Why You Should Insulate Attic BEFORE Upgrading to a Higher Efficiency HVAC System

One of the things we hear quite often is people saying they just bought a new HVAC system that was supposedly very energy efficient, but they are only seeing a small decrease in their home heating or cooling bill.

It’s understandable why some people get confused here but chances are they are missing something critical to achieving the energy savings that their new HVAC can really give them.

Many times that missing ingredient is proper attic insulation. When an energy efficient HVAC system is matched up with good attic insulation they can combine to give you some pretty dramatic energy savings.

Knowing the different types of attic insulation that exist is definitely a crucial part of that. Here are some key thoughts about attic insulation that every homeowner should know.

Why Attic Insulation Is Important

Experts agree that the majority of heat loss or gain that takes place in a home is done through its attic. This estimated heat loss can be as high as 25% depending on what type of insulation your attic has. With an alarming potential for heat loss like that it’s easy to see why you need to pay special attention to how your attic is insulated.

In winter, when you heat your home that heat rises and your attic insulation is the first line of defense to stop that heat loss and save energy.

In summer, hot humid air also penetrates into your attic and makes your home harder to cool. Radiant heat from the sun beating down on your roof also plays a role in energy loss from attic heat buildup.

What Does Insulation R-Value Stand For

When you are deciding which type of new insulation you want to install or determining what type of insulation is there; you will often hear the term R-value used. That’s because all the different types of installation have an R-value rating.

So what exactly is R-value?

If you are looking for a scientific type explanation it’s a number that represents the measure of the resistance of heat flow through any type of material. What’s R-value in more Lehman’s terms? It is a number that represents how well a certain type of material stops heat flow from one area to another.

So obviously the higher R-value any type of insulation has the better it will stop heat flow into your house through your attic and also stop heat loss from your home into your attic.

Here are some common R-value target numbers for attic insulation based on the climate where you live

  • Hot climates: Target R-value is 30
  • Moderate climates: Target R-value is 38
  • Colder climates: Target R-value is 49

Be careful when looking at R-values on certain types of insulation because it may be rated by inch of thickness instead of the overall R-value of the insulating product.

Don’t Just Go By R-Value When Buying Insulation: Here’s Why?

There are actually 4 ways that heat can build up in your attic and then penetrate into your home or heat from your home can escape through your ceiling into your attic. You can’t just look at an insulation types R-value in most cases because it only takes into consideration 1 of the 4 ways in which heat is gained or lost.

Keep in mind you don’t have to worry about all 4 types of heat penetration in certain climates and certain times of year. That means everyone doesn’t always need the absolute best insulation money can buy to do the job in that locale.

Here are the 4 means of heat travel into and out of your home:

1. Conduction – This is where R-value comes into play when looking at attic insulation. R-value measures heat transfer through solids or what otherwise is known as conduction.

2. Convection – This is the process of how heat travels through anything but solids. Natural convection occurred within the insulation itself, there is clear convective loss through some insulation material like loose-fill fiberglass. Convection is a bigger concern for those living in cooler climates because it has to do with heat loss through your ceiling if your attic is poorly insulated.

3. Radiation – This has to do with sunlight or other types of heat transfer that takes place due to electromagnetic waves that are in the infrared spectrum. This is a much bigger factor in warmer climates where the sun shines all day than it is in cool or temperate zones.

4. Air Infiltration – This is simply how well sealed any structure is. It has something to do with the ability of inside air getting out of a structure or the ability of outside air to come into any building through cracks and crevices.

A professional such as an insulation expert or HVAC expert should be able to tell you which of these means of heat transference you need to consider when putting new insulation in your attic.

The Different Types of Attic Insulation

There are 5 common types of attic insulation that are used in homes today. Most people do not realize there are some real differences between different types of attic insulation. That means there are some that work better under more environmental circumstances than others and are probably more expensive than other types of attic insulation too.

The 5 Most Common Types of Attic Insulation

R-value per inch
How InstalledCharacteristicsCost
Fiberglass Batt2.9 to 4Laid in By Hand and Pre-cut to Fit in Between StudsThe least expensive type of insulation$
Rigid Foam Board5Cut to fit so it’s great for retrofit jobs and new constructionActs an air barrier that adds structural strength too.$$
Spray Foam6.5Sprayed into placeCompletely seals up air gaps.$$$
Blown-In2.2 to 3.8Blown into placeGreat for irregular shaped or tight space$$
Reflective or Radiant BarrierN/ABest used as an extra layer of foil insulation that goes over the existing insulationApplying radiant barrier insulation in conjunction with regular insulation$

Here is an overview of the 5 most commonly found insulation types:

1. Fiberglass batt

This is the least expensive type of insulation on the list and also the least effective. It’s best used in warmer climates where moisture is not a big threat. It is insulation that is most commonly made using fiberglass fibers and it’s made in predetermined lengths and widths to fit in standard joint spacing. It comes in rolls so it’s easy to move around and is very lightweight. It’s a favorite of many do-it-yourselfers because it’s so easy to install.

