The main complaint that I hear from new customers is that their deck finish only looked good for one or two seasons and then it started to break down. In the mid west, we get temperatures in the 100 degree range for weeks at a time, and just a couple of months later, 0 degrees for weeks at a time. That is some very extreme expanding and contracting going on in the fibers of your wooden deck, no different than that of an accordian. Choosing the correct finish is crucial to the life and look of your deck, but just as important, are the steps and prep work to achieve that perfect finish. Following are the steps and considerations that I take in as I am figuring out how to approach each deck finish. Before you begin, remove everything from your deck, chairs, tables, grills, bird feeders, etc, take them down.
Step 1: Wood Rot
Get rid of all wood rot right at the beginning. Some places are obvious, others, aren’t so obvious. Check where two boards meet on the decking, if there is any softness to it, get rid of it. It will not get any better, and unlike trim boards on your home, bondo, or fillers, are not an option. Most board replacement is fairly easy, so make sure that you, or your contractor, take the time to get all of the rot out before anything else takes place.
Step 2: Wash
There are two types of wash that you need to consider for your deck prep; power washing, and soft washing. Many contractors just power wash your deck and call it good, I’ll get deeper into this in the next step, but power washing is not the only consideration to look at. If your deck has existing stain remaining on it and you are wanting a natural finish, power washing alone will not get you to that end, you’ll need to incorporate a stripper into the mix. Strippers can be applied by a garden pump sprayer, by brush, broom, etc, and they are designed to strip the surface completely to bare wood. You will need to mask off everything in the area that you do not want stripped; house, bushes, anything underneath your deck, because if one tiny drop gets on any surface, damage is done. When stripping, I do not recommend standard power washing afterwards to rinse, you will need to soft wash. Algae is also a factor that needs to be dealt with. There are numerous algaecides on the market that you can choose from, simply spray on, scrub with a stiff brush, and rinse off.
What I prefer for deck cleaning is a soft wash, or, lower pressure cleaning. You can apply cleaning chemicals with the power washer, and also remove them without damaging any surfaces because there are different, low pressure, tips involved than that of your standard power wash. Side note: you can also use this method for your homes’ roof, siding, sidewalk, etc. A soft wash pushes out water at a higher volume-lower pressure, and is a better alternative to the standard power wash.
Step 3: Sanding
In my opinion, this is the most critical step to a superior deck finish, it’s the step that separates a great deck finish from the mediocre. Deck sanding is about as fun as wallpaper or popcorn removal, but it doesn’t take a rocket scientist to understand the benefits from it. Here is why: when you power wash, you are actually pushing the wood fibers down; they lay over like long grass next to your downspouts in a rainstorm, hindering stain penetration. But when you sand, you are cutting the fibers down to nothing, like a little boys crew cut, and allowing stain to go deep into the pores. I start with 40 grit with a six inch sander, and do all of the handrails, stairs and decking. I don’t use floor sanders because most of the time, even on brand new decks, the boards are uneven, and you are not able to get 100% of the surface. A 20×20 deck will take approximately 8 hours to sand, and roughly 50 disks of paper. Disks are very inexpensive, $20.00 for 50 disks, so I change the disk every couple of minutes. Once complete, I take a leaf blower to get rid of all sanding dust.
Step 4: Masking
Now, you are almost ready to apply your finish, but do not get excited to see color, and skip this step. I run 8 foot plastic on the house next to the deck, mask behind posts, cover or move anything underneath the deck, mask the siding under the deck as well, cover greenery, concrete, anything that you don’t want to get finish on. Make sure it’s tight, you might start in the morning when it is calm out, and by 10AM, the wind could pick up and lay plastic over a wet finish, not a good thing, use a lot of tape.
Step 5: Applying Finish
I will do a post on which finishes are best for your project at another time, for this post, I will stick to the application side of it. If we are doing the spindles, I will start there. We start on the outside and have a painter on the inside holding a 4×8 corrugated plastic to shield the over spray. We spray through an airless, and turn the pressure down to about 20%. This makes an ugly pattern when it’s sprayed, I know, but we brush it out once the finish is on the spindles, so it doesn’t matter what the pattern looks like, I’m just getting the stain to the substrate at this point. Next, we will do hand rails. It’s tempting to 2nd coat or 3rd coat handrails because they dry so fast and it does make them look much better, but you must read the manufacturers instructions before doing this. Some stains are designed for one coat and that is all. The stain was formulated to penetrate wood surfaces, when you apply a second coat, its not penetrating anymore, it’s just sitting on top of the previous coat, and will fail. By fail I mean, come off in sheets!
Lastly, the decking. You have to make sure that you do not stop, for any reason, in the middle of a board. End to end, and keep a wet edge. I spray the decking and have another painter following right behind me with a large paint brush attached to a roller pole. I have attachments, but if you are attempting this yourself, duct tape always works. Spraying your deck with out back brushing never turns out good. It always looks light, like it didn’t cover and penetrate well. Back rolling is better than nothing at all, but I’ve found that the brush is the best way to produce the finish that I’m charging for.
Deck maintenance is a major expense, but if you keep up on it, all you have to pay for is staining, if you let it go, you have to look at carpenters replacing boards, and nobody wants to look at carpenters! (HA HA)