Skip to main content

Homepage Header Links

  • About
  • For Partners

Homepage Header Search box

 
ENERGY STAR
  • Find Products
    • Product Finder
    • Rebate Finder
    • Ask the Experts
    • Product Specification Search
    • Best Value Finder
    • Frequently Asked Questions
  • Save at Home
    • All Ways to Save
    • DIY Home Assessment
    • Heating & Cooling
    • Seal & Insulate
    • Expert Home Improvements
    • My ENERGY STAR
  • New Homes
    • Features & Benefits
    • Find a Builder
    • Partner Resources
    • Program Requirements
    • Working with ENERGY STAR
    • Become a Partner
  • Commercial Buildings
    • Benchmark
    • Save Energy
    • Earn Recognition
    • Resources by Audience
    • Resources by Topic
    • Training
    • About Us
  • Industrial Plants
    • Industrial Partnership
    • Plant Certification
    • Challenge for Industry
    • Industries in Focus
    • Treasure Hunt
    • Get started
    • Program Administrators
    • Service & Product Providers

You are here

Home » Energy Savings at Home » Seal & Insulate » A Do-It-Yourself Guide to Sealing and Insulating with ENERGY STAR » Sealing Air Leaks: Basement

Energy Savings at Home

Advice, tools, resources and inspiration to help you save energy

Sealing Air Leaks: Basement

Stopping the Chimney Effect

Outside air drawn in through basement leaks is exacerbated by the chimney effect created by leaks in the attic. As hot air generated by the furnace rises up through the house and into the attic through leaks, cold outside air gets drawn in through basement leaks to replace the displaced air. This makes a home feel drafty and contributes to higher energy bills. After sealing attic air leaks, complete the job by sealing basement leaks, to stop the chimney effect.

Seal All Gaps and Cracks around Rim Joists

Though you may not be able to see cracks in the rim joist cavities, it is best to seal up the top and bottom of the inside of the cavity. Also, rim joist air sealing is especially important at bump out areas such as bay windows that hang off the foundation. These areas provide greater opportunities for air leakage and heat loss. Caulk is best for sealing gaps or cracks that are 1/4 inch or less. Use spray foam to fill gaps from 1/4 inch to about 3 inches.

We also recommend you seal penetrations that go through the basement ceiling to the floor above. Generally, these are holes for wires, water supply pipes, water drain pipes, the plumbing vent stack (for venting sewer gases), and the furnace flue (for venting furnace exhaust).

Materials Checklist for Basement Sealing

  • Silicone or acrylic latex caulk and caulk gun
  • Expanding spray foam
Caution: When sealing the furnace flue (which will be encased in a metal sleeve) use high-temperature caulk. Run a bead of high temperature caulk around the pipe sleeve and around the metal frame.

Areas to Foam or Caulk

  • Along the gap between the sill plate and the foundation
  • At the bottom and top of the rim joist on each end of the house
  • All electrical, water, or gas penetrations and any venting ducts that pass to the outside

What About Insulating the Rim Joist?

After air sealing the rim joist area it is relatively easy to insulate each cavity with rigid foam insulation or fiberglass batts. If using batts, just cut the insulation to fit and place against the rim joist without compression, gaps, or voids. If using rigid, foam into place.

This could also be done in conjunction with finishing the basement, when you would insulate the basement walls floor-to-ceiling. Attic and basement air sealing will go a long way to improve your comfort because your house will no longer act like an open chimney.

Learn about Sealing Air Leaks OR
Continue to Adding Attic Insulation

Seal & Insulate

  • Why Seal and Insulate?
  • Methodology for Estimated Energy Savings
  • Look for ENERGY STAR Certified Insulation
  • Identify the Problems You Want to Fix
  • Determine the Effort Required
  • Assess the Level of Opportunity
  • Attic Air Sealing Project
  • Attic Insulation Project
  • Basement & Crawlspace Air Sealing and Insulating Project
  • Sealing Behind Window & Door Trim Project
  • Applying Plastic Over Windows Project
  • A Do-It-Yourself Guide to Sealing and Insulating with ENERGY STAR
    • Getting Started
    • Locating Air Leaks
    • Sealing Air Leaks: Attic
    • Sealing Air Leaks: Basement
    • Adding Attic Insulation
    • About Attic Ventilation
    • Glossary
  • Rule Your Attic! For Comfort and Savings
ENERGY STAR

Homepage Footer Main Menu

  • Find Products
  • Save at Home
  • New Homes
  • Commercial Buildings
  • Industrial Plants

Footer Menu

  • About
  • Recursos en Español
  • Partner Resources
  • Contact Us
  • FAQs
  • Newsroom
  • Privacy

Homepage Footer last menu

  • US EPA logo
  • US DOE logo