Construction Instruction

Airtightness is about more than comfort and energy efficiency. It’s also about the economics.

If you’re not factoring this in, you’re likely leaving margin on the table:

1️⃣ Air leakage accounts for 20–40% of your mechanical load. Tighten the envelope, and you can often downsize systems by $1K–$2K+ per home.

2️⃣ Dollar for dollar, airtightness beats insulation. Going from 4–5 ACH down to 1.5–2 ACH is roughly equivalent to adding 3” of continuous exterior insulation often at a fraction of the cost.

3️⃣ Fewer callbacks and lower risk.
Build tight and ventilate right, and you’ll see:
✔️ Fewer comfort complaints
✔️ Less condensation risk
✔️ Better long-term performance

Bottom line:
Airtightness is a business decision as well as a building science fundamental.

If you’re still treating it as optional, it might be time to rethink the math.

🚨 Tiny detail. Big building science lesson.

Do unsealed nail pe*******ons actually matter?

We put it to the test at Ci using calibrated equipment and ASTM testing procedures to compare enclosure performance with sealed vs. unsealed nail pe*******ons and the results were clear:

💧 Unsealed nail pe*******ons leak.

Sometimes, better building comes down to getting the small details right. Building science helps remove the guesswork and turn best practices into proven performance.

👉 Are you sealing nail pe*******ons on your projects?

💨 Your Walls Might Be Leaking More Than Air…They’re Leaking Performance.

Justin joins Robby Schwarz of to hunt down hidden air leaks in this home.

Using a smoke pencil, they uncover a 10 Pascal pressure difference inside an interior wall where it should be reading ZERO.

The culprit? Air leaking from the attic, through the wall cavity, and out an unsealed electrical outlet.

Just ONE unsealed electrical outlet = roughly 1 square inch of leakage area.

Now multiply that across an entire house. 😱

Small details = big consequences for:
✔️ Comfort
✔️ Energy efficiency
✔️ HVAC performance
✔️ Callbacks

Seal your electrical boxes because airtightness is built one detail at a time.

“Building science never stands still… and neither can builders.” 👊🏽🏠

Jerry Charles with Symbolic Homes in Los Angeles, CA, has now attended Construction Instruction training THREE times.

As a luxury, custom builder working on very large, highly detailed homes, Jerry explained that staying current with building technology, mechanical systems, comfort strategies, and performance details is critical to delivering better homes for his clients.

But when you only build a few homes every several years due to their massive scale, often 20-30K square feet each, gaining knowledge in the field about cutting edge technologies and top building science recommendations can be a challenge.

That’s why builders from across North America come to Construction Instruction:
✔️ To sharpen their skills
✔️ To better work with trades and subs
✔️ To stay ahead of evolving building practices
✔️ To build more comfortable, durable, high-performance homes

We’re incredibly grateful for the trust and kind words, Jerry. 🙌

The best builders never stop learning.

Check out our 2026 Ci Live class schedule today and register now to secure your seat at www.ci-live.com.

HVAC Professionals & Home Builders - You Don't Want To Miss This!

Construction Instruction is the building industry's go-to resource for building science education.

With over 100 years of combined experience, our building science experts - Justin Wilson, Gord Cooke, Andrew Oding and Mark LaLiberte - are industry legends.

Join us for this two-day advanced workshop on high-performance mechanical solutions that support the industry’s shift toward all-electric, energy-efficient construction. This class also addresses ventilation design, plumbing efficiency, and hot water delivery strategies, giving professionals the tools to integrate mechanical and water systems into whole-house performance.

Ci Live Class: Mechanical Mastery
June 23 & 24, 2026 in Denver, CO
Register today at www.ci-live.com

Most existing homes have opportunities for major improvements in comfort, indoor air quality, durability, and energy performance, but retrofit work comes with its own unique challenges. 🔧🏠

In this project, Justin is joined by Eastside Heating & Air Conditioning to retrofit an existing home with significant upgrades to the mechanical system and crawlspace to improve:
• Ventilation
• Indoor air quality
• Comfort
• Overall building performance

While most of our Ci training classes have focused on new construction, we have years of hands-on experience applying building science principles to existing homes and we’d love your input. 👇

WE WANT YOUR FEEDBACK:

Would you be interested in attending a 1-day Building Science for Existing Homes / Retrofit class?

