Installing spray foam insulation is difficult work; here’s how to do it like a pro
Keeping our homes warm in the winter and cool in the summer is easier said than done—and it seems like we have to spend an arm and a leg on utility bills to do so. Installing better insulation is one of the best ways to keep your house comfortable throughout the year and bring down those energy costs.
Spray foam insulation is one of the most effective materials, but it’s also challenging to install. Below, we’ll walk you through how to install spray foam insulation on your own—and when it might be better to hire a pro to tackle the job.
Spray foam is a highly effective form of insulation that can be installed in your walls, ceilings, and floors. You use a foam gun to literally spray the insulative material—usually polyurethane, but other types are available—in wall, ceiling, and floor cavities and wait for it to cure.
Spray foam insulation is a great barrier (especially in closed-cell form) with a high R-value. It’s also highly resistant to mold and insects and works great at filling in small crevices and hard-to-reach spots that traditional insulation can’t easily fill. It’s even a great way to soundproof a room.
However, spray foam insulation is expensive, and it can be difficult—and dangerous—to install.
On average, spray foam insulation costs $2,750 to install, though prices typically run between $1,400 and $4,150 for most homeowners. Several factors can impact your overall costs, including:
The type and material of spray foam insulation: There are two types of spray foam insulation: open and closed cell. Open-cell foam is more affordable but less effective than closed-cell foam. Materials can also impact the insulation cost—polyurethane spray foam is the most affordable, but you can also choose from soybean, vegetable oil, and even water-based spray foam.
Where in your home you’re installing it: It’s easier to install spray foam in some places throughout your home than others. For instance, garage spaces may not need as thick of insulation as the attic, so insulating a garage usually costs less.
Size and thickness: Because we think of costs per square foot, it makes sense that the larger the space you’re insulating, the more you’ll spend. Similarly, installing 1 inch of spray foam insulation is more affordable than installing 3 inches, but a 3-inch installation is likely to be more effective.
Depending on where in the U.S. you live, proper home sealing and insulation can save you between 7% and 20% on heating and cooling costs, according to Energy Star.
And because foam insulation has some of the highest R-values of any type of insulation, you’ll likely get greater savings with spray foam insulation than you would with the common and more affordable fiberglass batt insulation.
Here’s what you need to do before installing spray foam insulation in your home:
The best time to install spray foam insulation is when a home is being built, but this only applies to new construction homes. If you have an existing home in which you’d like to install insulation in the walls, you’ll need to remove the drywall and any existing insulation first.
This is an important step: If you leave the old insulation in place, the spray foam might not be able to fill every nook and cranny. Plus, old insulation could retain allergens or trap in mold growth and prevent proper air circulation.
It’s possible to install spray foam into an existing wall without dismantling the drywall, but this job should 100% only be left to a licensed contractor.
Working with spray foam insulation is serious business. It contains dangerous chemicals that can cause skin, eye, and lung irritation and damage if you’re exposed.
Wear a head-to-toe protective suit so all of your skin is covered. In addition, you’ll need to wear protective goggles for your eyes and chemical-resistant gloves taped to the suit. Wear a face mask or, ideally, a respirator to avoid inhaling the chemical mists and vapors.
We urge you to take this step seriously for your safety. Because the risk of coming into contact or inhaling harmful chemicals is present, we highly encourage all homeowners to reconsider the DIY installation. If you have any doubt about your ability or safety, call a pro to handle this work.
Once spray foam cures, it’s really hard to remove. Empty the room of any furniture and other belongings that you don’t want to get sprayed during the installation. If the room has carpet, cover the entire floor with layers of drop cloths or plastic sheeting to be safe.
Just leave box or pedestal fans nearby and point out of the room (and out of the home) to ventilate the fumes away from you.
Pro Tip: Wear a pair of shoes you don’t like. They’re likely to get covered in spray foam during the installation.
While you want to fill the gaps between windows (and doors) and their framing with the insulation, you don’t want to spray the windows (and doors) themselves. Staple plastic over these openings to avoid spraying them with foam material.
Similarly, cover outlet holes with tape to avoid getting spray foam insulation inside them.
Once you’ve removed the existing insulation, put on the proper protective gear, and removed or covered everything you don’t want to get sprayed, you’re ready to install the foam insulation. Here’s how:
If the moisture content of a surface is above 20%, the spray foam may not adhere. It never hurts to do a quick test with a moisture meter before starting the installation.
Once you start spraying the foam insulation, you don’t want to stop unless you have to. The replaceable tips get clogged every time you stop spraying for around half a minute—meaning you’ve got to remove the tip from the foam gun, install a new tip, and lube it up.
