Cleaning Composite Decks

Get tips for cleaning composite decks to ensure that you'll be able to clean yours effectively and safely.
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HDSWT903_02-Cleaning-Composite-Deck_s4x3

As seen on HGTV's Don't Sweat It, this composite deck design has great shade and a nice railing with plant decor.

By: Sean McEvoy

Composite decking is one of the most popular decking materials, and with good reason—it's durable, attractive and inexpensive. But even the most ardent fan of this type of deck won't be a fan of cleaning composite decks.

That said, if you follow the recommended instructions for cleaning your composite deck, you can expect it to stay looking great for years. It's generally suggested that you use a power washer to clean a composite deck. Be sure to check with your deck's manufacturer or installer to determine the recommended tip to and pressure setting to use.

Refinish Your Deck in a Weekend

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Refinishing a Deck

A deck can be a valued extension of the home, but time and the elements  will take their toll. If it has been a few years or even decades since your deck has been given the attention it deserves, it may be time to refinish with necessary repairs, a thorough cleaning and a fresh coat of paint or stain.

Photo By: Photo by Mick Telkamp

Determine Your Needs

A deck that is just a couple of years old or has received regular maintenance is still likely to benefit from a good cleaning. An older deck may need repairs to railings or steps, replacement of split or splintering planks and decisions will need to be made regarding the type of stain used to protect and beautify the structure.

Photo By: Photo by Mick Telkamp

Sweep and Assess

Clear any furniture or plants from the deck, grab a broom and clear off  surface debris. As you traverse the deck, make note of any split, splintered or rotting lumber, raised screws or nails, rusted hardware  and any other problems which will need to be addressed.

Photo By: Photo by Mick Telkamp

Select a Cleaning Solution

Diluted bleach is a popular choice for deck cleaning, but isn’t necessarily the best choice. Over time, stain is more likely to fade or discolor and bleach can hasten the degradation of the wood. Instead, select a cleaner formulated specifically for deck cleaning and follow manufacturer instructions regarding dilution and application.

Photo By: Photo by Mick Telkamp

Apply Cleaner

Deck cleaner can be spread by using a brush or broom to sweep across the surface or applied using an inexpensive tank sprayer as shown here. Make sure all edges, corners and gaps are treated as will as the deck surface. Follow manufacturer instructions regarding use, but in most cases, the solution should be left to soak on the wood for a period of time before continuing.

Photo By: Photo by Mick Telkamp

Pressure Washing

A pressure washer is a powerful tool for cleaning a deck. Take care to select a nozzle appropriate for the job. Spray nozzles are categorized by the angle of the spray. A zero degree “red tip” provides the most powerful stream, but can damage the soft wood. Consider a nozzle with a spray angle of 25 or even 40 degrees to clean your deck without scarring the surface.

Photo By: Photo by Mick Telkamp

Controlling the Spray

Hold the spray wand at an angle to push dirt and grime away from the contact point. Use consistent motion and distance for uniform cleaning without the risk of pitting or scarring.

Photo By: Photo by Mick Telkamp

Repeat Cleaning Process, If Necessary

If it has been a long time since the deck has been pressure washed or has been subject to unusual mildew or staining, a second application of deck cleaner and another round of pressure washing may be needed for a thorough cleaning. If you were on the fence about applying a new stain to the deck, it may be easier to decide once you’ve seen it at its cleanest.

Photo By: Photo by Mick Telkamp

Tap Down Exposed Nails

Wood shrinks over time and nails that were driven flush with the surface of the deck may need to be tapped down.

Photo By: Photo by Mick Telkamp

Replacing Planks

Planks that have cracked, split or rotted may need to be removed. Individual planks may be pried up and replaced with new lumber of the same type. Although a structurally sound choice, newer wood will not match older when using a clear sealer or a semi-transparent stain.

Photo By: Photo by Mick Telkamp

Selecting a Stain

If the lumber used to build your deck looks just perfect in condition and color, you may elect to apply a clear sealer. For most of us, the deck will benefit from a little color, but the choice of stain used will vary with preference and deck condition. A deck that is in good condition with minimal splintering and uniform color throughout is a good candidate for a semi-transparent stain, which soaks into the wood and leaves the grain of the wood visible. Solid stains, as we use on this project, coat the surface of the wood like paint and will hide replaced lumber and minor weathering. If the condition of the wood is especially weathered, a resurfacing stain containing grit is a forgiving choice and can hide cracks as deep as 1/4".

Photo By: Photo by Mick Telkamp

Apply Stain

Plan to stain once deck is completely dry and no rain is in the immediate forecast. Tape off edges as needed and make sure no debris is present. A paint pad or roller can be used to apply stain to the deck, but care should be taken to apply evenly. Solid stains are more forgiving, but uneven application or “touch up” spots will stand out when using semi-transparent stains.

Photo By: Photo by Mick Telkamp

Corner, Gaps and Railings

A paintbrush should be used in corners, railings and in gaps between planks. Railings and gaps between deck boards require special attention and can impact the amount of stain and time needed for the project.

Photo By: Photo by Mick Telkamp

Solid Stain

While the look of solid stains obscure wood grains, pitting, scarring and other indicators of age and use are hidden.

Photo By: Photo by Mick Telkamp

Leave an Escape Route

Apply stain from corner or wall to deck edge to allow an egress when finishing up.

Photo By: Photo by Mick Telkamp

Continued Maintenance

A yearly cleaning and inspection will keep the deck looking good, but expect to re-stain in anywhere from three to 10 years, depending on the type of stain used. Proper care and maintenance of your deck can drastically increase its lifespan with minimal expense.

Photo By: Photo by Mick Telkamp

Once you've swept all debris from your deck, you're ready to power wash. Be sure to start washing in a place that you wouldn't have too much trouble replacing—a smaller board or a step, perhaps—in case your setting is off for some reason. Better to damage a small portion of the wood in a less prominent location than a centrally located, larger piece.

Once power washing is done, you'll want to apply a degreaser/stain remover, or a professional grade deck cleaning solution. Be sure to follow the manufacturer's instructions for mixing. One other factor to consider is that it's often recommended that you apply the cleaner in the early morning or evening hours so that the cleaner doesn't evaporate in the sun.

Once the cleaner has been on the boards for the period the manufacturer recommends, spray the deck clean with the power washer. You should then allow at least 24 hours before applying any further treatments or stains to the deck, in order to ensure that it's completely dry.

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