AITC A190.1.

6. Timber Design:

General.

Provide sizes and shapes shown on plans. Final cross sections will be based on manufacturer’s standard widths and depths. Manufacturer to provide design values (stresses) to fulfill structural demand in accordance with applicable provisions of AITC 117 “Design, Standard Specifications for Structural Glued-Laminated Timber of Softwood Species.”

Camber.

Except as otherwise indicated, fabricate horizontal load bearing members with a camber as shown on the drawings.

Steel Connections.

Provide fabricated steel connections to join laminated to laminated, and laminated to supports exclusive of items embedded in concrete or welded to structural steel or connected to stud walls.

• A. Steel work to conform to A.I.S.C. Specifications.
• B. Steel shall conform to ASTM A-36.
• C. Bolts shall conform to ASTM A-307.
• D. Shop paint fabricated steel with one coat of rust inhibitive primer. Bolts are not shop painted with primer.

7. Appearance Grade:

Provide Grade timbers complying with AITC 110.

Choose one of the following Appearance Grades.

• AITC Premium provides a smooth surface free of knot holes or voids, should be specified when members are to stained.
• AITC Architectural is suitable for applications where appearance is a factor; knot holes and loose knots over 3/4 inch in diameter are not allowed.
• AITC Industrial can be specified when appearance is not a factor; for applications including floor beams, concealed construction or industrial installations.
• Rustique features a weathered, roughened surface that can be factory stained to provide a rustic motif; dark stains develop more uniform color.

8. Finish:

Factory applied penetrating sealer or factory finished with one (1) coat of Unit Structures' standard color selection stain. Unit Structures will submit samples of finish for approval.

9. Factory Applied Protection:

Immediately after end-cutting each member to final length, apply a saturation coat of end sealer to ends and other cross-cut sections.

10. Product Handling:

Schedule delivery and installation of glue-laminated wood members to avoid extended on-site storage. Comply with AITC III-“Recommended Practice for Protection of Structural Glued-Laminated Timber during Transit, Storage and Erection.”

Keep laminated wood members as dry as possible during all phases of construction. If jobsite storage is necessary, place members on blocking away from ponding water and cover with a waterproof covering which will not allow ultraviolet ray penetration.

Time of removal of factory wrapping is optional, but it must be emphasized that factory applied wrapping provides additional protection from damage in handling and in-transit only. If further utilization of the wrap is desired for protection after shipment, the members should be inspected and provided with additional protection as necessary. If it is impractical to replace wrapping, ALL of it should be removed. Do not leave members partially exposed due to potential sun bleaching. Do not allow moisture to accumulate inside wrapping. Do not remove wrapping on individually wrapped members until it will serve no useful purpose, including protection from the weather, soiling and damage from work of other trades.

It is imperative that the field handling instructions sheet (white/red envelope) that comes with the material shipment be thoroughly reviewed before unloading.

11. Installation:

**Installation is not the responsibility of Unit Structures, LLC.**

General.

The anchor bolt settings and/or bearing elevations (not Unit Structures' responsibility) must be held within 1/8" of the dimensions shown on the shop drawings.

All members must be adequately braced until the complete structural system (all pertinent construction materials) has been installed.

Correction of minor misfits and a reasonable amount of cutting, reaming, redrilling or alignment with drift pins will be considered a legitimate expense of erection.