Johns Manville Attic Insulation: The San Antonio Owner’s Guide
We install and replace Johns Manville attic insulation throughout San Antonio, with most projects running between $1,800 and $4,200 depending on attic size and the R-value your home needs. We stock Johns Manville ComfortTherm and Climate Pro batts on our trucks, so a standard attic top-up or replacement is usually completed same-day. If you’re reading this because your attic felt unusually hot last summer, or your upstairs bedrooms never hold temperature, or you found damp or matted insulation while hunting for holiday decorations, the fix is likely simpler than you think.
Which Johns Manville Models This Applies To
Johns Manville makes three primary attic product lines, and the compatibility details matter more than most homeowners realize. ComfortTherm is the kraft-faced batt line, with a vapor retarder meant for climates where the warm side faces the living space. In San Antonio, that facing direction is a frequent retrofit mistake. Climate Pro is the blown-in loose-fill fiberglass, and it’s what we recommend most often for San Antonio attics with odd joist spacing or low clearance. Attic Protector is a formaldehyde-free batt sold at big-box stores, and while it’s fine product, the R-value per inch runs slightly lower than Climate Pro. Check the printed facing label: it will say the R-value, the square footage, and a lot number that starts with a “JMV” prefix. Snapping a photo of that label helps us quote accurately over the phone. As an independent installer, we’re not tied to Johns Manville corporate, but we’ve installed their products in San Antonio homes for years and know which SKUs hold up in Texas attic heat.
Signs Your Johns Manville Attic Insulation Is Failing
- Upstairs bedrooms run 8 to 12 degrees warmer than downstairs. This is the most common first sign. Fiberglass batts lose loft over time, and once they compress or settle below their rated depth, the R-value drops significantly. The fix is almost always a top-up or re-blow, not a full tear-out.
- You can see the tops of your ceiling joists from the attic hatch. If the insulation height doesn’t cover the joists, you’re below R-19 in most cases. Older San Antonio homes along McCullough and in Alamo Heights often had R-19 batts installed in the 1980s, and time plus foot traffic has flattened them.
- Damp, matted streaks across the insulation. That’s moisture moving through the attic, usually from bathroom vents terminated in the attic instead of through the roof. Wet Johns Manville fiberglass loses almost all insulative value and needs to be removed, not fluffed back up.
- Rodent or raccoon tunnels through the batt. Pests nest in the warm fluff and leave paths that act as thermal funnels. We see this regularly in San Antonio’s older neighborhoods where gable vents have widened gaps.
- A fine layer of dust or insulation particles on stored items. Fiberglass doesn’t decompose into dust, but aged facing paper breaks down and sheds fibers. If your stored boxes look gritty, the material has reached the end of its service life.
Replacement Cost & What’s Included
In San Antonio, you can expect Johns Manville attic insulation installation to range from $1,800 to $4,200 for a typical 1,200 to 2,000 square foot attic. The lower end covers a blown-in Climate Pro top-up to reach R-38 over existing material. The higher end covers full removal of old or damaged insulation, air-sealing of penetrations, and a fresh blown-in application to R-49 or R-60. What changes the price: attic access size, whether old insulation has to come out first, and the depth of joist bays in older construction. Every quote from us is written down before any work starts, and it’s the exact number you’ll pay, not a starting point. The installation carries our 365-Day Done Right Promise: if something wasn’t done correctly, we return and fix it. No debate, no fine print.
DIY or Call Us?
You can safely peek into your attic to check insulation depth and look for damp spots. We encourage that; it helps you speak the language when you call. What you shouldn’t try on your own is removing large amounts of old Johns Manville fiberglass, especially in a San Antonio attic where summer temperatures can hit 140 degrees. Fiberglass dust is a lung and skin irritant, and properly disposing of saturated or pest-damaged batts requires protective gear that most homeowners don’t own. Blown-in installation requires a calibrated machine and an even hand; rental units from big-box stores tend to leave thin spots and heavy spots that compromise the final R-value. If your insulation is damp, matted, pest-damaged, or more than 20 years old, give us a call at (903) 437-9164. We’ll walk the attic, give you a number, and you’ll have it in writing before we touch a single rafter.
FAQs
Fiberglass batts and blown-in insulation are rated to last 30 to 40 years, but San Antonio’s extreme attic heat shortens that lifespan meaningfully. We typically see meaningful loss of performance in 15 to 20 years in San Antonio homes, especially if the attic has had moisture issues. Call (903) 437-9164 and we can assess whether yours needs a top-up or a full replacement.
Yes, in many cases we can repair it. If a section is compressed or pushed aside from foot traffic, we can re-fluff and reinstall the batts. But damp, matted, or pest-soiled Johns Manville fiberglass should be removed and replaced, not patched; those materials hold moisture and odors that simple repair won’t resolve. The price to repair versus replace depends on the extent of the damage, and you’ll get a clear recommendation with a written quote either way.
A standard Johns Manville attic insulation removal and re-blow in a typical San Antonio house takes one day, usually 4 to 6 hours, including setup and clean-up. A simple top-up over existing insulation can be done in 2 to 3 hours. We lay drop cloths across your hallway, wear shoe covers from the front door to the attic hatch, and take a photo of the clean-up before we leave.
We stock Climate Pro blown-in fiberglass and ComfortTherm batts on our trucks, so we rarely need to order. If your job calls for a specific Johns Manville SKU we don’t carry, we can usually have it by the next business day. Either way, you’ll know before the work begins exactly what product is going in and what it costs.
For San Antonio’s climate zone, we recommend R-38 as the minimum and R-49 to R-60 for homes where the upstairs runs hot or the HVAC struggles in August. Older homes with R-19 batts are running at roughly half the thermal resistance they should have. Neil Barron has walked enough San Antonio attics to know that what the label says was installed in 1985 and what’s actually performing now are often two different numbers. We verify actual depth, not just age.
Written by Neil Barron, Owner, Thistledown Insulation San Antonio at Thistledown Insulation San Antonio, serving San Antonio and nearby areas.