Once you’ve determined that you need insulation for your attic, whether you are replacing existing insulation or adding new insulation, you should take time to do some research on what insulation is best for attics. Regardless of how big your house is, where it’s located, or how old it is, every house needs to have proper insulation in the attic. This will help to regulate the temperatures throughout your house and can also help you save some money on energy bills by promoting energy efficiency. The tough question becomes – how do you know which attic insulation is best for your house? There’s not necessarily a one size fits all approach for this, so it’s important to sit down and do some research before purchasing. We will walk you through some of the aspects that you should consider when choosing insulation for your attic along with the different types of insulation that is typically used for these jobs.
R-Value
You’re probably already thinking what does an “r-value” have to do with choosing attic insulation. To the surprise of many people, the r-value plays a significant role and is the first aspect that should be considered. To better understand this term, an r-value is a unit that is used to measure a certain material’s ability to withstand the transfer of heat. There are different r-values designed for different circumstances and it is best to check with the Department of Energy to see what is recommended for your home. The rule of thumb is that the value should be anywhere in between R-30 and R-49 with some exceptions for extremely cold areas. Some of the factors that go into determining an r-value include the following:
- Insulation material type
- Thickness
- Density
- How the insulation is installed
Insulation is often measured in “r-value per inch”, meaning that if you want to achieve an r-value of 30 with insulation that provides an r-value of 3.0 per inch, you would need 10 inches of that type of insulation.
Types of Insulation Materials
Even though it is recommended to choose a material that has the highest r-value, that does not always mean that it is the best choice of insulation. Different materials will each have their own pros and cons to consider before choosing. Here’s a brief overview of the most popular types of attic insulation materials and their strengths and weaknesses.
Blanket Insulation
This type of insulation is available by the batt or by the roll. It is a common choice among homeowners who are looking for more of a DIY project to be able to easily install it on their own. It is available in many different options including fiber glass, mineral wood, plastic fibers, and natural fibers. It is a relatively inexpensive option, however, it yields a generally low r-value and you must trim it precisely for a snug fit.
Fiberglass
When it comes to insulation material, fiberglass is typically the most common option you will come across because it tends to be the least expensive. However, just because it is cheap does not mean it will be the best option for you. The r-value typically ranges from 2.2 – 3.8 per inch for fiberglass insulation. It comes along with many advantages that are appealing including being good at resisting moisture and insects, fire resistant, and it does not generally shrink over time. It’s an affordable option but may not yield the r-value that your attic needs.
Cellulose
Another insulation material is cellulose which is made up of recycled paper or wood. This provides a somewhat more environmentally friendly option in comparison to fiberglass. The r-value typically ranges from 3.1 – 3.8 per inch making it slightly higher than fiberglass. Some of the advantages of this material include fire resistance and versatility. On the other hands, a few disadvantages include not being moisture resistant and prone to settling quicker than other insulation materials.
Mineral Wool
Mineral wool is an insulation material that is created by melting down stone and recycled slag. It comes at a higher price point than the other materials but has an r-value between 3.7-4.2 per inch and other advantages that makes it worth the price. Some of these advantages include providing a fire barrier, water resistance barrier, and being effective at blocking out sound. While there are not really any disadvantages with this material, it can be hazardous to inhale during installation.
Cotton
Cotton insulation material is derived from recycled blue jeans and offers a solid option for your attic’s insulation needs. Some of the highlighted advantages include an r-value of 3.7 or higher and it offers a safer option for anyone who is installing this material. It does come in at a higher price point than fiberglass and cellulose but it typically has a better r-value.
Foam
The last type of insulation material is foam which is typically regarded as the best possible choice for your attic insulation. There are two different types of foam insulation that you can choose from:
- Open cell foam provides an r-value of around 3.5
- Closed cell foam provides an r-value of an outstanding 7.0
As you can imagine, this option has so many advantages and comes with little to no disadvantages at all except for the price point for some individuals. A few of the main advantages with spray foam insulation include top notch air sealing, water resistance, fire resistance, durability, and it can also serve as an effective sound barrier.