Construction lumber, especially pressure treated lumber, is sold so wet I don’t think it really matters. I’ve actually never tried to calculate wood movement for construction lumber because who the fuck cares? But for furniture lumber which is dried to between 6 and 14% moisture, there is a formula:
width of the board in inches x percentage of moisture change * expansion coefficient for a particular species.
Yellow pine (extremely common construction lumber) has an expansion coefficient of .00263. A 2x4 (actual dimension 1.5" by 3.5") that undergoes a 4% moisture content change will grow/shrink 3.54.00263 = 0.03682 inches, or just over 1/32". That’s in width; it’ll vary by less than half that in thickness. Wood basically doesn’t move along the grain; the board won’t get appreciably longer or shorter.
Maybe they mill, store, and sell under the same moisture conditions?
Also, how big is the difference in size and moisture for the same piece of wood? I would expect that moisture is usually not higher than 90% and not lower than 10% or something like that, but don’t know how it really is
Once it leaves the mill they go to various stores and regions with different conditions. Some places store them inside, others outside.
Once I buy it at the store and take it the site, it’s now different from the store. You should acclimate all lumber for 48 hours before using it as well, this is so the wood doesn’t swell or shrink more after installing it.
A 2x10 can be anywhere from 9-1/2 to almost 8-1/2 depending on final site conditions.
I think if I was you I’d go have a talk with your sawyer, talk about “man if I wanted my wood this wet I wouldn’t have broken up with Meagan. Is your kiln in working order?”
You are just off on the amount that the wood can shrink from being rough sawn at 2” to final delivery. If one board came from a mill on a humid area, it would shrink less before milling meaning it will shrink more onsite, if the board comes from an arid region, it’s already shrunk lots before being milled. So won’t continue to shrink more.
This is the reason why you can’t predict the milled measurements and they use nominal sizes…. Not to mention the group is SPF, so it can be multiple species that shrink differently.
The difference between just basic book knowledge and actually using the material for a living mate.
Also, the hell is a sawyer? Wood comes from mills.
Okay, are we talking about “boards sold as 2x10s might vary in width from board to board?” Because I took you to mean that a given dried and milled 2x10 might move up to an inch, which it had better fucking not. Because yeah, the likes of Georgia Pacific are going to be a bit sloppy with the final dimensions of 2x10s, because it rarely matters that much for what that board is going to be used for.
I’m a woodworker, I buy rough sawn lumber dried over a period of months, I shop dry it for a couple weeks then mill it myself. I can predict with a fair degree of accuracy how much it will move.
A sawyer is an occupational term for a person who operates a sawmill. My sawyer’s name is Bill.
How does that work when wood varies due to moisture content? If they give precise mm measurements, only 20% of boards will meet those criteria.
All they are giving is the planned dimensions instead of nominal in mm form, it’s still not precise, it can’t be.
Construction lumber, especially pressure treated lumber, is sold so wet I don’t think it really matters. I’ve actually never tried to calculate wood movement for construction lumber because who the fuck cares? But for furniture lumber which is dried to between 6 and 14% moisture, there is a formula:
width of the board in inches x percentage of moisture change * expansion coefficient for a particular species.
Yellow pine (extremely common construction lumber) has an expansion coefficient of .00263. A 2x4 (actual dimension 1.5" by 3.5") that undergoes a 4% moisture content change will grow/shrink 3.54.00263 = 0.03682 inches, or just over 1/32". That’s in width; it’ll vary by less than half that in thickness. Wood basically doesn’t move along the grain; the board won’t get appreciably longer or shorter.
Maybe they mill, store, and sell under the same moisture conditions?
Also, how big is the difference in size and moisture for the same piece of wood? I would expect that moisture is usually not higher than 90% and not lower than 10% or something like that, but don’t know how it really is
Once it leaves the mill they go to various stores and regions with different conditions. Some places store them inside, others outside.
Once I buy it at the store and take it the site, it’s now different from the store. You should acclimate all lumber for 48 hours before using it as well, this is so the wood doesn’t swell or shrink more after installing it.
A 2x10 can be anywhere from 9-1/2 to almost 8-1/2 depending on final site conditions.
So, more than 10% difference, that’s enough to be a problem, indeed
A yellow pine 2x10 might move a tenth of an inch, not a full inch.
These were bought at the same time and are both 2x10 installed a couple days ago. You can even see the difference in the connection in the picture.
Over 3/8 of an inch and they both still need to dry.
I think if I was you I’d go have a talk with your sawyer, talk about “man if I wanted my wood this wet I wouldn’t have broken up with Meagan. Is your kiln in working order?”
9-3/8 is spec, the hell you talking about?
You are just off on the amount that the wood can shrink from being rough sawn at 2” to final delivery. If one board came from a mill on a humid area, it would shrink less before milling meaning it will shrink more onsite, if the board comes from an arid region, it’s already shrunk lots before being milled. So won’t continue to shrink more.
This is the reason why you can’t predict the milled measurements and they use nominal sizes…. Not to mention the group is SPF, so it can be multiple species that shrink differently.
The difference between just basic book knowledge and actually using the material for a living mate.
Also, the hell is a sawyer? Wood comes from mills.
Okay, are we talking about “boards sold as 2x10s might vary in width from board to board?” Because I took you to mean that a given dried and milled 2x10 might move up to an inch, which it had better fucking not. Because yeah, the likes of Georgia Pacific are going to be a bit sloppy with the final dimensions of 2x10s, because it rarely matters that much for what that board is going to be used for.
I’m a woodworker, I buy rough sawn lumber dried over a period of months, I shop dry it for a couple weeks then mill it myself. I can predict with a fair degree of accuracy how much it will move.
A sawyer is an occupational term for a person who operates a sawmill. My sawyer’s name is Bill.
Okay I just wanted to make sure you were talking out of your ass. Your mill and miller uses hand tools? Because that’s what a sawyer is dude…
Give it up. Yes a 2x10 can move 1/2 while drying, if you used them, you would know and understand this.