How to stain and seal a deck

Deck Stain - Before and After

A big source of problems and complaints for all wood finishes is over-application of the coating. Many do-it-yourselfers and even some painting contractors believe that when it comes to coating, more is better. This is simply not the case and is particularly a problem for decks. Most deck finishes are designed to penetrate the surface of the wood. Putting too much of these coatings on the wood leads to a buildup of material, forming a film which can ultimately peel or crack. You don’t want to have to sand the deck and start over, so don’t go crazy with applying the stain.  For water repellent products, over-application can result in a surface which is overly waxy, sticky, or slick. Over-applied stains will often result in sticky surfaces, since the coating buildup interferes with their ability to dry properly.

For the best results you should stain cedar, redwood, exotic hardwoods, and clear pressure treated decks soon as possible after the deck is built and every Spring afterwards. However green treated pressure treated wood should be allowed to dry out for 30-90 days before applying the first stain.  This allows the wood to dry out as much as possible.  If you stain it too when the wood is still wet, you will run the risk of peeling or cracking.

Surface Preparation: Proper surface preparation is an important factor in the ultimate performance of coatings for pressure-treated wood or any wood surface. Surfaces should be clean, dry, and free of mildew before coatings are applied.  Also, check the weather forecast and make sure you have dry weather for the next few days.  If you deck is older, replace loose or damaged boards, tap in popped nails, and patch cracks with wood filler.  If you deck is brand new, you can obviously skip this step.  Some light sanding may be required.  An orbital sander with 60-80 grip paper should do the trick to create a level, consistently porous surface that will absorb more stain, resulting in a better wood finish.

Application Methods:

To apply a seal to the deck, you should use either a brush, Paint Sprayer, or roller. Brushing is considered to be the best technique for detail work such as pickets and railings. However, for large horizontal deck surfaces, spray application is quickest and easiest. Either airless power sprayers or pump hand-held sprayers can be used. You can rent one at your local hardware store or you may choose to purchase the sprayer since you will have to do this every 2-3 years.  It is important when spray applying finishes to back brush or back roll the wet coating. This evens out the finish and eliminates drips and lap marks. Pads are also well suited to coat decks. Individual boards should be coated along their entire length to prevent lap marking. Paint rollers are more suitable for applying siding finishes than for deck coatings. However, they can be used successfully to apply clear finishes and water repellents to decks. As for most exterior coatings, it is vital that deck finishes be applied under proper weather conditions. Solvent borne coatings are a bit more forgiving than water-based formulations and can usually be applied when outside temperatures are in the range of 40-90°F. Water-based products should not usually be applied if outside temperatures will fall below 50°F within 24 hours after application. Again, you should not stain and seal a deck if rain is forecast for the 12-24 hour period after coating. This will prevent the possibility of water spotting or wash-off. Once the coating dries,  it will be resistant to water.

Label Instructions: Since each commercial formulation is a little different, the manufacturers label instructions should be consulted and understood before the product is used. This is important not only from an application and performance standpoint but also with regard to user safety and environmental considerations. Unfortunately, many consumers fail to read the product label until after they experience a problem, at which point it may be too late for easy corrective action. Wear Proper Clothes: To protect against skin irritation, a long-sleeved shirt, long pants and goggles. Also use an OSHA approved mask to protect against inhalation of vapors if using solvent based products.   Keep your pets away during the process.  You don’t want paw prints on your freshly stained deck.

Depending upon exposure, application technique and deck use conditions, water repellants and clear finishes can perform for up to two years before the need to be restained  . Since these are transparent finishes, application is usually easy, requiring no more than one to two hours for the typical deck.

Steps for Staining and Sealing a Deck:

Prior to use, mix all cans together to insure uniform color.  Even If you are using a standard factory mixed color you should not eliminate this step. You need to be assured that you are starting out with the same color and even factory mixed colors can vary from batch to batch.
Take an empty 5 gallon bucket and add up to 4 gallons of stain, mix thoroughly using a paint stirrer.

Method of Application:
Apply liberally to dry wood to the point of saturation, two coats applied wet on wet are ideal, this allows the wood to soak up as much as possible. Do not allow to puddle, remove any excess after 10 minutes or so. Have a helper follow behind you with a roller or brush to get the areas you miss.  It doesn’t hurt to have another pair of eyes on the job.

The preferred application methods are: a quality paint brush, an airless sprayer (rentable), a pump-type garden sprayer, stain pad or a short nap roller, 1/4″. Individual boards should be coated along their entire length to prevent lap marking.

The wood coating should saturate all checks or splits. All exposed ends should be coated several times until all wood pores are saturated.
Care and Maintenance:
Stained wood surfaces may need to be retreated every 2-3 years or earlier depending on weather exposure.  If you live in Texas like I do, you need to check it every year and look to areas that need touch up.

You can store the rest of your paint or stain can upside down so that they will last longer.


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