NOVEMBER 2025CONSTRUCTIONBUSINESSREVIEW.COM 19Building Code LimitationsWe all recognize that the building code sets the minimum design requirements to pass permit review through the building department. For example, using the minimum air space code-required for masonry cavity walls is often inadequate due to construction tolerances and the buildup of multiple materials. What was designed as a code minimum of one inch of air space can turn into an air space of three quarters of an inch to one half of an inch or less. It would be better to apply industry knowledge and allow for construction and material variability, providing an air space of one and a half to two inches to ensure adequate air space for constructability, not just to meet the building code. These one and a half to two inches air space dimension aligns with industry recommendations or "best practices," designed to ensure adequate air space in the cavity wall.Manufacturer's Minimum RequirementsConsider a plaza waterproofing project with subsurface drainage below a natural stone surface under habitable space in a cold climate. Many manufacturers offer waterproofing products capable of being installed flat without failure. However, in a flat condition with construction tolerance, the surface could be back-pitched and still within construction tolerance. Water will pool on the substrate and depending on the design and location, this could jeopardize the plaza finish material by causing saturation, discoloration or freezing in colder climates. Additionally, standing water over time could place extra stress on joints or installation imperfections, potentially causing failure beyond the warranty period. Best practice, accounting for construction tolerances, is to pitch the substrate at a minimum of one eighth of an inch per foot toward the subsurface drains. This ensures effective water management and helps mitigate potential issues. Additionally, I recommend installing a drainage board over the waterproofing to provide a clear pathway for water to reach the drains efficiently.Manufacturer's Warranty RequirementsOne of the ongoing challenges I face is navigating warranty requirements. While it's important to meet at least the minimum standards to preserve warranty, I believe we shouldn't be designing or building solely to satisfy warranty. Instead, we should focus on the specific details of the project, the building type (e.g., university building vs. gas station) and the interactions between adjacent materials, such as metal expansion due to heat or chemical and adhesive compatibility. After all, a warranty is limited in duration and in many cases, it falls short of the actual life expectancy of the product or system. For example, foundation waterproofing is installed in a location where, if the material, installation or design fails, it is extremely expensive to correct. Most waterproofing warranties, even the best-in-class warranties, will not cover the removal and replacement of the overburden to correct the condition. Typically, the manufacturer warranty only covers product defects, not design practices. So, if we build to a warranty and not best practices or lessons learned, it could end up costing ten to one hundred times more than the original install cost, even though the material will be provided by the manufacturer (the least expensive component of the waterproofing system).Our profession should be grounded in experience and a clear understanding of the "why" behind each decision, not limited by warranties or the minimum standards outlined in the building code. It is a disservice to the owner and the profession. Research, understanding and learning from past failures and successes--that is the way to serve the owner and protect the industry. Lately, I have been working with designers to build consensus on designing to various conditions or what is right based on decades of experience, miles of construction and mountains of research and standards that take the "why" into account. While it's important to meet at least the minimum standards to preserve warranty, Zussman believes designers and builders shouldn't be designing or building solely to satisfy warranty.
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