Whether you’re working on a new home build or making energy efficiency improvements to an existing house, you may be wondering how to install insulation in ceiling spaces—or if you should install attic insulation in the first place.
What options do you have for ceiling insulation products? Should you attempt a project like this on your own or hire an attic services professional? If you opt for DIY, which safety tools will you need while you work with insulation materials?
Our experts will weigh in on all of the above and more in this guide. If you’re looking to learn how to insulate a ceiling, read on.
Should You Insulate the Ceiling Between Floors?
Before we get into the how-to section, let’s explore an important question—should you insulate your ceilings in a two-story home? What about a building with multiple floors?
The US Department of Energy recommends that, for optimal home energy efficiency and HVAC system performance, homeowners should insulate:1
- The floors of attic spaces
- Attic access doors
- All walls and floors of every finished attic space
- All exterior walls
- All interior walls bordering unconditioned spaces (e.g., between a bedroom and garage)
- All interior floors above unconditioned spaces, like:
- Crawl spaces
- All band/rim joists
However, it’s important to note that:
- Building codes don’t always require insulation in all of these areas.
- Building codes, while generally similar, slightly differ from state to state; This also applies to roof insulation.
All of this said, insulating between floors is optional. But, keep in mind that:
- Band joist—the pieces of wood that border an entire joist network, usually forming a square or rectangular “frame” around a series of studs—insulation will provide some heat flow transfer protection for interior spaces.
- Insulating between floors can provide additional energy efficiency, sound dampening, and increased effectiveness for zoned HVAC systems.
In an ideal scenario, your home should be as insulated as possible—that includes insulating between each floor of your home.
How to Install Ceiling Insulation
Let’s break down how to install ceiling insulation between the floors of your home. The process will greatly differ based on the phase of construction your home is in, the types of attic insulation materials you’ll use, and the materials used to build your home.
New Construction Projects
The easiest way to insulate the space between floors, by far, is to complete this process while your home is still under construction. In most cases, you should start insulating when:
- All framing is complete, including:
- Interior walls
- Truss installation
- Roof sheathing (since insulation shouldn’t be exposed to rain or snow)
- Electrical rough-in is complete, including:
- Light switches
- Wiring (but the wiring doesn’t have to be hooked up yet)
- Early HVAC ductwork is complete, including:
- Vent placement
- Air handler placement (if the air handler is indoors)
- Duct installation
Installing batt insulation between floor joists is most easily completed from above before drywall sheets are installed. However, blown-in insulation products may make more sense to install once drywall has been attached to one side of the floor joists.
Remember that some state building codes require batt, faced insulation to be stapled to the joists.
Home Renovation Projects – 3 Methods
If your home is already complete, and you’re adding adequate insulation between floors after the fact, you face additional challenges. But it’s not impossible—you’ll need to choose one of three methods.
Method 1: Total Drywall or Subfloor Removal
If you have the time and budget, completely removing either the ceiling drywall on the first floor or the subfloor on the second floor is the easiest way to access the area you’re trying to insulate.
You can remove ceiling drywall on the first floor by:
- Removing light bulbs, can lights, and hanging fixtures from the ceiling
- Using a hole saw to cut a preliminary entry into the ceiling between two joists
- Use a stud finder or a strong magnet (which will detect metal drywall screws)
- Donning gloves, goggles, and respirators and separating the drywall from the studs with your hands (or with hand tools)
But, work cautiously—while using hole saws, hammers, and pry bars, avoid damaging HVAC ducts, wiring, and receptacles.
To remove the subfloor and work from above, you should:
- Remove all furniture from the room.
- Wear gloves, goggles, and a respirator while you pull up the flooring.
- Once the subfloor is exposed, use a cordless drill or impact driver to remove the screws connecting the subfloor material (likely plywood) from the floor joists.
Once the entire floor joist network is exposed (from either side), you can install your insulation product of choice (batts, blown-in, or spray foam).
Method 2: Cutting into the Existing Drywall Ceiling
If you’re not interested in removing and replacing all of your ceiling drywall, there is a workaround. But you’ll need more tools, time, materials, and expertise to take this route. Make sure you have:
- A hole saw
- A stud finder (or a strong magnet)
- Joint compound (sometimes called “mud”)
- A putty knife
- ½” or ¾” plywood
- Drywalls screws
- Long enough to penetrate both the drywall and a ½” or ¾” piece of plywood
- A cordless drill or impact driver
- Room paint
For this route, you’ll need to use a blown-in insulation product. Here’s how to install it:
- Using your stud finder/magnet, locate all of the joists.
