Insulation, how does it work & what works best for me?

Insulation is an important part of home building for various reasons. Let UBuildIt explain why!
Home Building

Heating and cooling your home represents almost one half of the money you will spend on energy every year.  If your home is poorly insulated, those costs can be even greater. The amount of insulation as well as its effectiveness is "key" to your energy usage. By nature, heat flows from a warmer area to a cooler area due to the difference in temperature. So in winter, the warm air in your heated rooms will move to the cooler unheated areas such as the attic, garage, crawl spaces or outside.  During summer, the warm outside air will transfer to the cooler interior of your home because of the higher temperature outside as well as the admission of sunlight.  In either case, your HVAC (Heating - Ventilation - Air Conditioning) system must work to replace or remove the heat lost or gained.  The effectiveness of your insulation will directly impact how hard your HVAC system must work which then directly impact your energy costs.

energy bill pie chart

Insulation's role is to slow down the transfer of heat.  This is measured in its ability to resist air flow, which is called R-value (resist value). The higher the R-value is, the greater its resistance to heat.  Its R-value will be determined by the type of material it is made from, the thickness of the insulation and the density of the insulating material itself.

There isn't just one correct R-value for all areas of the country or for all areas of the house.  Shown below is a table prepared by the U.S. Department of Energy for Targeted Insulation levels for different areas of the country and locations within your home. Take a minute to review this chart and see where you are.

Target Insulation Levels

Location Southern Region Northern Region
Good Great! Good Great!
Ceiling/Attic R30 R38 R38 R45
Walls R13 R19 R19 R23
Floors R9 R25 R25 R30
Basement Walls any any R11 R19
Slab any any R4 or R5 R8

If you want to know what the R-value of the insulation in your current home, either look for an "energy label" containing the home's R-values near the main electric service panel or near the hatch or stairway.  If you can't find a posted energy label, look directly on the insulation for the R-value or measure the actual thickness of the insulation.

In addition to the R-Value, installing your insulation correctly is critical to its effectiveness.

There are five common installation problems that can occur.

installation problems

1. One of the types of insulation is Batts. If it is compressed it will provide less resistance to heat and can provide a channel for air and heat movement.

2. If your Batts or Vapor Barrier is stapled to the inside of the studs, unwanted air movement can occur between the studs and the insulation.  It should always be stapled on top of the studs, allowing the Batt to completely fill the cavity in which it is placed.

3. Not completely filling irregular areas or small voids with insulation can cause heat loss.  A void of 1-2 percent can result in a 25-40 percent loss in R-value in that area.  It is for this reason; different types of insulation may be used in the same home.

4. If you don't install loose-fill cellulose insulation to its property density, heat loss can occur.  The proper density is called fluffing.

5. Heat can be conducted through the studs and joists of your home.  This is called short circuiting or bridging the insulation.  With careful design and proper installation, this can be minimized.

While your contractor will be looking out for these common problems, it is helpful for you to know what will be affecting your energy costs for the life of your home.

Some areas of your home will have a greater opportunity for heat loss than others.  If you have to prioritize which to insulate first, this is the recommended order:

  1. Attic, including the attic door or cover hatch
  2. Beneath floors above unheated spaces such as garages, unfinished basements and crawlspaces
  3. Around walls in an heated basement or unventilated crawlspace
  4. Around the edges of a slab-on-grade foundation.

As you work with your architect or designer and contractor, ask questions about how your home will be insulated.  This planning can save you money in the future as well as protect the earth's precious resources.

What are the different types on insulation in a home?

One inch of insulation = 30 inches of concrete

There are nine types of insulation used in home construction and remodeling today.  The type of insulation used can be based on the area of the house needing insulation as well as the cost.

The R-Value of Fiberglass insulation is 3.14 per inch

rolls and batts

1. Rolls and Batts - These are blankets of flexible products such as fiberglass or rock wool and come in continuous rolls with widths suitable for standard wall stud spacing and attic or floor joists.

