Attic Insulation

Attic Insulation


Cooler in the Summer AND Warmer in the Winter!!!!

The attic is by far the most important area of your home to have insulated. We suggest homeowners make certain their attic is well insulated before insulating any other area of their home. All too often homeowners believe they have adequate insulation in their attic and in fact only have a small fraction of what they should have. Like many things in life, some people rather not know and just presume things are fine, all the while their heating and cooling bills are unreasonably high or they’re suffering with an uncomfortable home. Check your attic insulation!

Attic insulation works both during the summer and during the winter. In summer it blocks heat from coming into the home and in winter it holds heat from rising out. The result is a more comfortable home with lower energy bills year-round. For a better understanding of how insulation works, see our section How Insulation Works.

The attic can be insulated using rolled fiberglass, blown fiberglass or blown cellulose. Your choice, but we strongly feel the blown cellulose is the best insulation material to choose from. Cellulose is more effective, more efficient, longer-lasting and safer than fiberglass. For more information on materials, see our sections on Cellulose vs. Fiberglass, or our section on Blown vs. Rolls.


Many homeowners believe they have sufficient insulation already in their attic. In fact, you want to have enough insulation such that you have a performance rating of at least an R-30. Cellulose develops an R-30 rating with approx. 8″ of thickness, while fiberglass requires closer to 12″ in order to attain the same R-30 rating. Also, in areas more inland where the climate is not as mild, you may want an R-38 rated material.

insulation thickness


How much attic insulation do I need?

The performance of an insulation material is measured by “R-Value”, where the “R” stands for Resistance. The thicker the insulation, the greater/higher it’s R-value.

The standard building code for attic insulation in Los Angeles County is R-30, but this code has been around since the 1970’s back when gasoline was less than a dollar per gallon! Today we’re seeing more counties and areas adopt a thicker rating, and that would be the R-38. It’s the same insulation material, just different thicknesses. R-19, R-30 and R-38 is just like a Quart, Pint or Gallon of water. Same stuff, just different amounts of it!

If you live near the coast or in an area that has a mild climate, you probably would do fine bringing your attic up to a total of R-30, but further inland and in warmer areas we strongly recommend R-38, it can keep a home an additional 5-8 degrees cooler in the summer as compared to the R-30.

Some people equate the R-30 and R-38 with an automotive analogy, one engine option offering 30mpg and the upgrade engine offering 38mpg, so if you live in a more moderate climate or plan to be in your home for a long time, the R-38 is probably a worthwhile choice! Also, we generally charge only enough to cover our material cost when installing an R-38.

Most homes have some old or “existing” attic insulation already in their attic. Typically we just add more insulation to what you already have in order to bring the attic up to an R-30 or R-38 rating. Many homeowners presume the old insulation needs to be removed, but this is rarely the case. The existing insulation may be dusty, filled with old roofing debris and look quite tattered, but it’s just old material; it doesn’t contain asbestos nor contain anything that wouldn’t be rendered safe once new & fresh material is installed over it. Also, there’s no chemical interaction or problem with mixing various insulation materials either. We actually can save you money by using your existing insulation as a base and installing enough additional material over it to bring the attic up to R-30 or R-38. If you still believe you may need to remove your old insulation, please see our section on Insulation Removal.

Attic insulation is quick and easy, most homes can be completely insulated in just 2-3 hours and you don’t require a permit from the city. We enter the attic through a crawl-hole, typically located in the hallway, closet or garage. The process is quiet, clean, and you don’t need to leave your home while we work. We also utilize a dust-reduction system and keep our jobs nice and clean. Our truck parks on the street or in your driveway and most everything happening inside your home is very quiet and non disruptive. Homeowners have had us insulate their homes in the afternoon and then hosted dinner parties later that night, insulating your home is not a major production.

Not just an improvement… it’s an investment!  Dollar-per-value, attic insulation is unbeatable. Typically paying for itself through savings within a year, it’s perhaps the best investment you’ll ever make to your home. It pays for itself and then continues to save you money. Because our government recognizes the importance of having proper insulation, there are often Rebates to provide incentive to homeowners to insulate.