- With the hole saw, cut 4” holes into the spaces between joists (ideally, centered).
- Keep the cutouts—you’ll need them to repair the wall.
- Place an insulation hose into the hole, and blow the insulation product until the space is full.
- Remove the hose, and cut 3” x 8” strips of plywood.
- Insert a plywood strip into each hole, securing it with screws above and below the hole.
- Replace the hole cutout, and attach it to the plywood using a drywall screw.
- Cover each closed hole with a joint compound, let it dry, and apply a fresh coat of paint to the room.
There are two important things to note during this process:
- When feeding the rigid insulation hose into each hole, send the hose as far back as you can, start blowing, and slowly remove the hose as you fill the entire space between the two joists. If there’s an obstruction in the middle of the joist (like a duct), you may have to cut additional holes to achieve total coverage. Full coverage is critical to optimal insulation performance.
- Make sure to sink your screws flush with or past the drywall as you attach the plywood and replace the hole cutouts. This will ensure that the joint compound completely covers and hides the screws.
Method 3: Cutting into the Subfloor
This method isn’t unlike the one above. However, instead of cutting holes into the ceiling drywall, you’ll cut holes into the subfloor from above.
Again, you’ll have to use blown-in insulation for this method. And you’ll need the same materials as above, except for joint compound, a putty knife, and room paint.
The process is similar, too, but make sure to heed the note in the previous section regarding full coverage and the potential need for additional holes in the event of obstructions.
- Remove the furniture and flooring from the second-floor area.
- With your stud finder/magnet, identify the floor joists.
- Using the hole saw, cut 4” holes into the subfloor (preferably centered between joists).
- Insert the rigid insulation hose into the hole, filling the space between each joist completely.
- Use the plywood method described above to reattach the hole cutouts to the subfloor.
- Cover the subfloor with flooring material and replace the furniture.
Safety Tips for Ceiling Insulation Installation
While exploring how to insulate a crawl space ceiling, we would be remiss not to mention safety protocols.
Insulation materials are usually made from skin irritants like fiberglass or treated with pest-prevention chemicals that shouldn’t come into contact with your skin for prolonged periods. So, while you’re working to install fiberglass attic insulation, or other insulation materials, make sure to don your:
- Safety goggles or other eye protection
And, if you take any of the hole saw methods above, you may also benefit from ear protection. As always, make sure to turn off the electricity to your home anytime you’re using power tools to cut into or fasten objects to the walls or ceiling.
What Types of Insulation Are Best for Ceilings?
Installing insulation between floors while your home is still under construction allows the most flexibility for product choice. Since the area is still exposed, you can use batts, blown-in products, spray foam, or panel insulation to achieve your desired results.
And, if you’re pulling up the entire subfloor on the second story, you have similar options since you’ll be exposing the whole space.
But, if you opt for one of the hole saw methods described above, you’re locked into the blown-in method:
- Without access to the entire space at once, you won’t be able to insert batts or panels between every joist with full coverage.
- Spray foam also requires full visibility of the space being insulated. Unlike blown-in products, it won’t just fill the space where it’s sprayed—it will stick to the first surface it encounters.
Attic Construction: Quality Insulation Services in San Diego, Orange County, Phoenix, and Beyond
Learning how to install insulation in ceiling spaces can be intimidating—or even disheartening if your home is already complete. But rest assured that if you are looking for the best insulation for soundproofing walls or upgrading your insulation for energy efficiency purposes, there are experts willing to help you achieve your goals.
Seeking advice on insulation installation or attic cleaning services?
Look no further than Attic Construction. In 2011, we started an attic services brand that would deliver high-quality installation, excellent customer service, and expert product selection advice. Since then, we’ve been helping families throughout the southwest meet their home improvement aspirations.
If your attic needs an overhaul, reach out to us for a free attic inspection and estimate. We can’t wait to help you with your next project!
- US Department of Energy. Where to Insulate in a Home. https://www.energy.gov/energysaver/where-insulate-home