These can be purchased with or without vapor retarder facings as well as a one with a special flame resistant side for basement walls where the insulation will be left exposed.  This type of insulation is great for areas which have standard stud and joist spacing and are relatively free of obstructions.  They do not readily fit irregular spaces and can create insulation voids. Loose Fill or Sprayed-in-Place insulation is more effective in these irregular locations.

A void of 1-2 percent can result in a 25-40 percent loss in R-value in that area

loose fill insulation

2. Loose Fill - This insulation is made of cellulose which is recycled, shredded newsprint and is chemically treated to resist fire, and fungal and insect growth.  These shreds are blown into space with special pneumatic equipment and are well-suited to irregular areas where other types of insulation are difficult to install well.

The R-Value of Cellulose Insulation is 3.70 per inch.

Cellulose must be installed at a density of 3.5 to 4.4 pounds per square inch to ensure it will not settle and that gaps do not form.  When having cellulose installed, always get a written guarantee of the settled depth from the installer.

Manufacturers use recycled waste materials in the production of loose fill insulation.  Cellulose contains more then 75 percent recycled newsprint.

sprayed in insulation

3. Sprayed-in-place - This insulation uses cellulose, fiberglass and mineral wool that are mixed with an adhesive and blown into wall cavities.  When properly installed, wet-spray insulation resists settling and shifting, and allow the cavity to be completely filled.

foamed in place insulation

4. Foamed-in-place - This type of insulation is typically more expensive than the fiber insulation but is very effective where higher R-values are required or, in irregular areas of your home which would not be adequately covered by a Batt type insulation.  Foamed-in-place insulation is either polyurethane or isocyanurate and is applied by a professional using special equipment to meter, mix and spray the foam into place. Foam can be used for a variety of applications but is especially effective with irregular-shaped surfaces and narrow openings such as shim spaces around doors and windows.  The foam does not act as a vapor barrier and should be protected from prolonged exposure to sunlight.

foam board insulation

5. Foam Board - Foam boards are rigid and lightweight, and provide structural support and acoustical insulation.  These are designed to be used in confined spaces such as exterior walls, basements, exposed foundations, attics, concrete slabs and cathedral ceilings.

radiant barrier

6. Radiant Barriers - These are manufactured from aluminum foils and are used to reduce cooling loads.  The common use is under roof rafters to reduce the heat gain from the sun or, on walls that absorb direct sunlight, I.E., walls facing west without an effective roof overhang.  Because they are designed to reflect the heat, they work well in warm climates but are not recommended in cold climates.

reflective insulation

7. Reflective Insulation systems - Similar to the Radiant Barrier, the Reflective Insulation is made from aluminum foils with a backing of kraft paper, plastic film, polyethylene bubbles, or cardboard.  It is typically used between roof rafters, floor joists, or wall studs because it is most effective in reducing the downward heat flow.

insulating concrete forms

8. Insulating Concrete Forms (ICF) - These serve as both insulation and as part of the wall assembly of your home.  The forms are made of two foam insulation boards and are connected by plastic ties.  Concrete is poured into the forms and the forms are left in place for their insulative value.

ICFs can cost up to 4 percent more than the standard wood framing but a home built using this product requires an estimated 44 percent less energy to heat and 32 percent less energy to cool when compared to an equivalent wood-framed house. (U.S. Dept. of Energy)

foam board

9. Structural Insulating Panels - SIPs are made up of rigid form core insulation, laminated between two (2) layers of wood sheathing called OSB (Oriented Strand Board).  SIPs replace several components of conventional building such as studs, joists, insulation, vapor barrier and air barrier.  SIPs are most commonly used to build exterior walls but are also used for floor and roof systems.

Work with your contractor and architect, or designer, to carefully plan how the insulation in your home will maximize the effectiveness of your HVAC system and lower your ongoing energy needs. Your UBuildIt Construction Consultant can help you with these types of decisions.

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