From About This Project
At the turn of the last century, the homeowner (or carpenter, for that matter) didn’t have many fastener choices for joining wood or metal to concrete. The common solution was a hardened nail, or a wood plug with a screw driven in the center. Now, at the turn of this century, we find ourselves with more solutions than the typical homeowner needs. In this article, we’ll show you our favorite concrete fasteners that’ll solve most of the concrete-fastening problems you’re likely to encounter. We’ve categorized fasteners as light-duty, medium-duty and heavy-duty, but keep in mind that there are no hard boundaries here. Some fasteners rated as light-duty can pass for medium, and so on. Also, some of the heavy-duty fasteners come in thinner and shorter forms for lighter-duty applications.
LIGHT-DUTY
Plastic Anchors
These are the fasteners you’ll buy and use most
often. They’re great for fastening shelf brackets, towel bars, rake and
shovel brackets, shower doors, pipe and conduit retainers, and most anything
else lighter than 50 lbs. They require a pilot hole at least as deep as the
screw will penetrate (keep in mind the thickness of the material you’re
fastening). Each package will tell the hole size and the screw size (Nos. 4
through 12) that’ll work best.
BEST USES: Concrete, concrete block, mortar, brick, tile and stone.
COST: 10¢ to 25¢ apiece and even cheaper in bulk. Figure extra for screws.
HOW TO USE: Drill a pilot hole at the proper location with a hammer drill and masonry bit to the depth your screw will penetrate. Tap the plastic anchor into the hole. It should fit snugly but drive in easily with a hammer. If the hole gets a bit large, use a bigger screw to push the plastic against the walls of the hole.
DRAWBACKS: If the concrete is soft or crumbly, the plastic anchor may break free and turn as you turn the screw. To fix this problem, cut an extra anchor into lengthwise strips with a utility knife and (with the screw removed) drive the strips alongside the existing anchor.
Get a Hammer Drill
Don’t burn out your favorite 3/8-in.
drill
All the fasteners shown here require a pilot hole to slip the fastener or anchor into. The best way to drill a hole into concrete, concrete block, mortar and brick is to use a hammer drill. A standard drill will do OK in soft brick and mortar, but it’ll just frustrate you and burn out bits in harder materials. If you don’t have a hammer drill, borrow, rent or buy one. Most hammer drills have a switch or collar so you can change over from hammer drilling to regular drilling. You’ll find plenty of other uses for it. You can buy a good-quality hammer drill for less than $100.
Percussion masonry bits have hardened
tips to break the concrete as they spin. The force of the hammering action from
the hammer drill quickly cuts a hole into the
concrete.
Soft Metal Shield Anchors
These anchors were the mainstay for many years, especially
before plastic anchors were developed. They still work well today and are
especially good in softer materials like brick and mortar that can’t take
the stress from heavy-duty anchors.
BEST USES: Concrete, concrete block, mortar, brick, tile and stone.
COST: 20¢ to 85¢ apiece plus extra for screws.
HOW TO USE: Use the same way you’d use a plastic anchor. Drill the correct pilot hole (see package instructions), tap the shield into the hole and screw the wood or metal piece to the wall.
DRAWBACKS: At times, soft metal shield anchors can strip out, especially with larger diameters and when you apply too much torque with a wrench. Fastener failure is tough to repair. If the fastener becomes loose in the hole, remove it. Cut strips of wire solder and push them in alongside the anchor as you tap it back into the hole. The added thickness of the wire will help the shield grip the hole as you tighten the screw.
Choose the Right Fastener
Hammer-Set Anchors
The best feature of hammer-set anchors is that
they’re quick to install. You don’t have nuts and washers to fuss
with; just drill the hole to the right depth and hammer it home. These are
great for hanging 3/4-in. furring strips and metal brackets and
straps.
BEST USES: Concrete, concrete block, mortar and brick.
COST: 50¢ apiece (no screws to buy).
HOW TO USE: Hold your wood or other material in position and drill through it into the concrete to the correct depth. Slip in the anchor. To finish the job, strike the exposed pin with the hammer and drive it in.
DRAWBACKS: Once you anchor hammer-set fasteners, there’s no easy way to remove them without destroying the material or the fastener. If the fastener works loose, leave it in place and drill another hole. Don’t use hammer-set fasteners in crumbly concrete or mortar. Use a plastic anchor instead.
MEDIUM-DUTY
Sleeve anchors
These anchors are available in several sizes and will hold
up to 200 lbs. The sleeves pinch the sides of the predrilled hole and get
tighter as you tighten the screw or bolt.
BEST USES: Concrete, concrete block, mortar and brick.
COST: $1.25.
HOW TO USE: First, drill the proper size pilot hole (3/8-in., 1/2-in., etc.) through the wood or metal and into the concrete. Slip the sleeve anchor into the hole. Hold the object you’re fastening firmly against the wall because the anchor will draw it only slightly tighter as you tighten the screw or nut. Tighten the fastener until it’s secure.
DRAWBACKS: If you overtighten the nut, the fastener will break or break the concrete around the hole. If this fastener fails, you’ll need to drill another hole a few inches away and try again.
Concrete Screws
Using concrete screws is the fastest method for attaching
furring strips, windows and doors, conduit clamps and electrical boxes. Drill
the special-size pilot hole (see package for exact bit size) and drive the
concrete screw’s super-hard, large profile threads into the concrete with
a power screwdriver. Buy 3/16-in. dia. screws for lighter-duty and 1/4-in. dia.
screws for heavier jobs. The beauty of this fastener is that if the piece needs
to be removed, you can just back the screw out. They’re available in hex
or Phillips drive heads.
BEST USES: Concrete and concrete block.
COST: 20¢ to 30¢ each (cheaper in bulk).
HOW TO USE: Use a special bit in your hammer drill to drill a pilot hole through the workpiece (if it’s wood) and right into the concrete. Drive the screw with a power screwdriver. Hex heads are easier to drive but the heads will protrude slightly above the surface after tightening.
DRAWBACKS: Not good for crumbly concrete or mortar. Keep some extra screw drive tips around; the screws are so hard that screw tips break often.
HEAVY-DUTY
Sleeve Anchors
These
anchors in the large 3/8-in. to 1/2-in. dia. versions are perfect for anchoring
heavy, weight-bearing framing members such as deck ledger
boards.
BEST USES: Concrete and concrete block.
COST: $1 to $2 each.
HOW TO USE: Drill right through the wood and into the concrete with a masonry bit and hammer drill. Use a depth stop to get the correct depth and then blow the dust out of the hole with a turkey baster (don’t use your breath, because the dust will blow back in your face). Push the anchor into the hole and tighten the nut and washer to wedge the backside of the fastener against the concrete. Don’t overtighten. Try to get the anchor into the solid portion of the concrete block for added security and strength.
DRAWBACKS: Overtightening can cause them to break free. Use a hand wrench like a socket and crank them tight. Don’t torque them like a lug nut on a car wheel. If the fastener fails, drill another hole a few inches away.
Wedge Anchors
These are extremely strong anchors for attaching framing
members to solid concrete. They come in a variety of lengths and from 1/4 in.
to 1 in. in diameter.
BEST USES: Concrete and stone.
COST: $1.50 to $3 each.
HOW TO USE: Drill a hole the size of the anchor through the wood and into the concrete. Thread the nut on a few turns and tap it into place with a hammer. Be sure the washer is in place and tighten the nut with a wrench.
DRAWBACKS: Permanent. Once they’re in, you can’t get them out.