Code-Approved Product Saves Costs and Avoids “Red-Tags”|
Adhesive anchors are known for their strength, versatility and performance. They are used in residential and commercial construction for a variety of applications, such as rebar dowelling, securing seismic hold-downs and mudsills in concrete, anchoring steel columns, mounting ledgers and anchoring machinery. Contractors often prefer adhesive or epoxy anchors over cast-in-place anchors for their ease of installation and flexibility; engineers specify them for their strength and performance.
Retrofit contractors have also seen the benefits of adhesives. Materials, such as brick, clay tiles and cinder blocks, used in older buildings can be very soft. When anchors are needed to retrofit these buildings, adhesive anchors are often used because they bond well with the soft material, often exceeding the strength of the base material.
Largo Concrete, a structural concrete contractor in California, was awarded a rebar dowelling job for a multifamily retrofit project in Emeryville, a small city in the Bay Area. To retrofit the building, threaded rod was extended through the floors of the buildings and up through the ceilings where large diameter holes had been drilled. Rebar was epoxied into the existing walls to add strength. This system served as the support for the new walls.
To complete the job, more than 12,000 holes needed to be drilled and epoxy dowelled. Rebar dowelling is a multiple-step process and proper installation is key. “First you must select the correct type of adhesive to use,” said Wendy Allen, a field engineer for
Simpson Strong-Tie Anchor
Systems. “There are several types of adhesives on the market. Manufacturers often have different adhesives for various applications, such as one for masonry and another for concrete. It can get confusing when juggling multiple products for similar uses. It can also be problematic when the wrong type of adhesive is used.”
After selecting the right type of adhesive, the next step is to drill and prepare the hole. Concrete dust settles when the hole is drilled. It’s important that the surface receiving the adhesive is clean and dust-free. After drilling the hole, the installer must blow out the hole with oil-free compressed air. Next, the hole is cleaned with a nylon brush and then the hole is blown one more time with compressed air. Depending on the temperature of the base material, once the adhesive is dispensed it can cure in as little as 16 hours.
Simpson Strong-Tie’s SET Epoxy-Tie® adhesive was specified for the Emeryville project. SET is part of Simpson’s Anchor Systems product line and is a two-component, epoxy-based adhesive. The resin and hardener that make up the adhesive, automatically mix in the static mixing nozzle provided with the product. When dispensed into a drilled hole, the epoxy adheres to the anchor or threaded rod in the hole. Since SET is a high-strength epoxy, it’s suitable for use with both small and large diameter inserts.
Although SET was the specified product, the contractor had 90 tubes of another epoxy on the jobsite. “SET is a versatile and cost-effective option, but contractors don’t always see the direct benefit of using one product over another,” said Tom Klisiewicz, a territory manager for Simpson Strong-Tie Anchor Systems.
The project required all sizes of rebar, up to a number 10 bar. The epoxy on the job didn’t have ICC-ES code report values for rebar sizes larger than a number eight. “The code report listing ensures that a third party has reviewed the data provided by the manufacturer. Often times, building inspectors won’t accept a product unless it has an ICC-ES code report. It could have been a big problem if Largo had used that product without knowing the potential risk,” explained Klisiewicz.
After realizing the epoxy on the job wasn’t approved for the larger rebar, Klisiewicz held a meeting with Largo. Klisiewicz showed the project manager copies of the code reports for both SET and the other product. He pointed out the differences between the two products and the benefits of using SET. “The code reports can be difficult to sift through, and often times the specific details are not clear,” said Klisiewicz. “Part of our job is to know these details, so we can help customers choose the right product for the application.”
Simpson’s SET is code approved for use on rebar up to size 11. Since the other product didn’t have an ICC-ES code report for the larger rebar sizes required for the project, the contractor would have had to buy two different products for the job or risk receiving “red tags” from building inspectors when the mistake was noticed. Both situations would have resulted in added costs.
“After seeing the code reports, the project manager quickly realized SET was the right choice for job,” said Klisiewicz. “We not only helped the project avoid a ‘red tag,’ we also reduced costs by using only one product.”
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