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Back to Basics: Vapor Control Layers Explained | UnBuild It Podcast #163
Vapor is one of the most misunderstood parts of building science—and in many assemblies, it helps buildings dry rather than making them wet. In Part 3 of the Back to Basics series, Steve, Jake, and Pete break down vapor control, vapor permeability, drying potential, and why decades of confusing code language created so much fear around vapor.
As Steve puts it, “Vapor is not a liability, it is an asset.” Buildings get wet. In most climates and assemblies, the ability to dry through vapor diffusion is an important part of keeping moisture-sensitive materials safe.
The crew explains why you need to understand the vapor permeability of every layer in an assembly, where to find reliable material data, and when to go directly to manufacturers for standardized test results. They also get into indoor humidity measurement and why accurate hygrometers are more important—and more expensive—than many people realize.
This is Part 3 of the four-part Back to Basics series covering Water, Air, Vapor, and Thermal control.
162 - Back to Basics: Air Control Layers Explained
Airtightness is one of the most important—and most measurable—parts of building performance. In Part 2 of the Back to Basics series, Steve, Jake, and Pete break down how air control layers work, why continuity matters, and how blower door testing exposes the difference between theory and reality.
The crew starts with several principles that apply across multiple control layers: staying in one plane makes continuity easier, simpler details are more likely to succeed, and combining control functions in a single material can reduce opportunities for failure. They also revisit one of their favorite ideas: eliminate “confused spaces.” Attics, crawlspaces, and other areas should clearly belong either inside or outside the building enclosure.
Then the conversation gets specific to airtightness. Blower doors do not lie. ACH50 provides the quantitative result, but finding the actual leaks—their size, location, and number—is just as important. The boys discuss why one blower door test is rarely enough, how wind, stack effect, and fans drive air leakage, and why two mediocre air control layers do not equal one good one.
For renovations, the sequence is simple: blower door test first, air seal second, insulate third.
161 - Back to Basics: Water Control Layers Explained
Water is the number one enemy of building durability—and the first control layer every builder, architect, and designer needs to understand. In Part 1 of a four-part Back to Basics series, Steve, Jake, and Pete break down the principles of water management that every high-performance building depends on.
The conversation starts where most rain begins: the roof. From roof design and drainage to flashing strategies and capillary action, the crew explores how liquid water moves through buildings and why good design is the first line of defense. They also discuss how patterns of water damage in both historic and modern buildings reveal timeless lessons about moisture management.
One of the episode's most interesting discussions comes when building science theory meets real-world practice. Steve approaches water management from an architect's perspective, while Jake explains the practical realities builders face every day. The result is a thoughtful conversation about balancing ideal building science with constructability in the field.
This is Part 1 of a four-part series covering the four fundamental building control layers: Water, Air, Vapor, and Thermal.
160 - Designing Homes for Extreme Weather & Natural Disasters
How do you design a home for floods, wildfires, earthquakes, hurricanes, tornadoes, or ice storms? In this episode, Steve, Jake, and Pete explore what it really means to build for extreme events—and why there’s no one-size-fits-all solution.
Drawing from real-world experience, Steve and Jake discuss how high-performance homes can be adapted to withstand the specific hazards of a site’s climate and geography. From flood-resistant foundations and safe rooms to wildfire resilience and high-wind detailing, the conversation focuses on matching building strategies to the level of protection each client wants to achieve.
The discussion also highlights an important philosophy: building professionals aren’t there to judge a client’s concerns—they’re there to understand the risks, explain the tradeoffs, and design solutions that meet the client’s goals.
Whether you’re building in a floodplain, earthquake zone, hurricane corridor, or wildfire-prone area, this episode explores the principles behind resilient, durable homes designed for the unexpected.
159 - Climate Zone 7 Ceilings, Universal Design & Alternative Foundations
Three listener questions lead to three very different building science discussions—from cold-climate roof assemblies to aging-in-place design and innovative foundation systems.
