A sleeve anchor is a post-installed mechanical expansion fastener. ITW describes the Dynabolt as a split expansion sleeve over a threaded stud body with an integral expander, nut and washer. Tightening the nut or head draws the cone into the sleeve, which presses the sleeve against the hole wall.

The anchor is installed through the fixture into a hole drilled to the anchor’s nominal diameter. Tightening the nut 2 to 3 turns expands the sleeve (ITW installation step). The expansion is concentrated near the cone end, not uniform along the sleeve.

Manufacturer-listed uses include electrical junction boxes, conduit, shelf ledgers and light brackets in concrete, block and brick. Sleeve anchors are not wedge anchors. They share the idea of mechanical expansion but differ in components and requirements, as the comparison below shows.

Seven dimensions and parts show up in every sleeve anchor discussion.

The sleeve is the part that touches the hole wall. For the Dynabolt it provides contact over a large area of the hole wall.

See the Nut Size Chart and Washer Size Chart for general hardware dimensions.

They are different numbers. The nominal diameter names the anchor and the drill bit, and the bolt diameter is smaller.

Inch-series sleeve anchors come in six nominal diameters: 1/4, 5/16, 3/8, 1/2, 5/8 and 3/4 in. Not every manufacturer supplies all six, and lengths, head styles and materials vary.

ITW and Simpson both tell installers to use a carbide-tipped bit whose diameter equals the nominal anchor diameter. For inch-series products the bit is made to ANSI B212.15, which sets the finished hole diameter range. A 3/8 in. sleeve anchor takes a 3/8 in. carbide masonry bit. Do not extend this rule to concrete screws, adhesive anchors or other expansion systems. For those, see the Concrete Anchor Drill Bit Size Chart and the general Drill Bit Size Chart.

A properly sized hole is critical to anchor performance. A worn bit can drill an undersized hole, and an oversized hole lets the sleeve expand without a firm grip. Rotary-hammer drills with light, high-frequency impact are recommended. In archaic or hollow base materials, set the drill to rotation-only mode.

The outer sleeve diameter names the anchor. The internal bolt is a size smaller, as the ITW table shows.

Effective anchor length is not the same as overall length or sleeve length, and every manufacturer defines length in its own way. The table uses ITW Dynabolt hex-nut models in zinc-plated carbon steel, where effective length is measured as ITW defines it and the stated maximum fixture thickness is the published value for that model. Avoid mixing lengths from different manufacturers.

Notice the pattern in the table: effective length minus minimum embedment equals the maximum fixture thickness, for example 4 − 1-7/8 = 2-1/8 in. for the HN-1240. That relationship is the basis for the length calculation in the next section.

A preliminary check compares the effective length with the fixture thickness plus the required embedment. The manufacturer’s published maximum fixture thickness is the authority.

Read it straight from the product table. Do not assume a universal relationship across brands.

Minimum embedment is product-specific. Simpson defines nominal embedment as the distance from the base material surface to the installed end of the anchor, measured before torque is applied, and effective embedment as the distance to the deepest point where load is transferred. ITW publishes the minimum embedment for each Dynabolt diameter, and it can change with the base material.

Do not use one term for another. Deeper embedment does not automatically raise load resistance in proportion, and the base material must be thick enough for the depth.

Check the thickness of the concrete or masonry against the product data. See the section on concrete thickness below.

Drilled-hole depth and embedment are different numbers. The hole needs room for the full embedment and for the dust that settles at the bottom. ITW says to drill the hole to any depth exceeding the minimum embedment and to clean it. Simpson says to drill to the specified embedment depth and blow the hole clean with compressed air (overhead installations need not be blown clean), or alternatively to drill deep enough to hold both the embedment and the dust.

Use the manufacturer’s instruction for cleaning. Do not apply a universal overdrill allowance, because the allowance comes from the selected product.

Sleeve anchors are torque-controlled. Under-tightening can leave the sleeve unexpanded and the anchor loose, and over-tightening can damage the base material or the anchor. Simpson warns that failing to apply the required installation torque can cause excessive displacement or premature failure, and that expansion anchors lose some pre-tension after setting. Use a torque wrench and the selected product’s instructions.

The values differ between manufacturers for the same diameter, which is why torque must come from the selected product. Hilti HLC and DEWALT Lok-Bolt AS have their own instructions. For general torque concepts, see the Bolt Torque Chart.

Head style changes fixture clearance, appearance and tool choice. ITW lists hex nut (HN) and Phillips flat head (FS) models in its Dynabolt product data, with flat heads designed for a standard 80 to 82 degree countersink, and Simpson supplies hex-head, acorn-head and Phillips flat head styles of Sleeve-All. Other styles exist, and availability varies by product, diameter and base material.

The most common styles. A wrench size table for each product shows the tool needed.

Flat heads sit flush, acorn nuts give a finished look, and tie-wire heads are for specific suspended attachments with a rated load direction.

