There’s lots of ways to stay on the level. You could use a fancy tool like a
laser or water level, but by far the most common and easy-to-use tool for the
task is the spirit level.
They’re all pretty much the same:
- There’s one bubble for checking if a surface is horizontal (or level)
- There’s another bubble for checking if a surface is vertical (or plumb). Some
levels have an extra little window and mirror built in to the plumb bubble to
make it easier on your neck.
As a rule of thumb, use the longest spirit level available. This will give you a
better overall measure of level or plumb, but if a long one won’t fit, there are
shorter ones made for the job.
Take care of your levels, because if they get damaged or bent they won’t work
properly. The I-beam style of levels is very robust, and can actually be struck
with a hammer to make it easier to knock something into line.
There are some other nifty types: such as the post-level, which straps to a post
(say a fence or pergola) to measure in two directions at once; or the tiny
little line-level, which hangs on a stringline for paving, concreting or