FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In
News

A Shortcut for Air-Sealing Houses

By Scott Gibson
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles
A misting nozzle disperses a liquid sealant into the air, and air pressure carries it into wall and ceiling cavities, where it plugs leaks.

Any building scientist worth his energy-modeling software can tell you that uncontrolled air leaks lead to a variety of problems in houses, including increased energy consumption, lower comfort, and the possibility of moisture condensation inside walls and ceilings.

That’s why builders who specialize in superefficient houses spend so much time tracking down and correcting air leaks. The process can involve a number of materials and sealants, such as special gaskets, tape, and caulk, plus a lot of time and attention to install them correctly.

In the end, builders see how well they’ve done with a blower-door test, which measures how leaky the building envelope is with the aid of a powerful fan. If you’re seeking Passivhaus certification, a fan pressure of 50 pascals can induce no more than 0.6 air changes per hour. That’s very tough to achieve.

If air-sealing seems like a specialized skill beyond the reach of many builders, help is on the horizon in the form of technology originally developed to seal air ducts. When fully developed and commercialized, the process could turn air-sealing into a speedy, routine operation.

Technology developed at University of California

According to an account by Daniel Mathews at EarthTechling, this story starts at the University of California-Davis, which invented a process 16 years ago for sealing existing ductwork. It was later marketed by a startup company called Aeroseal.

A fine mist of sealant is forced under pressure into ducts. The sealant gravitates toward leaks as it tries to escape and eventually plugs them up. The process is not unlike blood clotting at a wound.

The inventor, Mark Modera, director of the university’s Western Cooling Efficiency Center, wondered whether the same process could be used to seal whole houses, Mathews wrote. It was tested on three Habitat for Humanity houses being built in California.

“In these ‘already-sealed’ houses, it reduced leakage by about 50%,” Mathews said. “(WCEC has already developed monitors and software that graph the whole-house leakage rate in real time, while they are sealing it.) Before commercializing the technology, they plan to refine it a little more, hoping to reach leakage rates too small to measure. Remember that the sealant has been effectively sealing ducts for 12 years already.”

Not for furnished, occupied houses

When the house is ready for sealing, a blower door is set up. In the center of each room in the house, workers mount a nozzle capable of producing a fine mist and connect it with a supply line to a container of liquid sealant. Then the house is pressurized with the blower-door fan.

As the house becomes pressurized, air is forced through holes and gaps in the building envelope, carrying some of the sealant mist with it. Just as the compound seals leaks in air ducts, it plugs holes in the building.

No one is inside the building during the procedure, so they won’t have to breathe in any of the sealing compound. Once the material has solidified, Mathews reports, it is considered nontoxic and even low-VOC.

But Modera says the process is best suited for new houses or houses that are empty.

“We tried it in an existing home,” Modera told a reporter for The Record in Stockton, Calif. “I don’t feel comfortable thinking about doing it when there’s all the furniture in the house, but when someone moves out and you have an empty house, I think it will help.”

Treating occupied houses may be possible in the future, he told the paper, but it may be a year or two before the process is ready for commercial use even in new houses.

Testing process on Habitat houses

Three Habitat for Humanity houses in Stockton have been air-sealed with the process through a grant from the California Energy Commission.

After construction workers went through the houses to seal obvious air leaks with caulk, the houses were pressurized and misted with sealant, reducing leakage by an additional 50%, according to the newspaper.

It took about an hour to seal each 1200-sq.-ft. home. Workers monitored progress from the garage via cameras located in each of the rooms.

“We get a kind of laboratory to do our tests,” Modera said, “and they get their homes sealed up. Everybody’s happy.”

In theory, no limit to the process

Once fine-tuned, the process should substantially reduce the amount of time and effort builders spend on air-sealing a house with conventional tools and materials, says project manager Curtis Harrington, and potentially eliminate it completely. “In theory, we can seal any size hole,” he says. “It just takes longer.”

While the sealing is taking place, the blower door is providing “continuous feedback” on how tight the house is getting, Harrington says, and researchers now typically stop when they’ve run out of sealant.

Researchers are currently experimenting with a modified version of a water-based acrylic sealant made by Tremco but plan on testing several types.

How tight can the process make a house? Harrington says it should be possible to get blower-door results of 1 air change per hour at 50 pascals of pressure. That’s not a Passivhaus result, but it’s a very tight house.

Fine Homebuilding Recommended Products

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

8067 All-Weather Flashing Tape

Available in 2- to 12-in. widths, this is a good general-purpose flashing tape that sticks well to most things. It features a two-piece release paper, water-shedding layers, and good UV resistance.
Buy at Amazon

Affordable IR Camera

This camera is super useful for tracking down air leaks in buildings. The one-hand pistol grip arrangement frees your other hand for steadying yourself while maneuvering tricky job sites.
Buy at Amazon

Reliable Crimp Connectors

These reliable, high-quality connectors from Wirefy work on 10-22-gauge wire have heat-shrink insulation to keep out water and road salt.
Buy at Amazon

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters
×

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

New Feature

Fine Homebuilding Forums

Ask questions, offer advice, and share your work

  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

View Comments

  1. nvman | Dec 02, 2013 11:16am | #1

    What happens to the excess material?
    How does it affect flooring (carpet, hardwood) and painted surfaces?
    Is it easy to clean off a window?

  2. rogerhanberg | Dec 02, 2013 12:35pm | #2

    Very Interesting - and promising.
    As your aware half our annual heating costs are attributable to air leakage.
    Our city building bylaw requires all new houses have a max. air leakage req. of 1.5 ACH(certified by an independent blower dr. test.)We presently have several builders airsealing under.5 ACH. This technology could bring it close to ziploc bag airtightness.
    Add a balanced HRV and the owner would have an extremely efficient,comfortable castle.

    Question: Are you presently using waterbased acrylic or is that what you may use in the future. If not what are you using?

    Thanks for all the leading bldg. science articles.

    r.w.h.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

More News

View All
  • Exploring Innovation at Batimat: A European Perspective on Building Excellence
  • The Inflation Reduction Act: A Year of Tax Credit Claims in Review
  • Saint-Gobain, TimberHP, and CertainTeed Announce Partnership
  • New Efficiency Standards for Water Heaters from DOE Projected to Save $7 Billion Each Year
View All

Up Next

Video Shorts

Featured Story

FHB Podcast Segment: Repairing an Old Home While Maintaining Its Integrity

Learn about different approaches to making updates and repairs to older homes with historic charm.

Featured Video

How to Install Cable Rail Around Wood-Post Corners

Use these tips to keep cables tight and straight for a professional-looking deck-railing job.

Related Stories

  • Podcast Episode 684: Masonry Heaters, Whole-House Ventilation, and Porch Flooring
  • Podcast Episode 683: Barndominiums, ERVs, and Radon Mitigation
  • Podcast Episode 682: Basement Flooring, Architectural Salvage, and HVAC Ducts
  • Fine Homebuilding Issue #331 Online Highlights

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

Video

View All Videos
  • Podcast Episode 678: Live from the Builders' Show-Part 2
  • Podcast Episode 677: Live from the Builders' Show-Part 1
  • FHB Podcast Segment: The Best of the Fine Homebuilding Podcast, Volume 8
  • FHB Podcast Segment: Larsen-Truss Retrofit to Existing Stud-Frame House
View All

Fine Homebuilding Magazine

  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers
  • Issue 327 - November 2024
    • Repairing Damaged Walls and Ceilings
    • Plumbing Protection
    • Talking Shop

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 81%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data