How to Prevent Your Worst Building Assembly Fears from Coming True

Expensive callbacks and lawsuits can result when you don’t attend to the assembly details.

Directional drying is designed into high-performance buildings, and all three control layers must continuously manage water, air, and heat. Note how the air barrier is primarily accomplished at the interior and how difficult it is to prevent thermal bridging at structural framing if exterior rigid insulation is not used.Photo Credit: Steve Baczek Architect

We’ve all heard the nightmare scenarios: water leaks that mar the finest architectural features of a new building; air leaks that cause hidden mold or rot inside the walls; thermal bridges that compromise occupant comfort and energy performance.

Money on the line

These scenarios have two things in common: first, they could all land you in court. Second, they are all preventable if you’re giving each building assembly detail the time and attention it deserves.

During a recession, most firms are already working with knifeblade-thin margins, so it can be tempting to cut corners. While the “extra” work required to get the details right might seem expensive in the short term, it’s a good long-term investment.

In this month’s EBN feature article, Peter Yost and I take a look at how industry leaders are changing the way they practice architecture in response to the increasing complexity of—and increasing demands on—our buildings and building assemblies.

Energy demands put the pressure on

We all want energy-efficient buildings, but there are tradeoffs: when you decrease the energy flow through a building assembly, you have to be a lot more careful about every little air leak and thermal bridge; otherwise you risk moisture problems.

This challenge is even greater because more sophisticated, multilayered building systems may have properties we don’t know about or forget to check. For example, all building materials—not just the ones we call retarders or barriers—affect vapor movement to some degree; serious moisture problems can occur if the permeability of each assembly component is not accounted for in assembly design.

Tricks of the trade

In our article, we go through the four essential features needed to ensure good hygrothermal performance, and we’ve included lots of beautiful, detailed cross-sections from leading residential and commercial building science experts to give you ideas for solving common problems, such as:

Also Read

How "Smart" Vapor Retarders Work

Hidden Seam Failures? We Put Flashing Tapes to the Test

Sustainable Sealants: The Problem of Predicting Service Life

• Continuing thermal, air, and bulk water barriers at the parapet of a low-slope commercial roof
• Achieving thermal barrier continuity where a residential wall meets the slab
• Allowing water drainage at a commercial foundation without compromising the thermal barrier
• Continuing the air barrier at window heads and sills in a deep residential exterior wall
• Creating a continuous air barrier at a residential eave
• Minimizing thermal bridging through a commercial balcony assembly

Special building science issue

As a matter of fact, this whole issue of EBN is chock full of building science know-how and includes:

• a primer on WUFI, the sophisticated hygrothermal modeling software that’s gaining prominence in the industry
• a product review that shows how HOBO data loggers are being used by building practitioners—they’re not just for researchers anymore
• a book review of Building Science Corporation’s new offering, High Performance Enclosures, by John Straube, Ph.D., P.Eng.

Upcoming report

I’ll just leave you with a little teaser: our whole editorial team is currently expanding on all this work in a new report on high-performance building assemblies. It’s due out just before the holidays—so put it on your wish list, and watch this space for more details soon!