How to Clean & Stain a Timber Deck

It is very important that this is a two-part job:

Part 1 is how to Clean a Timber Deck, while Part 2 explains how to stain the deck.  You must clean the deck before staining.

You will need the following;

  • Eye protection.
  • Rubber Gloves
  • Paint Scraper
  • Stiff Bristled Brush (plastic bristles)
  • Plastic Drop cloths (to protect plants)
  • Push Broom
  • Deck Cleaner
  • Penetrating Oil Stain or Deck Sealer
  • Water based stains should be avoided UNLESS you have to walk on the
  • Deck within a couple of hours.

You should do an annual inspection on your deck looking for any loose boards or other structural components and look for rotting wood. Tell tale signs of rotting wood include discoloration, mould and softness when pressed with a hard object such as a screwdriver. If any soft wood or dry rot is discovered, replace the piece.

(See How to Replace Rotted Boards following this article)
The first step is to prepare the wood surfaces by removing loose surface finishes and paint. Using a sharp paint scraper remove any loose solid stain, paint or finish. What does not come off by scraping will have to be removed by hand sanding.

For sealed film finishes such as varnish or paint, you will need to strip this off with a chemical stripper. Sanding would be a better option. This is however a fairly difficult task and is probably better left to the experts.

Make sure you have on your rubber gloves and eye protection when using a chemical stripper. Apply the chemical stripper according to directions. Usually you will apply it in smaller sections and wait for it to work, and then scrape the loosened finish away from the wood. For stubborn areas, you may have to apply the stripper a second time. You can also get in tight corners by using a putty knife. Rinse the stripper away as required by the instructions.

If the deck is simply weathered and only needs Cleaning follow the steps below.

Once the wood is scraped and stripped if necessary, the next step is to apply the deck cleaner. There are a few types of deck cleaners or deck restorers on the market.

They typically fall into three main types of cleaning base categories

Oxygen Bleach cleaners, This is effective in removing mildew stains and greying caused by ultra-violet sun exposure on the wood and effective in cleaning the wood of dirt and deposits. The wood returns to its original colour after cleaning with this type of cleaner.

Oxalic Acid Based cleaners do nothing for removing mildew stains but are effective for removing tannin stains. Tannins are natural occurring water-soluble resins of a reddish brown colour found in wood such as redwood, cedar and oak. Usually this type of cleaner is used as a supplement to Oxygen Bleach cleaners if tannin staining is a problem.

Your Hardware store has Timber Deck Cleaning products, ask for their advice.

Protect your shrubs and plants with a plastic drop cloth. It is also a good idea to hose down the surrounding area with water to immediately dilute any deck cleaner over spray. If you splash the Cleaner onto paintwork, it WILL stain it.

Wet the Paintwork 1st Mix the deck cleaner according to directions and put on eye

protection and rubber gloves. Spray or Broom the deck cleaner onto the deck.

Do not try to cover the entire deck surface at one time. You will want to work in sections and let the deck cleaner do its work.

Let the cleaner set for a period of time as recommended by the manufacturer, usually between 10 and 20 minutes. Once it has been working for the specified time, use a hard bristled broom and scrub the deck clean. Please note that if you leave any stains they will be visible later. It will probably be impossible to get the deck 100% clean. Just do the best you can. Sanding is the only option if the Deck will not come clean enough for what you expect. Work with the wood grain, not against it. Rinse with water scrub to remove any remnants of Cleaner. Repeat the process on the next section of deck. Allow the deck to dry for about 2 days before applying the Protective coating.

Select a penetrating clear or tinted sealer or solid colour stain, as you desire. Buy a clear or semi-transparent stain if you want the grain of the wood to show through. Buy a solid stain if you want the finish to look like paint. Do not use paint. Make sure the stain or sealer is “Water Repellent” I prefer a Tinted Transparent Stain, IE. Cedar. This will help even out any colour differences due to aging or stained spots.

DO NOT: Use clear finishes such as polyurethane or varnish as they will degrade under the sun’s UV rays. Using a Lambs wool Applicator and a Roller Tray for the stain. Apply the sealer or stain. The wood may be very porous at this point and may absorb the sealer or stain quickly. Two or three coats will allow the Stain to build up. Do not apply too much at one application. For railings, balusters and in between deck boards a Lambs Wool Applicator may not work so use a brush if required.

Let dry as per the Instructions on the can. Try to apply one coat of Stain at least once a year and all you will need to do is wash the deck with a household cleaner and apply the stain. Then you will keep the deck looking good for much longer.

How to Replace a Deck Plank

Locate the damaged section between one or two joists, whichever will make the cut look more natural.

With a framing square as an edge guide for the jigsaw cut the damaged section of plank out alongside the inside edge of one of the joists. Repeat the process and cut the other edge of the damaged plank again alongside the inside edge of a joist. Remove the damaged section of deck board. With the damaged plank removed, you now need to install supports at either end of the opening for the new deck board. Cut two (2) 300mm (12″) long sections of 50mmx100mm (2”x4”) support blocks.

Take one of the 300mm (12″) support blocks and place it centered under the opening alongside one of the joists and pulled hard to the underside of the deck boards. Nail the support block to the joist face with two (2) 65mm (3″) spiral shank galvanized nails. Repeat this process for the other end of the opening, fastening the second support block to the other joist face in the same manner. With the support blocks in place, it is time to install the new plank. Cut the new deck plank to length, making sure to make a square cut on each end. Note the end grain pattern of the replacement plank and orient the end grain rings so that they curve upward. This will help prevent cupping as the plank weathers. If the decking is not cedar, redwood or pressure treated lumber; it will need to be treated with a preservative.

Do this before installing the plank. Drill pilot holes through the new plank into the support structure below and fasten with 65mm (3″) galvanized (Stainless Steel) decking nails or deck screws. If you drill first the timber will not split!

If replacing full lengths of board you can use the existing sub structure to support the boards without needing to install new supports.

Enjoy that timber deck!

Handy Hint – How to Clean & Stain a Timber Deck was provided by the Maroochydore Handyman. If the job looks a bit tough, do not hesitate to contact us.