And more importantly…what retrofit topics would be MOST valuable to you, your team, or your projects right now?

Comment below with the area you’d most want covered:
🔧 HVAC upgrades
🏠 Air sealing
💧 Moisture management
🌬️ Ventilation
🪟 Window & door replacement details
⬆️ Converting unconditioned spaces to conditioned spaces
📋 Diagnostics & troubleshooting
👷 Other? Tell us below.

Your feedback will directly help shape future training classes and content topics.

We genuinely want to build training that helps solve real-world jobsite challenges, so thank you in advance to everyone who takes a moment to share their thoughts.

Did you know that air pressure inside a house changes depending on the outside temperature?

One of the biggest reasons is something called the "Stack Effect."

When it’s cold outside and warm inside, warm air inside the home naturally rises. If there are gaps and air leaks in the upper parts of the house, especially the attic, that warm air escapes outside. As it leaves, the house pulls in cold air through leaks lower in the building to replace it.

The result?
❄️ Drafts
💸 Higher heating bills
🌡️ Uneven temperatures
❌ Comfort complaints

This is why attic air sealing matters so much in high-performance construction.

Insulation alone isn’t enough if air can still move through gaps and pe*******ons. Proper attic air sealing combined with grade 1 insulation installation helps reduce uncontrolled air leakage, improves comfort, lowers energy use, and supports better overall building performance.

The tighter and more controlled the building enclosure, the better the home can perform in every season. 🔧🏠

New from the Ci Lab!

We’ve been building something behind the scenes to make air sealing a lot more visual and real for the field.

This new demo setup uses 6 interchangeable panels with different pe*******on types and sizes so you can actually see how air moves, where it leaks, and what happens when you seal it properly.

The reality of most jobsites is that there are wires, pipes, and odd pe*******ons everywhere and there is a lot riding on getting it right.

This air sealing demo helps connect the dots between what we talk about and what you’re dealing with on site every day.

Our goal at Ci is to give you practical ways to build tighter, more comfortable homes without guesswork.

This new demo is yet another reason to join us in person at a Ci Live class to get hands-on with building science.

There's more to air distribution than just getting air into a room.

And a few small decisions can make a big difference in the level of comfort, performance, and the number of callbacks:

• Register Placement Matters: Exterior walls still make sense, but aiming airflow toward those loads (like windows) helps you actually offset them.

• Not All Registers Are Created Equal: Restrictive designs can choke airflow and direct it to less optimum areas.

• Eliminate The Guesswork: Load calcs + Manual D = delivering the right amount of air where it’s needed.

• Velocity Drives Comfort: It’s not just CFM. Proper air speed helps mix the air distribution within the space and eliminate hot/cold spots.

Key Takeaway:
When airflow is intentional, comfort follows and so do fewer issues on site.

If you want to sharpen the mechanical portion of your builds, come see us at Ci Live.

Our two-day Mechanical Mastery class on June 23rd & 24th is an advanced course on all things HVAC & mechanical. We’ll walk through practical ways to get this right in the field.

Register today with the link in our bio.

What does 40 years in the building industry teach you?

That milestone gives you a lot of perspective.

Gord Cooke, a building science partner with Construction Instruction, recently reflected on his career in the building industry and said something that might resonate with many of you - especially those who’ve spent years in the field trying to bridge the gap between theory and what actually works on a jobsite.

He started as an engineer, but quickly realized that building performance isn’t something you fully learn in a classroom.

It comes from listening to builders’ real challenges and being asked tough, practical questions.

Early on, when builders asked “Why does this matter?”, the answer wasn’t always clear. That led to something important: a commitment to continued learning.

Through training, mentorship, and years of experience, a clearer picture emerged:

Building science is about understanding how the pieces connect together so that the same decisions can:
• Improve energy performance
• Increase durability
• Enhance comfort and indoor air quality

Milestones like this are also a reminder of how important mentors, peers, and builders in the field are and how they all play a role in shaping what we know and how we apply it.

Thank you to the people who ask questions, share knowledge, and keep pushing for better-performing homes and to an industry that quite literally builds for generations.

Congratulations Gord on this amazing career milestone!