How to clean wooden decking
Photo by Matthias Oberholzer on Unsplash

Cleaning Wooden Decking

Like any other part of your home, wooden decking requires regular cleaning and maintenance to keep looking at it best. Even more so as it is exposed to the elements all year round. There are several effective ways to do so, but most will fall under two main categories; power washing or using cleaning solutions. Understanding when to use these methods will ensure your deck remains in tip-top shape.

How often should I clean my decking?

The single most important action you can take is to give it a deep cleaning once or twice a year. Preferably, thorough deck cleaning should be carried out in early spring when the weather starts to warm. Alongside a deep clean, you should carry out regular light cleaning and sweeping once every week or two. This is important to keep your wooden decking free of leaf debris, dust and pollen that can speed up the rotting process and increase the cost of repairs.

What you will need

Your choice of tools and supplies depends on the type of cleaning you want to carry out. When conducting a thorough wash using a pressure washer, the following are the items you’ll need:

  • Pressure washer
  • Broom
  • Deck cleaners (homemade or off-the-shelf)
  • Sheets of plastic
  • Mop & bucket
  • Sandpaper
  • Sealant
  • Protective gear (goggles and rubber gloves)

For regular clean-ups, the following items will suffice:

  • Deck cleaners (homemade or off-the-shelf)
  • Sprayer
  • Push broom or long-handled brush

Cleaning without a pressure washer

Your deep cleans are important, but it is how you maintain your decking the rest of the year that has the biggest effect on durability and safety.

For these regular washes, you don’t need to use a pressure washer or powerful cleaners. Often, all that is required are consistent but thorough sweeps and occasional hand-scrubbing with mild cleaners like a vinegar + baking soda solution.

Sweeping a wooden decking is a pretty straightforward task that won’t take much of your time or effort. Grab a broom or a long-handled brush with hard bristles and use it to brush away leaves and dirt. Pay particular attention to crevices and especially those between boards where debris can collect. You might also want to use this opportunity to identify and fix any wobbly rails, loose screws, nails and boards.

Wooden decking covered in leaves
Photo by Emma Frances Logan on Unsplash

Cleaning with a pressure washer

Power washing is not something you do every day or week as it can damage your wooden decking. Before doing a thorough wash, prepare your deck as follows:

1. Sweep the area

To get started, remove any flower pots and furniture placed on the deck and sweep thoroughly to get rid of everyday dirt like leaves and dust. Use a sharp object such as a knife or screwdriver to remove any debris stuck in between boards.

2. Gently wash away the remaining dirt

Sweeping alone may not remove stubborn and dried-up dirt like mud and grime. This is where washing with water comes in. Use a wet mop to clean any soiled spots on the decking.

3. Cover plants growing by the deck

Use plastic drop cloths or sheets of plastic to cover any shrubs or grass growing near your decking. The aim is to protect these plants from harmful chemicals or excessive water pressure used for deep cleaning.

Choosing the right pressure setting and spray tip

Before power washing, it is vital that you first understand how much pressure your wooden decking can tolerate. According to WoodWorkWeb, different types of woods have varying strengths (measured in pounds per square inch or psi for short) as listed below:

Wood type Level of pressure tolerated (psi)
Cedar 990
Pine 1390
Redwood 1040
Douglas fir 1290
Black oak 1910

HGTV advises that for softwood from coniferous trees like pine and cedar, anything in the range of 500-600 psi is enough. Harder woods can tolerate more, but you shouldn’t use a pressure setting of more than 1,500 psi. If you are unsure about how much is considered too much for your decking type, start by testing various pressure levels on an inconspicuous area of the decking or check the wood type online.

Concerning the spray tip (or nozzle), a fan tip with a 40-60 degree spread will work fine for most decks. A rotating tip can also do the job equally well if you know how to use it properly.

4. Pressure cleaning your deck

Start with the nozzle of your cleaner at least 30cm away from the decking boards. Start the spray and then bring it closer until you can see that the water is cleaning without damaging them. Now, methodically work your way across the entire deck.

If you notice any stubborn areas or weak areas, pass over them lightly and save them for later. If your decking has grooves in it, you will need to work along the length of each board to remove the build-up of any dirt lodged there completely.

As you work, you’ll notice that the spray kicks up a lot of residue onto the surrounding area. This can be managed with a shielded nozzle to direct all the dirt in one direction or by working so that you always have your back to your house or anything you don’t want to cover with deck residue.

If you work methodically, all of the dirt you’ve loosened can be worked towards the edge of the deck. Any left after you’ve finished with the pressure washer can easily be rinsed off or swept up.

5. Apply a cleaner

Ideally, pressure washing will clear the majority of dirt and stains from your wooden decking. However, in some cases, other interventions in the shape of cleaning solutions are needed to deal with stubborn spots caused by mildew or rot.

Choose a product that’s designed to clean or brighten deck wood and one that also works well in pressure washers and sprayers. A couple of excellent options to consider here are oxygen bleach products and oxalic-acid cleaners.

6. Rinse with plain water

Let the cleaner sit on your decking for around 10-20 minutes (or as recommended by the manufacturer) then rinse it away with plain water.

7. Weatherise your deck

This step is optional but vital if you want to preserve the integrity of your wooden decking and protect it from harsh weather conditions. Here, you can use sealants and other similar wood treatments to prevent the formation of moulds and mildew on your decking. Besides, if summer is approaching, applying a sealer can help to block ultra-violet rays from harming the wood. This process can also effectively protect your decking against water damage during the rainy seasons.

If possible, lightly sand your deck before applying the treatment to remove loose pieces of dirt that might have remained after washing or spraying with water. Use a hard-bristled brush to apply a few coats of the sealant and allow it to dry completely before returning your furniture and flowerpots to the area. It is highly advisable to wear the correct protective gear including goggles, gloves and a safety mask when applying a wooden decking sealer.

Important dos and don’ts

Dos

  • Always cover any vegetation surrounding your decking before starting your washes if using a chemical treatment.
  • Consult application instructions provided by the cleaner’s manufacturer to minimise risks of harming your deck.
  • Conduct an annual inspection on your deck to identify potential safety concerns. Look for tell-tale signs of rotting wood, loose nails and rickety boards.
  • Seal your deck at least once a year. To test if the decking needs sealing, pour some water on its boards. If it beads up, your deck is probably safe. But if it soaks into the wood, it’s time to apply a new sealant coat.

Don’ts

  • Don’t overuse pressure washing to clean your wooden decking. Once or twice a year is enough. Too much may lead to excessive wear.
  • Don’t use chlorine bleach cleaners. They harm your decking and make it appear whitewashed.
  • Don’t use very fine sandpaper when sanding as this can clog your wooden deck and prevent the sealer from soaking in as needed. Mike Holmes of the celebrated Holmes on Homes recommends sandpaper with a 60/80 grit.

Conclusion

Cleaning and maintaining a wooden deck doesn’t have to be complicated or expensive. For starters, give the area a thorough pressure washing once or twice a year, and don’t forget to take necessary precautions to avoid damaging the wood.

Also, sweep and hand-wash your deck regularly to prevent a buildup of dirt and debris that may speed up rotting. Finally, sand and seal the wood boards once a year to protect your decking and keep it looking like new.