Insulation Insight for New Homes and Upgrades

Insulation keeps the home warm during winter and the home cool during summer. The right material and application should save energy, reduce utility bills, and help maintain a more constant temperature for a comfortable home. All exterior walls that separate the conditioned and unconditioned spaces should be insulated to create a thermal envelope. A wide range of products are available to totally insulate a building.

Homeowners should understand that insulation levels are specified by R-Value, a measure of the product’s ability to resist heat traveling through it. The higher the R-Value, the better the thermal performance.

The recommended insulation level depends on the geographic area of your home. According to the Department of Energy, the warm, southern areas of the country should have enough attic insulation to achieve a value of R-30 to R-60. The northern, colder areas of the U.S. require attic insulation of at least R-49 to be cost effective.

The amount of insulation required to achieve a certain R-value depends on the type of insulation being used. For example, 3-1/2 in. of fiberglass may achieve R-13, while 2 inches of rigid foam polystyrene achieves R-10. The R-value will be printed on the package of the insulation product so you can easily calculate how much is required. R-Values of individual products can be added to achieve recommended levels. An R-11 added to R-38 equates to

R-49.

These days, insulation products are designed for each specific use. For the most energy-efficiency, a combination of products can be used to create a total insulating system. This includes products for insulating the foundation walls, exterior walls, crawl space (underfloor), basement walls, floors, HVAC ducts and more.

A home's exterior walls should have a moisture barrier and insulation installed upon construction. Other areas of the home that you determine to have inadequate insulation can usually be retrofitted to increase the R-value.

The major types of insulation include fiberglass, blow-in, spray-foam, rigid foam, and various types of gap-filling products.

The amount of insulation required to achieve a certain R-value depends on the type of insulation being used.

Measure your depth of insulation to see if more is required to achieve the adequate

R-value recommended for your geographic area. You can find the recommended

R-value for your location at www.energy.gov.

Common Insulation Materials

Fiberglass rolls and batts—Fiberglass insulation is the most commonly used product. It's inexpensive, easy to install, and can be used in walls, attics and crawlspaces. Fiberglass rolls are long, continuous lengths of insulation which are unrolled, measured, and cut to fit specific areas. They’re best for insulating long runs in crawlspaces and attics. Fiberglass batts, on the other hand, are pre-cut lengths available for 8- and 9-ft. walls and are sized to fit between wall framing.

Pro tip—If you install additional fiberglass insulation over existing attic insulation, be sure to use unfaced rolls or batts. Once the joist cavity is full, you can install an additional layer of unfaced insulation over the ceiling joists to reduce heat loss through the wood.

Fiberglass insulation is the most commonly used product in the USA. Photo © Certainteed

Mineral Wool Insulation—Mineral wool is a type of fiber insulation, similar to fiberglass, but is made from natural materials and not glass. There are two kinds of mineral wool available for home insulation—rock wool, which is made from fibers of stone, and slag wool, which are fibers made from iron ore waste. Mineral wool tends to be more expensive than fiberglass, but has proven noise-reduction and sound-absorption properties, and it’s durable and typically non-combustible.

Cellulose Insulation—Made from cellular plant material, such as corncobs, recycled

newspapers, cardboard, office paper, and other everyday paper products, cellulose is

an eco-friendly insulation with an average lifespan of 20 to 30 years. The material is applied with a blowing machine and can settle around and conform to most obstructions in walls and attics. Attic spaces can be overfilled leaving no empty spaces. Loose-fill cellulose

is relatively cheap but has an R-value of about 3-1/2 per inch of thickness.

Rigid foam insulation—Polystyrene sheets can be used for retrofits in basements and in areas of the home where there's not enough room for batts or blow-in. Sheets up to 4×8 feet are available at home stores in thicknesses typically ranging from 1/2 to 1 inch. The material is easy to cut with a straight edge and a utility knife, and installation is similar to fiberglass batts.

