Humboldt Redwood T&G Panel

Before you begin the process of installing and conditioning your new Humboldt Redwood Premium T&G Panel product, please read through these helpful tips and recommendations. You may also download the California Redwood Associations helpful brochure, Redwood Siding Patterns and Applications.


Nailing recommendations refer to nailing siding to every stud or (for vertical coursing) each 2×4 blocking line, at not more than 24 inches on center. Selection of proper nails is important. Siding nails with annular-ringed shanks provide the best holding power. All nails must be either stainless steel, aluminum, or top-quality, hot-dipped galvanized. Electroplated galvanized nails are not recommended. Poor quality nails will react with Humboldt Redwood’s natural decay-resisting extractives, and will cause unsightly stains. Nails can be countersunk (not more than 1/16 inch) or driven flush with wood surfaces. Unfilled nail holes may not be particularly noticeable where natural finishes are used as long as proper quality nails have been used. At mitered corners, or near the edge or end of a piece, pre-drill the nail hole to avoid splitting the wood. Nails must be long enough to penetrate into studs (or stud and wood sheathing combined) at least 1-1/2 inches. Do not fasten siding to only composition or pressed fiber sheathing as those materials provide no nail-holding power. Do not use staples for the Humboldt Redwood Premium T&G Panel product. Staples do not provide adequate holding power and most are not corrosion-resistant.

Preventing Moisture Problems

Proper interior and exterior wall construction prevents moisture problems. Building paper should have a permeability rating of 5 perms, the vapor barrier, a maximum of 1 perm. Moisture is the largest cause of siding, paneling, and finish problems. Most problems can be avoided if precautions are taken during construction. Understanding the dynamics of Humboldt Redwood’s reaction with moisture are important. New energy-efficient construction techniques increase the amount of humidity within homes and commercial buildings. Efficient insulation, storm windows, weather-stripping, as well as heating equipment and appliances that retain warmth add to the build-up of interior moisture vapor. This invisible moisture is one of the least understood and most troublesome causes of structural and finish failures. It moves as invisible moisture vapor from the warm interior of the house toward the cold exterior. Vapor travels through plaster, insulation and wood and may condense into water as it approaches the colder exterior surfaces of the sidewall. This can sometimes result in structural damage as well as siding cupping and nail popping. Water entering the siding can also cause finishes to blister, peel and discolor. Vapor barriers are necessary to prevent migration of moisture vapor. They must be applied to the warm side of the stud wall, directly under the finish material. There are several types; the most frequently used are either plastic or aluminum sheet material with a rating of one perm or less. Those sheets should overlap at least 2 inches at their edges. Ordinary building felt is not a vapor barrier. When re-siding an existing house without a vapor barrier, an effective solution can be to paint the inner side of the exterior walls with a vapor barrier paint. Attic areas should be adequately vented to prevent vapor from condensing on cold surfaces or penetrating through the ceiling. Critical sources of humidity, such as kitchens, baths and laundries, are best ventilated by fans that exhaust outdoors. Crawl spaces should be well ventilated all around the house; the vent area should equal about 1/50th of total floor space. Keep vents free of obstructions. Movement of vapor into stud spaces from crawl spaces may take place as water evaporates from the ground under the house, and can be preventing by laying polyethylene film over the ground. Basements may be a source of considerable dampness and require effective ventilation.


Surfaced siding and paneling have a smooth, planed face, emphasizing the wood’s grain and color. Saw-textured siding and paneling have re-sawn faces providing a rough textured appearance that holds finishes extremely well.

Storage and Handling

The Humboldt Redwood Premium T&G Panel product is a quality finish product and should be handled with care. At the job site, the Humboldt Redwood Premium T&G Panel product should be kept completely under cover and off the ground. Water-proof coverings should allow air to circulate between the covering and the panels. Keeping the panels clean and dry will help to eliminate the possibility of finish problems.


It is recommended that a water repellent containing a mildewcide be applied to all surfaces of the Humboldt Redwood Premium T&G Panel product before construction begins. This will inhibit the movement of moisture as well as mildew growth, two conditions which can severely damage a finish coating. When a clear, bleached, or semitransparent finish is to be applied later, a preliminary coat of water repellent will protect against weathering and construction staining prior to final finishing. For best performance, special care should be given to end grain; cut ends should be coated before installation. The Humboldt Redwood Premium T&G Panel product should always be back-primed.

General Application Information

Careful attention to construction detailing is necessary to prevent moisture penetration into the siding and the wall cavity. Flashing over window and door headers and at other horizontal siding breaks should be sufficiently sized, well placed, tightly anchored and sealed with caulking. Thorough caulking of all joints with a non-hardening compound is important, particularly at the butt joints of short length siding laid vertically. High performance caulks such as polyurethane, polysulfide or acrylic latex are recommended for best results. The lowest edge of siding should be at least 6 inches off the ground to prevent moisture problems. It is particularly important that end grain at the bottom of vertical siding be coated with water repellent. The use of a drip cap at the lower edge of the siding is recommended. A water repellent building paper, with a permeability rating of at least 5 perms, should be applied over sheathing. This will help reduce water and wind penetration. Note: There have been reports of problems arising from the combination of wood siding and rigid plastic foam sheathings. Request a Redwood Technical Data Sheet, Using Redwood Siding Over Rigid Foam Sheathing.


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Washougal, WA 98671

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