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I inherited a deck with my new house. I'm thinking about resurfacing the deck because the boards are badly discoloured, although they appear to be structurally sound.

I'm trying to convince myself that purchasing a $500 thickness planer and planing 1/16" or 1/32" off the surface of the boards is a better use of funds than just buying new boards. Will I have problems running 16' deck boards through a planer and will I get a nice result? Will the pressure treated chemicals, or the years of tree muck adhered to the surface of the boards wreck the planer blades?

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    Before disassembling your entire deck board by board, have you tried pressure washing it?
    – Doresoom
    Apr 4, 2016 at 20:02
  • Is the decking screwed or nailed? If it has been around for a while it may be very difficult to unscrew the boards. Better do a test removal before buying a planer for the project. On the other hand, a planer is great for a woodshop!
    – Ashlar ♦
    Apr 4, 2016 at 21:54
  • I would love to see a picture. Pure discoloration can be addressed.
    – Matt
    Apr 5, 2016 at 1:13
  • I took the boards off before the winter. It was a bit of a pain, but needed to be done for some other renos. Hence my thought to run them through a planer while I have them off... I'll try laying them out in the driveway and see what a pressure wash does to them.
    – Rob
    Apr 5, 2016 at 19:21
  • A decent pressure washer will fix these right up more than likely. You may want to spray them down with a little bleach water a few minutes before if they have mold. Done it plenty of times and they always come back looking like new.
    – Colton McCormack
    Apr 5, 2016 at 19:49

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Cleaning the deck is the right call here. I wouldn't in general countenance planing PT stock (or doing any other operation to it in bulk, especially sanding). Yes you can protect yourself from the dust at the time you're working it but without being alarmist, every particle of it should be considered a potential toxin.

Pressure-washing alone can do an amazing amount to restore the original appearance of your deck boards, you can literally go from grey and filthy to like-new condition:

Pressure-washing results

!!

Video for anyone doubting that power-washing alone can do this, here.

If your boards are especially dirty and/or weathered use of one of the commercial cleaning solutions and/or 'deck brighteners', coupled with pressure-washing, is sure to sort the boards out.

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  • The "wants new tool" part of me doesn't like your answer :), but I'm going to try a pressure-wash and see where it gets me. As soon as the weather gets a little nicer that is. There's a big tree growing through the middle of the deck which drops sap all over it so I may have to add a chemical cleaner in as well.
    – Rob
    Apr 5, 2016 at 19:19
  • @Rob, totally understand the "wants new tool" bit, but I'm sure you'll come up with a gooder reason fer gettin' it :-) Seriously though, a thickness planer or a jointer is perhaps the one power tool that could be considered a must for the home woodworker (if budget allows) to make processing of rough stock time efficient given the typical limited time in the shop. Plus when you don't plane all the time it's hard for the work not to be punishing physically, even with far far less material to deal with than this project would have called for! Best of luck with the deck.
    – Graphus
    Apr 6, 2016 at 10:41
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Will I have problems running 16' deck boards through a planer and will I get a nice result? Will the pressure treated chemicals, or the years of tree muck adhered to the surface of the boards wreck the planer blades?

In terms of chemicals, it depends. ACQ (Alkaline Copper Quartenary) treated lumber has high levels of copper, which can promote corrosion of steel (I think due to galvanic corrosion in the presence of water, which can act as an electrolyte). The older CCA (chromated copper arsenate) lumber does not have this problem.

There should be no issue running pressure-treated boards through a planer, however, if you do a little housekeeping afterward. Give the planer a good blasting off with an air hose after you finish for the day to reduce the amount of PT sawdust left in the machine. The ACQ chemical needs time (and water, I believe) to begin corroding the steel parts. One day of the sawdust sitting there shouldn't really hurt anything.

The years of tree muck might be a bigger issue. Hardened sap can dull planer blades pretty quickly, as will the years of accumulation of dirt and grime.

Another possible issue is stray metal pieces embedded in the decking that you would miss with a visual inspection. You can buy a metal-detecting wand to try to pick these out, but that's a tedious process for the hundreds of linear feet you'll be processing as compared to just buying new stock.

I'm trying to convince myself that purchasing a $500 thickness planer and planing 1/16" or 1/32" off the surface of the boards is a better use of funds than just buying new boards.

