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
How-To

Making Fiberglass Insulation Work

A quality batt installation requires proper air-sealing and attention to installation details–in other words, you need patient, conscientious installers to get your money's worth when insulating walls with fiberglass.

By Lee Kurtas Issue 246 - Oct/Nov 2014
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Synopsis: Fiberglass insulation is the most popular residential insulating product sold today. Unfortunately nearly all of it is poorly installed, so it doesn’t perform as well as it could. Common groovy installation problems include gaps or voids around pipes, ducts, and wires, and batts that are compressed or improperly sized for the cavity. Lee Kurtas, an insulation professional in Houston, describes how to install fiberglass insulation so that it fits right and provides good thermal performance. He describes the sequence of a whole-house insulating job, including air-sealing and where to start insulating, then discusses how to efficiently and effectively delegate the work, and where energy raters are likely to focus their inspections. A comprehensive sidebar describes the RESNET rating system and provides illustrations on what  RESNET Grades I, II, and III look like in an insulated wall without drywall. Photos: Patrick McCombe

When building science and home efficiency really took off in the mid-1990s, insulation contractors started hearing regularly about how the type of insulation used affects a building’s energy efficiency. Blower-door testing and thermal imaging of existing homes proved that fiberglass — as it’s typically installed — didn’t perform as well as other types of insulation, especially spray foam. As a result, builders and architects doing projects with energy-performance benchmarks started specifying spray foam as a way to ensure better airtightness and thermal resistance.

These builders and architects liked spray foam because it seals around penetrations such as pipes, ducts, and wires, and because it fills odd-shaped cavities quickly and easily. But spray foam does have a significant downside: cost. Insulating a typical new home with spray foam in my area costs two to three times what it costs to use fiberglass. Because of its low cost, fiberglass insulation is easily the most popular building insulation here in Houston and in the rest of the country. For example, fiberglass makes up 85% of my company’s insulation business, while spray foam represents only 10%. The rest is cellulose.

Provided it is installed according to the highest standards, fiberglass performs very well. My company has developed a cost-effective and quality approach you can adapt to meet the same standards.

Installed right, fiberglass works

For fiberglass to be effective, its installation must involve three factors. First, the building must have a durable and continuous air barrier such as taped sheathing. Second, any gaps and mechanical penetrations must be fully air-sealed with durable tape or sealant. Finally, the batts must be fit and placed with care and minimal compression.

When these three factors are present, fiberglass performs as well as other insulation types. And that’s not just my opinion. Summarizing their recent findings in a multiyear head-to-head test of six insulation types, researchers at Building Science Corporation (BSC) said, “When walls are constructed with the same R-value in the stud space, and are air-sealed both inside and outside, they exhibit essentially the same thermal performance regardless of the type of insulation material used.”

The important caveat in that quote — “and are air-sealed both inside and outside” — refers to the air barrier that separates interior and exterior air. Creating a good air barrier and detailing penetrations properly are essential to getting the maximum energy performance from fiberglass batts.

What is an air barrier?

It can be helpful to think of a home’s air barrier as an air-filled balloon. The balloon’s skin, which represents the air barrier, separates inside air from outside air. For the balloon to hold air, the skin must be sturdy enough and continuous enough to resist the air pressure inside the balloon. It’s an apt analogy, because a balloon, like a home’s air barrier, is not perfectly airtight. Even the most stringent building-performance programs allow some air leakage. The goal is to make the air barrier as complete and free of leaks as possible.

 

For more photos, illustrations, and details, click the View PDF button below:

 

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.

Disposable Suit

This suit provides full body protection to help you stay clean from head to toe when installing insulation. We recommend wearing sweats underneath for additional coverage.
Buy at Amazon

Great Stuff Foam Cleaner

It’s important to clean and maintain a professional foam-dispensing gun, and this product fits the bill. It has a spray applicator for general cleaning, plus it screws onto the dispensing gun so you can clean the inside.
Buy at Amazon

Staple Gun

Although powered staplers are very popular, you still need a manual stapler on the job site. This staple gun from DEWALT® is reliable and easy to fire, reducing fatigue over prolonged use.
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
View PDF

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

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Up Next

Video Shorts

Featured Story

FHB Summit 2025 — Design, Build, Business

Join some of the most experienced and recognized building professionals for two days of presentations, panel discussions, networking, and more.

Featured Video

Builder’s Advocate: An Interview With Viewrail

Learn more about affordable, modern floating stairs, from design to manufacturing to installation.

Related Stories

  • Install Denim Insulation Like a Pro
  • Insulation for Homes in the Wildland Urban Interface
  • FHB Podcast Segment: Sometimes Spray Foam Makes Sense, Sometimes It Doesn't
  • A Practical Approach to Exterior Insulation

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
  • Install Denim Insulation Like a Pro
  • Insulation for Homes in the Wildland Urban Interface
  • FHB Podcast Segment: Sometimes Spray Foam Makes Sense, Sometimes It Doesn't
  • FHB Podcast Segment: Designing and Building an Efficient Slab-On-Grade Home
View All

Insulation

View All Insulation Articles
  • Makeshift Foam Tip for Tight Spots
  • Insulation Shield for Wafer Lights
  • Ranch Redux
View All Insulation Articles

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • 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 2025
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

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 70%

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