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Baffles | Are They Necessary for Batt Insulation?

There are two features of attics that are important for the health and comfort of the whole home. The first is ventilation, and the second is insulation.

Baffles stop the latter from obstructing the former. This is notably important when insulation is in loose-fill form. But even though batts have more structural integrity, baffles still have value when installing batt insulation.

Baffles are required by code in attics containing air-permeable insulation. This includes fiberglass, mineral rock, and cellulose batt insulation. Batts are less likely to block vents, but can still shift and cause issues. Baffles also funnel air from soffit vents to top vents, improving airflow.

Baffles Stop Insulation From Blocking Vents

Baffles are designed to ensure the maintenance of an opening between insulation and the roof decking for the passage of air from the soffit vents to the upper vents.

They also act as a channel to direct air from the lower vents to the upper vents, preventing this air from being slowed by and dispersed through the insulation.

Attic baffle and batt insulation illustration.jpg

Attic insulation baffles are available in a range of materials, including:

  • Plastic
  • Foam
  • Cardboard
  • PVC

They are typically placed in the rafters or joists of the attic to create the space between the roof and the insulation, and also to create a false back, blocking insulation from reaching all the way to the “walls” of the attic over the soffit vents.

Maintaining the passage of air prevents heat build-up in the attic. It also stops condensation from forming just below your roof, which can lead to all manner of problems, including wet insulation. Considering how expensive attic insulation is, you definitely want to keep it safe!

Baffles Stop R-Value Loss by Access Points

Baffles can be used around access hatches and doors in the attic to prevent the R-value of the insulation from being compromised.

At these points, the insulation can be compressed by the doors, depending on how they open.

Loose-fill insulation can also shift and fall through the opening, reducing the thickness of the covering and also introducing insulation into your living space.

Baffles are just one of the ways that insulation can be contained and protected at attic openings, so if you use another method, you don’t need them for this.

Important for Blow-in Insulation

Blown-in insulation can be made from various materials—cellulose, rock wool, or fiberglass. Regardless of the material, the loose-fill insulation is loose, light, and fluffy. It is installed with the help of a specialized machine that blows the material into wall or ceiling cavities. 

Durovent UDV2248 Rafter Ventilator Pack of 70

Baffles are an essential element of blown-in insulation installations. They ensure that the insulation does not fall over the soffit vents during installation and that it will not do so over time.

Blown-in insulation is loose-fill insulation, which makes it more likely to fall out of the attic opening when the access hatch or door is opened. This makes baffles (or the like) important here as well.

Batt Insulation Is Easier to Control

It is much easier to control batt insulation.

Unlike blown-in insulation, batts are pre-cut pieces, usually with a paper or foil facing. They are designed to fit between standard wood studs and joists. 

In theory, you could install the batts freely, manually leaving enough space between them and the roof decking for air to circulate.

However, this is not an option because baffles are required by code with all air-permeable insulation installations in vented attics.

Why Baffles Are Still Required With Batts

Guaranteed Proper Ventilation Channels

If you were to measure the batts as you proceed or guess the required space, you would risk not providing enough ventilation. There are rules about how much net area must be made available by the baffles.

Insulation Installation Will Go Faster

With a baffle system, you can just press the batts into place, trusting the baffles to prevent it from going too close to the vents.

SmartBaffle 24 Insulation Baffle for 24" Rafter Bays

This eliminates the need for precise measurements, which can be tedious and time-consuming. It also ensures that insulation is installed correctly for optimum performance.

Protects Against Shifting Batts

Over time, batt insulation can shift. If they shift over the soffit vents, then you will have all the problems of limited airflow through the attic that your meticulous measuring and installation was supposed to prevent.

Not only that, but if your insulation slips, it can create gaps, which lead to decreased efficiency. This reduced efficiency can cause problems such as higher energy bills and a less comfortable home.

Batts can shift for a variety of reasons, including but not limited to the following:

  • Poor installation – Poorly fastened insulation may move from its original place, exposing the area and causing air draughts. 
  • Animal activity – Your attic insulation may have been invaded by pests such as bugs, small critters, bats, and other insects.
  • Changes in humidity or temperature – As the air around the insulation warms and the relative humidity increases, the insulation may expand. In extreme cases, excessive humidity and temperatures can cause the insulation to buckle.

Still Prevent R-Value Loss at Access Points

Hatches opening and compressing insulation is still a problem with batt insulation, even if it is less likely to fall through the opening.

Installing a baffle over the insulation here means that the door cannot squash the batts, reducing their effectiveness.

The Cost and Installation of Baffles

The average cost of baffle installation is around $0.50 per linear foot (they are the standard width found between rafters). This means an average-sized attic (1,500 square feet) would cost around $750.

In addition to the low cost, baffles are incredibly easy to install.

Installation usually doesn’t require advanced construction skills or special tools unless you are retrofitting baffles into a vaulted ceiling, which will require a professional.

Ultimately, it’s a relatively small investment when compared to the potential cost of repairing damage caused by moisture build-up. Not to mention the fines you might have to pay for not complying with the building code.


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