Johns Manville Attic Insulation Nationwide | Walt’s Insulation

Johns Manville Attic Insulation: The Fullerton Owner’s Guide

Johns Manville attic insulation installed in Fullerton typically runs $1.65 to $3.40 per square foot for removal and reinstallation, including materials, labor, and disposal. We stock Johns Manville fiberglass batts, blown-in fiberglass, and spray foam on our trucks, so most Fullerton homes can be done same-day or within 48 hours. The way most homeowners find out their insulation has failed is a sudden spike in the electric bill, a bedroom that won’t hold temperature, or the discovery of rodent damage during a roof inspection.

Call (657) 216-9948

Johns Manville makes solid insulation products, but even the best material can’t do its job once it’s been compressed, water-damaged, or chewed through. And in Fullerton’s climate, with summer attic temperatures regularly hitting 140°F, degraded insulation loses its effectiveness fast. If you’re reading this, you probably already know something’s wrong. Here’s exactly what to do about it.

Which Johns Manville Models This Applies To

Johns Manville has three main product lines we work with in Fullerton attics: ComfortTherm batts (the wrapped ones, usually R-13 to R-38), Climate Pro blown-in fiberglass (R-30 to R-60), and Corbond spray foam (open and closed cell). The easiest way to identify what you have is to look at the facing on your batts. ComfortTherm has a white polyethylene wrap with the JM logo and R-value printed every few feet. Climate Pro bags are yellow and clearly marked.

Here’s the compatibility gotcha most homeowners don’t know: Johns Manville batts are cut slightly differently than Owens Corning or CertainTeed equivalents. The nominal width is the same, but JM’s friction-fit tolerance is tighter, which means if a previous contractor installed a mix of brands in the same bay, you’ll get small gaps along the edges. Those gaps add up. In a typical Fullerton ranch home with 1,200 square feet of attic, a quarter-inch gap along every joist bay can cut effective R-value by 15 to 20 percent. We match JM with JM when we top off or re-insulate, and if you have mixed brands, we’ll tell you honestly what needs replacing and what can stay.

We’re an independent contractor, not affiliated with Johns Manville. But we’ve installed their products since 2000 and know the line inside out. If you’re not sure what you have, snap a photo of the facing or the bag and text it to us before we come out. It saves a trip.

Signs Your Johns Manville Attic Insulation Is Failing

• Rooms directly under the attic won’t stay cool in summer or warm in winter. This is the most common complaint in Fullerton, especially in older ranch homes near the Arboretum. The insulation has either compressed below its rated R-value or was never deep enough to begin with.
• You can see the tops of your ceiling joists. If the blown-in fiberglass has settled below the joist line, your attic is under-insulated. Climate Pro settles less than older cellulose products, but 20-plus-year-old installs often show significant loss.
• Damp spots, mildew smell, or water staining on the insulation. A roof leak or bathroom fan vented into the attic destroys fiberglass’s ability to trap air. Wet insulation is doing zero work, and it’s holding moisture against your framing.
• Rodent droppings, nesting material, or chewed tunnels through the batts. Rats and mice love Johns Manville fiberglass for nesting. Once they’re in, insulation needs full removal and replacement, and the attic needs rodent proofing first.
• Your AC runs constantly from June through October. Fullerton summers punish under-insulated homes. If your unit is running nonstop and the house still feels warm by 4 p.m., the attic is almost certainly part of the problem.

I’ve crawled through hundreds of Fullerton attics and found every one of these problems, sometimes all in the same house. The good news is all of them are fixable, and most are fixed the same day we start.

Replacement Cost & What’s Included

For a Fullerton home, here’s what you’re looking at:

• Blown-in fiberglass removal and full reinstall (Climate Pro, R-38): $1.65 to $2.20 per square foot
• Batt removal and replacement (ComfortTherm, R-30 to R-38): $2.10 to $2.75 per square foot
• Spray foam (Corbond closed-cell, 3 inches): $2.80 to $3.40 per square foot
• Attic air sealing before insulation: $1.00 to $1.50 per square foot

What drives the range: how much old insulation needs hauling out, access challenges (low-pitch roofs are brutal), whether there’s rodent contamination, and how much air sealing the attic actually needs. Every quote includes removal, disposal, reinstallation, and cleanup. We give you the price before we start, and that’s the price you pay. No surprises. Our labor is covered by the Done Right Promise: if it’s not right, we make it right. For life.

We also offer a free second opinion on any written estimate you’ve gotten from another Fullerton contractor. Bring it to us and we’ll go through it line by line with you. And if you’re a senior or a veteran, it’s 10 percent off. Always.

DIY or Call Us?

You can absolutely check a few things yourself before calling anyone. Look in the attic with a flashlight and see if your insulation is above the joists, dry, and evenly distributed. Check for daylight coming through around can lights, bathroom fans, or plumbing vents. That’s all safe and worth doing.

What you shouldn’t do is remove old insulation yourself, especially if there’s any chance of rodent contamination. Hantavirus is real, and it lives in rodent droppings. Improper removal kicks contaminated dust into your living space and your lungs. Blown-in fiberglass also requires a commercial blower machine and proper respirator gear, and working in a 140-degree Fullerton attic in August without ventilation is genuinely dangerous. I’ve done this work for over two decades and still respect the heat. If you want to tackle the air sealing around light fixtures yourself, go for it. For the insulation itself, call us at (657) 216-9948 and let our crew handle it. We do the job right the first time, because we’re the ones who have to stand behind it.

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