The Land Up Learning Series

Central Texas is hot during the summer. Like MEGA hot. In July 2022, Austin’s mercury hit 110 degrees and the city went 21 straight days above 100. If you have an older home with little or no insulation, this can make things very uncomfortable and downright dangerous. We’ve spent time in uninsulated Texas houses and have seen summer inside temperatures hit the low to mid 90s…with air conditioning.

While most houses have insulation on the exterior walls, (those that separate the house from the outside) many older houses didn’t come with standard insulation built in behind the interior walls between rooms, or crucially, in the attic/ceiling crawl space. This means precious conditioned air seeps out of rooms quickly keeping your electric bill high and your back sweaty during the summer months.

The attic in your older house may look like this

Noise can also be an issue in an older house without insulation. Insulation helps to prevent sounds from easily traveling through the drywall, studs, and floors. While this may not be a significant concern in a single family house, it can be in a condo or duplex if you can hear your neighbors stomping around or using appliances like a washing machine.

So how do you install insulation without tearing out your drywall and getting into a heavy renovation? Well, the easy answer is to pay someone to do the work for you, but if you’re like us, your ‘DIY’ DNA will not let you pay thousands of dollars for a service you can do yourself for a fraction of the cost.

The alternative is to roll up your sleeves and add new insulation into your walls and attic crawl spaces using a machine that literally blows in material through a hose (hence “blow-in” insulation). But before we get into that process, let’s start with the basics; what are the different types of insulation and how are they installed?

Types of Insulation

Lay-In Insulation

Fiberglass

This is probably what most people picture when they think of insulation; large rolls of cotton candy like fiberglass that is laid into a bare wall between studs. Since they are sheets (also called ‘batts’) or rolls, they are installed by hand during new construction or a remodel that requires the removal of drywall.

The lay-in fiberglass material is highly effective as a thermal barrier but unless you are going to rip out your existing drywall, it’s not going to be an option for retrofitting an older house with insulation.

If you have access to your attic and enough space to move around inside you can lay sheets of insulation on the attic floor (which serves as the ceiling for the room below). However, if you don't have sufficient space to access your attic (like in a condo) then lay-in insulation will not work here either.

Rockwool

Another type of lay in insulation is Rockwool. Rockwool comes in sheets like fiberglass but it’s actually made of stone. There are different versions of Rockwool but the main type is really only effective in the reduction of sound transmission and fire suppression. It’s a great choice if you are looking to dampen sound in something like a laundry room or a home office, but it won’t give your interior walls the same level of insulation from heat and cold like other materials. There is another type that provides thermal insulation like fiberglass, but it will also require you to remove drywall to lay it in.

Spray-In Insulation

You’ve probably seen a smaller scale version of this product at the hardware store, it comes in a pressurized can and you squirt it out through a straw into cracks or gaps (like around windows). We’ve found working with spray-in foam to be a pain because it is extremely sticky and estimating the amount it will expand can be tricky. That being said, it is also an option, though it’s expensive and we personally would leave it to the professionals.

Blow-In Insulation

This brings us to the subject of this blog. Blow-in insulation consists of loose clumps (‘loose fill’) of insulation that are fed through a hose by a blower that sprays into a hollow wall or an attic/ceiling crawl space. The goal is to spray the clumps of insulation until they build up a thick layer and eventually create a thermal and noise barrier.

There are two main types of loose fill, fiberglass and cellulose. Fiberglass will provide the best protection against temperature, but it will not give you as much noise reduction as cellulose. Fiberglass insulation also has a big downside that cellulose doesn’t; it’s really irritating. And we don’t mean that figuratively, if it comes in contact with skin it can make you feel very itchy. We’ve gotten it in our eyes before and it was a miserable experience.

Loose fill fiberglass insulation just waiting to make you itchy

Cellulose is more of a jack-of-all-trades; it’s slightly less effective as a thermal insulator but better as a noise barrier. Cellulose also has the additional benefit of being flame resistant and helps to slow the spread of a fire if one does break out.

We chose to go with cellulose insulation since it offers an all purpose mix of thermal and noise protection. Cellulose insulation is primarily made from recycled materials and has a slight scent of newspapers (which is probably only familiar to readers of a certain age). It comes in compacted bales of 25 lbs and needs to be broken apart by hand into its final loose clump form.

