ST. LOUIS Blog

Why Insulate Rim Joists?

December 7, 2021

Homeowners can improve their home’s level of energy efficiency and comfort easily and affordable with professionally installed rim joist insulation

So... What's a rim joist?

Joists are structural elements that make up a building's floor and ceiling frame.  Rim joists are the wood that butts up to floor joists and wraps around the perimeter of the floor framing. Their purpose is to give strength and stability to the other floor joists, helping keep floor joists level and upright. 

Why insulate rim joists

The rim joists in homes are often not insulated or under-insulated, especially in older homes.  When rim joist insulation is neglected, you lose energy efficiency and drafts enter through the basement sill plate.  

How can I tell if my rim joists are insulated?

An easy way to tell if your rim joists are under-insulated is if your floors on the main floor are cold.  This is a sign of drafts entering the home. Another sign is if snow melts quickly around thr foundation of the home. This is a sign of your hard earned heating escaping the home through the rim joists.  Also, pay attention to your energy bills. High electric and gas bills are a sure indicator of a home that can use energy efficiency (insulation and air sealing) upgrades. If Your basement is unfinished, you can easily look at your rim joists to see if any insulation is present. 

The Chimney Effect / Stack Effect 

The stack effect (chimney effect) is the movement of air caused by thermal differences. In winter, cool air enters the basement, warms and rises through the attic. In the summer, the opposite occurs - hot air enters the attic, cools and falls to the basement. 

The stack effect dramatically reduces energy efficiency and can make your indoor home temperatures uncomfortable in extreme weather (hot or cold weather).  The stack effect can be minimized and controlled with proper air sealing and insulation in both the attic and the basement.

What are the benefits of insulating rim joists?

Simply put, insulating and air sealing your basement rim joists will keep heat in and unwanted drafts out and minimize the stack effect. 

Benefits include:

• Consistent home temperatures 
• Warmer floors in the wintertime
• Cooler floors in the summertime
• Lower energy consumption
• Lower carbon footprint
• Lower energy bills
• Minimal basement air leakage
• Better moisture control 
• Better indoor air quality

Contact Koala Insulation of St. Louis, your local insulation contractor, today to solve the mystery of your hot or cold room! 

Call Today: (314)-279-5064

Reference: https://www.energystar.gov/sites/default/files/asset/document/DIY_Guide_2016.pdf

Related Posts:

"A SEASON OF SHIVERS” PREDICTED FOR THE U.S.  https://www.almanac.com/winter-extended-forecast-farmers-almanac

How To Tell If Your Home Is Under Insulated https://koalainsulation.com/saint-louis/blog-detail/How-To-Tell-If-Your-Home-Is-Under-Insulated

5 Reasons One Room Is Hotter (or Colder) Than The Rest Of The House https://koalainsulation.com/saint-louis/blog-detail/5-Reasons-One-Room-Hotter-Colder-Than-the-Rest-of-the-House

4 Reasons Insulation is Important in St. Louis https://koalainsulation.com/saint-louis/blog-detail/4-Reasons-Insulation-is-Important-in-St-Louis

Tax Credits for Energy Efficiency: Insulation, Air Sealing, Solar https://koalainsulation.com/saint-louis/blog-detail/Tax-Credits-for-Energy-Efficiency-Insulation-AirSealing-Solar