Pro tip—Maintain a minimum 3-inch gap between any electrical fixtures and the surrounding insulation. This is a safety measure required by electrical code, and if necessary you can nail wood barriers between ceiling joists to keep the insulation away.

Blow-In Insulation

Fiberglass is the most commonly used insulation product, available in rolls, batts, and as

a blow-in product. Photo © Certainteed.

Blow-in (AKA loose-fill) insulation is a good choice for placing a lot of insulation in enclosed walls or in narrow spaces, like between ceiling joists in cramped attics. Blow-in insulation

(usually fiberglass or cellulose) can achieve uniform coverage even in hard-to-reach areas, and the job can easily be done by a DIY'er with a weekend to spare. Homeowners can rent machines from home centers to blow in the product. The process requires someone outside the house who feeds the insulation material into a pneumatic machine where it is blown under high pressure through a long, flexible hose as another person directs it into the attic and walls.

Note that for small, targeted areas, loose-fill insulation can generally be applied by hand. However, the material comes in densely packed bales which are fed into the hopper of the insulation blower where rotating teeth or prongs at the bottom of the hopper fluff up the cellulose. The resulting feathery texture of the blown-in product achieves better insulation value than densely packed material.

Applying blow-in insulation is a two-person job that requires someone outside the house to feed the insulation into a machine where it is blown through a long, flexible hose while another person directs it into the attic and walls. Photos © Owens Corning

Pro tip—To fill enclosed walls with blow-in insulation, an access hole can be cut in the wallboard near the ceiling to fill the stud cavity. Once filled, the hole can be patched or concealed with trim molding.

Spray-Foam Insulation

In seconds, spray foam expands to provide a flexible foam blanket of millions of tiny air cells, which fills building cavities and seals cracks and crevices. Photo © Tiger Foam.

Spray-foam insulation is especially popular in new construction when the exposed framing can be filled without obstruction. Spray-foam insulation installs fast and seals, soundproofs and insulates. In seconds, the foam expands to provide a flexible foam blanket of millions of tiny air cells that fills building cavities and seals cracks and crevices. It dries quickly, and any excess material can easily be trimmed away, leaving the surface ready for drywall.

Most spray-foam products are dealer-installed and arrive on a truck with complex equipment to seal the entire house. However, some companies make products available to the do-it-yourself homeowner. For room additions, remodels and targeted areas in the attic or basement, check into disposable self-contained polyurethane kits, which are engineered for professional-duty but also easy to use.

DIY tip—Spray foam from brands such as Great Stuff and DAP is available in handheld cans for small, targeted applications around plumbing fixtures, gaps in framing, and for sealing windows and doors. For application around windows and doors, it’s important to select a low-expanding product intended for the specific application, otherwise the expanding foam can warp and distort the shape of door and window casing.

SIDE NOTE 1

PINK Next Gen Fiberglas

Something to note for both pros and DIY'ers.... PINK Next Gen Fiberglas from Owens Corning is ready to fit snugly into the wall cavity right out of the package. It is easy to handle, soft as cotton, and cuts cleanly with a single pass. This makes it easier (and less itchy) for DIY’ers to handle and makes it easier for pros to manage budgets and timelines, enabling up to 23 percent faster installation compared to previous fiberglass products.

SIDE NOTE 2

Radiant Barrier

A radiant barrier retains heat much like aluminum foil does with a potluck casserole. This reflective barrier can be used in homes to reduce heat transfer like traditional insulation.

On a hot day the sun heats a home’s roof and attic, which in turn emits radiant heat to varying degrees throughout the house. A hotter attic means a hotter house, so radiant barriers block the sun’s rays from transferring heat to your attic, reflecting up to 96-percent of solar energy. Less heat moves from the attic to the living area, so there's less need to crank up the air conditioner. Furthermore, this two-way reflective barrier behaves

similarly in the winter.

According to Energy.gov, “Radiant barriers are more effective in hot climates than in cool climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can reduce cooling costs by 5 to 10 percent when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it's usually more cost-effective to install more thermal insulation than to add a radiant barrier.”