In coastal and mild climates, you’ll want to bring your attic up to R-30:
  • If your attic has little or no existing insulation, you’ll want to install an R-30 rated material.
  • If your attic has 3-5″ of existing insulation, you’ll want to install R-19 to achieve a total of R-30.
In inland and warmer/colder climates, you’ll want to bring your attic up to R-38:
  • If your attic has little or no existing insulation, you’ll want to install an R-38 rated material.
  • If your attic has 2-3″ of existing insulation, you’ll want to install an R-30 to achieve a total of R-38
  • If your attic has 5-6″ of existing insulation, you’ll want to install an R-19 to achieve a total of R-38
Does R-38 really make a difference?

In the summer of 2005 we conducted a study. In Thousand Oaks, Newbury Park and Agoura (all areas moderate in climate) we went to 5 newer homes that had R-30 already installed in them. We added more cellulose insulation to bring the attic’s up to an R-38 rating; each home reported a 5-8 degrees cooling improvement! Does R-38 really make a difference? Absolutely!

It should be noted that the newer homes used in the study were all insulated with rolled fiberglass batting. Batting is essentially a bunch of rolls that are placed between the ceiling joist. By its nature it only goes between the joist and does not go over them. Rolled material also has a compromised fit around plumbing, piping and electrical wiring. By our blowing additional insulation over the existing R-30 rolled fiberglass, we not only increased the R-value to R-38, but also better sealed the whole ceiling much more effectively, so our improvement was two-fold.

Other factors to consider

Besides your location, there are many other factors that can dictate which R-Value would work best for your home:

Roofing material

Asphalt-composition roofs are much hotter than wood-shingle or wood-shake roofs of the past. Think about a park bench basking in the summer sun, if it were made of wood and you sat on it, it would be warm but certainly not terribly hot. If the same bench where made of rock, it would be significantly hotter! Also, the older wood-based roofs had natural ventilation, by comparison the asphalt-composition roofs are much more sealed. Asphalt-composition roofs are the most common and hottest roofs on homes.


Attics that have whirly-birds, fans, dormers and vents tend not to get as hot. By keeping the attic cooler, the insulation doesn’t have to work as hard. If you’re attic is well ventilated, you may be fine with just bringing it up to R-30.

Pitch of the roof

A higher pitched roof has more “stand-up” area inside it. While this makes it easier to walk around, it also provides more area and space for the heat to rise. The further the heat is away from the ceiling and insulation, the better. So if you have a very tall-pitched/steep roof, here again you may be fine with just an R-30.

Color of roof

A darker color gets hotter than a lighter color, something few homeowners consider when selecting the color of their roof. A black-colored roof will absorb much more heat into an attic then a light-grey colored roof.

Shade from trees or canyons

A tall shade tree, high canyons surrounding the house or other structures can often offer a nice break to keep the roof from being baked by the sun. Quite often homeowners get that large tree trimmed and suddenly their home is noticeably warmer! Shade trees can be invaluable for both looks and staying cooler in the summer!

When Everguard arrives at a home, we always assess the whole picture; we look at your roof, ventilation and all these factors along with the amount of existing insulation you have in order to help us determine which R-Value is best suited for your home.

Most homes already have some old or existing insulation in their attic. We leave the old material alone and do not remove it. The old material may have settled, packed and be a bit dusty/dirty, but there is no harm leaving it there. In fact, we routinely use the existing material as a base to build upon.

Blowing - attic insulation


Working in an Attic After Insulation

Homeowners often express concern about working in the attic after it has been blown with insulation. The good news is that homeowners often report that working in blown insulation is not nearly as difficult as they had imagined. The loose-fill material can simply be displaced with a dustpan and shifted out of the way temporarily when areas need to be worked in. Also, non-itchy cellulose provides an R-30 with only 8.1″, which is much easier to work in then the 12″ of very itchy fiberglass required to achieve the same R-30 rating.

Cellulose is easy to work in, it washes off easily and effortlessly. Fiberglass, even when rolled out, can still be dangerous to breathe and leave you miserably itchy. After insulating with blown material, many homeowners have installed recessed lighting, wired for computers, alarms and other such devices with no reported problems. The blown material does not become hard or damage from being walked on. You need only take care to stay on top of ceiling joist when working in the attic.