peter wrote:
I'm shopping for an auto laser level -- a device that mounts on a
wall and projects a vertical and horizontal laser beam on the wall. I
want to check the posts and beams in the crawl space because I
suspect there is some uneven settlement, or a sagged joist (some
posts have been replaced recently and may be cut too short, causing
the joist to sag). What prompted this project is part of my hardwood
floor has split into two levels about 1mm apart.

I thought a laser level would be perfect because it projects a
straight line so I can checked for joist straighness and
"horizontal-ness" by projecting the beam near the edge of the joist.

I saw something like this at hardware store for $40.
http://www.lowes.com/lowes/lkn?actio...180&lpage=none

Although for this project I can do without the vertical beam, it may
come in handy someday.

There are many styles of self-leveling laser level. The one above
needs to be attached or held against a wall/post and it projects
beams on the wall. Another type mounts on a tripod and project a
horizontal beam 360 degree around.

Does anyone have any thoughts on the instrument or the way I plan to
use it?

The only problem I see is that you are looking at the wrong side of the
joists if you're just checking the bottom of the joist. The 2X ? can vary in
width and not give you the reading your looking for. I suggest you use the
laser but measure to the bottom of the floor to the beam and then determine
what is off and how to go about lifting and correcting.

Rich