Types of Insulation
Which Type of Insulation Should You Buy?
Choosing the best type of insulation for your home can be a real challenge, but the goal is always the same. An even layer of insulation that completely fills every space between the framing. Front to back, top to bottom and every little nook and cranny in between.
There are basically four different types of insulation you can use in your home:
Blankets of Insulation
Blankets of Insulation - Fiberglass and Rockwool - R-3+ per inch
This is the most common type of insulation available in the large home improvement stores. It's sold in large compressed bundles of varying widths and thicknesses because the space between the framing and the depth of the framing are always different.
For example, walls are usually built with 2X4s spaced 16" on center from each other. A 2X4 is actually 3 1/2" deep. The 16" on center framing leaves 14 1/2" of space to fill with insulation. The right insulation for this wall would be 3 1/2" deep and 15" wide.
This cotton candy like insulation earns its R-value by trapping air in between tiny fibers. These tiny air pockets slow down heat as it tries to pass through the insulation. Compressing the insulation squeezes out some of the air pockets decreasing its R-value.
Batts and rolls are basically the same with one minor difference. Batts are pre-cut to fit between common stud cavities in walls, floors, and ceilings. Rolls are a just the long continuous version of the insulation that you cut yourself. If you're lucky enough to be insulating walls with 92 5/8" cavities, the pre-cut batts are the way to go. If you're insulating anything else, you're better off buying rolls and cutting each piece to fit.
Blown In Insulation - Cellulose and Fiberglass - R -3.5+ per inch
Blown in insulation is exactly that...blown through a tube into your home.
This type of insulation is sold in compressed blocks which are broken down into tiny pieces by a powerful machine known as an insulation blower. The blower forces the insulation through a large hose. As the insulation flies out of the hose, the installer directs the flow of insulation into place.
The main benefit to using blown in insulation is how perfectly and completely it fills the space in between the walls, floors and ceilings of your home.
These tiny pieces of insulation do a great job at insulating because they spread evenly throughout the space wrapping around any obstacles like the outlets, wires, pipes and ductwork. This type of insulation eliminates gaps and voids missing insulation which comprimise the insulating power of your home's insulation and cost you a fortune in energy costs.
Blowing Insulation into an Attic
The most popular project for using blown in insulation is adding insulation to attics. Here, the insulation can be blown right over top of existing insulation to any depth or r-value. It's a fast and easy DIY project that two people can do in an afternoon.
Blowing Insulation into Walls
Skilled professionals can blow insulation into a home with existing walls and ceilings without destroying the walls. Instead, small holes are cut into the wall and the insulation is blown through a small tube into the wall cavity. The holes can be drilled inside or outside of the home depending on the situation. This is a great way to get insulation into some of the 58 million U.S. homes that have no insulation in the walls or ceilings.
Spray foam insulation is a combination of chemicals which are heated and sprayed out of a machine through a hose. The spray foam chemicals mix together at the tip of the hose creating a thick paint-like goo that sticks to anything it touches including wires, pipes and ducts. Within seconds, the foam begins to expand to trapping a gas inside billions of tiny bubbles. As the foam expands, it forms a continuous even layer of insulation and creates an air tight seal. Exactly what insulation needs to do, right?
Spray Foam Insulation - R3 - R8 per inch
The 2 Types of Spray Foam - Open Cell vs. Closed Cell
The first thing you need to know is there are two different types of spray foam with different characteristics and applications.
Open-Cell Spray Foam
The cheapest spray foam option is known as open-cell. So called because the bubbles inside of the foam never completely close. As the foam expands, air gets trapped in between the broken bubbles. This divides the space into billions of tiny air pockets that slow down heat as it tries to pass through. Open-cell spray foam is a much softer type of foam because of the broken bubbles. These bubbles allow water to pass through them, which can be good or bad depending on the application. Although open-cell spray foam does a great job at filling in and around wires, pipes and other obstacles, it's insulating power is not all that spectacular: R-3.5 per inch.
Closed-Cell Spray Foam
The bubbles or cells in closed-cell spray foam are closed and tightly packed together. This makes closed-cell spray foam much denser and stronger than open-cell spray foam. It will not absorb water or allow air to pass through it. This is because the bubbles in closed-cell foam are filled with a gas making them much smaller and a better insulator. Closed-cell spray foam tops the charts in insulating power with an impressive average of R-7 per inch.
DIY Spray Foam Insulation
Yes, it is possible to do-it-yourself. Disposable kits that come with everything you need to safely install spray foam insulation are the newest craze in insulation. They are great for small jobs where keeping the wind and moisture out are crucial. They are also great for a technique known as Flash and Batt.
Flash and Batt
Using the Flash and Batt technique, you begin by spraying the wall with a thin layer of closed-cell spray foam. This creates an air tight wall cavity with a vapor barrier. Next, you fill the rest of the space with fiberglass batts or rolls. The theory here is to increase the insulating power of the wall and to overcome one of fiberglass insulation's greatest weaknesses, convective heat loss. Convective heat loss is due to air moving through the walls, like when the wind blows and pushes cold air into your home. The closed-cell foam stops the air and the fiberglass insulation can work properly.
Foam Board Insulation
Perhaps the least understood insulation product on the market is known as foam board or rigid insulation. It comes in sheets like plywood or drywall and in thicknesses from 1/2" to 2".
It gains it insulating power like spray foam, in that foam board has billions of tiny bubbles which are set in a medium like polystyrene or polyurethane. The three main types you'll find at your local building supply store are Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), and Poly-isocyanurate (ISO). Each one has its own unique applications.
Foam board is typically installed on the outside of your home during a major renovation or underneath a concrete floor before its poured. But it's most popular DIY application is for insulating your basement walls and floors. The foam boards are glued and screwed directly to the foundation and floor then sealed off with special tape and spray foam.
Foam board is a perfect match for basements which are always under constant attack from moisture. EPS and XPS foam boards are typically used because they are semi-permeable, which means the allow moisture to pass through and allow the wall or floor to dry instead of rot. Learn more about basement insulation.
Poor Man's Spray Foam
Installing foam board into a wall, floor or ceiling is about a painstakingly slow as installing fiberglass. However, it does create an air tight continuous layer of insulation similar to spray foam at a fraction of the cost.
This is also an easy DIY project you can do yourself.
I call it Poor Man's Spray Foam and I've done it throughout my home with great results.