Johns Manville Attic Insulation Nationwide | Walt’s Insulation

Johns Manville Attic Insulation: The San Antonio Owner’s Guide

We stock and install Johns Manville attic insulation across San Antonio, and most jobs run between $1,800 and $4,200 depending on square footage, existing insulation condition, and whether air sealing is included. Same-day and next-day installation is available for most neighborhoods, including Alamo Heights, Stone Oak, Helotes, and Castle Hills. Most San Antonio homeowners call us after they’ve noticed one of three things: a room that won’t hold temperature no matter what the thermostat says, an electric bill that climbed steadily over two or three summers, or they went up into the attic and realized the insulation that was there twenty years ago has settled down to about half of what it should be.

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A quick note before we go further: Walt’s Insulation is an independent San Antonio insulation contractor. We install Johns Manville products every week, and we stock their full attic line, but we’re not affiliated with the manufacturer. That independence matters because it means we tell you the truth about what’s working in San Antonio attics, not what a corporate sales sheet wants us to push.

Which Johns Manville Models This Applies To

Johns Manville makes three attic insulation products we install regularly in San Antonio: ComfortTherm batts, Climate Pro blown-in fiberglass, and Spider spray-applied fiberglass. If you’re looking at an older San Antonio home built before 2005, you likely have either loose-fill fiberglass that’s settled or batts that were install-fluffed and never actually delivered the R-value stamped on the label. Newer homes, especially in developments around Cibolo, Boerne, and the far West Side, tend to have either Climate Pro or Spider already in place, and both hold up better in our heat than the older loose-fill material.

Here’s the compatibility gotcha most San Antonio homeowners don’t know: blown-in fiberglass doesn’t need to “match” the old stuff. If your attic currently has settled fiberglass from any manufacturer, we can blow Johns Manville Climate Pro right over the top to bring the whole layer back up to code without removing anything. That’s not true for spray foam or cellulose. Cellulose, in particular, settles badly in San Antonio’s dry heat, and if you have it, we’ll recommend full removal before we add anything new. The only time brand matching genuinely matters is when you’re adding batts alongside existing batts in an unfinished area like a garage ceiling, and even then, R-value and width matter more than the logo. Standard batt widths for San Antonio homes are 15 inches between joists and 23 inches for wider spacing, and Johns Manville sells both.

The other decision is OEM versus equivalent. For attic insulation, “OEM” just means the Johns Manville label you’re already familiar with. Alternatives like Owens Corning or CertainTeed will perform identically at the same R-value, but if you want to keep the warranty documentation simple and you’ve already got JM in part of the house, we’ll match it. We stock ComfortTherm and Climate Pro on the truck, and we can have Spider material in San Antonio within one business day when a job calls for it.

Signs Your Johns Manville Attic Insulation Is Failing

• Rooms that run 8 to 12 degrees hotter than the thermostat setting in summer. San Antonio’s July and August heat loads are brutal, and insulation that’s settled or thinned out can’t slow the radiant heat coming through the roof deck. Your AC runs longer, and the rooms directly under the attic take the worst of it.
• Electric bills that keep climbing while your usage habits haven’t changed. CPS Energy rates have gone up, yes, but if your June-to-September bills are growing faster than the rate increases, the attic is usually the first place we look. We’ve seen settled insulation cost San Antonio homeowners $80 to $150 extra per month during peak cooling season.
• Visible settling when you shine a flashlight across the attic floor. If you can see joists poking above the insulation line, the material has settled. In San Antonio’s heat, fiberglass loose-fill can lose 20 to 30 percent of its loft within ten to fifteen years, which drops its effective R-value along with it.
• Drafty or cold spots in rooms below the attic, even with the windows closed. This usually comes from air leakage around can lights, plumbing penetrations, or the attic hatch itself, not the insulation. But the fix is the same visit: we air seal those penetrations and then blow fresh Johns Manville material over the whole floor.
• Signs of moisture or critter activity up top. San Antonio attics are magnets for roof rats and squirrels, especially in older neighborhoods like Monte Vista and Jefferson. If rodents have been nesting in your insulation, it’s compromised, and we’ll recommend removal, rodent proofing, and fresh blown-in material in one pass.

Replacement Cost & What’s Included

For a typical single-story San Antonio home with 1,500 to 2,000 square feet of attic floor, adding Johns Manville Climate Pro blown-in insulation to reach R-38 runs $1,800 to $2,700 installed. Homes that need full removal of old or rodent-contaminated material, or that want to go up to R-49, land between $3,000 and $4,200. Two-story homes nearly always cost more because the attic is smaller but access is tighter, and we price those by actual square footage, not by head count of bedrooms.

Every quote we write is upfront and line-itemed: material cost, labor, removal and disposal if needed, and air sealing as a separate line so you can see exactly what you’re paying for. We don’t bury a “fuel surcharge” or a “miscellaneous labor” line anywhere in the estimate. And every San Antonio attic we insulate is covered by our Done Right Promise: lifetime workmanship, on us, no fine print. If we didn’t do it right, we fix it. That’s the whole promise.

All work is covered by our lifetime Done Right Promise. And we answer the phone live when you call.

DIY or Call Us?

If you want to check what’s up there, that’s fine and we encourage it. Shine a flashlight across the attic floor from the hatch, note whether you can see joists above the insulation line, and take a look for dark spots that suggest moisture. That’s a useful ten-minute inspection you can do without touching anything.

But here’s where we draw the line, and it’s not because we’re protecting our calendar. Blown-in insulation done wrong in a San Antonio attic creates two problems: first, you’ll never hit the labeled R-value if the material isn’t fluffed correctly, and second, if you block soffit vents or bury can lights without proper covers, you’re trading one problem for a fire hazard and a moisture problem. Fiberglass fibers also don’t belong in your lungs, and our techs wear proper respirators and suits on every single job. If you’re just topping off a small area around a hatch, that’s manageable with the right machine rental and protective gear. If the whole attic is thin or settled, call us at (866) 751-4428 and let us do it properly. We own our equipment, our guys do this every day, and you’ll spend less than you think getting it done right instead of twice.

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