2. Rigid foam board

Rigid foam board is a step up from basic fiberglass batt insulation and that’s because it forms an effective air barrier which basic fiberglass insulation does not. This insulation does not fill gaps and it has to be cut to fit with a razor knife before nailing it down. One of its better characteristics is it will add some structural strength to whatever surface it’s applied to also. It’s a favorite of those who quickly want to add another layer of insulation over the existing fiberglass batt insulation in an attic.

3. Spray foam

This is what is known as a two component polyurethane foam. That means it has two chemicals that are mixed together to form this insulation and after the mixing it is then blown into place in your attic.

Unless you are just applying it to a small attic it is best left for professionals to apply it.

This is currently one of the most popular and best working types of insulation. It really needs to be professionally done so that also adds to the cost of installation. Since its blown into place it can be used very effectively in irregular shaped attics and it also seals any air gaps it’s applied over.

As an added bonus, having this type of insulation installed in your attic will also make your home more attractive to prospective buyers if you should ever decide to put it on the market.

4. Blown-In

You can think of this as batt insulation that does not come on a roll. It’s made using fiberglass, cellulose or other types of materials just like batt insulation is. The handy thing with blown-in insulation is since it does not come on rolls it works great for use in tight spaces and irregular shaped attic areas. It does a decent job as a vapor barrier and stops most air gaps where it’s applied. It’s also cheaper than using spray foam insulation. One drawback is it needs special equipment to blow it into place.

5. Reflective or Radiant Barrier

His is not really a traditional type insulation because it’s not thick enough to stop traditional heat flow. What it does do is form an effective barrier against radiant heat transfer such as that heat flow that is produced by the sun’s infrared waves.

It’s worth mentioning here because when it’s combined with other forms of insulation its thought to save homeowner’s an additional 5% to 10% on home heating and cooling bills.

It is basically a foil like material that comes in rolls and is cut to fit. It’s very simple to apply and is not extremely expensive. This material is highly recommended in hotter climates where it’s most effective.

Use a 3 Prong Approach for Optimal Attic Energy Efficiency Contribution

Insulating your attic is great and the higher quality insulation you use the better but don’t stop there. There are three things that will help make your attic a big player in contributing to your homes energy efficiency.

They are:

1. Insulation

We have already talked about the importance of attic insulation a lot in this article.

2. Sealing Air Gaps

Sealing up air gaps in your attic is important for two simple reasons.

Air gaps in your attic need to be sealed in winter because hot air is naturally drawn towards cooler air and it will be harder to heat your home.
Air gaps in your attic need to be sealed up in summer months to prevent excess amounts of warm air from getting into your attic and making it harder to cool your home.

3. Ventilation

Proper ventilation in your attic keeps heat from building up too much inside and lessens the strain on your attic insulation during the warmer months of the year. It’s also another weapon against humidity that causes damaging moisture and unhealthy mold buildup in your attic.

Attic ventilation can be achieved by doing such things as adding attic ridge and soffit vents that help in the colder months and regular attic roof vents to help reduce warm air buildup in your attic during the summer.

Installing an attic fan is highly recommended if you live in an area where you run your air conditioner more than just a few months a year. Install a solar powered attic fan for even greater energy savings.

Final Thoughts

Without a doubt, a properly insulated home will help you save money on your energy bill when used in conjunction with one of today’s modern energy efficient HVAC systems. And as we have discussed having your attic properly insulated and sealed up is a major part of that home insulation process.

How do you know if the attic insulation you currently have is insulating your home properly? The answer is most people don’t have the knowledge to determine that unless they do some extensive research. Instead of taking the time to do research we recommend calling someone who does have the knowledge to determine if your attic insulation is adequate for your needs.

This includes insulation experts, general contractors and most HVAC personnel. You can also try our handy online HVAC estimation tool.

So before you start thinking your new HVAC is not giving you the type of energy savings you expected when you purchased it, make sure your attic insulation is checked to make sure it’s doing the job properly that it was intended to do also.

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