Form a plan of attack before you start so you can minimize these disruptions. Know where you’ll spray first and how you’ll access it. Set up ladders in advance, or ask a buddy (also in protective gear) to be on hand to move your ladder around for you.
Before you start, you should also get a feel for how the foam gun works. Have your buddy hold open a giant garbage bag or get a large cardboard box that’s open only at the top. Then practice spraying in the bag or box to understand how the gun works.
First and foremost, spray the hard-to-reach nooks and crannies of the room and any areas susceptible to air leaks. Then spray the perimeter of each wall cavity in a thin layer (about half an inch—this will expand to an inch).
Wait a few minutes, and then start filling inside the perimeter in a thin layer. Wait for this layer to cure before starting another layer. If you rush this and install a new layer over an uncured layer, the insulation’s R-value (and effectiveness) will be reduced.
Continue in layers that are 2 inches thick at most. Keep adding layers in the wall cavities until the insulation is as thick as the wall studs.
After the final layer has cured, take a blade or handsaw to scrape off any areas where the foam is raised and uneven. You want an even layer of foam that is flush with the wall studs. Otherwise, you’ll have trouble installing the new drywall.
If you had to remove existing drywall to access the wall cavity, you’ll need to purchase and install new sheets of drywall after the foam has cured. You’ll also want to paint the new wall to match the rest of the room.
Never tackled this type of project before? Here’s how to hang drywall after your insulation is all set.
The steps above detail how to install spray foam insulation in wall cavities, but it’s also possible that you want to insulate your floors or ceiling. The steps are similar, but how you access the area you need to insulate will be different:
When insulating the floor, you’ll be working from the basement or crawl space. This can be tough, claustrophobic work—we typically advise you to leave this to the professionals.
When insulating the ceiling, you’ll be working from the attic. You’ll have to work around additional holes in the ceiling for light fixtures and vents. Always walk on ceiling joists—not the drywall ceiling!
Installing spray foam insulation can be an expensive investment. Here are a few tips to keep in mind to keep costs down:
Fiberglass insulation is much more affordable than spray foam insulation, but it’s also less effective—and it’s not great for filling in those nooks and crannies.
That’s why many home insulation pros recommend using spray foam insulation strategically Install it in those otherwise hard-to-fill spots or spots that are particularly prone to air leaks, such as around:
Electrical outlets
Window and door frames
Air vents
Wherever pipes pass through walls
You can also use spray foam to insulate the perimeter of wall cavities—areas where air is more prone to leak through. Then install fiberglass batts inside the rest of the wall. Using fiberglass to fill the bulk of the open cavities means you’ll need less spray foam overall and will thus spend less on materials.
We’ve already covered some of the dangers of working with spray foam insulation, but keep in mind that fiberglass is dangerous, too. Wear the proper safety materials so that the fiberglass doesn’t come into contact with your skin or eyes and that you don’t inhale it.
Hiring a pro to cut costs may sound counterintuitive, but paying for labor now can actually save you in the long run. By hiring a local spray foam insulation contractor, you can avoid purchasing or renting expensive tools and equipment for the installation.
More importantly, you can ensure accurate installation. If you make a mistake during a DIY spray foam insulation installation, you actually risk allowing more air leakage, which means your energy bills could go up.
Paying more for spray foam insulation than you would for simple fiberglass insulation can be a tough pill to swallow. But if you’re able to afford the upgrade to a better, more effective material, it’ll pay off in the long run in reduced utility costs.
While it’s possible to install spray foam insulation yourself, the work can be challenging. Moreover, there are serious health and safety risks to consider, and if you don’t install the insulation correctly, you may not see any improvement in your home’s heating and cooling efficiency—you could even make it worse.
For these reasons, we almost always recommend that you find an insulation company near you that can tackle this work.
It’s possible to install spray foam insulation on your own, but it’s challenging work, and it can also be dangerous if you don’t take all the necessary precautions. Simple mistakes can also lead to a less effective installation. In most cases, it makes more sense to hire a professional to install your spray foam insulation.
Before installing spray foam insulation, you need to remove the existing insulation, clear out the area of anything you don’t want to get sprayed or cover it with protective plastic sheets, don your protective gear (including a full-body suit, goggles, gloves, and a ventilator), and cover windows and doors with plastic. You should also check the moisture level to ensure it’s low enough for the spray foam to adhere to the wall.
Spray foam is a highly effective insulative material that can dramatically reduce your energy bills and create a more comfortable living space. It does have a couple of drawbacks, however. First and foremost, spray foam insulation is much more expensive than fiberglass batt insulation. In addition, spray foam insulation is a dangerous chemical material; this is a project that is best left to pros for proper and safe installation.
