If you're going to injure your back while remodeling, it most likely will happen when performing acrobatics with drywall. That's why ultra light drywall holds such promise.
What is ultra light drywall?
Ultra-light drywall is a generic term for drywall that is about 25% lighter than standard drywall.
Weight savings is the chief positive of ultra-light boards. Other qualities that are neutral or slightly negative are the higher cost, brittle consistency, and poorer sound mitigation.
Who makes it?
U.S. Gypsum (USG) and Georgia-Pacific are the two leading manufacturers of ultra-light drywall.
When this article was first written, only one manufacturer, USG, was producing ultra-light drywall under the brand-name Sheetrock UltraLight Panels. It comes in both 1/2" and 5/8" non-fire-rated thicknesses.
Since then, Georgia-Pacific (GP) began making a light drywall product called ToughRock Gypsum Board in 1/4", 3/8", and 1/2" thicknesses. This product is slightly less than 44 1/2 pounds per 1/2" thick sheet at 4' by 8'. In terms of weight, it is comparable with Sheetrock UltraLight.
What makes it lighter?
There are many theories—higher starch content, more air pockets—but no one outside of the companies knows for sure. Calls to the companies have gone unanswered.
Contractors on forums have posited that the board is infused with fiberglass or other strengthening fibers. According to spec sheets, the board is composed of gypsum or calcium sulfate dihydrate (85% or less), cellulose (10% or less), starch (5% or less), and crystalline silica (5% or less), an ingredient list roughly the same as with conventional Sheetrock.
Others have theorized that a slightly higher degree of pregelatinized corn starch and a special type of surfactant help account for the lightness and strength.
Another theory concerns the introduction of a gaseous foaming agent to the gypsum slurry. Not only are more air pockets introduced to the wallboard, but these are better-shaped pockets and provide superior structural strength.
Weight Difference: Ultra-Light vs. Standard Drywall
Ultra-light weighs 13 pounds less than standard 1/2" drywall sheets... but it's not quite that simple.
A 1/2" thick sheet of drywall measuring standard 4'x8' weighs around 57 pounds. Many homeowners find this manageable, especially with a helper. According to USG, a 4'x8' Sheetrock® UltraLight Panel weighs 13 pounds less, for a total of 44 pounds.
When you get to the 5/8" thicknesses, this can often tip the balance. A 4'x8' sheet of 5/8" drywall weighs 74 pounds. Most pros can handle this weight (even if they don't love it), but fewer DIYers can heft this kind of weight.
Remember, this is not a steady, static barbell-type weight; this is a weight that is flopping around and threatening to dominate you.
Consider that these sheets come bundled in twos. If you choose to keep the paper binding strip in place, you might conceivably be able to carry a bundled pair of 4'x8' half-inch ultra-light sheets alone.
Transporting in pairs saves time. More importantly, it reduces the monotonous "drudge factor" of carrying what can feel like hundreds of drywall sheets onto your work site.
Which is the stronger of the two?
Does lighter translate to weaker? USG and GP are vague about whether ultra-light is stronger than conventional drywall, or at least as strong.
USG notes that their light wallboard has "superior sag resistance" and that it hangs well on ceilings with 24" on-center joists. They also say that the product is "stronger pound-for-pound than standard 1/2" drywall."
USG does not clarify if this qualifier "pound-for-pound" means that Sheetrock UltraLight is stronger only proportionally-speaking, but that conventional drywall is still as strong or stronger.
Datasheets for the product say that, for hardness and flexural strength, it "meets or exceeds" ASTM C-1396 Specifications, but no hard numbers are shown.
On a panel-by-panel basis, the ultralight version may still be weaker than conventional drywall. Anecdotal evidence from installers and contractors points to a brittle consistency and edge breakage tendencies.
Who should buy this drywall?
Professionals: USG's product is largely marketed to the professionals—either drywall hangers who carry the product every day, 5 days a week or to contractors who need to think about issues such as workplace injuries and productivity. Adopting ultra-light drywall may have a significant impact on a contractor's bottom line at the end of the year.
Homeowners/DIYers: On the scale of most DIY drywall projects, the weight savings is inconsequential. If you mind carrying an extra 13 pounds from the store to home and doing this 10 or 15 times, then buy the ultra-light product.