Concrete is one of the strongest, most durable and energy-efficient building materials out there. It is readily used in a variety of construction projects, being both flexible and easily shaped. A good insulator against heat, sound and termites, it is a popular material in the walls of both residential and commercial structures. But when the need arises to add fixtures to concrete, often there’s confusion as to the type of fasteners to use. There are numerous fasteners, or anchors, that you can use to add objects to concrete. This, to a large degree, depends on the fixture, and the type of concrete. For medium to heavy-duty tasks, the concrete anchor screw is a popular choice.
What are Concrete Screw Anchors?
Concrete screw anchors may look like ordinary screws, but they’re much tougher, meaning they can carry heavier loads, and have a pronounced thread that burrows its way into the material during installation. These are single piece anchors that can remain permanently fixed, or if you change your mind, removed when needed. Different types are available, depending on head designs, size and shape, so you can place different fixtures into the concrete with the fit and finish you’re after.
Where are Concrete Screw Anchors Used?
One of the main reasons to use a concrete screw anchor is versatility. It can be used in solid or hollow-core concrete, as well as cracked or uncracked concrete. Concrete can crack over time due to temperature changes, high fatigue and weight loading. The use of expansion anchors is unsuitable in such cases, as it causes even further deterioration. Concrete screws anchors however not only avoid cracking but can increase the integrity of the concrete, while allowing for an anchoring point for fixtures. In addition, they can be spaced more closely and are the best anchoring solution for close-to-edge fixtures. Typical uses include piping and heating supports, overhead applications like suspended ceilings, heavy-duty doors and windows, industrial shelving, as well as adding furring strips, timber frames and electrical enclosures.
Types of Concrete Anchor Screws
Depending on the application, there are a range of concrete anchor screws. Each provides a different finish to the substrate.
The majority of anchor screws used in concrete have a hex head. This allows for maximum strength. The anchor screws are tapped into the concrete then further embedded by tightening the head. Hex head concrete anchor screws can be half or fully threaded, with the latter providing better holding consistency as it grips to the concrete along the whole length. You’ll also find flanged hex head anchors, generally in smaller sizes and for light applications. No washers or nuts in both hex head anchors means they give a clean, tight finish.
When you need a flush finish against the concrete surface, use a flat head concrete anchor screw. These anchors can be more versatile in a range of uses, though lack the overall strength of hex heads.
Eye Bolt Screws
To affix overhead hangings in concrete, the simplest and fastest solution is to use an eye bolt concrete screw anchor. These self-tapping anchors are particularly good for cabling and lighting fixtures.
Sizing and Materials
Concrete anchor screws are available in different lengths and diameters and the correct size for your anchoring needs. Larger hex head anchors are typically used in heavy-duty applications, while flathead and eyebolt screws are usually smaller. All consist of high tensile stainless steel, some with added zinc coatings in galvanised variants, making them ideal for outdoor use.
Installing Concrete Screw Anchors
This is a relatively simple process when compared to other concrete anchors. First, you need to drill a hole in the same width as the screw anchor, preferably using a hammer drill. To allow for the thread to do its thing, the hole needs to be slightly longer than the overall length of the anchor. Any dust is removed using a metal brush or air tool. The screw is inserted through the fixture and into the drilled hole. To get the best holding grip for the thread, drive the concrete anchor screw slowly into the hole and tighten to the specified torque. Pay attention not to overtighten the anchor to avoid breaking.
Benefits of Concrete Anchor Screws
When compared to other anchors, concrete anchors are proving increasingly popular in a range of mechanical and electrical fixtures. They are easy and quick to install using basic tools, and are simply tightened to the recommended torque. Since they don’t expand, they can be placed at closer intervals and along edges without the risk of damaging the concrete or hindering holding performance. Besides concrete, some concrete anchor screws can also be used in other materials, notably solid and hollow brick, stone and wood.
The different types also allow adding different fixtures along walls and ceilings, making them a versatile anchor. Concrete anchor screws are preferred in overhead fixtures, as they require less work and time. They can be used both indoors and outdoors, have high tensile and holding strength and are resistant to environmental factors, like water, heat and corrosion. And possibly the best reason to use concrete anchor screws is their low price. Get them at your local hardware store or online.