How To Insulate A Vaulted Ceiling

vaulted ceiling

Vaulted ceilings add unmatched visual appeal to a property, but they can be difficult to insulate. We understand the struggle.

To help you out, we’ve put together this comprehensive guide for anyone looking to learn how to properly insulate vaulted ceilings. From choosing the right materials to applying the insulation properly, we cover everything step by step. 

Blanket Insulation for a Vaulted Ceiling

Blanket insulation includes fibreglass batts, denim, or mineral wool insulation. However, fibreglass batts combine affordability and functionality, making them the optimal choice here. 

Here are the tools you need:

  • A step ladder
  • A staple gun (electric, manual, or pneumatic)
  • A caulk gun
  • A measuring tape
  • A long knife

Note: Fibreglass can accidentally release tiny shards of glass during the installation process.

So, wear skin, lung, and eye protection. A mechanical scissor lift would be more practical than a step ladder if you’re working on a high ceiling.

Now that we covered the materials, let’s see how you can install this insulation.

Seal All Openings

Your first step to insulate a vaulted ceiling is to seal all the openings that could let air in. These include holes around wires, overhead lights, PVC pipes, etc.

You might think you don’t need to check the light switches, but you’d be surprised how much air they let in. These air leaks can reduce the insulation’s ability to manage heat fluctuations.

You can use premium materials and hire the most professional contractors money can buy to install your insulation, but as long as you have gaps in your ceiling, that insulation will never work as efficiently as it could. So, get up your ladder and use the caulk gun to seal these holes.

Measure Your Ceiling

Fibreglass batts may be more affordable than the other blanket insulation options, but that doesn’t mean they’re cheap. The last thing you want to do is buy an excessive amount and end up selling half of it for a lower price.

So, take your measuring tape out and measure the length and width of your ceiling. Multiply them, and you get the area you need to cover.

For instance, if your ceiling is 20 feet long and 12 feet wide, you have a 240-square-foot area to insulate. We know you probably don’t like maths, but your wallet will thank you.

Here’s the thing: Fibreglass batts come in different sizes and packages. Measuring the dimensions of your ceiling will also help you decide the most suitable size and how many bales you should get.

These bales usually include 60-65 square feet of R-38 insulation. For a 240-square-foot area, four bales would do the trick. Adjust these measurements to fit your ceiling.

Cut Your Batts

Chances are your batts won’t fit the rafters right away. So they probably need to be cut to size. You can measure the width of the area between the joists and cut your batts accordingly.

Sometimes, it helps to try installing them first, as you can then accurately determine how to cut them. 

Install the Batts

Installing the batts is easier than it looks. All you have to do is fit them between the joists, then staple them on both sides.

You may not always have to use a staple. The batts can tightly fit their position without it, but it helps ease your mind. If a staple doesn’t get the job done, you can always use button cap nails.

While you can install the batts yourself, we recommend asking a friend to lend you a hand, as it makes for a more optimal workstation.

Expanding Spray Foam Insulation for a Vaulted Ceiling

If you want to use expanding spray foam insulation, you can find DIY kits available online or in any home improvement outlet nearby.

These usually include two tanks: One contains polyurethane, and the other contains isocyanate. You also get hoses, spare tips, and various accessories that make the insulation process easier.

Here’s the catch: These DIY kits are suitable for small areas — 1000 square feet or less. Any larger, and we recommend you hire a contractor. Not only would a professional work more efficiently and safely, but it might work out cheaper than buying several DIYl kits.

Don’t know where to find an insulation installer? At Insulation Advisor, we can help you find the best contractors in your area. 

Here’s what you need to use spray foam insulation:

  • Protective drop cloths
  • Heat blankets
  • Protective clothing

Let’s go through the process step by step.

Cover the Surrounding Area

Spray foam is like glue; once it sticks to an object, it’ll be a hassle to remove. That’s why your first step is to cover everything you don’t want to apply insulation to with drop clothes.

Don’t forget to cover any electrical boxes in the room. Spray foam won’t damage them, but they’ll be hard to clean up afterwards.

Use Heat Blankets

The most crucial aspect of using isocyanate and polyurethane tanks is keeping them at a proper temperature — ideally between 70-85℉.

So, you may want to cover them with heat blankets to maintain proper temperature. If the tanks arrive cold, you can use a space heater to quicken the warming process.

Spray the Foam

Some tanks come with the hose already connected. Others require you to install it yourself. It depends on the brand.

Give the tanks a good shake to ensure the foam comes out in a smooth stream. Before you spray it on your ceiling, you want to test it on a small piece of cardboard.

Spray the foam, wait 45 seconds, then touch it. If it turns solid, then it’ll settle properly on your ceiling.

As we’ve already established, the kit comes with several tips. Each provides a different volume. So, use the one that feels more intuitive. 

While spraying foam isn’t inherently complicated, there are various factors to consider in this scenario. The first one is your distance from the ceiling.

This determines how flat the foam will be and how much rise you get. We recommend keeping a small distance from the ceiling.

Pro tip: Keeping the tanks standing upright the entire time you’re spraying the foam ensures you get a smooth, even spray.

Exterior Ceiling Insulation for a Vaulted Ceiling

Interior insulation isn’t your only option. You could also do it from the outside. It’s one of the most effective ways to go about it.

However, you should only resort to this method if your house is still under construction or you’re changing the entire roof. Otherwise, it’d be too expensive.

Choose rigid foam boards, and you won’t have to worry about ventilation issues anymore. There are plenty of board options on the market, but we highly recommend extruded polystyrene or polyisocyanurate boards.

Not only do they offer a high R-value per inch, but they also don’t retain moisture. So, the effectiveness of your insulation won’t decrease over time.

Just install the boards on the roof deck, add sleepers, then cover everything with thick OSB sheathing. Around 7-16 inches (around 18-40cm) of thickness should be enough. Now, add the roof material you want and it’s job done.

How to Insulate a Vaulted Ceiling: Conclusion

Now you understand how to insulate a vaulted ceiling. While it sounds like too much of a hassle, the results are worth it. Not only will it manage temperature fluctuations, but it’ll also reduce your energy bills.

For blanket insulation, seal the openings that let air in, take the right measurements to cut your insulation precisely, and install the batts cautiously.

To install expanding foam insulation, cover the surrounding environment, heat the foam tanks, and maintain an even stream. Exterior insulation can be just as effective, too.Just place the rigid foam board, install the sleeper, cover everything with thick OSB sheathing and you’re done. Of course, we understand it might be overwhelming for you. So, get a quote from Insulation Advisor today and have professional contractors get that job done.

Frequently Asked Questions

Q: Can I use blown-in insulation for my vaulted ceiling?

We recommend steering away from blown-in insulation when you’re dealing with vaulted ceilings. Eventually, gravity will move the insulation to the bottom, resulting in cold spots and uneven insulation layers. 

Q: How much foam should I spray in one space?

The answer might sound weird, but it doesn’t matter that much. You can go overboard if you want. Some pros overfill a space to ensure they don’t leave any gaps or cracks.

Then, go back with an insulation trimmer and remove excess foam. You can also underfill the space then spray additional layers later.

Q: Can I use reflective insulation on my vaulted ceiling?

It depends on your priorities; reflective insulation works well in hot climates and can last for a long time. However, it’s useless in cold weather and is a bit expensive. If these two cons aren’t important to you, go ahead and install it.

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