Authors: Jesus A. Barreda & Lee Baggs

It is said that one of the most challenging details in a building is the edge of the slab; where the façade meets the main structure. The edge of slab ecosystem has a major impact on the structural performance and serviceability of the building and ultimately, the cost of the project. Some of the elements of the edge of the slab that must be carefully considered are relative movements, fire safety, waterproofing, thermal performance, moisture protection, air infiltration, acoustics, adequate support of the curtain wall brackets, adequate structural anchorage, and construction tolerances. The design requirements for each element creates specific challenges on its own. However, orchestrating these complex systems in today’s fast track construction industry creates a few layers of additional intricacy. This is one of the main reasons why glaziers are constantly evolving and looking for innovative ways to drive increased efficiency and simplicity. The old expression “if it ain’t broke, don’t fix it” is no longer applicable. Industry leaders are constantly evolving pushing the market to new frontiers. Innovation, code compliance, simplicity, and on-time execution have been the story for the curtain wall façade anchorage selection over the last years.

The curtain wall industry is becoming more technical, sophisticated, and regulated by the day. The ongoing construction and façade trends such as unique building shapes, taller buildings, fast track construction, lighter (and sometimes weaker) construction materials, thinner slabs, larger façade panels, job sites with limited storage areas, and other factors, are part of the reason why market leaders are continuously pushing the industry to new boundaries. As if the above challenges were not enough, COVID-19 has taken the construction world by storm. COVID-19 has superimposed additional layers of complexity such as logistic challenges due to raw material shortages (which has led to increase in prices), longer transportation times by carriers, and market uncertainties. Now more than ever, your construction supply chain must be robust. To help ensure this robustness, a contractor must strategically select a supplier who is working on both the front and back end to help ensure the contactor can reach success. Synergy between all pertinent parties is imperative to profitable project execution. Hilti’s Façade Team is there to build trust and long-term relationships with our customer as it fosters a collaborative partnership each step of the way; by helping with bidding, design, planning, approvals, execution, and field fixes. We dive deep to help find an optimal, cost-effective solution rather than provide a general recommendation which may eventually need additional engineering oftentimes leading to additional costs. Our team provides personalized project services to address different contractors’ preferences in tandem with the depth of engineering needed in this day in age.

Concrete embed channel inserts are one of the first elements of the edge of slab ecosystem that get installed, yet one of the last elements in the design sequence. In fact, the design parameters that can influence the performance of an embed are decided months (or years) prior to the time when the embed is designed. Therefore, having an engineering team that specializes in embed designs for façade applications, is flexible enough to cope with different customer’s preferences, and is capable of managing the above-mentioned market trends and challenges can bring substantial value to your project. A relatively minor modification can downsize the embed design. It could even result in downsizing from an embed with rebars to a standard embed which ultimately translate into increased project profits. Understanding the structural levers that can be pulled and are acceptable for glaziers is the key. However, selecting a feasible, structurally sound, and model code compliant curtain wall anchorage is not enough to set up a project for success. In order to maximize the probabilities of success, the following key factors are carefully assessed by our Façade Team when making the embed selection:

1)   Project Prioritization:
Confirm the project’s schedule in order to prioritize it appropriately. In addition to helping prevent project submittal delays, understanding the project’s schedule allows the lead engineer to specify an embed that can be delivered on time.
 
2)   Design criteria and Code Compliance:
Design criteria such as wind loads, slab thickness, concrete type and compressive strength, seismic requirements, jurisdiction requirements, etc. are carefully reviewed to help ensure all the critical factors are considered in the design stage.
 
3)   Engineering Design:
The design criteria is utilized to size the cast-in inserts. Other unique challenges that impact constructability such as column hits, clashes with metal decks, acute corners, etc. are proactively evaluated. Field fixes are also part of the engineering services provided.
 
4)   Ease of installation:
When it comes to embed layout, there is usually a trade-off between feasibility and simplicity; typically, the simpler the layout (e.g. one embed type for the entire job), the more expensive the solution. Balancing these two factors is carefully considered in the embed recommendations.   

(Our R&D team has developed an Adaptive Torque (AT) Module to allow our t-bolts to be properly pre-tensioned with a Hilti impact driver to help drive efficiency and reduce install times on site. More on this topic soon!)
 
5)   Engineering Proposal:
A best in class engineering proposal provide our recommendations along with the pertinent project information, design criteria, and design assumptions in a simplified format to ease the review and approval process.
 
6) Project Planning:
We have a dedicated project management team that will coordinate material needs with construction schedule. Packaging, custom labeling, color coding, are among the many façade services that are provided to help ensure success.

Our industry is yet to fully experience the result of the pandemic. The already present effect, is that some of these previously optional best practices have now become adopted by most of the industry as standard and are almost required to ensure a successful project. In many ways, COVID-19 has accelerated, standardized, and improved some of the slowly growing market trends and best practices that we have been experiencing in this industry over the last few years. Adopting and enforcing such practices now, will help ensure a successful design and execution of the curtain wall façade embeds, therefore ultimately leading to more successful projects with higher profitability. The industry is moving towards service-based solutions. When it comes to the curtain wall façade anchorage, there is no way around this trend other than having a fully dedicated façade team. Our Hilti Façade Team plays a fundamental role in not only assisting with the embed selection process but can also play a critical role during the planning process. With regard to successful projects, the non-structural aspects of the engineering design sequence are as equally important as the structural aspects. A cohesive strategy, with coherent actions, is allowing our Hilti Façade Team to be that more reliable partner but do not take our word for it, try it out for yourself! 

To submit a façade engineering request, please reach out to your local Account Manager, Field Engineer, or Façade Business Developer, or email our engineering team at US+CA.HAC@Hilti.com