Insulation PRO Tips

Adding insulation to your home is a simple way to decrease your heating and cooling bills every month. Gaps in your home’s insulation allow heat to escape and cold air to seep in. In order to improve your house’s insulation, all you need to do is fill all of these gaps with insulating materials. Doing this is fairly straightforward and easy, but doing this right requires following these 8 insulation tips.

1. Never Compress Insulation

The thinking is that if one blanket keeps you warm, two blankets will keep you twice as warm. This is, in fact, true. The R-value of materials is additive, so adding a second layer will double the insulating factor. This thinking leads many people to overstuff their wall spaces with twice as much insulation as they should, but this actually decreases its effectiveness.

Fiberglass insulation is designed to have a lot of air pockets. It is these air pockets that make the fiberglass effective at slowing the transfer of heat. Imagine a burning house. If one wall is on fire, any walls its touching will catch ablaze fairly quickly. If the burning wall cannot pass its heat directly to the next wall, but instead must first heat the air inside the living room until it is hot enough to cause the wall on the opposite wall to catch fire.

In the same way, air pockets in fiberglass insulation slow the transfer of heat. By compressing the insulation to stuff more in a wall cavity, you end up squeezing the air pockets out of the fiberglass (shrinking the rooms of the house so the walls all touch), allowing heat to flow through more easily.

2. Lay it on Thick in the Attic

In spaces with exposed studs, you aren’t limited to a certain thickness of insulation batt. In these areas, you are free to install insulation with the highest R value, which is also the thickest. Because the studs are exposed, there’s no need to keep the insulation flush within the wall. You can let the insulation spill up and over the studs for increased effectiveness.

In fact, if your R value does not have flooring, you can really double down with a second layer of insulation.

First, fill the cavities between the floor joists with unfaced fiberglass insulation batts. It’s important that you use unfaced insulation to prevent the build-up of condensation between layers, which can lead to mold and rot. It’s best to make the first layer of insulation flush to the height of the floor joists so there is an even surface for the second layer, preventing gaps.

Lay the second layer of insulation perpendicular to the floor joists. This will crosshatch the insulation, preventing gaps.

What’s stopping you from adding a 3rd layer, perpendicular to the 2nd? Not much, other than the fact that you can no longer see the floor joists and might step through the ceiling of your top floor while installing. (That would result in quite a gap, greatly reducing the effectiveness of your insulation.) There is a risk, however, that by adding too much insulation, any moisture that finds its way there will not dry out as easily, resulting in mold growth or rot.

3. Get the Correct R-Value For Your Climate

The type of insulation you should use depends on the heat and humidity you live in. The Department of Energy has created this map to suggest different R-value insulations based on regional climate zones in order to maximize energy efficiency.

R-Zone Values


4. Paper or Plastic? On no Vapor Barrier at All?

A vapor barrier is designed to keep hot air out of your wall space, where it can condense if exposed to a wall cooled by air conditioning or external weather. Fiberglass insulation is sold both faced (with a Kraft paper barrier on one side) or unfaced.

If using faced batts, you can simply pull the Kraft paper out so it overlaps the Kraft paper of the batt next it, then staple it in place.

If using unfaced batts, you can create a vapor barrier by stapling a sheet of plastic over the wall. It’s important to overlap any seams because if the barrier isn’t airtight, moisture can penetrate the barrier and be harder to dry out than if there were no barrier.

In cold climates, you want to put the vapor barrier on the interior side of the wall to prevent hot air from the house’s furnace from making it to the wall cavity. If it does, it can cause condensation on the inside of the exterior side of the wall, which is cooled by the cold winter temperatures.

In hot, humid climates, on the other hand, you want to install the vapor barrier on the exterior side of the wall because a more likely source of condensation formation in such climates is the hot summer air against the inside of the interior side of the wall, which is cooled by air conditioning.

Sometimes it’s better to not have a vapor barrier at all. In the event that moisture does make its way into the wall cavity, a vapor barrier will end up doing the exact opposite of its intended effect. It will trap the moisture in the wall instead of allowing it to dry out. This can lead to the growth of dangerous mold and the rotting of the wood studs.

