This time of year gets my family into spring cleaning mode, and our deck doesn’t get a pass just because it’s outside. After months and months of rain and persistent dampness, our beautiful capped composite deck picks up a bit of a green hue from the accumulated moss—literally, it turns green. Something I’ve learned about decks is that there’s deck cleaning protocol for North America in general, and then there’s deck cleaning protocol for the Pacific Northwest, that's on another level altogether. Our climate is just not kind to decks.
This cleaning method is very specific to composite decking, but across the board, any deck you have is going to need a similar regular cleaning. If you have a wood deck, read this.
Step 1: Move Furniture and Prep the Deck
Corte-Clean is a cleaner formulated for composite decking, so anything that is not made of composite material needs to be covered, including wood, metal, and glass. That means all removable furniture should be removed from the deck until you’re finished. If you have any permanent structures that can’t be temporarily relocated (like your railings or our fire pit) use plastic sheeting and tape them off to keep them protected. Finally, wet down any plants adjacent to the deck to help protect them.
Step 2: Remove Debris
Before cleaning, get every leaf and loose piece of debris off the decking surface. We have a blower, but you can use a broom. Try using a putty knife to get in between the boards on the deck, and unstick any standing dirt.
Step 3: Mix Cleaning Solution
Make sure you put on gloves before you get started!
Corte-Clean comes as a powder, and we’ll be mixing it with water to make a solution to spray on the dry deck. Dispense the powder into a pump sprayer: It’s basically a big bottle with a little pump that builds up pressure so you can spray the contents onto the deck. The pump sprayer is the easiest way to coat the deck evenly. Keep in mind that when you’re using a pump sprayer, you have to make sure all of the crystals are mixed into the water—otherwise they will get into your sprayer, and clog it. (That only happened to me with three-or-so pump sprayers before I learned my lesson.) Mixing with warm water will dissolve granules more quickly.
There’s a little scoop in the bag to help you measure the Corte-Clean powder. The packaging says you should start with two to two-and-a-half scoops per gallon, and up to five (if your deck is in desperate needs of help). The Corte-Clean website has specific instructions for capped composite decking. For that kind of decking, you’re supposed to use one to two scoops. We tried it with one scoop, and then we moved to two because we needed that extra help. If you're not sure if your deck is capped composite or not, look at the exposed end of a board. Capped composite boards will generally have a hard, outer coating (like an M&M candy) surrounding the rest of the board.
Step 4: Apply Cleaning Solution and Scrub Where Needed
Pump up the sprayer and spray the solution onto the deck—working in 10 square foot sections.
Corte-Clean recommends only spraying up to 10 square feet at a time, because you need to let the solution sit before scrubbing the deck and rinsing the surface. The solution has to be wet when you scrub and rinse it, so if you do too big of a section the product starts to dry too quickly and the timing gets off. This is pretty typical of deck cleaning; It’s similar to using Penofin cleaner on a wood deck. You can do different sections at a time instead of waiting 20 minutes for each section. Let one section sit while you’re scrubbing another so you stay efficient. If it begins to dry, mist the deck with more Corte-Clean. You want to keep it wet during that 20 minutes, so it has a chance to dislodge all the grime.
Corte-Clean explains in their instructions that you can clean a composite railing at the same time as your deck (if you have a composite railing, that is). They recommend that you clean the railing by starting at the top and working your way down to the bottom.
Depending on the state of your deck, you may need to scrub. We found this out the hard way—by not scrubbing during the first go-around. The deck was still green and slimy after we rinsed it, which was a pretty clear indicator that we needed to go back and put some more work in! Again, this is just the cost of living in the evergreen Pacific Northwest.
Note: Rain boots are not a necessity for this job, but if you don't have them I would go for old shoes that you don’t care about. If you have an unwieldy hose, your feet will get wet.
Step 5: Rinse Well
Once you’ve scrubbed, rinse the deck and move on to the next section until the entire deck is clean.
Something I noticed was that I rinsed and rinsed and rinsed, and there still seemed to be little sudsy bubbles on the deck. I worried that it would be bad if I didn't rinse every last bit off! But I looked it up later and learned that the bubbles are part of the Corte-Clean design. You can leave it sudsy, and it will reactivate and continue to clean the deck when it gets wet again.
Working on this project confirmed a suspicion I’ve had for a while: that the rules for cleaning decks in the Northwest are different than they are elsewhere. There’s a higher degree of cleaning you have to deal with. Corte-Clean suggests doing this treatment twice a year, which I think might be the difference between using a ton of elbow grease and not having to scrub the deck at all. But for now, I’m just going to enjoy a deck that looks brand new.
A special thanks to Swansons Nursery for lending us the beautiful flowers and plants seen in the decking photos below! To find some great flowers and plants for your own deck or garden, check out Swansons Nursery.