A sleeve anchor advertised for concrete is not automatically qualified for every structural application. Resistance depends on the concrete strength, whether the concrete is cracked, the embedment, the edge distance, the member thickness and the loading direction. Simpson also advises that mechanical anchors should not be installed in concrete younger than 7 days, and that anchors installed in concrete younger than 28 days should be rated by the concrete’s actual compressive strength at installation. See the Concrete PSI Chart and the Concrete Strength Gain Chart.

ITW publishes Dynabolt ultimate values in normal-weight concrete at 2,000, 3,000 and 4,000 psi, and separate values for lightweight concrete. Tests follow ASTM E488.

ACI 355.2 sets criteria for deciding whether a post-installed mechanical anchor is acceptable for uncracked concrete only, or for cracked and uncracked concrete. ACI 355.2 applies to expansion, undercut and screw anchors with a minimum effective embedment of 1-1/2 in. and a nominal diameter of 1/4 in. or larger. Shallow anchors below that depth fall outside its scope. Qualification belongs to the specific anchor and is documented in an evaluation report. Not every economical sleeve anchor is evaluated for cracked concrete, seismic loads or safety-critical use.

A higher strength usually raises the published ultimate values, as the 3/8 in. Dynabolt example below shows.

ITW specifies the Dynabolt for anchorage into concrete, grout-filled concrete block, hollow concrete block and brick. Hilti and DEWALT sleeve anchors also list masonry uses with product-specific limits. Performance in solid concrete cannot be carried over to hollow block or brick.

Solid brick and solid units behave differently from hollow units. Sound, solid material is a requirement, and weak or deteriorated masonry is not suitable.

In hollow units the anchor bears on thin face shells, so larger diameters may not be advisable. Set the drill to rotation-only mode in hollow base materials, and do not install into mortar joints without the manufacturer’s approval.

Ultimate loads are the loads at failure in the manufacturer’s tests. Allowable loads divide those values by a safety factor, which ITW sets at 4 to 1 in its tables. Strength-design values under ACI 318 are a different framework, so manufacturer allowable tables are not automatically ACI design strengths. Failure modes include steel failure, pullout, concrete breakout and masonry failure.

Spacing is the center-to-center distance between anchors. Edge distance is measured from the anchor center to the free edge. Anchors installed too close together, or too near an edge, share or lose concrete and can fail at a lower load. Use only the selected product’s approved values, and do not publish a universal rule such as 6d or 10d as a guaranteed sleeve anchor minimum.

As one example of product-specific data, ITW’s concrete masonry table states that the tabulated values assume anchors at least 12 diameters on center with a 6-diameter edge distance for full efficiency, and that values are reduced by 50 percent if spacing and edge distance are cut to 6 and 3 diameters, with linear interpolation between. Other base materials and products have their own values. For cast-in-place foundation anchors, see the Anchor Bolt Spacing Chart, but note that its rules are not universal sleeve anchor requirements.

Read the spacing and edge-distance notes on the table you use.

Edge distance matters because the concrete cone that breaks out near an anchor is cut short at a free edge, and the anchor’s expansion force can split thin edges. Corners and thin members are worst. Reduced capacity at small edge distances is built into product tables, as the ITW footnote above shows.

Measure from the center of the anchor to the nearest free edge. The nearest edge in any direction governs.

Where the distance falls below the full-capacity value, capacity drops according to the product data, and below the minimum edge distance the anchor should not be used.

A sleeve anchor must have enough base material around and below it. Embedment depth, minimum member thickness and the remaining concrete below the hole are three different things. Do not assume an anchor suits a thin slab just because it physically fits. Simpson notes that anchoring into members thinner than its catalog recommends needs a qualified designer’s evaluation.

Check the manufacturer’s minimum thickness for each diameter and embedment, and locate reinforcement before drilling (see the Concrete Cover Chart for cover context). Do not drill through a slab-on-ground or a slab with post-tension tendons or embedded items without approval.

Sleeve anchors are supplied in zinc-plated carbon steel and 304 stainless steel. ITW lists the zinc-plated Dynabolt for interior, non-corrosive environments with a low corrosion level (shelf ledgers, electrical boxes, conduit) and the stainless steel Dynabolt for slight to moderate pollution with a medium level of corrosion (cladding and brick ties). Hilti’s HLC-H hex head sleeve anchor is carbon steel, zinc-plated, for indoor, dry conditions.

Simpson also notes that some hardened fasteners may fail early if exposed to moisture and are for dry interior use. Zinc-plated anchors should not be assumed suitable outdoors. Also consider dissimilar-metal contact with the fixture.

The installation instructions for the product override generic practice. Installation tests are run with anchors within about 6 degrees of perpendicular, and tilting an anchor can reduce its capacity.

Use a rotary hammer with light, high-frequency impact, eye protection and dust control.