Johns Manville Attic Insulation Nationwide

Which Johns Manville Attic Insulation Products This Applies To

Johns Manville makes three attic insulation categories you’re likely to find in San Francisco homes, and each has its own failure profile. Identifying which one you have matters, because the fix is different for each.

Blown-in fiberglass (Climate Pro, Attic Protector): This is the loose white or yellow fiberglass that fills the attic floor. Climate Pro is the material we remove and replace most often in San Francisco. It compacts over time, especially in older Victorians and Edwardians where roof leaks and foot traffic through the attic have compressed it. Attic Protector is the formaldehyde-free version, and it holds up slightly better, but both lose R-value once moisture from coastal fog works its way in.

Fiberglass batts (JM ComfortTherm, Kraft-faced R-19 through R-38): These come in rolls or pre-cut batts. ComfortTherm batts are wrapped in a plastic film, which keeps fibers contained but traps moisture if installed against a cold surface. That’s a real problem in the Sunset and Richmond Districts, where the marine layer pushes humidity into unconditioned attics for months at a time.

Spray foam (JM Corbond III, JM Corbond IV): Closed-cell and open-cell spray foam jobs. Corbond III is the closed-cell product; it’s dense, acts as an air barrier, and tends to fail at flashing or roof-deck transitions where it’s been improperly applied. If you’ve got spray foam, you’ll usually notice a smell, a stain on the drywall below, or heat loss in a specific spot rather than across the whole attic.

Identifying what you have is straightforward. Check the paper or plastic facing on any batt for the JM logo and product name. For blown-in, look at the color and texture: Climate Pro is loose and fluffy, white to light yellow, and settles in a way that leaves noticeable low spots. If your home was insulated before 2008, you may still have an older JM product no longer in production, and we can match the R-value and coverage without trying to match the exact SKU.

On the OEM-versus-aftermarket question: for Johns Manville specifically, we use genuine Johns Manville products on JM removals and replacements. There are aftermarket blown-in fiberglass options that meet the same R-value spec, but coverage rates and settling behavior vary, and when a homeowner has already paid for JM once, we don’t trade them down to an equivalent they’d have to research from scratch. You’ll know exactly what’s going in, and it’ll say Johns Manville on the bag or batt.

Signs Your Johns Manville Attic Insulation Is Failing

• Upstairs rooms run 10 to 15 degrees hotter in summer or colder in winter than the rest of the house. This is the most common complaint we hear in San Francisco, and it usually means the insulation has compacted or been displaced. Blown-in fiberglass loses loft over time; once it’s flat, the air pockets that trap heat are gone.
• Your furnace or heat pump cycles constantly on foggy days. When the marine layer sits over the city, a properly insulated attic should slow heat transfer enough that your system runs in normal cycles. Short-cycling means the thermal barrier isn’t doing its job.
• You can see bare joists or low spots through the blown-in. R-38 blown-in fiberglass should sit roughly 12 to 14 inches deep, depending on the product. If you’re looking at joist tops, you’ve lost coverage, and the fix is a top-up or full removal and replacement.
• Damp or musty smell coming from the hatch, especially in the Sunset or Richmond. Fiberglass doesn’t absorb water the way cellulose does, but the paper facing on batts absolutely does. Once that kraft paper gets wet, it holds moisture against the drywall below and starts smelling like a wet basement.
• Mold spots on the attic-side drywall or on batt facing. This is a ventilation problem compounded by insulation that’s trapping moisture. It’s also the point where you should stop investigating and call someone who does this for a living. Moving moldy insulation without a respirator is a quick way to make a bad problem worse.

Johns Manville Attic Insulation Cost in San Francisco

The installed price range in San Francisco for Johns Manville attic insulation replacement runs $2,100 to $4,800 for most homes. Here’s the breakdown:

• Removal of failed insulation (blown-in or batts): $800 to $1,600 depending on attic access, depth, and whether it’s wet or moldy.
• Air sealing (can lights, top plates, penetrations): $400 to $900. We don’t skip this. Adding insulation over leaky penetrations is like putting a down jacket over a screen door.
• New Johns Manville blown-in fiberglass to R-38: $1,200 to $2,300 for a typical 1,200 to 1,800 square-foot attic.
• New Johns Manville batts to R-38: $1,800 to $3,200, depending on whether we’re fitting around existing framing and how much cutting is involved.

The range comes down to three things: how much square footage you have, what R-value the space is built for, and how difficult the access is. A third-floor walk-up attic in a Noe Valley Edwardian with a 22-inch hatch is a different job than a ranch in the Outer Parkside with pull-down stairs.

Every Alden Insulation job in San Francisco starts with a written price before we touch the attic. The number you approve is the number on the invoice. That price includes parts, labor, air sealing, cleanup, and a written 365-day guarantee. If the insulation fails inside a year, we come back at no charge.

Should You DIY This or Call a Pro?

Here’s an honest split. You can safely check the depth and condition of your Johns Manville insulation with a flashlight and a tape measure. Go up, stay on the joists, and see what you have. If it’s blown-in, measure the depth in a few spots. If it’s batts, look at the facing for moisture stains and the JM product name. That’s the full safe DIY list.

What you shouldn’t do is remove moldy, rodent-soiled, or water-damaged insulation without the right respirator and containment. Insulation fibers in the lungs aren’t something you notice that day. What you also shouldn’t do is crawl around a low attic without knowing where the joists are and where the drywall starts. One misstep through the ceiling turns a $3,000 insulation job into a $1,500 drywall repair and a very bad evening.

If you want to do the assessment and let us do the work, call (559) 245-9792. We’ll send a background-checked, uniformed technician to measure, photograph, and give you the written price. If you’re not ready, the assessment still tells you what you have and roughly when it needs to be addressed.

Frequently Asked Questions