Adhesive bonding prcduoes eoonomical rcdwood building products

By Chrrles J. Jourdrln Supervisor, Technical Services California Redwood Association

EVEL siding, T&G paneling and 2x6 decking are familiar redwood lumber products. However, adhesive bonding makes available a variety of other redwood products which you can recommend to your customers.

Creating in many cases a better performing and more cost effective product, adhesive bonding also conserves forest products. Glulam, IJoists, LVL, Paralam, OSB and waferboard are all adhesively bonded engineered wood products. While redwood doesn't compete directly with these for most structural applications, its natural durability, high dimensional stability and aesthetic appeal provide a number of glued products.

Classified by the U.S. Forest Products Laboratory as a wood that glues easily under a wide range of conditions. redwood heartwood and sapwood take and hold glue equally well. Since good machining of the surface is essential in preparation for gluing, redwood's quality of being easy to work with either machine or hand tools is a plus.

Redwood plywood is manufactured as exterior siding, but is used for interiors as well, Produced in accordance with U.S. Products Standard PS l-83, its manufacture and quality control are overseen by the American Plywood Association. All panels bear the APA grade trademark.

Redwood veneers (Species Group 3) are used in the fabrication of APA 303 Series Specialty Siding. Five-ply, 5/8" thick panels are manufactured with redwood face and back veneers and a redwood center ply. Cross bands are fir or another species at mill option. Solid redwood plywood is available upon request. Veneers are bonded with waterproof phenolic resin adhesives.

Face veneers are available in heartwood or heartwood and sapwood. Redwood plywood siding is manufactured in a number of surface patterns and textures including the popular T l-l l. For interior applications, there are 3/8" panels.

Redwood glued laminated (glulam) beams are not as readily available as fir or pine glulams. However, this unique product should be specified where natural durability and appearance are paramount.

The Uniform Building Code approves the use of glulams manufactured from woods with natural resistance to decay in applications where structural members are exposed to the weather and not protected by pressure preservative treatment or other means. Glulams can be manufactured entirely of redwood heartwood for this purpose or with the weather exposed portion of heartwood and the interior portion from a non-durable species. Waterproof adhesive resorcinol is used.

FltlGEff iointed redwood can be used successfully in renovation as illustrated by this Victori'an mansion remodeled into condominiums.

Standard Specifications for Grades of California Redwood Lumber for structural laminations lists five special all purpose grades. Identified as Ll through L5, these visual grades correspond to clear all heart, clear, select heart, construction heart and construction common. Laminating grade descriptions are similar to those for general purpose grades except for restrictions on slope of grain and ring count.

If your customer's redwood project requires large curved beams or arches, redwood structural glulams can be the best recommendation. Fabricated from certified kiln dried laminations, they will not shrink once installed.

Redwood siding, facia and trim are available in economical finger jointed form. By cutting clear wood sections from between the knots of shop grade lumber and gluing them end-to-end, long lengths of high grade lumber are manufactured. The short pieces of certihed kiln dried clear stock are joined with catalyzed urea resin adhesive and cured bY high frequency electrical energy to create a durable highly moisture resistant bond.

Finger jointed redwood siding is produced in patterns including bevel, shiplap and T&G. Single and double plowed facia and S4S boards are also manufactured. Other standard redwood patterns are available by special order. Because all knots are cut out prior to gluing, grades are clear all heart and clear. Vertical grain or mixed grain can be specified.

Story at a Glance Summary of redwood glued products... manufacture and application suitability...rec'

ommendations for use.

Redwood glued-up panels are produced by combining hnger jointing and edge gluing. These come in 3/4" or ll/16" thicknesses. Most are used for overhead garage doors.

Adhesive bonding combined with redwood's characteristic durability, stability, aesthetic appeal and ease of machining produces economical redwood construction products which a dealer can recommend with confidence.

These case-hardened screws are hot-dipped in molten zinc, and ale excellent tol use with Prcssurc treated lumber, cedar and rcd' wood. Outdoor uses include decks, boat docks, stePs, Patios' furnltur€, lences, flower boxes, or any project wherc long-term cor' rosion-resistance and exceptional holding power ane required. No pre-drilling necessary. PhilliPs head sets flush.

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