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Home Insulation Guide - 10 Frequently Asked Questions about InsulationHeat Loss Diagram

People have tried just about everything to insulate their homes - straw, mud, seaweed, even feathers. Fortunately, insulating materials have evolved, and so has their effectiveness. According to the U.S. Department of Energy, proper insulation in your home can reduce the amount you spend on heating and cooling by as much as 20% - that can add up to savings as high as $300 a year.

Why does my home need insulation?

Heat flows naturally from warm places into colder places. This means that all winter long, as your furnace is pumping out heated air to warm your home, that heat is trying to escape outside, or into an unheated garage, attic or basement. Conversely, in the summer, when your air conditioner is working hard to cool the house down, hot air is pushing its way indoors. In fact, the cooler the indoor temperature, the faster the heat wants to come in.

So whatever the season, home insulation is needed protection for your home. It provides a barrier to heat loss and heat gain, which means you'll use less energy running your heating and/or cooling system, and ultimately spend less on your utility bills. If you live in a newer home, chances are your insulation is sufficient for your regional requirements; check with the builder if you want to confirm the specifications. But if you have a home that was built more than 30 years ago, or you have any additions, you might have inconsistent or insufficient insulation in place. It's time to check and find out!

How much insulation does my home need?

The amount of insulation required depends primarily on the region you live in - colder winters generally mean a higher level of insulation is needed.The DOE has published a guide that shows, zone by zone, how much insulation your home requires.

Minimum R-Values

For more specific recommendations for your area, visit R-Value calculator from the Oak Ridge National Laboratory.

The goal for home insulation is to create a thermal envelope around your living spaces, with barriers in place that stop heated or cooled air from being lost. You need appropriately rated insulation in the attic, exterior walls, and (in many cases) under the floor. If you have an unheated basement or attached garage, the connecting walls also require insulation. The above guides will help you determine the correct R-value for insulation for the different parts of your home.

What does R-value mean?

In the DOE insulation guide, the amount of insulation required is designated by an R-value, which is simply a measure of thermal resistance. The higher the R-value, the more effective the insulation will be. An inch of wood has an R-value of 1, which means it is not very effective at keeping heat from passing through. Concrete and brick is even lower. You can improve the R-value for buildings made from these materials by adding insulation.

The R-value will be prominently featured on any insulating product that you purchase. The Federal Trade Commission has strict guidelines about labeling on insulation. Make sure you read the label thoroughly to ensure it matches your needs, and that you are aware of any special usage considerations.

R-values are determined by the materials the insulation is made from (such as fiberglass, cellulose, polyicynene and polystyrene), how thick the layer of insulation is, and how dense the material is. You can increase the overall R-value with a multi-layered installation, for example combining blanket insulation with loose-fill. Just be sure to put the lower density product on top, because compressed insulation will not give its full-rated R-value.

What types of insulation are there?

There are many types of insulation available, depending on your specific needs and budget. This chart defines the most common types, what they look like, where they are best used, and how much they cost.

TYPE OF INSULATIONBLANKETLOOSE FILLFOAMRIGIDRADIANT BARRIER
WHAT IT LOOKS LIKEComes in rolls or batts in standard widths to fit between wall studs and attic floor joists.Blown-in loose fibers or fiber pellets. Spray-on foam.Board-like forms and molded pipe coverings, often faced with reflective foil.Aluminum foil with paper, cardboard or plastic backing.
MATERIALSFiberglass or cellulose (plant fiber). May have paper or aluminum foil facing. Fiberglass or cellulose (plant fiber, recycled paper fiber).Latex or polyurethane. Polystyrene or polyurethane.Aluminum foil
R-VALUE
(depending on thickness and/or material)
13 - 30 30 - 506.5 - 12. 53.8 -6.5 n/a
USAGE GUIDE
  • Walls, floors, ceilings.
  • Great for DIY.
  • Must cut to fit around pipes, wires, and outlets.
  • Wall cavities.
  • Unfinished attic floors.
  • Irregularly shaped areas and filling in around obstructions.
  • Good for sealing around windows, pipes and other small openings.
  • Larger application requires professional installation.
  • Foundations.
  • Wall sheathing.
  • Excellent at reducing heat conduction through wood and steel studs.
  • Most effective in reducing downward heat flow.
  • Keeps home cooler in hot, sunny climates.
COST PER SQUARE FOOT$0.20 - $1.00$0.45 - $2.25
includes installation
$1.30 - $2.50
includes installation
$0.20 -$0.70 $0.30 - $5.00


How can I find out if I need more insulation?

