DerbyDad03 wrote:
The description of the dry wall shims found at the site referenced
below contains the following statements.

"Ideal for floating butt-joints and framing irregularities. Save time
by shimming drywall to allow greater inset at joints. Ensures maximum
bonding of tapes with drywall."

http://www.amazon.com/Strait-Flex-Dr.../dp/B00236E27Q

How would these shims help with "floating butt joints", which I assume
are butt joints not centered on a stud?

The long edges of drywall are tapered and form a valley when two sheets
are jointed. That valley is filled with tape and mud and results in a
fairly flat surface after finishing. Butt joints have no taper, so you
start with a flat surface and add tape and mud, creating a hump which
must be feathered out.

If you want to float a butt joint between framing members you have to
use a backer board, say a 6" strip of plywood or waferboard. That will
give you the same flat surface which leads to a feathered out hump after
finishing. If you add shim strips to the backer board ==-----== then the
ends of the drywall will be sucked in, forming a valley much like you
get joining two tapered edges.


What do they mean by "allow greater inset at joints" and how would
this "save time"?

If your butt joint is going to fall on stud B, putting a shim on studs A
and C will leave stud B slightly inset, again making it easier to finish
the butt joint.