By CALEB ROTH

Homeowners often discover that wood decks and fences require more maintenance than expected. Without a clear guide, it’s easy to make mistakes. Naturally, I receive a lot of restoration questions about exactly how to go about cleaning a wood fence or deck from those seeking to beautify and protect these important exterior features.

Some contractors may lead you to believe that cleaning and prepping your wooden structure is quite complicated, and they may even overwhelm you with loads of fancy chemical names and industry lingo. This is merely a sales technique.

While there are certainly several things a homeowner should know about deck cleaning, the process is relatively simple. Here’s what you need to know to clean, restore, and protect your client’s fence and deck like a seasoned professional.

Is it necessary?

For those wondering if cleaning is “really” necessary, the truth is that – if you have a brand-new fence or deck – it probably needs little more than a quick sweeping to remove leaves and debris from the surface.

On some high-end projects, it is not uncommon for a professional to do a light deck cleaning to remove footprints, dirt and lumber stamps that often appear on brand new wood – but nothing more.

At the other end of the spectrum, older fences or decks may need more obvious cleaning as soon as 6-8 months post-installation.

Lumber begins to deteriorate as soon as it is cut, so the sooner a high-quality oil-based stain and sealer can be applied to preserve the wood, the better.  If your fence turns grey or begins to show black mold, the time to act is right away.

When considering how to clean a wood fence or deck, any maintenance is better than none.  There is ongoing debate about how to clean wood surfaces like these and what products to use.  If you ask 10 contractors, you will likely get 10 different answers.

First and foremost, any mold, mildew and grime must be removed, but you may not know how to go about eradicating it.  Just about any of the methods

detailed below will work well and give better results for wood staining and sealing on a fence or deck over doing nothing.

Option one is to simply wet the fence down, scrub it with a brush and rinse well to remove loose particles.  This largely removes grime but does not kill the mold and mildew that will eventually destroy your investment.

Is bleach safe?

Option two is most common, which entails mixing up a chlorine bleach solution at a 1:1 ratio to clean your fence or deck.

This will not only kill the mold and mildew but also remove oxidization and brighten the wood.

Simply put and without question, bleach works for these purposes. Some contractors will scoff at – or outright reject – this method, probably because they simply cannot charge top-dollar for this service.

It’s important to note that, in some cases, after the wood is cleaned with bleach, it might turn an unnaturally light colour. However, if you’re staining a fence or deck with a coffee brown, walnut or deep cedar-toned stain, you’re likely to achieve the desired colour.

The main goal is to achieve a clean slate and consistent colouring so that everything is uniform once the stain is applied.  Is bleaching exterior wood features for everyone? No, but it is certainly an effective way to clean a fence or deck before staining.

Premium options

A final option is what one might refer to as a high-end cleaning service. This is a three-step process, and we do recommend this method if your budget will allow.

It starts with a sodium percarbonate cleaning solution applied to the surface of the wood. That will need a little time to work its magic, but it will penetrate deep into the wood.

In doing so, it will kill the mold and mildew and loosen dirt and debris on the wood’s surface.  Once that is done, it’s time to pressure wash.

In many regions, the most common lumber types are treated pine and Red Western cedar.  With these and other lumber types – while pressure washing wood is effective – it is imperative that you do not go overboard with it.

Be sure to use a relatively low pressure to simply wash away the dirt and grime. Some pressure washing companies will clean your fence or deck with extremely high pressure and, while it may look good at first, it can actually destroy the integrity of the wood and cause felting (causing a permanently fuzzy look).

Once the wood pressure washing is complete, you will want to adjust the pH level of the material with a brightener, which will give the wood a beautiful, brand-new look. This will also create a great canvas on which to apply a high-quality, oil-based stain and sealer.

While different cleaning recommendations abound, the best option is to choose what you understand and are comfortable with.

Critical sealing

As a final step to fully restore a wood fence or deck, it is of the utmost importance to stain and seal the material. This should entail a deep penetrating oil-based stain and sealer in one.

Generally, we have found three commercial grade brands to be top quality and well-suited not only for fence staining, but deck staining as well – and as a wood sealer. Once the deck is cleaned you need to wait a few days for the deck to completely dry out, a moisture meter can help you determine this.

Thirteen percent or less moisture is the ideal condition. In my experience I have found that penetrating oil-based stains work best to preserve and protect the wood and have the most depth of colour. There are plenty of low-VOC oil stains on the market today to choose from.

Penetrating stains are my choice because they never peel, crack or flake away, which means maintenance later on is much easier than a finish that is peeling and requires harsh chemical stripping or sanding.  When you apply your stain be sure to mix the stain very well and if you are using multiple containers of stain intermix them to ensure colour uniformity.

Be sure to leave no puddling or pooling stain on the surface as this can create a tacky finish or dark spots. Once the stain is applied, I recommend cleaning up your work area and, after about 20 minutes, be sure to wipe up any stain that did not penetrate to leave a beautiful matte finish.

Stain-sealer combos

There is often confusion between stains, sealers, and stain and sealer combos.  Most standalone stains are made for interior use and require a clear topcoat for hardness, these do not work well on decking and should be left for interior use.

Clear sealers are often used on decking, but they contain very little if any UV protection and allow the wood to turn grey naturally.  This is more of a water seal and has its place.

The best bang for your buck when it comes to deck finishes is the semi-transparent deck stain and sealer. This gives you the best of both worlds, rich colour that blocks UV rays, keeping the wood colour beautiful and a sealer that protects from water intrusion, warping, cracking, and splitting.

Semi-transparent stains work well on most lumber species. However, if you have an exotic hardwood deck such as Ipe, Tigerwood, Mahogany, etc. you will want to opt for a clear oil sealer as pigmented stains cannot penetrate the dense wood fibres of exotic hardwood.

Best practices

The industry standard for cleaning a wooden deck is once per year with a very mild deck cleaning product and recommended stain recoats or touch-ups on decking are every 4 years on vertical surfaces like railings and privacy screens, and every 2 years on horizontal surfaces like floors, landings and the tops of railings.

Some stains will outlive these recommended staining intervals, but following this schedule will keep your client’s deck looking great for years to come.

Composites are great, but many composite decking owners complain that their deck can be hot under your feet.  Some composites also tend to fade over time, and they are more costly up front.

Many surveys show that most people prefer the look of a well-maintained wooden fence or deck over composites. Keeping your deck looking great isn’t difficult, it just requires some proactive maintenance.

– The writer is Founder and CEO of Restorative Industries, based in Alexandria, Tennessee (USA). The parent company of a vertically integrated ecosystem of brands dedicated to elevating craftsmanship, education, and operational excellence in wood care. He founded Staining University, a free national training initiative that’s empowered thousands of tradespeople. (www.RestorativeIndustries.com)

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