Integrated Design—Making Durability Part of the Process
Traditional homebuilding has had an approach similar an Olympic relay, where the baton is passed from one runner to the next until the finish line is crossed. With homebuilding, this used to be the method favored by most to accomplish the task of turning over a home to a new homeowner. With design and construction of homes becoming more complex, integrated design has quickly moved from a good practice to a necessity for homebuilders.
Why? Like it or not, new homes today function as a system of interconnected parts. Driven in large part by energy requirements found in building codes, homes today simply “work” differently from they did before. For example, the air sealing and insulation levels of the building envelope greatly affect the HVAC design, as well as the potential for a small, chronic window leak to actually dry out. The strategy used to meet wall insulation requirements also affects the weather resistant barrier (WRB) selection; window flashing, air sealing, wall bracing methods; and even the potential for condensation to form in the wall. As Figure 1–1 illustrates, a home’s durability is intricately wrapped up in these interconnected systems. To some extent these systems have always had connections. The difference is that in today’s new homes the “web” is woven much more tightly, and a change in one system “pulls” directly on other parts of the home.
At the core of durability are three of the major systems in a house: envelope, structure, and mechanicals. Each of these affects the other. On the periphery are the forces that can also affect each of these core systems. Builders and designers must recognize that each decision made affects (and should inform) many other systems or decisions.
Integrative design can bring order and predictability to this web. What does this mean to the builder? Providing leadership and facilitating effective communications. Similar to assembling a design team, assembling a construction team of like-minded individuals or companies interested in providing a superior product to the consumer would be one of the first and foremost tasks.
The builder gets the dialogue started before the project starts. As part of this dialogue the interconnections we see in Figure 1–1 are discussed, and implications for the contractors’ roles and work scopes are identified. The cast of trade partners involved in this process should reflect the project’s goals. For example, in a residential project with the objective of excellent building durability and a high level of energy efficiency, these goals necessarily involve trades like foundation, framing, HVAC, insulation/air sealing, windows/siding, and roofing. An energy consultant would also be involved. As a result of this deliberate communication process and adjusting work scopes and schedules, unexpected surprises such as delays or change orders are reduced, and durability and overall home performance improve. Applying this approach to both the design process and the construction process will help to ensure that a safe, strong, efficient, durable home will be the end result.