Restore your deck’s natural beauty while sparing your back — use a floor sander and polemounted brush.
You don’t need to wreck your back or your knees to resurface a neglected or badly finished deck. Just rent a floor sander, the kind you’d use on indoor hardwood floors, and buy a staining brush with a threaded base that accepts a broom handle. These two tools enable you to cover large areas quickly and tackle most of the work while standing upright.
Don’t confuse resurfacing with regular deck maintenance, which includes cleaning the surface every couple of years and applying a fresh coat of finish to protect the wood from moisture and sun. However, if the deck surface is badly weathered, or if the finish has failed and peeled, sanding is the best solution short of replacing the boards.
The deck shown here was painted with a solidcolor, waterbased vinyl/acrylic stain. The coating peeled, the nails popped and some of the boards cupped. Sanding not only removed all of the finish, it also helped flatten the irregular surfaces and exposed sound wood so the new semitransparent stain could bond.
It’s possible to blast away old finish and weathered wood with an 1,800to 2,600psi pressure washer, but this usually batters the soft wood and leaves the harder grain as knife edges that need to be sanded anyway. Resurfacing with a floor sander does the job in one step. Power washing also would have set us back a couple of days while we waited for the wood to dry thoroughly for sanding and finishing. We sanded this deck with the floor sander. Of course we could have sanded the whole deck with a belt sander. But using the floor sander was faster and easier on our backs. We finished the perimeter with a belt sander and touched up the edges of the planks with a scraper. We also used chemical paint stripper to clean a few knot holes. In hindsight, it might have been even easier to pressure wash the edges between boards rather than scrape them, but we didn’t want to wait for the wood to dry.
Using the sander
Before sanding a deck, counter sink all nails or screws and replace rotten deck boards. If a fastener protrudes above the surface, it will tear the sandpaper and could damage the sanding drum. We can’t tell you how deep to sink the fasteners; it depends on how much material you remove. But fasteners will rust if you sand off their protective coating, so sink them deep enough to avoid damage.
The Essex SilverLine SL8 floor sander we rented was far easier to control than the sanders available years ago. The motor automatically maintains a constant speed of 1,800 rpm regardless of the load. This provides greater control and more consistent sanding results. The sander also pivots back onto its casters unless you raise the handle, making the drum bear down on the surface. This reduces gouging as you start or stop each pass. The key to working quickly and easily is to let the sander do the work. Since the 115pound tool bears down on the surface, you don’t have to exert as much force yourself.
Like many decks, this one Was built with 2x6 (51/2in.wide) lumber. The 6 in. dia. Sanding drum is 8in.wide, so it sands the full width of a plank in one pass to achieve an even surface. It’s not important to remove every bit of weathered wood in a single pass. Working in long passes whenever possible gives the best results. Short back-and-forth passes may leave small gouges that show when you apply a finish.
To achieve uniform results, begin by sanding with the grain. The more cupped the planks, the harder they will be to sand. You may have to make multiple passes with different-grit paper or touch up tough spots. If the sander is not aggressive enough, you have two options: switch to a coarser grit or adjust your sanding angle. The least aggressive sanding direction is with the grain; the most aggressive is perpendicular to the grain. If sanding perpendicular to the grain is too forceful, consider switching to a finer abrasive.
You use upright floor sanders and portable belt sanders differently. You can skew a belt sander so the belt is at an angle to the grain while moving the tool parallel to the grain. That’s not possible with a floor sander. If you move the floor sander at an angle across the planks, it’s likely to splinter the edges and tear the paper, particularly if the boards are cupped.
A floor sander works whether you are moving forward or backward, but it is most effective and easy to control when you pull back against the direction of rotation. Lift the handle and walk backward slowly and evenly, stopping a safe distance from the opposite edge of the deck. Sand one plank at a time and ease the pressure on the sanding drum as you begin or finish a pass. This avoids lap marks.
Always use the highest-grit abrasive that removes the surface effectively without scratching it excessively. If you will be removing paint as we did on this deck, start with 20to 30grit abrasive. Try the finer grit first and only use a coarser one if you have to. You may want to make another pass with 40to 50grit to remove scratches before finishing with 60grit. If you’re not removing paint, begin with the 60grit.
While you’d use sandpaper as fine as 100 grit for final sanding of interior hardwood floors, do not go finer (higher) than 60grit when sanding deck boards. If the surface is too smooth, the finish will not adhere as well. Change the sandpaper when its performance drops.
Remove residual sawdust with a leaf blower before applying a finish. We finished this deck with a 1in.thick by 4in.wide polemounted Hanlon & Goodman Stainer brush. The fat applicator held lots of finish and the pole enabled us to make long strokes without bending over.
Follow the finish manufacturer’s instructions. To avoid lap marks or skips, finish the edges of a couple of planks and then coat the tops from one end of the deck to the other. Complete the rest of the deck a couple rows at a time.
The sander comes with a big dust-collection bag. Use it, even if you don’t mind making a mess outdoors. It’s unhealthy to breathe sawdust, especially from treated lumber. Empty the bag when it is half full — any fuller and the airflow and sanding performance will decline.
The floor sander is relatively quiet, but the smaller belt sander is loud enough to warrant hearing protection.
Be careful to keep the cord away from the sander while you work so it doesn’t wrap itself around the drum. It helps to drape the cord over your shoulder and start sanding near the power outlet so the cord trails over the sanded decking. Floor sanders draw a lot of power — about 14 amps — so plug into an unused 20amp circuit and avoid using a long extension cord.
Bestt Liebco (Hanlon & Goodman)
Philadelphia, PA www.paintbrushes.com, (800) 5239095
Essex SilverLine, Dracut, MA www.essexsilverline.com