If you don't have a planer already and want one for the shop, now might be the time to get one if you can use it for this project as well. I would be prepared to buy a set of sacrificial blades if you plan on using it for the decking since there's a very good chance they will get trashed.

Consider also the time invested in processing the boards plus the cost of the planer vs. the cost of new boards. Your time is valuable, too.

As a final note, you might just try flipping the boards over to expose a "fresh" side. My uncle recently did this for his deck and it worked surprisingly well.

As always with all pressure-treated lumber, don't burn the waste. The chemicals are no good for your lungs to breathe in.

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    Is this exactly what you meant to say: but that's a tedious process for the hundreds of linear feet you'll be processing.. I would think, with a wand, that it would be a simple and monotonous but also important step for the longevity of the planer knives and tool in general. I get the impression that you don't see the value of it given the potential time involved? Forgive me if I misunderstood. I recently ruined a set of knives with a staple that broke and when I planned 1/4" off it showed up and chipped my blades in 2 places before I noticed it.
    – Matt
    Apr 4, 2016 at 18:46
  • @Matt, what I meant is that wanding 100s of feet of lumber is more tedious than buying it new. Edited my post.
    – grfrazee
    Apr 4, 2016 at 18:48
  • Ah ok. That makes more sense.
    – Matt
    Apr 4, 2016 at 18:49
  • +1 for flipping the boards over!
    – FreeMan
    Apr 5, 2016 at 13:50
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Mostly no, but you could. I would not because if it is treated lumber you run a risk of removing the protective layer that makes the treated lumber, well... treated. So with that said I would not. But you could take the risk because it might have been penetrated deep enough. The chemicals will more than likely not even hurt the planer but the muck will, so remove that! With the chemicals I would clean up the planer after use just to be safe.

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  • +1, good point about possibly removing the chemical layer at the surface of the wood.
    – grfrazee
    Apr 4, 2016 at 18:39
  • To continue with the chemical removal you are reducing the life of the deck as it would be more susceptible to the elements (rot sooner until you retreat it with something else). Reducing the thickness would slightly contribute to that but PT lumber is favored on decks for its long life.
    – Matt
    Apr 4, 2016 at 18:51
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Rent a floor refinishing belt sander or a large orbital sander (24in disk) and keep the boards in place and sand them down. When you pull up those boards some will have a tendency to warp and twist which will be a nightmare to put back down straight.

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    Serious +1 -- that's some good thinking outside the box. I'd give the nod to the orbital version, as it's more forgiving than a belt. The OP will sadly have to come up with another excuse to get a planer.
    – Aloysius Defenestrate
    Apr 5, 2016 at 1:49
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    OOTB thinking is good, however, while planing creates chips and some dust, sanding will create clouds of toxic dust blowing around the neighborhood. The only good in this is if you don't like your neighbor's dog. (Just kidding. No, really, that's a joke!) There's also a strong chance of sanding through the pressure treated layer (the chemicals only get so deep), since it's easy to over sand a spot by being distracted, or trying to get that one nasty little stain that just doesn't want to come out.
    – FreeMan
    Apr 5, 2016 at 13:55
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I have actually done this for several decks. The first step after removing the boards is to pressure wash the boards, top and bottom, to remove as much accumulated dirt and debris as possible.

Check for any visible metal such as staples, tacks, etc and remove them, it also never hurts to run a strong magnet along both sides to be sure.

Stack the boards on an even surface and place cinder blocks on top of the stack(s) on both ends and in the middle to reduce bowing. Allow the wood to dry for at least 48 hours to lessen gumming issues on the planer blades.

As your planing the boards make sure to blow the dust off after every 5 or 6 boards, this will help keep the blades sharper longer. You will also want to check the blades for nicks and such every 20 boards or so.

Following these steps I have managed to plane PT deck boards for 3 to 4 decks before having to replace the blades.

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A thought occurred to me. Why not use a sander? Something that has a set height or, possibly better, a set pressure.

Since sandpaper is created to be worn you don't have to worry about ruined knives.

Use a course grit. If the boards feel too smooth afterwards wash them with high pressure.

Without investigating what kind of cool machines there are; why not take a hand held belt sander, fasten it to something, possibly weigh it down, put some fences around and then send a board through. Make the table beneath slippery and it might even pull the board through itself.
Then take a few pictures and write a few words and feedback!

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  • A planer would make more chips than dust. Sanding will just make dust. PT dust.
    – Matt
    Apr 5, 2016 at 11:53

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