rough 2x4's?

[cyber]

why do they smooth off (sand four sides) 2x4's? Wouldn't they be cheaper if they left them rough? "If I can not dance, I want no part in your revolution." Emma Goldman

[Joseph Meehan]

They don't sand them smooth. They cut them rough and slightly oversize and then dry them. They shrink as they dry and then they size them down to a uniform size.

[Richard J Kinch]

The critical purpose is to reveal the grade of the wood (number of knots, etc). Load-bearing applications like studs and joists need a certain degree of freedom from defects to reliably stand up to their rated loads. This can't be seen in rough-sawn condition.

In olden days, yes, rough lumber was indeed used for construction, at least into the 1930s. This caused a lot of problems. I once lived in an older home that had a buckled wall. We discovered the cause was a rough-sawn joist that had cracked from a knot most of the way through, but invisible from the rough surface.

It is also not necessarily "cheaper" to use rough-sawn wood, because lumber is cheapest when it is properly graded and sorted, and then priced based on that grade. Using clear lumber on studs instead of finish work is not cheap, nor is using flawed pieces in a load-bearing structure. Hamburger is cheap because it isn't made from filet mignon.

Every tree has a variety of cuts and quality in it, the grading and sorting is a vital part of what makes lumber a commercial product.

By the way, dimensional lumber is surfaced by a planer to smoothness, not sanded.

[Richard J Kinch]

Shrinkage from drying is only a few percent. A nominal 2 x 4 starts out with those literal dimensions, and is planed to 1.5 x 3.5 to reveal the grade.

[Houseknave]

So woosies like you who ask stupid questions don't get splinters in their pinkies and sue the wood companys.

Not with today's tort laws.