FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram 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
SUBSCRIBE TODAY

Save up to

70% off

the cover price

In-depth articles, up-close photography, and detailed illustrations in every issue.

Subscribe Now!
Subscribe
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
  • Join
  • Log In
Subscribe

Fine Homebuilding Project Guides

Insulation

Guide Home
Chapter
  • Energy Efficiency
  • Air-Sealing
  • Choosing Insulation
  • Installing Insulation
  • Water Management
How-To

An Easy Way To Build a Well-Insulated House

Builder Stephen Bonfiglioli describes how he builds an R-30 wall using strips of rigid foam insulation on the interior of the studs as a thermal break.

By Stephen Bonfiglioli Issue 250 - April/May 2015

Synopsis: Longtime builder Stephen Bonfiglioli describes how he builds an R-30 wall using polystyrene strips on the interior of the studs as a thermal break. The method is less expensive and easier to build than wall systems with similar R-values. Bonfiglioli explains how his wall system is constructed, and he gives details for the installation of electrical boxes and the whole-wall vapor retarder he includes as part of the wall system. He also discusses how he prevents moisture accumulation in the stud cavities.


You might say I’ve always been ahead of the curve as far as building performance goes. When i started building in 1977, my houses had 2×6 walls and R-19 insulation, while code-built homes had 2×4 walls with R-11 insulation. Other builders, subs, and suppliers said I was crazy for installing more insulation than the building code required, but I’ve always thought that building energy-efficient homes made perfect sense. In my quest for efficiency and comfort, I tried just about every high performance wall assembly there was, all of which seemed overly complex and expensive. Then one day 12 years ago, I asked myself, “What if I fur out the interior wall with strips of rigid foam and strapping?” I reasoned that the foam strips would address thermal bridging, add thickness to the wall to accommodate high-density fiberglass batts, and cost less than alternative methods. I have been building my walls this way ever since.

insulation details for windows and doors

Foam selection

I assemble lengths of 1-in.-thick high-density expanded polystyrene (EpS) foam and 1×3 strapping picked up from my local lumberyard. While the strapping is readily available, the high-density foam isn’t always a stock item, so I buy my foam from insultech in Bridgewater, Mass. This foam resists compression more than regular EPS, and it comes in convenient 1-1/2-in. by 4-ft. pieces. Alternatively, i could cut full sheets of rigid foam into 1 1/2-in.-wide strips on a tablesaw.

While it may appear to make sense to use extruded polystyrene (XpS) or polyisocyanurate insulating strips, both of which have higher R-values, R-value matters very little in this application. EPS is the least expensive type of rigid foam, and with an R-value of R-4 per in., it creates enough of a thermal break to sufficiently slow heat transfer through the framing.

Speed and strength

Once we have a new house dried in or a remodel gutted, we can add the foam strips to an entire 3000-sq.-ft. house in a day or less, saving us considerable time and money when compared to more-complicated wall assemblies. Also, because the foam strips are covered with 1x3s, drywall and trim can be installed with conventional fasteners instead of using long nails or screws to find the framing behind the foam. The 1x3s also allow the homeowners to hang pictures and shelves more easily later on.

Don’t forget the air barrier

Air-sealing is paramount when using fiberglass batts (see Making Fiberglass Work, FHB #246), so we fill any holes or gaps with spray foam before installing the high-density r-30 batts. We’re careful to fill the stud cavities completely with minimal compression.

 

An Easy Way To Build a Well-Insulated House spread

From Fine Homebuilding #250

To view the entire article, please click the View PDF button below.

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

Sign Up
View PDF
Previous: Dense-Pack Cellulose Insulation Done Right Next: How to Insulate Walls with No Sheathing

Guide

Insulation

Chapter

Installing Insulation

View Comments

  1. Stanfo3 | Jan 29, 2020 10:54am | #1

    Does this method satisfy the continuous insulation code for zone 6 (20+5)? If i use xps 1" strips that will satisfy code. Will the additional thickness of batt insulation along with furred walls be considered continuous (interior) and over r5?

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Insulation

Insulation

Trusted, comprehensive guidance from the pros for a home that is healthy, comfortable, and energy efficient

View Project Guide

View All Project Guides »

Become a member and get unlimited site access, including the Insulation Project Guide.

Start Free Trial

Energy Efficiency
  • Understanding Energy and Houses
  • Building Energy-Efficient Homes
Air-Sealing
  • Air-Sealing Basics
  • Air-Sealing Tools and Materials
  • Foundations and Floors
  • Walls, Windows, and Doors
  • Attics and Roofs
Choosing Insulation
  • Insulation Basics
  • Material Choices
Installing Insulation
  • Insulating Attics and Roofs
  • Insulating Walls
  • Insulating Floors, Footings, and Slabs
  • Insulating Foundation Walls
Water Management
  • Water-Management Principles
  • Materials
  • Installation Methods

Fine Homebuilding

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

Newsletter

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

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

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Careers
  • Copyright
  • Terms of Use
  • Site Map
  • Do not sell my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2022 The Taunton Press, Inc. All rights reserved.

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
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Account

  • Log In
  • Join

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

Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • Customer Support

Account

  • Log In
  • Join

Newsletter

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

Sign Up See all newsletters

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

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