The episode begins with a Climate Zone 7 tongue-and-groove ceiling question, comparing ZIP sheathing and smart vapor retarders for airtightness and moisture control beneath a vented attic. From there, a question about zero-threshold exterior doors expands into a broader conversation about Universal Design and designing homes that remain accessible throughout every stage of life.
The final discussion explores alternatives to traditional concrete foundations, including wood-based and prefabricated foundation systems. Steve and Jake weigh in on whether they would actually build with these systems, while Pete introduces an intriguing below-grade SIP foundation from Extreme Panel Technologies that was new to all three hosts.
Three listener questions, dozens of practical takeaways, and another deep dive into the details that shape better buildings.
Multiple Chemical Sensitivity & Building Performance - 158
How much can a building affect human health—and what happens when occupants become highly sensitive to their environment? In this episode, Steve and Pete are joined by retired building scientist and pulmonary physician Nathan Yost for a thoughtful discussion on Multiple Chemical Sensitivity (MCS) and its relationship to building performance.
Nathan shares insights from decades of experience working with clients dealing with chemical sensitivities, along with more recent medical understanding surrounding pregnancy, hormonal changes, and biochemical sensitivities. The conversation explores where building science intersects with health concerns, how indoor environments can influence occupant comfort, and what building professionals should consider when designing for sensitive individuals.
Steve also shares examples from recent projects where MCS concerns led to major changes in materials, specifications, and interior design decisions. The discussion even ventures into the controversial topic of electromagnetic fields and so-called “dead zones,” highlighting the challenges of balancing occupant concerns with evidence-based building practice.
It’s a fascinating conversation about the overlap between buildings, health, and the limits of what construction professionals can realistically control.
157 - Four Building Science Puzzles: Expansive Soils, Radiant Barriers & More
Four listener questions. Four very different building science challenges. One highly technical episode.
Steve, Jake, and Pete tackle a collection of building puzzles that span foundations, roofs, wall assemblies, and moisture management. The discussion starts with expansive soils and why successful construction often depends on engineered foundation systems designed to accommodate soil movement. From there, the crew examines attic radiant barriers, where they work best, and why climate matters when evaluating their performance.
The conversation then shifts to a cold-climate stucco retrofit involving exterior rigid insulation, reinforcing a core building science principle: prioritize the four control layers in the right order—water first, airtightness second, drying potential third, and thermal control fourth. Finally, they unpack the risks of a “diaper wall” assembly, where moisture-sensitive materials become trapped between low-permeance layers, and discuss how weather protection and airtightness can reduce those risks.
A highly technical episode packed with practical problem-solving, building science fundamentals, and real-world application.
156 - Building Standards vs Better Buildings?
Do certifications, standards, and professional credentials actually lead to better buildings—or just more paperwork? Steve, Jake, and Pete tackle one of the more uncomfortable questions in the building industry: why so many standards fail to consistently produce better outcomes in the real world.
The conversation ranges from ASTM standards and manufacturer testing to architectural credentials and industry certifications, questioning where standards genuinely help—and where culture, habits, and resistance to change become the bigger obstacle. Steve makes the case that the industry’s biggest challenge may not be technical at all, but cultural.
The crew also digs into one of Steve’s standout ideas: “chase friction.” Instead of accepting inefficient details, weak processes, or recurring failures, the goal should be to constantly look for the points of resistance that reveal where buildings can improve.
It’s an opinionated discussion with a few disagreements along the way, but the central takeaway is clear: meaningful progress only happens through rigorous education—for both building professionals and clients alike.
155 - ZIP-R on the Roof? Structural, Hygrothermal & Durability Tradeoffs
Can ZIP-R panels work on a roof—and should they? Steve, Jake, and Nick Sabol from Huber’s Technical team dig into a topic that’s getting a lot of attention in the field.
This episode breaks down the full set of considerations behind putting insulated sheathing on the roof deck: structural loading, fastening and shear, hygrothermal behavior, condensation risk, and long-term durability. The crew looks at where the idea makes sense, where it doesn’t, and what you need to understand before trying it on a real project.
It’s a detail-heavy conversation that connects theory to field conditions—exactly where most “good ideas” succeed or fail. And for Pete’s top resource on this one? Call Steve.
