How to Insulate a Vaulted or Cathedral Ceiling with Spray Foam

By: Amanda Emery on June 18th, 2025

If you’re thinking about spray foam insulation for your vaulted ceiling or cathedral ceiling, you might be wondering: How is this actually done?

Will it turn your house into a construction zone? Is it going to be a mess or hard to live through?

Great news; The process isn’t as disruptive as you might think. In this article, we’re walking you through the differences between a vaulted and cathedral ceiling, and the step-by-step process to add spray foam insulation so you can go into your project with confidence.

What's the Difference Between a Vaulted Ceiling and a Cathedral Ceiling?

Before we get into the installation process, let’s break this down.

Cathedral Ceiling: Follows the pitch of the roof, meeting at a point in the center like a tent or classic church ceiling. These typically have smaller cavities.
Vaulted Ceiling: Can take on a variety of shapes and doesn’t have to follow the roofline. It might arch, curve, or go flat across. These often have larger cavities, giving spray foam more room to work its magic.

Both can be insulated with spray foam, but the approach is a little different depending on what you’re working with.

Step-By-Step: Spray Foam Insulation in a Vaulted Ceiling

Let’s take a look at exactly how insulating a vaulted ceiling with spray foam is done.

1. Prepping the Space

Before the first cut is made, a good spray foam contractor will prep your home thoroughly.

Plastic covers go over cabinets, countertops, and built-ins.
Paper is laid down to protect the floors from dust and debris.
This isn’t just a courtesy; it’s necessary to keep your home protected during the install process.

2. Measuring and Cutting Access Panels

The crew will measure the ceiling and start cutting 2-foot strips into the drywall.

Why 2 feet?

It allows them to access multiple cavities at once.
It makes replacing the drywall easier, since one sheet of drywall can cover multiple cuts.

They also take the time to create an action plan to work around recessed lighting and other features, ensuring everything is accessible without causing damage.

3. Removing Old Insulation

Before spray foam insulation goes in, any existing material, like fiberglass batts, must come out.

The crew uses special tools to hook and remove old insulation cleanly.
This ensures a clean surface for the foam to adhere to, which is crucial for optimal performance.

4. Spraying the Foam

Here comes the fun part – spraying the open cell spray foam insulation into the vaulted ceiling.

The crew will spray from the edge of the ceiling to the center, using a long-range nozzle.
Then they’ll switch to a shorter nozzle to fill in the peak from the inside to the outer edge.
Every inch of that cavity is coated to create a seamless air seal.

All of this is done with carefully contained spray areas, so foam doesn’t end up where it shouldn’t.

5. Replacing the Drywall

Once the foam is in, it’s time to button things back up.

Drywall goes up where the initial strips were cut.
Then, the seams are mudded and prepped, but here’s where you’ll need to talk to your contractor.

You’ll want to ask your contractor about your finished result:

Will this be a rough patch (basic mudding and sanding, but no paint)?
Or will this be a fine finish, with full sanding and painting included?

It’s a small detail that makes a big difference in the finished look.

Ready to Insulate Your Vaulted or Cathedral Ceiling?

If you’re ready to make your home more comfortable and energy efficient with vaulted or cathedral ceiling spray foam insulation, we’ve got you covered.

Visit our Dealer Finder to locate a RetroFoam dealer in your area who may also specialize in spray foam insulation for vaulted ceilings or cathedral ceilings.

Key Points:

Vaulted ceilings don’t follow the roofline and often have more cavity space than cathedral ceilings.
Spray foam contractors cut strips into the ceiling for access because this minimizes the mess and speeds up installation.
Old insulation must be removed before spray foam is applied to ensure proper adhesion.
Crews use different nozzles to hit every part of the cavity, especially at the roof peak.
After spraying, the drywall is rehung and patched; however, be sure to clarify with your contractor whether it will have a rough or fine finish.
Spray foam insulation in vaulted ceilings creates a solid air seal, improving comfort and energy efficiency.

Can RetroFoam Be Used to Insulate the Ceiling?

How to Insulate a Tongue and Groove Ceiling

How to Prep for Spray Foam Insulation

About Amanda Emery

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor. As a journalist, she has won several awards from The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. Amanda uses her experience as a journalist to write content that will help educate homeowners on foam insulation benefits. When Amanda isn’t writing, she’s spending time with her husband Chris, daughter Lilith-Maeve, and rescued huskies Danger and Wendigo. She also loves knitting, making art, and cooking.