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Deck Maintenance: Sealing and Staining



A wood deck requires regular sealing to prevent splitting and cracking. Back-brushing to distribute the stain or sealer evenly will give a level finish.
A wood deck requires regular sealing to prevent splitting and cracking. Back-brushing to distribute the stain or sealer evenly will give a level finish.

A properly applied stain or sealer is part of regular maintenance to protect your deck from stains, mildew and damaging rays. Sealers and stain products exist for almost every type of deck, including pressurized wood, softwoods and even composite decks. Selecting the appropriate product to match the deck material and applying it the proper way will ensure a long-lasting, good-looking deck.

Stain or Sealer
Sealers are clear products that protect against moisture but do not offer protection against the Sun’s damaging ultraviolet (UV) rays, which fade a deck. Stains are basically tinted sealers that provide color and UV protectionthe darker the tint, the greater the UV protection. Stains are sold under names that indicate the darkness of the product, from clear transparent sealer, to semi-transparent, semi-solid and solid. A solid stain is more like a coating and may hide the grain of the wood while a semi-solid or semi-transparent stain will allow grain and texture to show through. Distributors may also add pigments to customize the color of the stain to match exterior features like fences, sheds or siding. When purchasing more than one can of stain or sealer, mix the product into one receptacle prior to application to guarantee a consistent result.

Composite deck manufacturers sometimes recommend treating a deck with a protector or finish to guard against the stains, mold and mildew that can plague these decks. Some stain manufacturers carry a line of stains and protectors made specifically for composite deck materials.

Stains may also contain additives to enhance performance. Some stains contain mildewcides and fungicides to retard the growth of mold and mildew. Others include citronella to repel mosquitoes.

Oil-Based and Acrylic-Based Stains and Sealers
Stains and sealers may be oil-, water- or acrylic-based. Professionals like Mark Crump of Be Clean Pressure Washing Services in Richmond, Va., typically prefer an oil-based stain. “I personally don’t use water-based stains,” he says. “I prefer an oil-based stain that penetrates the wood rather than sitting on top of it.”

Acrylic or latex stains tend to be thicker and are often marketed for their quick turnaround time. “Some of these acrylics let you wash the deck in the morning and stain it in the afternoon,” says John Sundquist, owner of American Deck Maintenance, Inc. of Northbrook, Ill. Unlike oil-based stains, which can harbor molds and mildews, an acrylic stain is inert and will not provide food for mold and mildew growth. However, acrylics are relatively new to the stain industry and some professionals have avoided using them. “Acrylic has a long way to go,” says Sundquist. “It has only been on the market for a few years.” Whether it is better to strip an old acrylic coating or apply a new coating directly over the old one is still open to debate.



Stains, sealers and finishes are designed to protect decks from damaging rays, mildew and mold. Renewing the protective finish is part of routine deck maintenance.
Stains, sealers and finishes are designed to protect decks from damaging rays, mildew and mold. Renewing the protective finish is part of routine deck maintenance.

Application Techniques
Stains and sealers are applied the same way—with a sprayer, roller or brush. Although a pump spray can be used to apply stain, many professionals prefer a roller-and-brush application because it helps the stain penetrate the voids and crevices.

A deck should be cleaned and allowed to dry before applying a stain or a sealer. Most professionals recommend waiting 24 hours after cleaning before applying stain or sealer and to apply stain during the cooler part of the day and out of direct, baking sunlight. “Some products are temperature-sensitive,” says Mathew McKinley, yard manager for Redwood Products of Oklahoma City, Okla. He prefers to stain in the early morning hours, after the dew has burned off.

A technique called back-brushing is important when applying stain. It involves going back to brush out any stain or sealer puddles. Stain boards covered in sheepskin or cloth can also be used to work the stain into the surface. It is common for applicators to roll a stain over a section of the deck and follow up by back-brushing with a brush or pad to work the stain into cracks and in between boards. Most stain and sealer manufacturers recommend waiting at least 24 hours after application before using the deck.

Hiring a Pro
Professional deck maintenance contractors will have access to high-quality stains that are harder for non-professionals to find and may use commercial airless sprayers for speedy stain application. A professional will typically get the job done quickly. “When we do a job, we are often able to clean the deck in an hour and stain it in an hour,” says Crump. When considering paying for a professional clean and stain, homeowners should make sure the contractor inspects the deck prior to quoting a price. “Most contractors will base the price on time and materials, and they price by the job,” Crump says. He adds that a typical wash and stain for a 10’x 15’ deck would cost about $150, but costs will vary by region, size and the nature of the job.

Credit: Renovate Your World