S2S, S3S and S4S Lumber – What Gives?

Article - November 28, 2006

As this picture implies, lumber terminology can venture into boring territory. But it’s a necessary evil and if you want to make informed purchases, you must have at least a rudimentary understanding of how wood is graded and sold. One terminology set you’ll run into refers to how much work has been done to a board prior to purchasing and that’s exactly what emailer Skee was confused about when he wrote me:

In your show dedicated to the lumber store, the nice lady at the counter mentioned some terms you didn’t cover. Specifically, S2S, S3S and S4S. Yet another stumbling block for the newbie. Could you demystify these terms as well?

The SxS designation simply refers to how many sides have been pre-surfaced. S2S= surfaced two sides, S3S = surfaced three sides and s4s = surfaced four sides.

S2S – The board has been run through a planer producing two flat faces, but the edges are left rough.

S3S – The board has been surfaced S2S first, then one edge is ripped straight (also known as SLR1E or straight line ripped one edge).

S4S – The board has been surfaced on both faces (S2S) and received a rip on both edges, resulting in a board with two flat and parallel faces and two flat and parallel edges. This is the stuff you usually find for sale in the hardwood section of the big box stores like Home Depot and Lowes.

So what should you buy? Well it might depend on where you shop. If Home Depot is your only option and you want red oak, S4S is the only game in town. If you want your material in a more rough state, you’ll need to check out your local hardwood dealer. Personally, I like the wood to be as rough as possible. By milling in my own shop I am certain I’ll end up with perfectly-flat boards and in many cases they’ll be thicker than 3/4″. Pre-milled stock tends to hit that 3/4″ figure on the nose. To make matters worse, since wood constantly moves those S4S boards that were once nice and flat are usually anything but by the time their in your shopping cart. And did I mention you pay a huge premium for that milling service? So if at all possible, invest in a planer and a jointer as it saves you money and headaches in the long run.

Check out this video for more basic lumber terminology and purchasing tips.

Spagnuolo vs. Marks Epic Battle

Discussion

Michael Carnright March 21, 2007 5:39 am

I find this website to be very help in today’s world

http://www.acronymfinder.com

I put in s2s and bam :-)

Reply
Steve November 16, 2007 7:06 am

You can also add other lumber yard talk like SLR1E, FAS&SEL, B and Better, and the various common grades you can purchase. A discussion on kiln dried vs air dried lumber might be appropriate here too. Gee, should I make this a question of the week?

As a kid we always had wide, long FAS&SEL boards, and kind of became wood snoobs. In my 20’s when I was in my first teaching career I learned to appreciate all of the marvelous defects that can appear in wood. We made a lot of small projects and the wild grain and knots really added a lot to the projects.

Reply
Jed March 15, 2012 3:11 pm

Wait – how can S2S be planed on both faces if one of the edges isn’t jointed? Doesn’t that mean 3 sides need to have been surfaced (if the procedure is to joint a face, joint and edge, then plane the other face)? I thought both faces could not be guaranteed to be parallel if this was not the procedure.

Reply
- thewoodwhisperer March 15, 2012 5:16 pm
  
  Hey Jed. Faces can be made flat and parallel independent of the edges. Yes we usually do plane one face, then an edge, then the other face, then the other edge, but that’s only because we are trying to surface the wood on all 4 sides in preparation for our project. To make s2s, all you need to do is joint one face, then send that board through the planer with the jointed face down. When its said and done, you have S2S with two parallel and flat surfaces.
  
  Reply
  - matthew curran April 27, 2022 8:08 pm
    
    what sides are done normally on s2 ?
    
    Reply
Justin Stokes December 8, 2013 5:21 pm

Thanks Marc! Find myself coming back to your site more and more often.

Reply
Steve Norman February 23, 2017 7:10 am

Mark,
I purchased some 4/4 walnut that I was told was S3S. At the time they stated the two edges were jointed and one face was milled flat.
The boards were 88″(+/-) and I had them ripped in half so I could carry them in my car.
When I arrived at my shop I found the edges were NOT straight and either face had a cup to it.
I jointed the edges ( 3 passes ea. ) and still found the cup to be there on the one face they stated was milled but just needed sanding.
My question is, should S3S be at the stage where a glue up can be down then just final sanding?
The panel I’m making was to be a final at 40 wide by 30 height at 1″ thick.

Thanks,

Steve

Reply
Kevin January 10, 2018 10:47 am

I’m working on an old house were the 2″ x 3-3/4″ studs are flat or joined on the edges and not on the sides, what is the called?

Reply
- Andrej Dekleva March 13, 2019 11:21 am
  
  california framing
  
  Reply
- Craig Sloan November 18, 2022 3:33 pm
  
  My dad was a construction superintendent in California before the change and after, even when they had both on the jobsite and they had to pick through to make sure they matched. Industry standard was 1.5×3.75, then it switched to 1.5×3.5, no doubt to increase profits. So what you have is exactly what you said, an old 2×4.
  
  Reply
Lombard January 24, 2018 9:15 pm

My architectural home with the inside walls all finished with the 1x4horizontal linea look with the3/8 inch black spaces was burnt down and I am looking to find this clear grade tight knot material. Where can I find it at a reasonable price, Any ideas?? thank you

Reply
Joseph O’Connor November 15, 2018 11:38 am

If you’re just starting to build your workshop and cant buy everything right away, could you buy S3S wood and get by without a jointer and planer?

Reply
- Roman C January 5, 2019 7:15 am
  
  My answer to this would be an easy yes (if you have a tablesaw). You just must do your due diligence in selecting the boards you purchase to verify square. As mentioned above, the milling was done long before it reaches your shopping cart so there is woods natural tendency to move. This is why these boards need careful selection if you do not have the jointer/ planer. Just look down the length of the board and only take the straightest ones. PS: You may be there a while so don’t feel bad for having a pile of their wood in your “No” pile while searching. I feel everyone has done it.
  
  Reply
Shelby J. Kuenning April 4, 2020 12:17 pm

I just heard Tom Silva say, on Ask this Old House, which I check out occasionally to help keep up with new materials and equipment, tell someone that s4s meant, “Sanded four sides.” I’m a master carpenter and carpentry instructor and this stuff, which they do sometimes in that show, drives me nuts. They are mentoring people. I once contacted them regarding a similar issue that was actually more critical and they reflected and made excuses. I’m glad to see a site like this that is actually giving people accurate information.

Reply
Bob McCulloug December 27, 2020 3:16 pm

I am building a pair of freestanding wine racks out of black walnut ( 3/4 inch stock ).
Each unit requires 8. board feet of walnut. If I want S4S it’s going to cost me about $200 dollars per unit. That’s an absolutely ridiculous price to pay for domestic lumber.
In short, you pay dearly to plane the boards to 3/4 inch and plane the surfaces. plus the ripping of the edges. I am 88 years old and have been working wood for many years.
A bit of advice. Save up a few dollars and buy yourself a decent, used jointer and planer. You won’t regret it in years to come.

Bob

Reply
- VJ March 15, 2021 6:38 am
  
  Thank you Bob
  I am 80 yrs old from U K and just taking interest in woodworking
  no knowledge of any terminology but I am a grafter so when I found your comment- most helpful
  
  Reply
Jerry April 16, 2024 10:47 pm

What is the designation for lumber that’s rough on one flat side, and sanded on both edges and the other side?

Reply

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S2S, S3S and S4S Lumber – What Gives?

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