How to Insulate a Vaulted Ceiling in 5 Simple Steps

Countless prospective homeowners dream of one day living under a vaulted ceiling. But many also worry that the extra space isn’t worth a steep increase in heating and cooling costs.

The good news is that vaulted ceilings can be insulated. The process is just a bit different — and, often, trickier — than insulating a home with an attic.

For the average homeowner, knowing exactly how to insulate a vaulted ceiling isn’t necessary. Chances are, a professional contractor will handle the installation for you.

Yet it certainly doesn’t hurt to understand the best materials and techniques for getting the job done!

Should a Vaulted Ceiling Be Insulated?

Standard flat ceilings aren’t always insulated. This is because the attic space above is insulated instead.

When it comes to vaulted ceilings, however, attic space is rarely in the picture. So applying insulation to the ceiling itself is a must.

If the lack of insulated attic space wasn’t a big enough factor on its own, rooms with vaulted ceilings also tend to be much bigger than their standard counterparts.

This equals higher heating and cooling costs compared to a room of the same size without a vaulted ceiling.

In many cases, heavy insulation is the only way to make a vaulted ceiling anywhere close to energy efficient.

What Type of Insulation Is Used for Vaulted Ceilings?

Despite the unique challenges associated with building around vaulted ceilings, there are a number of insulation types available to choose from.

The most popular insulation options include fiberglass, cellulose, and spray foam.

Fiberglass

Fiberglass is the simplest insulation solution for many vaulted ceilings, especially cathedral-style ceilings. Fiberglass batts can be tucked between the ceiling rafters or joists.

Cellulose

Cellulose insulation is another great option if you have access to a skilled installer. A special technique must be used to install cellulose insulation in a vaulted ceiling. But this material is the best choice for filling up odd nooks and crannies in a vaulted ceiling.

Spray Foam

Again, special care must be taken when installing spray foam insulation in a vaulted ceiling. As long as the correct product is used, however, spray foam works just as well as any other insulation option.

Vented vaulted ceilings can be insulated with open-cell spray foam.

If your vaulted ceiling is unvented, closed-cell spray foam is needed. This type of spray foam will prevent moisture from entering the insulated spay and causing serious problems down the road.

How to Insulate a Vaulted Ceiling in 5 Simple Steps

1. Determine Insulation Needs

Before insulation can be installed, you’ll need to take an inventory of your ceiling and its specific needs.

The amount of space between your home’s roof and vaulted ceiling will determine the thickness of the insulation you can install.

If the space between your roof and ceiling is narrow, the type of insulation that can be used may be limited.

One of the most important factors when choosing insulation is the local climate. While all homes benefit from proper insulation, some areas pose unique problems in terms of heat, cold, or moisture.

Many municipalities recommend or require a minimum insulation rating based on the average temperature. Be sure to check with your local agency and ensure your new insulation meets these guidelines.

2. Plan for Potential Moisture

Insulation alone won’t protect your home from the elements. You also need to account for moisture.

Knowing whether or not your ceiling is ventilated is extremely important. Vented ceilings are less prone to moisture problems.

Meanwhile, care must be taken when insulating an unvented ceiling to prevent moisture buildup.

There are several ways to deal with excess moisture in a vaulted ceiling, and the best option for you will depend on many factors.

For vented ceilings in cold climates, a vapor barrier may be used to block excess moisture.

3. Protect

protect
Image: Fulton Martin

As with any insulation project, protective clothing is essential. Anyone who is in the area during installation should wear coveralls, goggles, a dust mask, goggles, and other necessary gear.

Seal and cover the surrounding area with plastic drop cloths as needed.

4. Install the Insulation

install the insulation
Image: ADDO RE

Install your chosen insulation product across the entire ceiling.

If you’re using fiberglass batts, cut the pieces to size so they fit between the ceiling joists or rafters. Use smaller pieces to insulate around vents, light fixtures, and other elements.

Before applying cellulose insulation to a vaulted ceiling, mesh screens must be installed between the rafters or trusses. These screens give the cellulose something to grip to, preventing drips.

For spray foam, install a layer of rigid foam board in place of the mesh screens.

5. Finish

finish
Image: The Lodges at Gettysburg

Once the insulation is in place, it’s time to finish the vaulted ceiling.

Apply drywall over the insulation layer, using gaskets or caulking to seal around light fixtures and other features. Finish the ceiling with a smooth layer of drywall mud or your preferred texture effect.

Final Thoughts

Insulating a vaulted ceiling is not that much different from insulating any other type of ceiling. It does, however, require a little extra know-how and skill.

Striking the perfect balance of insulation, ventilation, and moisture management are essential to building a vaulted ceiling that will hold up for many, many years to come.

If even one of these factors falls short, your vaulted ceiling could cease to be energy efficient (or worse!).