PET and Pre-cuts—same thing, right? Well, yes and no.
PET refers to “precision end trimmed” lumber which just means that the boards are cut to a stricter tolerance than normal lumber. On the other hand, pre-cuts most commonly refers to lumber that is simply pre-cut to specific sizes.
Not only does PET adhere to a strict tolerance of at least 1/16th of an inch, the ends of each piece are precisely cut to be “square”, which can be quite helpful when fitting lumber together in construction projects. Pre-cuts usually refers to studs that are cut to a very precise length (PET) for framing common wall heights. So, the easy way to think about PET and Pre-cuts is:
Not all PET lumber is a “pre-cut” stud, but all pre-cuts are PET.
Pre-cuts need to be precise because they are sized to accommodate specific wall height standards. Eight- and nine-foot walls for example use studs that are pre-cut to 92-5/8” and 104-5/8” respectively. (Different regions of the country may vary slightly as to the exact height of “common” walls.) TThis allows for the stud to sit between a single bottom plate and two top plates of 2-by lumber, while also leaving room for drywall on the ceiling.
With all of that factored in, using pre-cut studs leaves you with standard ceiling heights and a lot less labor required for the job. Naturally, the squared ends also contribute to making the framing easier and more consistent throughout the project.
As the name suggests, pre-cuts aren’t really designed to be cut on the job site. Not only because you’re paying a premium for their specific length and squared ends, but also because you lose a bit of material from a board each time you make a cut. That’s why typical dimensional lumber tends to be just a bit longer than its advertised length. If you have to cut an 8-foot board down to for 2-foot pieces, you don’t want that board to be exactly 96” because you’ll end up with three 2-foot pieces and once piece that is about three sawblade widths too short. For some projects, that might not make a significant difference but scaling that up to larger ones and you might run in to problems.
So be sure to choose the right lumber for the job and reduce wasted energy and lumber making cuts when you don’t have to!