STEP 1: Inspection—Is it a keeper?
The most common places for hidden rot are where wood meets wood (butted boards) or wood meets concrete. If you haven’t protected your deck in a long time or not at all, take something hard and pointy, like a flathead screwdriver, and poke around. You will probably find soft or even hollow boards that require replacement.
Counter sink nails by driving the screws and/or nails further down into the wood, so the deck can be sanded without shearing off the tops. Tighten screws on the salvageable floor boards, and then poke the joists to see if any are rotten.
Your joists should be pressure treated wood, at least 2x8 in size and no more than 16 inches apart, with hangers attached to the ledger board if your deck is attached to the house. Look under the deck to see if the posts are cracked and/or crooked. Are there concrete piers under the posts, and if so, have they heaved? There is no sense in refinishing the surface if the substructure is rotten and/or unsafe.
By code you must have a 36-inch high rail system if your deck is higher than 24 inches off the ground. Check it for movement and rot. Your rail should have 4x4 (at least) posts every 4-5 ft. secured to the deck with bolts. Your balusters—the vertical pickets on your handrail—must be vertical, secured by two 2x4 rails spaced no more than 4 inches apart. And always remember to check the building codes in your area, and that your deck meets them.
STEP 2: Power Wash—It all comes out in the wash…or does it?
A power washer is a removal tool—not a finishing tool! It can also be a weapon in the wrong hands.
A 2500/3000 PSI (pounds per square inch) with 2.2/2.5 GPM (gallons per minute) pressure washer is plenty to do the job. Use a wide fan and determine how close the wand should be to the surface by experimenting on an area that is relatively unnoticeable. If you see the fibres of the wood starting to rise (bur) back off slightly.
If your deck has a significant amount of old product on it you may want to apply a stain/paint remover. Just be sure to follow the instructions on the container and wear proper protective gear. You should also be careful not to get any product on your garden and/or lawn. But if the old product on the deck is raised and chipping the washer should be able to remove most of it without needing to rely on harsh chemicals.
An anti-mildew treatment is key during this stage and is highly recommended. I still like TSP (Trisodium Phosphate) for its effectiveness, plus the formula is now biodegradable. Again, test your concentration level and wand distance on an inconspicuous section of your structure. You want it to be as strong as possible without burning.
As you start to see wood grain you will probably feel inspired to move ahead and stain—but don’t be hasty! If you were really successful at this stage, you have probably removed approximately 80 percent of the surface mildew, leaving approximately 20 percent behind. This still allows residual fungus deep inside the pores of the wood to rise and settle on top of the boards. Leaving this mildew and staining over it allows it to continue to grow under your protective coating, and eventually rear its ugly head when it pops through in the form of peeling.
The inconsistences in the porosity of the surface created by the spray will also cause flaws in the coverage of your protective coating. Large wide open pores or cells will take in a lot of stain while small or closed pores will not take any. This is why it’s important to sand your deck before staining it. But remember to let your deck dry a couple days after power washing it before moving ahead to the third step.
STEP 3: Sanding—A hidden art form
For this stage you will require sunshine, a belt sander, palm sander and a sanding sponge along with belts and paper. This is the least glamorous part of the project to say the least; it’s dusty, dirty, and tough on the muscles—and potentially a health hazard without the right protective gear. An N95 rated (or higher) respiratory mask, tight-fitting work gloves and goggles are required.
Many people use the upright floor sanders that you can rent at your local home improvement store. I can’t blame them for this because there’s usually a lot of deck to do in a short amount of time. The problem I have with these machines is that they are made for indoor hardwood floors. They are heavy, 8 inches wide and perfectly flat. Your deck boards are not generally 8 inches wide, nor are they perfectly flat. If your deck boards were installed correctly (crown-up) they should be slightly convex. If not, over time they may become slightly concave (cupped).
Neither surface can be sanded with that large machine without taking too much wood off some boards and/or not enough on others. This is why my crew (the dedicated pros that they are) are down on their hands and knees with handheld 4-inch belt sanders that are easier to manipulate. We start with a heavy 50-grit belt and work backward on the boards to remove the remaining mildew and old product. The palm sander helps to finish the board ends and other areas that can’t be reached by the belt sanders. We also do what we respectfully call an Amish style sanding where we use a sanding sponge wrapped in sand paper and by hand, sand the areas that the palm won’t reach.
We then do a finishing and detail sanding by taking a lighter 60/80-grit and repeat the process. Finish sanding is meant to create consistency in the porosity of the wood, so the stain coverage is consistent and is absorbed as much as possible into the wood. Remember: Large open pores absorb a lot of stain while crushed pores take no stain. Detail sanding means that every nook and cranny has been addressed so that we will have a well-protected work of art when completed.
Many think that staining is the only artistic part of the project, but proper preparation of your canvas is an art form in itself. If you leave your belt or sandpaper on too long it will crush the cells and not allow the stain to absorb. If you use the wrong grit on a bare surface it can leave marks or scars that won’t show up until you stain. If the finish is inconsistent, your translucent stain will go on blotchy. If it rains during your project and you can’t protect the surface, your finish sanding is a do-over because the moisture has furled your surface. Direct sunlight will cause discolouration so the part you sand today will be a different shade than what you sanded yesterday, which is a big deal if you want a natural wood grain finish.
STEP 4: Staining—Maintenance vs aesthetics
After all that hard work it’s time to decide how to protect it.
Here are your stain options:
Clear – Let’s get rid of this one right away and forget we ever heard the term! Clear coats should never have been created for outdoor use. They provide no protection from sunlight and dissipate almost as fast as they go on.
Translucent – It’s the only way to have a protected natural wood grain finish. A translucent coat is meant to accentuate your canvas by highlighting your newly restored wooden structure. You have different colour choices, such as light, dark or reddish. The lighter “natural” stains will allow that wonderful colour spectrum of wood grain in cedar to be the star. It’s a one-coat application that has to be a gentle balance between too little
and too much.
Semi-transparent – These provide more consistency in colour and wood grain. They are an option for those who want a wood feel without the eccentricities of the different colours coming through. But know that after additional maintenance coats it loses its transparency.
Semi-solid – These have a little more pigmentation than semi-transparent coats.
Solid – Just like it sounds, a solid stain is like paint and can be colour-matched to other structures. Perfect for horizontal surfaces, it’s very clean and can provide great accent and contrast when combined with natural finishes. Apply 2 coats within 24 hours.
All stains should be applied with a proper stain brush. With a brush you can work the stain into the surface of the wood and control the consistency. Sprayers don’t give you that luxury and can get very messy with floating stain landing on windows, pools and even automobiles. Rollers will keep you off your knees but can create pooling that will peel.
Follow these steps and you should be well on your way to getting that deck you’ve always envisioned. For more information on what to do next and how often you should refinish your deck, check out my article The Truth About Deck Maintenance.