We get lots of questions about this when the weather cools down and people want to go back out to their lower humidity, mosquito free backyards! Taking a look in the backyard, algae and mold can form on a deck, especially in heavy shade which we have often here in Hampton Roads, Norfolk, Virginia beach, Chesapeake and Portsmouth VA. The algae and mold not only look bad, it can be very slippery when wet.
Here’s what to do with that deck to make it great! If the algae and mold are fairly light you can wash it off with a deck cleaning solution. First wet the deck down with water and spray the solution on. The directions on the bottle will probably say to let it sit for 15 minutes but I have found that if you scrub the solution in with a broom, then spray it again and then let it sit, it works much better. Do not let the solution dry out during the 15 minutes, keep spraying the deck if you have to. When you wash it off, use a hose with a good strong nozzle.
If your deck has a heavy coat of algae and mold it may take 20 or 30 times to get it clean with a deck cleaning solution. This is when it is time to get on your knees with a scrub brush or use a pressure washer. If you use a pressure washer you should know that the wood on your deck will be a little rougher when you are finished. The wood between the grain that is in the first stages of decomposing will be stripped away giving you a texture somewhat like a rough sawn cedar. If you have tender feet and walk around on your deck barefoot often,may not want to pressure wash. The great thing about pressure washing is that it will take your deck down to bare wood and you can start fresh with a stain or sealer and achieve the look you are going for. With a deck cleaning solution you probably won’t get down to bare wood but i have found that if you get it to an even gray tone you can use a natural colored stain (not clear) and achieve a nice look.
Okay, so you are done scrubbing or spraying onto staining !- The 2 main bases for stains are oil and water. Oil based stains penetrate the wood better but if they do not have an algaecide they will grow algae easier than a water based stain. The algaecides used are not environmentally or people friendly. Water based stain does not last as long but does not promote the growth of algae and is safer for people and the environment.
Types of stain include clear, semi-transparent and solid. The clear stains are water most people call water sealer. It basically leaves the deck with its natural color and must be applied every year or when you notice the water no longer beads up on the deck. Semi-transparent stains allow the grain of the wood to show through but gives the deck any color you want. Semi-transparent stains lasts about 2 years. Solid color stains give a more solid look and allow almost no wood grain to show through. They last about 4 years and will begin to peel when they wear out. The peeling affect is very unattractive, much more so than just a fading stain. Once you go with a solid color stain you can’t go back without doing a lot of work.
For me, the semi-transparent stain is the best overall choice. I like the natural wood tone colors that give the deck a high-end wood look. Just remember, the stain should last a while so go with what suits you best and enjoy your like-new deck!