Hanging Heavy Things on Florida Block Walls and Drywall

TVs, mirrors, shelves and cabinets need the right anchor in the right wall. What is behind the drywall in a Florida home and how to fasten into it safely.

A surprising number of handyman calls start with something that fell off a wall: a TV that pulled its anchors out, a mirror that let go, a shelf that sagged and dumped its contents. Nearly all of them come from the same mistake, which is using the anchor that came in the box without knowing what was behind the drywall. Florida homes are different from houses in most of the country, and the wall you are drilling into is probably not what you think. Here is what is back there and how to fasten into it.

What Florida walls are made of

Most Polk County homes built since the 1960s are concrete block on the exterior walls. Inside, the drywall is attached to thin furring strips, typically three-quarter-inch wood or metal, fastened to the block, with a small air gap between the drywall and the block. Interior walls are ordinary wood or metal studs with drywall. So there are three situations: drywall over a furring strip, drywall over the air gap with block behind it, and a standard stud wall. Each takes a different fastener.

Exterior block walls

Furring strips are usually on sixteen-inch centers, and they are thin, so a screw into one holds far less than a screw into a stud. For anything heavy, the anchor should go through the drywall and the gap into the block itself. That means a masonry bit, a hammer drill and a sleeve anchor, wedge anchor or a quality concrete screw sized for the load. For medium loads, a plastic or nylon expansion anchor set into a drilled hole in the block works. What does not work is a drywall anchor sitting in the air gap; it grips nothing and lets go.

Interior stud walls

The rules most people know apply here. A stud finder locates the framing, and screws into studs carry the load. Between studs, a toggle bolt or a heavy-duty self-drilling anchor rated for the weight is fine for medium loads such as a mirror or a small shelf. For heavy items, a TV mount or an upper cabinet, the fasteners go into studs, and if the studs do not land where the mount needs them, a horizontal cleat or a section of plywood is fastened to the studs and the item is mounted to that.

Specific jobs

• TV mounts. On an interior wall, lag screws into at least two studs. On a block wall, concrete anchors into the block, not the furring. A full-motion arm puts a lot of leverage on the fasteners and needs the strongest option. Route cables through the wall where the code allows, using an in-wall rated kit.
• Heavy mirrors and art. Two anchors, level, and a French cleat for anything wide. The cleat spreads the load and makes hanging square easy.
• Floating shelves. The hidden bracket needs solid fastening at every point, into studs or into block. This is the item that fails most often with drywall anchors.
• Upper cabinets. Screwed through the hanging rail into studs or into the block with proper anchors. Never into drywall alone.
• Grab bars. Into studs, blocking or block with anchors rated for the pull, never a suction cup. Our post on aging-in-place modifications covers placement.
• Closet rods and shelving. Into studs at the ends and with a center support. Our post on closet and pantry shelving goes into it.
• Curtain rods. Light, but they get pulled. Anchors rated for the load, or into the window framing.

What is in the wall

Before drilling, think about what runs through the wall. Electrical drops to outlets and switches run vertically from the box; plumbing sits behind bathrooms and kitchens; the AC line set runs somewhere between the air handler and the outside unit. A stud finder with wire detection helps, and a small pilot hole before the big one is cheap insurance. Drilling into block on an exterior wall, watch for the electrical conduit that sometimes runs in the furring space.

When to call

A TV over a fireplace, a wall of cabinets, a large mirror in a bathroom or anything on a block wall is worth an hour of someone who does it every week. The cost of the visit is less than the cost of the thing on the floor. Our handyman list approach means it gets bundled with the other small items in one trip.

Inventive Home Improvement mounts, hangs and installs as part of our handyman services across Lakeland, Winter Haven, Combee Settlement and all of Polk County. Call (863) 633-5499 or request a free estimate.

Frequently asked questions

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