Clear, Knotty, or STK for a Tacoma Deck?

If you’ve priced cedar decking lately, you’ve probably run into the tags. STK, A & Better, Architect Knotty, Custom Clear. Nobody at the counter explains them much, and the spread between the cheapest board on the rack and the most expensive one is wide enough to change what a deck costs, sometimes by a lot.

Danu Rotari runs Decks Restore in Tacoma (most of his customers call him Daniel), and he’s been building decks around Tacoma, Pierce County and the South Sound for more than ten years. He works in treated pine, hardwoods like Ipe and composite as well as cedar, so cedar is one option among several for him. We asked him to walk us through the grades and tell us which ones he thinks earn their price in this climate. The conversation has been trimmed.

Cedar decking grades at a glance

Where do you start when someone tells you they want a cedar deck?

With knots, believe it or not. I ask how they feel about them, because that splits everything in two. You’ve got the clear grades, which are pretty much knot-free, and the knotty grades, where the knots are kind of the point. Then I ask if they want to keep that red color or if they’re fine letting it go silver. That one’s really a question about how much work they want to do every year. We talk price after that. But after the size of the deck, grade is the biggest thing moving the number.

The names on the tags are confusing. Why are there so many?

Because they come from different places and nobody lined them up. There are the official grading rules from the inspection agencies, there’s whatever the yard decides to call things, and then the Western Red Cedar Lumber Association has its own four decking categories: Architect Clear, Custom Clear, Architect Knotty and Custom Knotty. Some suppliers still sell clear decking under the old rule names too, like A & Better or D & Better.

Under all of it, cedar gets graded on looks. How many knots, how big, whether they’re tight, how much of that pale sapwood shows, how clean the face is milled. It’s an appearance grade more than a strength grade.

Where does STK fit in?

STK is Select Tight Knot. It’s a yard name, not one of the association’s four. The knots are sound and tight, meaning the knot grew into the wood around it, so it isn’t going to pop out in five years and leave you a hole. If you go looking in the grading rules, the closest formal grade is Select Knotty, which has the same requirement on the knots.

The catch, and people don’t always know this, is that STK is often graded on one face. Flip the board over and the back can be rougher. It can have some sapwood in it. And since it’s a trade name, STK from one yard and STK from another can look pretty different. I go look at a bundle before I order a whole deck’s worth.

Is clear worth the money?

For the floor? Usually not, in my opinion. You walk on it, you put chairs and a grill on it, and you’re looking at it from five feet up, where a tight knot just looks like wood. Clear earns its price on the stuff you touch and look at from a foot away: the cap on the railing, a built-in bench, the fascia boards around the edge. I like doing a knotty floor with a clear cap rail. It looks finished, and you’re only paying clear prices on a small part of the job.

Now, if somebody wants that really modern look with no knots anywhere, then sure, it’s clear across the board and we have the budget talk early.

You keep coming back to sapwood. Why does it matter so much here?

All the rot resistance in cedar is in the heartwood. That’s the reddish-brown wood from the middle of the log. The pale stuff out by the bark, the sapwood, doesn’t have the same natural oils, so it holds up more like any other softwood. In Tacoma your deck is wet from about October to April, give or take, and if it’s under trees or on the north side of the house it barely dries out between storms. Sapwood in a spot like that goes soft long before the boards around it.

So when the lumber shows up I’m looking at the ends and edges for that cream-colored stripe. Sapwood on the bottom of a board that sits out in the sun, I don’t really worry about. Sapwood on the top face in a shady corner, that board goes somewhere else. The clear heart grades are all heartwood on the face, by the way, which is part of why you pay what you pay for them.

Do knots make a deck weaker?

Tight ones don’t, as long as the framing is spaced right for the board. The cedar association puts out a span chart, and the board that catches people is the narrow one. A five-quarter by four [5/4 x 4] in a clear grade can go 16 inches between joists. Same board in a knotty grade, they say 12. Step up to five-quarter by six and it’s 16 either way, and the 2x4s and 2x6s go 24. Those numbers are figured for wet conditions and green lumber sizes, which, I mean, that’s Tacoma. So if you’ve got your heart set on skinny knotty boards, the joists go closer together and the framing costs more.

Loose knots are another story. Those can fall right out and leave a hole, so I keep the lower knotty grades for fences.

Kiln-dried or green?

I lean kiln-dried for most decks. Green cedar, unseasoned, is cheaper, but it shows up wet and shrinks after it’s down, so you gap it tighter at install and the gaps open up as it dries. Kiln-dried is already close to its final size. The gaps stay about where I put them, and you can finish it sooner. One thing to know is that not every grade comes both ways. The association’s Custom Knotty, for instance, is only sold unseasoned.

What about fasteners?

Stainless, or hot-dipped galvanized at a minimum. Cedar has natural extractives in it that react with plain steel, and you end up with black streaks bleeding out around every screw. If the house is near the water, up on the Ruston Way bluffs or out in Northeast Tacoma, I won’t use anything but stainless. The salt air chews through coatings faster.

People love the red when it’s new. How do you keep it?

Left alone, cedar goes silver in a year or so outdoors. Some people want that look, and the gray by itself isn’t hurting anything. Our problem here is shade. Gray, weathered wood in a shady spot grows mildew and gets slippery.

If you want to hold the color, you want a penetrating, semi-transparent oil stain made for decks. Not paint, and not anything that forms a film on top, because that peels once people start walking on it. You’ll also be recoating a deck more often than you would siding. The cedar association’s maintenance tips are pretty much what I’d tell you anyway. Leave gaps so the water drains, sweep the needles and leaves off, and every so often move the planters so the boards under them can dry out.

Would you ever frame a deck in cedar?

No. The frame is pressure-treated, rated for where it’s going, and the cedar goes on top. Cedar’s a great decking and trim wood. I just want treated joists doing the structural work down close to the ground, where they’ll outlast it.

What does grade do to the price?

This year, the cedar and redwood decks we’ve priced in Tacoma have landed somewhere around $40 to $60 a square foot installed. That’s framing, fasteners, permits, cleanup, all of it. Grade is a big part of where you end up in that range. Height matters too, and how much railing and how many stairs you’ve got. Cedar also moves with the lumber market, so if your quote is six months old I wouldn’t count on it still being good.

Say the lumber’s sitting in my driveway. What should I look at?

First thing, I’d pull a few boards out of each bundle and look at the ends. You’re looking for that pale sapwood. Then check the tag or the stamp on the bundle and make sure it says what you paid for. Flip some boards over, too, because with a one-face grade the back side can surprise you. Anything with loose knots or deep checks, or a twist you can see when you sight down it, goes in its own pile. Oh, and ask whether it’s kiln-dried or green. That changes how it should be gapped.

Last one. It’s your house and your cedar deck. What goes down?

I’d go with a good knotty grade, kiln-dried, with as much heartwood on the face as I could get, in five-quarter by six on 16-inch centers. Clear cedar on the rail caps and the benches, and stainless screws. I’d oil it the first summer, and I’d keep a broom by the back door, because there will be fir needles.