Tool Talk: Fastening to concrete

Not so long ago, in a land close by, when one wanted to fasten things to concrete, hand-cut nails were used. Boy, have times changed. Now there are easily a half-dozen ways of fastening things to concrete and we will have a look at the most popular and efficient of these methods in this short article.Geary.jpg

Easily the most basic and least expensive means of fastening a variety of materials to concrete are the above-mentioned hand-cut or concrete nails. These hardened steel nails are especially handy for fastening to concrete block and, even better, the joints between concrete block and other types of masonry. When used in conjunction with tube dispensed liquid adhesives, this is a good approach for attaching furring strips or other materials to some types of concrete. Older and fully cured concrete walls and floors may not allow hand-cut nails to be driven easily and, as a rule, other fastening methods are more effective. More on this later.

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Moving up a step we find plastic anchors that are cone-shaped, ribbed inserts that slip into predrilled holes. Next, corresponding screws are run through the material being fastened and into the plastic anchor. The plastic anchor expands as the screw is driven into it and this prevents it from pulling out of the hole. These anchors are ideal for holding electrical boxes of all types and typically come in a box of 100 anchors, matching screws, and a carbide-tipped drill bit. Both hex head and Phillips head screws, in a variety of sizes, are available.

Nail drive anchors have more holding power than plastic anchors and are quicker to install. Simply drill a hole through the material and into the concrete, masonry, brick, or block. Insert the anchor through the material and into the masonry until the head of the anchor is flush with the material. Next tap the nail until the head is flush with the surface of the material. As the nail is driven, the lead anchor expands and holds the material in place.

Self-tapping concrete screws (Tapcon is one popular brand) provide for a more secure hold and are a better choice for many fastening tasks such as attaching wall cabinets, book cases, exterior light fixtures, wooden headers, and electrical conduit clips. While predrilling is required, as the fastener is run into the hole, the screw cuts its own threads. The end result is a very secure hold. Available in 3/16- and 1/4-inch diameters and lengths up to 6 inches and in both hex head and Phillips head designs.

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Powder actuated concrete fasteners, where allowed by building codes, are probably the fastest method of fastening materials to concrete as there is no pre-drilling of holes required. Basically, a small powder charge (not unlike a .22-caliber blank cartridge) is used to drive a nail into concrete. The length and diameter of the fastener will determine the size of the powder charge, and all tool manufacturers offer recommendations so there is no guesswork involved. As a rule, powder actuated fastener guns with a 10-shot capacity are much better for production work than single shot guns.

Pneumatic framing nailers can also be used for fastening wood plates to green concrete. Special hardened steel nails must be used as conventional framing nails will bend rather than drive into concrete.

Sleeve anchor and wedge anchor fasteners are used when the greatest holding strength is required, such as when hanging heavy objects on walls and installing railings into concrete. Installation is similar to other fastening systems in that a hole must be predrilled through both the material and the concrete. Next, the sleeve or wedge anchor is driven through the material and into the concrete with light taps from a hammer. Lastly, the nut is tightened, which causes the anchor to expand inside the hole. Sleeve and wedge anchors are available in diameters from 1/4- to 1-inch and in lengths of 1 to 6 inches. Carbon, galvanized, and stainless steel anchors are available for a variety of fastening tasks in all types of materials.

Lag shield anchors are commonly used when lag bolts are required — such as when attaching headers to a masonry foundation for decking. Similar to other anchors, these are inserted into a predrilled hole. Next, a lag bolt is run through the material and into the anchor. As the lag bolt is run in, the anchor expands and holds the material to the concrete.

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When drilling holes in masonry, block, brick, and stone, the only choice is a carbide tipped bit. All of the major power tool manufacturers offer a line of carbide tipped masonry bits that are top notch — DeWalt has Rock Carbide and Bosch has Blue Granite carbide tips, for example. Spline, SDS Plus, and straight shanks are available and hole diameters range from 1/8 inch to 1-1/8 inches.

Flute design of carbide-tipped masonry bits is important and there have been some design innovations over the past few years. The most basic flute design is two flutes. More advanced flute designs will have single and double helical fluting with large gullets and, in some cases, one or more grooves in the gullet. High tech flutes and gullets remove material much quicker, have less contact with the walls of the hole, and therefore run cooler. This translates to quicker drilling and longer bit life. Expect to pay premium prices for advanced flute and gullet designs.

The new Anchor Drive Installation Kit from Bosch Power Tools and Accessories is the first all SDS-plus kit designed to help professionals installing medium to light duty anchors in concrete. The increased speed of drilling holes and installing fasteners in concrete translates into greater efficiency and reduced labor costs per hole.

For anchoring electrical boxes, hanging small diameter pipe and ductwork, or framing on concrete, the new Bosch SDS-plus Anchor Drive Installation Kit cannot be beat. The kit eliminates the need for professionals to change back and forth between drill and driving bits, or worse, carry two tools around the job.

Instead, after drilling a hole with one of the kit’s two high-quality 5/32 or 3/16 7-inch SDS-plus bits, users slide the kit’s 5-13/16-inch sleeve over the bit where it locks into place; the opposite end accepts a driving bit. The user then selects the appropriate bit and drives the anchor into place. The system is compatible with all Tapcon-style anchors currently on the market. When complete, slide off the sleeve and proceed to the next hole. The system’s one-handed operation saves professionals significant time and often frustration on the job. And with the canvas carrying case, it is a perfect fit into any toolbox or belt pocket.Concrete Fastener Selection.JPG

The only way to drill holes in concrete — in addition to using a carbide-tipped drill bit — is with a hammer drill and there are many good choices out there. The new lithium ion powered cordless hammer drills — offered by Bosch, DeWalt, Hitachi, Makita, Metabo, Milwaukee, and Ridgid — are all good choices. All of these manufacturers also offer dedicated corded hammer drills, which are a good choice when holes must be drilled in concrete day after day.

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