Lumber stamped S-GRN but I'm told it is KD

[Joseph Maxwell]

I'm looking at some 4x4 southern yellow pine posts at a local lumberyard (wholesale) that are a really good deal. They are stamped S-GRN but they say they are kiln dried on site to a max of 19% mc before being sold to retail yards.

But, I can go to a big-box store and get a doug fir 4x4 stamped KD. That means, correct me if I'm wrong, that it was kiln dried and then surfaced, right?

So which is preferable? A 4x4 SYP surfaced green and then dried to max 19%, or, I presume, a doug fir log that was kiln dried to a max of 19% and then surfaced? Wood type is not an issue.

Any insight is appreciated...

[Jamie Buxton]

In construction lumber, KD generally means it was dried to 19% EMC. 19% is just dry enough that mold doesn't like growing on it. However, 19% is still wet enough that the wood will shrink and warp and perhaps end-check as it dries down to the 9% level which is typical of interior wood. That shrinkage and movement is likely to be big enough that it overwhelms the difference between surfaced green and surfaced at 19%.

[Rick Fisher]

Well.. That is weird.. I have been selling lumber my whole life and sorta wonder about that one ..

If its stamped S-GRN .. It was surfaced while green.. If it was put in an actual kiln after that, it would have shrunk and would likely be undersized .. is it 4" x 4" or 3-1/2 " x 3-1/2 " .. ? or is it some odd size. ?

Kiln drying wood after surfacing is an afterthought, and I'm not sure I have seen it before..

Its more likely that its stock that sat in a warehouse for years and air dried, the terminology is just wrong at the retail store .. but who knows ?

If they broke up lifts, stickered them and stacked them in a kiln.. I would like to think they would have hit it with a KD stamp.. multiple stamps are not uncommon on reman lumber..

I would bet $25.00 its being called air dried because its been sitting for years .. They probably bought it distressed ..

If you find out, post here to let me know ..


Another oddity is the dimension.. Kiln drying 4x4 is a slower process than say 2" stock .. So they probably didn't dump it in with a regular load.. If its kd, they would have had to fill the kiln with it .. Maybe the species is more forgiving .. i dunno ..

[Joseph Maxwell]

Kiln drying wood after surfacing is an afterthought, and I'm not sure I have seen it before..

Glad I'm not the only one confused with it and thanks for the tip on the measurements. I'm going to call the guy back tomorrow and see what he says, but it should be new lumber as I believe they are a mill as well.

[Joseph Maxwell]

In construction lumber, KD generally means it was dried to 19% EMC. 19% is just dry enough that mold doesn't like growing on it. However, 19% is still wet enough that the wood will shrink and warp and perhaps end-check as it dries down to the 9% level which is typical of interior wood. That shrinkage and movement is likely to be big enough that it overwhelms the difference between surfaced green and surfaced at 19%.

You make a good point, Jamie. The whole question may be moot. I'll see what they say. They are 1/3rd the price of what I normally find in the orange store.

[Jerry Miner]

So which is preferable? Wood type is not an issue.


It is an odd story, but what's the question? If the MC is the same, and specie doesn't matter, then what DOES matter?

[Scot wolf]

S-GRN = Surfaced green

It could still be KD....and most likely is.

[Joseph Maxwell]

S-GRN = Surfaced green

It could still be KD....and most likely is.

I guess that is my main question-- is it reasonable to believe that a new piece of lumber could be kiln dried even though it bears a surfaced-green stamp?

[Scott T Smith]

Lumber that is surfaced green dries more quickly in the kiln. However, the final dimensions may vary a bit compared to lumber that is surfaced post-drying.

[Phil Thien]

Have you looked at the stock? Is it fairly straight?

Building a bench?

[Rick Fisher]

Actually Scott makes a great point.. it would dry faster ..

The weird thing is .. if they milled it .. and then dried it .. why not stamp it KD .

They can XXX out an old stamp.. but they don't even need to on a 4x4 .. Just stamp it KD ..

I have seen wood stamped with a potato and an ink pad .. ( Fella went to jail, but not for the potato part ) ..

[Jim Matthews]

Bargain or no - I wouldn't take the lift as it's mislabeled unless I could cut a board in half and check the MC in the middle.

If you're building something exterior and will treat this anyway, there may be no point in checking.

[Cody Colston]

Surfaced lumber will have, on-average, 17% less degrade than unsurfaced lumber. That could be the reason it was planed before drying.

The 19% MC is typical of construction lumber. That MC not only prevents fungal growth but it also greatly reduces the lumber weight for savings in transporting.

As for your question, "So which is preferable? A 4x4 SYP surfaced green and then dried to max 19%, or, I presume, a doug fir log that was kiln dried to a max of 19% and then surfaced? Wood type is not an issue."

The lower-priced wood is preferable.

[Joseph Maxwell]

I spoke to the guy again. They are a sawmill apparently specializing in posts (4x4 up to 14x14) and he said that they have to either stamp it KD-19 or S-GRN. They cannot kiln dry the larger pieces, so they all get the S-GRN stamp. The 4x4s are dried to 19% and then surfaced but carry the S-GRN stamp.

This is for shop tables and shelves, so it's not absolutely critical that they remain straight, but it'd be nice to minimize it. The nearest big-box store that carries untreated 4x4s is a 2-hr drive at $12/stick. This place is 30-minutes at around $4/ea.