Indicators that you need additional insulation include:insulation in attic

  • Drafts in your living spaces
  • Uneven temperatures between rooms
  • High heating and/or cooling bills
  • Cold floors in the winter
  • Pests (insects or rodents)
  • Dust smells from an attic or crawlspace

If you experience any of these conditions, it is time to inspect your insulation. A professional contractor can conduct a home energy audit, which includes an evaluation of your current insulation and pinpointing air leaks. Check with your local utilities; many provide this service for free, or can connect you with reputable inspectors. After conducting the inspection, they will make recommendations about improvements that should be made.

But If you like doing it yourself, there's no need to hire a professional. Evaluating your home's insulation can be done in just a few quick steps. When inspecting your home's insulation, make note of these factors:

  • What kind of insulation
  • How thick it is
  • Whether it's in good condition or not

Keep in mind there may be more than one kind of insulation installed. Also, watch out for compressed or sagging insulation that may no longer be providing adequate protection against heat loss. You will want to check:

Attic

Bring a ruler along with you and poke your head up into the attic. A quick way to evaluate how much insulation you have is whether or not you see a lot of wood. If the beams are showing, it's a good indicator that you need more insulation up there. But use the ruler to measure the actual depth of the existing insulation. While you're there, check to make sure that any ductwork present is insulated as well.

Walls

To check the insulation on exterior walls, you will need to look into a few wall sockets. To be safe, disconnect the power to the outlet first, then remove the cover plate and use a flashlight to look inside. You should be able to tell if there is insulation inside. Remember to check the walls in different areas of your house, upstairs and down.

Floors

If you have a room over an unheated basement, garage or crawlspace, the floor should be insulated to prevent heat loss. This can be harder to check, depending on the floor construction.

 

Once you've made your measurements, you should be able to calculate the existing R-value of your insulation and compare it to the DOE's guidelines.

Spray Foam InsulationDo I need to hire someone to install insulation, or can I do it myself?

Depending on the location and the type of insulation, it's quite possible to install insulation on your own. Installing blankets, batts and rolls are an easy DIY project, and machines for loose-fill insulation can be rented in many areas. Large-scale spray-on foam applications need to be installed by professions.

It is easiest - and most cost effective - to install insulation during the building process, or when structural renovations are already underway. If you are rebuilding or adding-on, talk to your contractor to make sure proper insulation is part of the building plan.

Should I dispose of old insulation?

If existing insulation is compressed, water stained, or moldy, it should be disposed. Keep an eye out for lightweight, loose-looking insulation with shiny flecks; if it was installed before 1990, it might have asbestos in it. Get it tested, and hire a professional to remove it.

If the existing insulation is in good condition, but there's just not enough of it, you can simply add more on top of it.

Should I insulate my garage or basement?

If you intend to use your garage or basement as additional living space (for example, if you want to use your garage as workshop) and you plan to use space heaters or cooling appliances, then you should definitely add insulation. This will cut down on the amount of energy you need to heat and/or cool the space.

But if you only use your basement or garage for storage, and you're not trying to heat or cool the space, then you only need to insulate the walls that connect to the main building to stop heat travelling between them.

Are there any health or environmental risks associated with insulation?

Blanket Insulation InstallationFiberglass insulation can irritate the skin and eyes, and both OSHA and the EPA have recognized it is a "possible carcinogen", but the American Lung Association has determined it is safe when properly installed. The greatest risk is to those who are installing it. It's a good idea to use goggles, dust masks and gloves when working with it.

The EPA has also determined that spray polyurethane foam can cause adverse health effects, most commonly asthma, though there are steps you can take to reduce exposure.

Homes built in the early part of the 20th century were often built with insulation made from asbestos, which has since been proven to cause cancer. If you live in an older home and think you might have asbestos insulation, you should contact a professional to evaluate removal options.

As far as the environment is concerned, insulation is intrinsically environmentally friendly because it reduces the amount of energy spent on heating and cooling. These days, most insulation products use a high percentage of recycled material, with the exception of spray foam insulation, which is a petroleum based product. As a non-renewable resource, this makes foam insulation the least environmentally friendly option available. The "greenest" option is cellulose insulation, which can be made from a variety of materials including recycled newspapers, blue jeans denim, and even soybeans.

Can I get tax credits for upgrading my insulation?

If you live in the US and installed insulation in 2012 or 2013, you can apply for a tax credit for 10% of the cost, up to $500. This credit includes move bulk insulation products, as well as air seal products such as weather stripping, caulk and house wrap. For more information visit the Energy Star site, orIRS.gov.

At this time, this federal credit has not been extended to 2014. However, check with state and local offices for rebates, discounts and other incentives that might be available.


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