Are Baffles in the Attic Necessary?

While you build a new home, renovate an existing home, or convert an attic to a living space, you might wonder, “Are baffles in the attic necessary for proper attic ventilation?”

Not always. 

The answer depends on the type of roof and vent space you have (vented or unvented) and how you want to insulate your attic space. But, if your home does require attic baffles, you simply can’t skip this crucial material. Let’s break down the entire debate in more detail.

What Are Baffles (AKA Rafter Vents), and How Do They Work?

Are baffles insulation? No, but they protect your insulation in a vented roof system. 

Baffles, also known as rafter vents, are vents that direct airflow in an attic.1 Baffles can be made from:

  • Wood
  • PVC and other plastics
  • Rigid foam
  • Metal

Before we describe how baffles work with attic ventilation, let’s define two different types of ceilings:

  • Traditional, horizontal ceilings – In a traditional ceiling, a joist network separates an unconditioned attic space from a conditioned interior space. The US Department of Energy recommends typeting the attic interior.2 Drywall (installed on the bottom side of the joist network) also typically separates the attic space from the conditioned space, forming a ceiling. 
  • Vaulted (AKA cathedral) ceilings – In homes with vaulted ceilings, there is no joist network between the roof decking and the home’s interior.

Homes with both traditional and vaulted ceilings need attic baffles if they utilize vented roofs, which feature:

  • Closed (or box) eaves, where the rafters are enclosed and vented via soffits
  • Ridge vents at the apex of the roof, and/or
  • Gable vents on the flat area between the roofline and the exterior walls

Baffles have three important roles in a vented roof system:

  • When the wind blows, baffles direct proper airflow from the soffits to the ridge or gable vents (or both).
  • They keep unconditioned air from directly contacting the insulation, which could cause unexpected heat transfer (also known as wind-washing).
  • They keep different types of attic insulation products (particularly blown-in insulation) from falling into and clogging the soffits.

Are Baffles Important?

“Are baffles in the attic necessary?” The answer depends on your roofing system. 

In an attic vent system, baffles are very important. But, if you have an unvented roofing system, you simply don’t need them. If your roof decking is permanently, directly affixed to your exterior wall, and your rafters are exposed on the outside of your home, you likely have an unvented roof system—also called a “hot roof.”3 

How to Install Baffles

Whether you have a traditional or vaulted ceiling, you’ll need the following tools and materials:

  • Baffles the same width as the distance between each rafter vent (in most cases, 18”)
  • A cordless drill or impact driver
  • Screws long enough to penetrate both the baffle and the roof decking (but no deeper)
  • A large piece of plywood to stand or kneel on in the attic
    • This will keep you from stepping on both the insulation and drywall
  • Safety equipment, including goggles and gloves

If you have a traditional, horizontal ceiling, you can install baffles with the following procedure:

  1. Gather your materials.
  2. From the attic, place one baffle between two rafters.
  3. Slide it down until it completely contacts the exterior wall.
    • The baffle should create a barrier between the insulation and the soffit area.
  4. Using your cordless drill/impact driver, attach the baffle to the roof decking with screws.
  5. If one baffle isn’t long enough to completely cover the attic floor insulation, attach another one above the first baffle in the same joist.

Repeat this process until you’ve added a baffle (or multiple) between every joist. Remember that the baffles don’t have to reach the ridgeline if you have a traditional ceiling—they just have to be taller than your insulation to prevent wind-washing. 

If you have a cathedral ceiling, this process is similar. But, if your vaulted ceiling is drywalled or covered with some other material, you’ll have to remove this to install baffles (and insulation). There are two things to note about this process:

  1. You’ll likely have to remove the entire ceiling surface, exposing the entire roof deck.
  2. Since there’s limited room for air flow in a vaulted ceiling, you’ll have to baffle the entire surface to direct proper airflow from each soffit to the ridge/gable vent, then install insulation around or on top of the baffles (or both). 

During the attic insulation installation, remember to take safety precautions—having a buddy secure your ladder or wearing a harness in high-ceiling areas can help prevent injuries. 

Depend on Attic Construction for All of Your Home’s Insulation Needs

Installing baffles can get complicated. Your ceiling structure and roofing system are both critical factors—and removing drywall, adding baffles and insulation, and replacing drywall in vaulted ceilings can be dangerous without proper safety precautions. 

To avoid a DIY disaster, call the experts at Attic Construction. We’ve been providing insulation removal, replacement, first-time installation, and attic cleaning services in Orange County, San Diego, and Phoenix for over a decade. We’ll help you safely and efficiently tackle all of your attic needs. 

Contact us for a free attic inspection today. 

 

Sources: 

  1. Green Building Advisor. Site-Built Ventilation Baffles for Roofs. https://www.greenbuildingadvisor.com/article/site-built-ventilation-baffles-for-roofs 
  2. US Department of Energy. Where to Insulate in a Home. https://www.energy.gov/energysaver/where-insulate-home 
  3. Brentwood. Hot vs. Cold Roofing: A Guide to Attic Efficiency. https://www.brentwoodindustries.com/resources/learning-center/construction/hot-vs-cold-roofing-a-guide-to-attic-efficiency/