Multi-Slide Doors: Trends, Materials, and Developments

May 11, 2020

What’s new and next in multi-slide doors? In this Q&A with the National Glass Association (NGA), Western Window Systems’ commercial sales director Brian Leizerowicz discusses improvements in high-performance glazing options, customized thermal strut systems, hardware developments, the advantages and disadvantages of the materials used in multi-panel doors, and more.

Tell me about the overall trends in multi-panel doors. How has the category evolved in the past five years? What is the next big thing?

There’s a clear emphasis on larger sizes, easier operation and hardware options, and better overall performance including thermal, air, water and structural ratings, and acoustic enhancements.

What is the primary driver behind product development?

Architects are adopting and embracing the indoor-outdoor concept with larger sizes and more focus on daylight and views, so in response, contractors and envelope consultants need systems that solve more of their issues with installation, integration into waterproofing systems, and accessibility, while managing their professional liability for long-term performance.

Tell me about different materials in multi-panel doors and advantages and challenges with each.

There are more products on the market constructed of wood/clad wood and steel, which certainly come with aesthetic benefits in terms of finishes and sightlines, but also carry the challenge of long-term maintenance. Aluminum is still the preferred material due to its structural and thermal capabilities and long-term finish durability.

How is technology influencing the product category? How is it being used?

Improvements in high-performance glazing options using triple silver coatings, gas fill and highly durable interior surface low-e coatings, improvements and customization of polyamide thermal strut systems, hardware developments that help reduce operating force and improve air/water/structural performance, dynamic glazing, automation systems, integration with vapor barriers and thermal envelope systems are all literally pushing the envelope on unit sizes we can construct while still maintaining code requirements and overall practicality.

Tell me about multi-slide versus bi-fold versus lift and slide doors. Is there a distinct functionality/appropriate use difference between them?

There is definitely a hierarchy in terms of pricing, performance, and functionality. All three systems are intended to provide the same general result of constructing large openings with excellent daylighting and views, and clear transitions between indoor and outdoor spaces; however, the technology and capabilities of the three distinct types of hardware component systems ultimately drive increases in cost and also the ability to manage air, water, structural, and also acoustic performance.

Multi-slide doors are easy to install and maintain and are a highly cost-effective means of creating huge openings for indoor-outdoor living. Bi-fold systems can provide slightly better air and acoustic performance and allow for single-track operation, but the hardware is higher cost, and the stacking location of the bi-fold panels needs to be well planned. Lift and slide systems provide excellent air, water, structural, and acoustic performance and the ability to move enormous panels with relatively little force, but the hardware components are highly engineered and add material costs to the overall system.