Selecting Anchors and Connectors for High-Wind Areas

Anchors and Connectors for High-Wind Areas

Selecting Anchors and Connectors for High-Wind Areas

CONNECTORS, ANCHORS and Fasteners

By Randy Shackelford, P.E., and Karen D. Hickey

Anchors  and Connectors for  High-Wind Areas

When building with hollow and grout-filled masonry block, it is often the case that some other material will need to be fastened to it. Besides having to anchor something into the top of a wall (such as roof framing), you frequently have to anchor material to the face of a masonry wall. This connection likely has to be able to resist vertical gravity loads, and in some cases, it has to resist sideways wind or seismic lateral loads, or even uplift loads. The loads on these connections can depend on the local building code and the region’s weather patterns. In high-wind areas like Florida, for example, a lot of residential construction is comprised of masonry walls with a wood or steel trussed roof. Tie-downs are especially needed in order to keep roofs on the buildings.

Hollow drop-in anchors.
Hollow drop-in anchors.

So, how do you determine the right anchor for the job? First, it’s important to know what anchoring and connecting products are on the market.

Anchors are heavy-duty fasteners that can be installed into masonry either after construction and curing (post-installed anchors) or during construction (cast-in-place). Common post-installed anchors include mechanical anchors, which screw in or expand in to engage the surrounding material, and adhesive anchors, which form a chemical bond with the surrounding material. While each type will require its own installation process, it is important to note that adhesive anchors will require thorough cleaning of the hole and a dispensing tool specific to the adhesive type and packaging.

To help you navigate the available products, Simpson Strong-Tie has created an Anchor Product Selection Guide that includes recommendations for masonry. Those anchors include:

The hex-head Titen screw. The hex-head Titen screw.
The hex-head Titen screw.
The Titen HD anchor.

 

Hollow Drop-In Anchor: A light-duty anchor designed to be installed into the face of either grout-filled masonry or hollow masonry. It comes with the tools to install into either material.

Titen Screw: A threaded, smaller-diameter anchor designed to be installed into either grout-filled or hollow masonry. Drill the hole with the included drill bit and install. The screw cuts its own threads into the base material. It is available in either a zinc-plated with baked-on ceramic coating, or 410 stainless steel. It comes with either a hex-head or Phillips head in 3/16- or 1/4-inch diameters.

Titen HD Anchor: A larger-diameter, higher-load version of the Titen screw. Simply drill a hole to the appropriate size using a standard-sized drill bit (not included), clean the hole, and drive the anchor in using an impact wrench. It cuts its own threads and does not impart an expansive force into the base material like other mechanical anchors do. It comes in either a zinc-plated or mechanically galvanized zinc finish. Loads are dependent on where in the masonry wall the anchor is installed.

The Heli-Tie helical wall tie and its installation tool. Heli-Tie helical wall tie
The Heli-Tie helical wall tie and its installation tool.

Heli-Tie Helical Wall Tie: A stainless-steel connector used to anchor brick and masonry building facades to structural members or to stabilize multiple-wythe brick walls. Once installed, it provides resistance to both tension and compression. It installs by pre-drilling a pilot hole through the facade and the backup material. Then the tie is driven until it is countersunk into the outer material, thus providing an inconspicuous connection. Most commonly, it is provided in Type 304 stainless steel, but it can be special-ordered in Type 316 for the highest corrosion resistance.

Adhesives: These come in either two-part epoxies or acrylic formulations. True epoxies can provide a little stronger anchorage in some cases, while the acrylic formulations cure faster and are more appropriate for work in cold weather. For application in hollow masonry, screen tubes are required, which allow the adhesive to consolidate behind the face shell of the block without having to fill the entire void with adhesive. Manufacturers have recently had to reformulate their adhesives to meet new codes for concrete anchorage, but Simpson Strong-Tie still offers some of the previous versions for use with masonry.

ScreenTube In Hollow CMU
ScreenTube In Hollow CMU.
  • SET-XP epoxy is a high-strength, two-part epoxy. Simpson Strong-Tie also offers an original formulation of SET epoxy for masonry applications. For both adhesives, the loads are dependent on where in the masonry wall the anchor is installed.
  • AT-XP is the primary Simpson Strong-Tie acrylic adhesive for concrete, but the original formulation, AT, is still available for masonry applications. As with other anchors, the loads are dependent on where in the masonry wall the anchor is installed.

While anchors are typically embedded or installed into masonry or concrete, structural connectors are made from light-gauge steel and are used to connect two members together, such as wood and masonry. These products generally need some type of fastener, such as a small masonry screw, to connect them into masonry. However, some connectors embed in the masonry wall during construction. Simpson Strong-Tie offers the following connectors for masonry applications:

CCQM series connectors.
CCQM series connectors.

