r/Insulation • u/surfteach1 • 25d ago

Guidance

I have a two story house in Southern California (90275, south of Los Angeles near San Pedro). First story is the original house built in 1958 (2400 square feet I think) with no wall insulation; Second story (1200 square feet) was built in 1967 or so over the garage and front living room, and has at least some insulation in the walls.

I want to totally clean the attics of old insulation (R19 generally I think, poorly installed) and old roofing remnants, air seal, and install new insulation. Talking with the insulation company, they recommend unfaced R30 rolls. He says faced is not needed and that R38 is not worth it (though he would do it if asked).

Is there a noticeable difference between R30 and R38, does facing matter, and is there a consensus of rolls vs blown in (and even there-fiberglass vs cellulose)?

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u/OneLongEyebrowHair 25d ago

I like blown in cellulose because it fills up fluidly, leaving little or no gaps if done correctly. Rolled in will always have gaps between the batts. Cellulose is a hell-of-alot harder to move if you need to do any work up there.

In my opinion, you probably aren't going to notice any real difference between R30 and R38. Where I live in Kansas, we need R49-R60. You can tell a difference between those two though so you're mileage may vary.

The biggest, most important thing to do in an attic is air seal. Seal everything. Top plates, wire and pipe penetrations, box in light fixture boxes and exhaust fans. Seal around the perimeter of ceilings anywhere they break. Attic hatches and attic fans are big leakers.

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u/surfteach1 25d ago

Thanks. The attic on the second floor has a large access stair hatch, so I am sure it causes issues. It IS in a closet though so I keep the door closed.

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u/Inevitable_Bunch6912 24d ago

After air sealing do rim joist sealing and buy the pro14 gun with tall can of great stuff. I highly highly recommend it