154 - Wildfire Zone Rainscreens & Smarter ZIP Sheathing Use
Do wildfire zones actually change how rainscreens should be detailed—and where does conventional thinking fall short? Nick Sabol from Huber’s Product Engineering team is back with Steve and Pete to continue the deep dive into wall details that actually work.
This episode focuses on rainscreen strategies in wildfire-prone areas and challenges the assumption that every risk requires a completely different assembly. The discussion also highlights Steve’s perspective on using materials like ZIP sheathing in unconventional ways—prioritizing performance and continuity over tradition when it makes sense.
From fire exposure considerations to air barrier continuity, the conversation connects real-world risk with practical detailing decisions. It’s a continuation of the Part I discussion, with a sharper focus on where building science meets evolving conditions like the Wildland Urban Interface.
153 - Wall Details That Actually Work: Water, Air & Rainscreens
What are the most critical wall details for managing water and air—and where do builders get them wrong? Nick Sabol from Huber’s Product Engineering team joins the crew for a technical deep dive into exterior wall assemblies that actually perform.
Pete, Jake, and Nick focus on two of the most failure-prone areas in construction: bottom-of-wall-to-foundation connections and window rainscreen detailing. The discussion breaks down how to properly manage bulk water, maintain continuous air control, and integrate systems so they work together instead of against each other.
Along the way, they introduce RAINA (Rainscreen Association in North America) and highlight why rainscreen strategies are becoming essential for durability across climates. It’s a detail-heavy episode with practical takeaways for builders, designers, and anyone serious about building enclosures—plus, for better or worse, no Dad joke this time.
152 - Thermal & Structural Loads: Insulation, Wood, and Concrete
How much load can insulation actually carry—and are we over-engineering residential buildings without realizing it?
This episode goes deep into the structural and thermal realities behind common building materials. The crew breaks down compressive loading on rigid insulation, long-term creep behavior, and how these factors influence slab and foundation design. From there, the conversation expands into thermal bridging challenges in wood and concrete assemblies, and how innovative framing systems like EcoSmart and Tolko aim to improve performance.
Along the way, they question a core assumption in residential construction: are we solving problems that don’t actually exist? The discussion highlights where engineering matters—and where it may be overkill.
And in true UnBuild It fashion, Steve closes things out with an unexpected design tangent involving beehives.
151 - Where Matters: Climate
Climate drives building performance. In the first episode of a three-part series, Pete, Steve, and Jake explore why climate matters so much in building science.
Steve kicks off the discussion with a simple analogy: Would you pack the same suitcase for Minneapolis in February, Honolulu in March, and New Orleans in July? Of course not. Buildings work the same way. Design decisions about insulation, vapor control, air barriers, and drying potential all depend on where the building lives.
The conversation walks through how climate zones influence building enclosure strategy and why national research from the Building America program has shaped modern high-performance construction. And of course, no climate discussion would be complete without Joe Lstiburek’s “Perfect Wall,” one of the most influential concepts in applied building science.
This is the first of three episodes exploring how location shapes building design. Next up: Site and Extreme Events.
150 - Social Media: The Best and Worst of Building Science
Is social media helping the building industry—or hurting it? Matt Risinger joins Jake and Steve as the Three Social Media Amigos to roast Pete, the resident social media skeptic, and unpack what online platforms really mean for builders, architects, and building science pros.
The conversation draws a sharp line between the dark side of social media—misinformation, marketing noise, and ego-driven content—and its best potential: real information transfer, community, and better buildings through shared knowledge. It’s entertaining, honest, and occasionally brutal (especially for Pete), but it also raises serious questions about how we learn, teach, and influence in a digital world.
The takeaway? Social media can either amplify expertise or dilute it. The difference comes down to intent, integrity, and how we use the tools.
149 - I’ll Tell You Where to Stick That Opinion
Who really matters most on a building project—and can the team actually work together? In this episode, the crew digs into the five “gears” of the building process: designers, builders, manufacturers, consultants, and building owners or users. The big question is whether any one of those gears is more important than the others—or whether good buildings only happen when they all mesh.
