Buyer guide

Home insulation, explained

Insulation is a big part of how comfortable a home feels and what you'll pay to heat and cool it through a Georgia summer. Here are the common types, the good and bad of each, the levels to look for, and what to check before you buy.

The basics

What R-value means

Insulation slows heat moving through the walls, attic and floors. How well it does that is measured as R-value: the higher the number, the better it resists heat. Thickness matters, so the R-value of an attic depends on both the type of insulation and how deep it is.

In Athens and Northeast Georgia, the biggest job is keeping summer heat out. Most of that heat comes through the attic, so that's where insulation pays off most. Walls and floors over crawlspaces matter too.

Insulation works with air sealing

Insulation only works well when air can't leak around it. Gaps around attic hatches, recessed lights, plumbing and wiring let conditioned air escape. Good air sealing plus the right insulation is what makes a home comfortable and efficient.

What you'll see

Types of insulation

Fiberglass batts

About R-3 to R-4 per inch

Pink, yellow or white rolls between studs, joists and rafters. The most common type in walls and many attics.

Good: inexpensive, easy to add or replace, doesn't burn.

Watch for: gaps, compressed or sagging batts, and batts falling out of crawlspace floors. Gaps cut their performance a lot.

Blown-in fiberglass or cellulose

About R-2.5 to R-3.8 per inch

Loose fill blown across the attic floor. Cellulose is gray recycled paper; loose fiberglass is white or pink.

Good: fills around wires and odd spaces, and it's one of the cheapest ways to bring an attic up to a higher level.

Watch for: thin or uneven spots, settling over time, and insulation that's been wet. Cellulose holds water if the roof leaks.

Open-cell spray foam

About R-3.5 to R-3.8 per inch

Soft, spongy foam sprayed onto the underside of the roof or into walls. It expands to fill gaps.

Good: seals air leaks as it insulates and quiets outside noise. Less expensive than closed-cell.

Watch for: it lets moisture pass through, and it hides the roof decking. More on spray foam below.

Closed-cell spray foam

About R-6 to R-7 per inch

Dense, hard foam. Often used in crawlspaces, rim joists and basements, and sometimes on roof decks.

Good: the highest R-value per inch, a strong air and moisture barrier, and it adds some rigidity.

Watch for: the most expensive option, and very hard to remove if repairs are needed behind it.

Rigid foam board

About R-4 to R-6.5 per inch

Foam panels on foundation walls, basement walls, under siding or on attic hatches.

Good: strong R-value in a thin layer, resists moisture, great for basement walls.

Watch for: seams need to be taped or sealed, and exposed foam in living space usually needs a fire-rated covering.

Radiant barrier

Not rated by R-value

A shiny foil layer on the underside of the roof decking, common in Georgia homes built in the last 20 years or so.

Good: reflects summer sun heat, which can make the attic noticeably cooler.

Watch for: it works alongside insulation, not instead of it. You still need insulation on the attic floor.

A closer look

Spray foam: the good and the bad

Spray foam is increasingly common in newer and renovated Georgia homes. When it's sprayed on the underside of the roof, the attic becomes part of the conditioned space of the house: the attic stays close to indoor temperature, which helps a lot when the HVAC and ductwork are up there.

Benefits

  • Air sealing and insulation in one step, so there are fewer drafts and hot or cold rooms.
  • A cooler attic in summer, which is easier on HVAC equipment and ducts in the attic.
  • Often lower energy bills than a vented attic with thin insulation.
  • Less dust, pollen and outside noise getting in.
  • Closed-cell foam also blocks moisture and adds some strength.

Drawbacks

  • It hides the roof decking. Inspectors can't see leaks, rot or damaged sheathing behind it, and a slow leak can go unnoticed.
  • Cost: it's usually much more expensive than blown-in or batts.
  • Hard to remove for roof or framing repairs.
  • Installation matters. Foam that was mixed or applied badly can smell or pull away from the framing. Ask who installed it and when.
  • Moisture and fresh air: a sealed attic usually needs a little conditioned air or dehumidification, set up by the HVAC contractor.
  • Some roofers, insurers and buyers ask more questions about foamed roof decks, and some shingle warranties have conditions about it.

Buying a home with spray foam?

Ask for the paperwork

Ask the seller for the installer's name, the date, the type (open- or closed-cell), the thickness or R-value, and any warranty. Ask your inspector to check the edges and any spots where the decking can be seen, and consider having a roofer look at the roof from outside.

Numbers to know

Levels to look for

Athens and most of Northeast Georgia sit in climate zone 3. These are the general targets for that zone; your inspector or an energy auditor can tell you what makes sense for a specific house.

Attic: R-30 to R-60ENERGY STAR's range for our zone. That's roughly 10 to 16 inches of blown-in insulation, or about 8 to 10 inches of open-cell foam on the roof.
Walls: R-13 to R-20A standard 2x4 wall holds about R-13 to R-15. 2x6 walls or foam sheathing reach higher.
Floors over a crawlspace: R-13 to R-25Batts between the floor joists, unless the crawlspace is sealed and the walls are insulated instead.
Under 6 inches in the attic?Older Georgia homes often have only a few inches. Adding blown-in insulation is one of the best-value upgrades you can make.

Home inspection

What inspectors check

Your home inspector looks at the insulation they can reach: the attic, the crawlspace and any unfinished basement. They can't see inside finished walls, though an infrared camera can sometimes show missing insulation. Common findings:

  • Thin or uneven attic insulation, or bare spots where someone walked or worked.
  • Batts fallen down in the crawlspace, or wet, moldy or rodent-damaged insulation.
  • Insulation touching recessed lights that aren't rated for it, or covering attic vents.
  • Gaps around the attic hatch or pull-down stairs that aren't insulated or weatherstripped.
  • Bathroom fans venting into the attic instead of outside, which wets insulation.

Older homes: vermiculite

Loose, pebbly, gray-brown or gold insulation in an older attic may be vermiculite, and much of it contains asbestos. Don't disturb it. If your inspector suspects it, have it tested by a qualified professional before any attic work.

Our home inspections guide →

Under contract

Insulation during your purchase

  1. Ask the seller what type of insulation the attic has and whether any was added, with receipts if they have them.
  2. Read the inspection report for attic depth, crawlspace insulation and any moisture or pest damage.
  3. Ask for utility history. A year of power bills tells you a lot about how the home holds up in summer and winter.
  4. For spray foam, get the installer, date, type and warranty, and have the roof checked.
  5. Plan upgrades. Adding attic insulation and air sealing is usually affordable, and Georgia Power and other utilities sometimes offer rebates.
Home inspections guide Insulation pros

Resources

Learn more

Good to know: this page is general information, not engineering advice. R-values are typical ranges; ask your inspector, an energy auditor or an insulation contractor about your specific home.