Fastening Outside Corner Bead
On an outside corner formed by a double layer of drywall, the corner bead can be fastened without nails or screws.
I’m an overconfident DIYer building a downstairs bedroom near the furnace and water softener. For noise control I’m using two layers of 5/8-in. drywall on the walls and ceiling, for a total of 1-1/4 in.
I need to put a couple of outside corner beads on the chase that surrounds some ducts. If I try to install standard steel corner beads, the nails or screws would miss the wood framing entirely. Could I just use something like contractor’s adhesive to hold them in place, or would a few screws be adequate even though they are hitting nothing but drywall? Also, I saw a video that implied that using a setting compound on corner bead is preferable because it’s more durable. Is this true?
—S.B. via the FHB Forum
Myron Ferguson, Ferguson Drywall Innovations Inc., replies: You’re right—the legs on metal nail-on corner beads typically are only 1 1/8 in. wide, which means you won’t be able to use nails or screws to secure them. For several years now, nail-on metal corner bead hasn’t been my bead of choice. There are just so many better options out there today. That being said, because metal is less expensive (although not by much), gives the perception of strength, is easy to find, and is what most folks are familiar with, it is still the most common type of bead used today. If you have already purchased metal nail-on beads, I think your idea of adhering them with construction adhesive would work as long as you hold them in place with 1/2-in. staples until the adhesive takes hold and make sure to wipe off any excess adhesive.
I prefer the paper-faced metal mud-set beads because they are fast and easy to install, and in my experience are less prone to edge cracking. In a situation like you describe, they are the best answer because they attach to the drywall only with no fasteners. You simply bed them in joint compound, which you’ll have on hand anyway.
As for your second question, the only compound I recommend for adhering the beads and for the first coat over nails on metal beads is all-purpose (heavyweight) premixed compound. Lightweight compounds like USG’s Plus 3 do not adhere as well and are best for fill and finish coats only. Setting compounds are harder compounds, which is why some people think they’re stronger. But setting compounds do not adhere as well as all-purpose, so I don’t recommend them for adhering the beads or even for the fill coat over the beads.
From Fine Homebuilding #319