Required Tools/Materials

Mask

Gloves
Goggles
Headlamp
Cellulose insulation -About $20 per bale, covers around 50 square feet
Blower -$190 per day rental, but if you buy a lot of insulation many stores will waive the rental fee. List price is $175 per day but we found that to not be the case for us.

The Process

Regardless of your loose fill selection, fiberglass or cellulose, the standard method of blowing it in walls and attics is to use a specific machine that is made for each type. Which brings us to the first downside of blow-in insulation; the machine we needed to use was 165 lbs, bulky, and a real pain in the ass to move around. Luckily, the accompanying hoses are long and you can get extra lengths so the machine doesn’t have to be moved as much. Even still, it can be backbreaking to deal with the machine, especially if you need to lug the thing up stairs.

The machine is both a blower and an agitator so when you feed the hopper the agitator breaks the clumps of insulation down even further and then directs the fill into the hose. To kick things off, you first break the bale into smaller pieces with your hands and feed the fill into the hopper. The agitator takes it from there.

Here’s the second, and main downside of the whole process; the act of breaking the bale down into loose fill that is ready to be blown into your house creates a ton of dust. You will definitely need a good mask and to cover up anything and everything that you don’t want to get coated with dust. This isn’t such a big deal if you are adding insulation as part of a larger renovation and aren’t worried about getting things a little dirty, but if your place is already well set up for day-to-day living then be prepared to spend some time covering everything you own.

So you might be asking, “How do I actually get the insulation into the spaces?”

When it comes to the attic, if you have a typical access door, then the process is easy; you just drag the hoses up the ladder and spray the insulation until you’ve built up the desired layer. Things go more smoothly if one person holds the hose to spray the insulation and a second feeds the hopper with loose fill.

But if you don’t have this kind of attic access, or you are going to blow insulation into the walls, then you’ll need to cut a hole in the drywall. This is the third drawback. Cutting holes into drywall is super easy, but fixing them back to normal is a lot of work and a subject for its own blog.

Luckily for us, we are doing a large renovation and weren’t squeamish about getting into minor drywall repair. Like most homes, we also had a few holes already cut into the ceiling that can be used for easy access. We needed to replace some light fixtures and a bathroom exhaust fan so removing those made for easy access points to our ceiling crawl space and the holes were big enough for the 4 inch blower hose.

Despite all the effort it takes to get ready to blow in insulation, the actual process of getting the cellulose where it needs to go is super simple. It’s as easy as pointing the hose and letting the insulation build up to the desired level.

One thing to keep in mind is that most insulation needs to be kept away from electrical equipment or hot water pipes. Cellulose insulation is rated to help prevent the spread of fire but even so, you don’t want material touching these potentially hot areas unless they are properly insulated themselves with things like putty and ceramic tape.

Was It Worth It?

Our whole blow-in insulation experience only took about five hours and most of that was renting the blower and getting the hulking thing in place. The process was definitely messy and dusty but the clean up was easier than what we’ve dealt with when cutting a lot of drywall.

The new insulation makes a massive difference in the amount of noise that gets transmitted through the walls. It doesn’t eliminate all noises but the difference is instantly noticeable. We were very happy to see that the acoustic qualities were as advertised.

As for the thermal properties, so far the house has stayed a constant 71-73 degrees without turning on the AC. Though the true test is coming as the Central Texas summer really starts to kick off, the current results are very promising. Getting a professional to do the same work can cost thousands of dollars and we spent a fraction of that with only a couple of hours of DIY work.

Finally, we had read some reviews of the cellulose material that talked about the smell being an issue after it was blown in but we didn’t find this to be a problem. The newspaper-like smell stuck around for about two weeks or so then dissipated on its own.

To wrap up, when a total renovation that includes removing drywall isn’t an option for you, consider blow-in insulation as a retrofitting alternative and save yourself from those sweaty nights cursing the Texas summer. You’ll also stay cool with some extra money in your pocket if you DIY.

At Land Up Realty and Investments we specialize in land but we understand the unique challenges faced by many homeowners in Central Texas. We not only offer expert advice on undeveloped land and ranches, but also enjoy sharing insights and tips on home DIY projects. Stay tuned for more upcoming projects!

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DIY: Blow-In Insulation