Steve cuts straight to the chase, sharing how he really feels about consultants (that would be Pete) and, in particular, energy modelers. The discussion gets lively, honest, and occasionally spicy, but the takeaway is clear: the best-performing buildings come from integrated teams that respect each role and work together from the start.
It’s a candid look at collaboration, friction, and why integrated design isn’t just a buzzword—it’s essential if you actually want buildings that perform as intended.
148 - Dumb Ideas? Vented Crawlspaces & Over-Insulating Window Frames
Are vented crawlspaces really a bad idea—and can you actually over-insulate a window frame? The crew gets fired up tackling two topics that refuse to die in building science conversations.
First up is crawlspaces. The boys dig into a bit of U.S. crawlspace history, what vented crawlspaces were originally intended to do, and why they so often fail to perform as hoped. They walk through what crawlspaces should and should not do, and why climate, moisture, and enclosure strategy matter far more than tradition.
Then Steve takes the lead on one of his favorite “dumb ideas”: over-insulating window frames. While improving window performance absolutely matters, the discussion makes the case that, except in very cold climates, obsessing over frame insulation can introduce new water-management risks—and distract from much bigger thermal priorities elsewhere in the enclosure.
Classic UnBuild It: strong opinions, real-world building science, and a reminder to focus effort where it actually moves the performance needle.
147 - Dehumidification in Dry Climates & Vented Crawlspaces? Seriously?
Can ERVs actually dehumidify a home? And does it ever make sense to use a dehumidifier in a vented crawlspace? Two listener questions spark a lively—and slightly ruthless—discussion that leads to one of Steve’s classic lines: “Suck it up, buttercup!”
The crew digs into how moisture really behaves in dry climates, what ERVs can and cannot do when it comes to latent load management, and why dehumidification strategies that work in one climate can be completely wrong in another. They also unpack the challenges of managing moisture in vented crawlspaces and why adding equipment isn’t always the right answer.
Along the way, the conversation takes an important turn into floodplain construction, with a great discussion—and a must-read resource—on FEMA breakaway walls and how they intersect with moisture management and durability. Plenty of tough love, plenty of building science, and lots of useful takeaways despite the rough ride.
146 - A Deep Dive on Windows: Glass, Performance & Condensation
Windows are one of the most confusing—and consequential—components of a high-performance home. In this episode, the crew takes a deep dive into window and glass selection, aiming to make things clear without letting your eyes glaze over.
The discussion covers dual-pane versus triple-pane insulated glazing units, IGU numbering conventions, and the relatively new i89 coating—including what it means for thermal performance and condensation risk. They also unpack the difference between center-of-glass values and full-window NFRC performance numbers, and why those distinctions matter when making real design decisions.
One gem of a takeaway sums it all up, with Jake quoting Steve: “The windows, the envelope, and the HVAC are one line item.”
145 - High-Performance HVAC Ducting & Appliance Exhaust
A detailed look at smarter HVAC ducting, better airflow, and what it really takes to manage appliance exhaust and makeup air in high-performance homes.
The boys dive into the how and why behind HVAC duct layout, register placement, and whole-house airflow. They break down how interior design, enclosure performance, and mechanical systems must coordinate—because ducting isn’t just about energy efficiency. Thermal comfort and indoor air quality matter just as much.
They also get into makeup air, kitchen ventilation, and what happens when houses get tighter and appliances get stronger. Lots of building science, lots of clarity, and (of course) a little UBIP chaos.
144 - Tips for Young Builders with Tim Hill – Risinger Build
What does it really take to grow as a young builder today? Jake and Steve bring in Risinger Build’s Managing Partner, Tim Hill, for a fast-paced, experience-packed conversation full of practical advice for builders looking to level up their craft, business, and mindset.
Jake and Steve give Pete the boot for this one—and for good reason. Tim joins them to share real-world insights on everything from building capital and managing budgets to client communication, niche-building, and avoiding the projects that drain your time and sanity. Across the episode, there are a “baker’s dozen” takeaways that every young builder needs to hear.