CCQM Series Connectors: These connectors embed in the top of a masonry pier to connect a wood structure to the masonry pier. These products came about after Hurricane Katrina, when construction along the Gulf Coast had to be built much higher off the ground than previously due to stricter flood insurance requirements. Contractors needed an easy way to connect the frame of the structure above to the top of the masonry pier. These connectors come in several configurations based on the layout of the framing above, either with the beams straight (CCQM), in a “T” configuration (CCTQM), in a cross configuration (CCCQM), or a corner (ECCLQM). The mason would embed these into the top of the pier prior to filling with grout. Placement is relatively easy, since usually the outside of the seat will be flush with the edge of the masonry pier. These would typically be hot-dipped galvanized along the Gulf Coast, but they are also available in grey powder-coat paint for installation in non-corrosive areas.

LGUM/HGUM beam hangers.
LGUM/HGUM beam hangers.

LGUM/HGUM Beam Hangers: These are hangers for connecting wood beams and trusses into the side of a masonry wall. They use the Titen HD heavy-duty masonry screws to fasten to the side of a grouted masonry wall to support various types of joists, beams or trusses. Years ago, typical HU-style hangers, installed with the smaller-diameter Titen masonry screws, were recommended for use to connect horizontal framing members to masonry walls. While this solution is still available, Simpson Strong-Tie realized there was a need for a product designed specifically for masonry. By using the larger-diameter Titen HD screws, far fewer fasteners are required (which equals less hole drilling) and higher loads can be achieved.

PA/HPA purlin anchors. PA/HPA purlin anchors.
PA/HPA purlin anchors.

PA/HPA Purlin Anchors: Building codes require that, in high-wind and seismic areas, framing for floor and roof diaphragms must be connected into the side of masonry walls to prevent the walls from being pulled outward by wind or seismic forces. These products have to be embedded into the side of the masonry wall by the masonry contractor, at the level where the floor or roof will be. They have embedment lines stamped in them to help the contractor know the correct embedment depth. The contractor also needs to ensure that there is some horizontal rebar placed in the wall at the strap location because the code requires the strap to hook around the rebar.

Embedded Truss Anchors: In high-wind areas, roof framing must be connected to the top of a masonry wall to resist uplift forces. In some areas, like Florida, builders have found that the easiest way to make this connection in residential structures is to use a strap that embeds into the top of the wall and fastens directly to the roof framing. Simpson Strong-Tie offers five distinct models of embedded truss anchors, with each model available in several lengths.

Now that you know some of the anchors and connectors available, you’ll need some help selecting from those products to determine what’s right for the job at hand.

Simpson Strong-Tie offers two separate software programs for selection of post-installed anchors. One, called Anchor Designer Software for ACI 318, ETAG and CSA, is used to select anchors for concrete. The other, Anchor Designer Software for Allowable Stress Design, is used to select anchors for grout-filled and hollow CMU. Both software programs give designers and contractors a lot of choices when a project calls for anchoring.

To use the Anchor Designer Software to choose an anchor, the user enters the following information: the general type of anchor desired, the diameter, the location of the anchor in the masonry wall, whether the masonry is grout-filled or hollow, the masonry thickness, the applied loads, and the anchor spacing, end, and edge distances. Then click continue, and the applicable solutions will be shown

For connector applications, Simpson Strong-Tie also offers software to help users pick the right connection. Their Connector Selector (Allowable Stress Design) software tells you which products are appropriate for your connection, then sorts them by lowest installed cost. The built-in Job List can track your projects and print a shopping list, including required anchors and fasteners.

For those who prefer a printed aid, Simpson Strong-Tie has a new High Wind-Resistant Construction Application Guide. Rather than being arranged by product, as the Wood Construction Connectors Catalog is, it is arranged by application, such as connections for roof to masonry wall. Technical information and installation instructions for all Simpson Strong-Tie anchors is contained in the Anchoring and Fastening Systems for Concrete and Masonry catalog.

The Anchor Designer software, the Connector Selector software, catalogs, and the High Wind-Resistant Construction Application Guide can be downloaded for free at www.strongtie.com.

Users can be assured that the products they use will perform as expected. All Simpson Strong-Tie products for masonry have been lab-tested. To develop the most economical applications, products often go through two or three iterations before they are fully developed and released.


Randy Shackelford, P.E., is manager of codes and compliance with Simpson Strong-Tie Co. He can be reached at rshackelford@strongtie.com.

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