5. Mind the Gaps

A blanket can only warm what it covers, and your house is only insulated where there’s insulation. Just your feet will be cold if they poke out the bottom of your covers, any gaps in your insulation are holes where heat can escape, and cold air can sneak in.

Make sure your insulation batts are the correct width for your stud wall. 16 inches on center is the standard in most cases, but studs could be spaced out 24 inches on center in ceiling rafters, garages, or sheds. The batt should fit snugly between the studs so that it stays in place without any other support, but isn’t compressed, which decreases the insulations effectiveness.

The space between studs is not always standard and unobstructed. The placement of doors and windows can result in spaces smaller than 16 inches in width, in which case you’ll need to trim a batt to the correct size. These wall cavities are also often obstructed by wiring, pipes, ducts, and electrical boxes.

If using batts, you’ll need to cut spaces around them so that all of the area is filled but the insulation is not compressed. If using loose fill, blown in insulation, you have to make sure the fill is falling past and surrounding these obstacles. Expanding foam can be more effective at forcing itself around such nooks and crannies.

6. It’s Not as Hard as You Think – Do it Yourself

For insulation projects, labor is typically twice as expensive as the materials themselves. Therefore, if you are willing to do the work yourself, you can save as much as 2/3rds the cost.

The work is not very complicated or dangerous. Many of the insulation materials, especially fiberglass, are very irritating to the skin, so it’s important to wear proper safety equipment. Wear long sleaves and gloves to avoid skin conntact. Wear safety glasses and breathing masks to prevent airborn particles from getting in your eyes and lungs. Keep food out of the construction zone and wash your hands well before eating to avoid ingesting it.

If installing fiberglass batts into an exposed stud wall, the only equipment you really need is a utility knife to cut the batts to the correct lengths and make adjustments so that the insulation can fit around obstructions like pipes and electrical boxes. If installing blow in insulation, you may be able to rent the blower equipment for as low as $70 per day. You’ll cut a hole a couple inches wide at the top of the wall, fill the cavity with insulation, then patch the hole and repaint the wall.

7. It’s Harder Than You Think – Hire a Professional

Even though adding insulation is a relatively simple project on paper, you may find that when you get into the finer details, it turns out harder than you think. That’s when it’s time to turn to the professionals.

Qualified contractors will know the answer to all the questions you have. They’ll know what type of insulation to use, and the recommended R values for different parts of your home, based on your location’s climate. They’ll know your state and local regulations, whether or not a vapor barrier is required, and on which side of the wall it ought to be installed.

Professionals also have a lot more experience, to they’re likely to know how to handle whatever odd complications that arise. They can measure the amount of fill going into the wall cavity. If it’s lower than it ought to be, they’ll know the fill is probably blocked by some obstruction, and how to get around it. They’re also going to get the job done a lot faster and easier than if you try to do it yourself.

8. Insulating is More Than Just Insulation

Insulation, whether fiberglass batts, blow in loose fill, or expanding foam, certainly makes up the majority of what keeps heat in your home during the winter and out during the summer, but it is far from the only thing. Having a house that is only kept warm by insulation is like going outside in a snowstorm wearing only a parka. While the parka does a lot to keep you warm, you’ll certainly be warmer if you’re also wearing a hat and gloves (and pants).

There are many other things you can do to close up gaps, prevent drafts, and increase the overall insulation of your home.

Caulking around windows, weatherstripping around doors, and storm doors and windows are a great way to further insulate your home.
Heavy curtains can dampen the cool air from a drafty window. Or, better yet, you can reglaze the window panes or even cover the window with plastic to make it air tight.
Double draft stoppers can prevent cold air from sneaking under doors.
When you rake up all the leaves in your yard, consider lining the bags around the perimeter of your house for an added layer of temporary, natural insulation.

Adding insulation to your home is a wise investment. The money you spend increasing the effectiveness of your home’s insulation is earned back each month with decreases heating and cooling bills. While doing a fairly good job is relatively easy, every gap left open decreases the overall effectiveness. By mastering these 8 insulation tips, you can improve your insulation from good to great. If you can do it yourself, the project will be cheap as well as effective. If you don’t trust your own abilities, a qualified professional can make sure everything is done just right. Either way, it will be worth the investment.