Owens Corning Attic Air Sealing Nationwide

Owens Corning Attic Air Sealing: The San Marcos Owner’s Guide

Owens Corning attic air sealing in San Marcos typically runs $1,800-$3,400 for a complete top-plate and penetration seal on a 1,500-2,500 square foot home, and we stock the compatible acrylic-latex sealants, fire-rated foam, and weatherstripping on every truck for same-day starts. Most homeowners figure out something’s wrong when their summer electric bill climbs past $280 despite the AC running nonstop, or when they feel a hot draft dropping from recessed can lights in July. The R-value tells you how slow heat moves through the material - the blower-door number tells you whether any of that matters.

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Which Owens Corning Models This Applies To

Owens Corning doesn’t sell attic air sealing as a named “system” with model numbers like they do with insulation batts. What we’re talking about is the air-sealing layer that belongs beneath every Owens Corning insulation install - the acrylic-latex caulk for top-plate seams, intumescent fire-rated foam around chimney and flue penetrations, and polyethylene weatherstripping for attic hatch frames. If your home was insulated by an Owens Corning-certified contractor between 2010 and 2020, you likely have their pink-labeled R-30 or R-38 batts sitting directly on drywall with no sealed air barrier underneath. That’s the failure pattern we see most in San Marcos.

To identify what you’re working with, check the attic floor for pink batts with the Owens Corning logo printed on the facing. Then look at the top plate - the horizontal framing member where your exterior walls meet the ceiling. If you see bare wood, gaps, or crumbling dried caulk, the air sealing was either skipped or has aged out. We carry Owens Corning-compatible sealants rated for the 140°F attic temperatures common in Hays County summers, plus aftermarket equivalents from Johns Manville and Knauf that meet the same ASTM C920 spec at a lower per-tube cost. Topside Attic Insulation San Marcos is an independent service provider, not affiliated with Owens Corning.

Signs Your Owens Corning Attic Air Sealing Is Failing

• Hot drafts from ceiling fixtures in summer. Unsealed can-light housings act like chimneys, pulling 130°F attic air down into your living space. In San Marcos, we measure attic temps above 140°F in August, so every unsealed penetration becomes a small radiator.
• Insulation batts that look clean on top but dark underneath. That discoloration is dust and dirt carried by air moving through the insulation. It means your conditioned air is leaking upward, bypassing the insulation entirely.
• Ice damming or heavy frost on the underside of your roof deck in winter. Warm, moist interior air hits cold sheathing and condenses. San Marcos doesn’t see Chicago-level ice damming, but we do see the moisture damage in February when a cold snap follows a warm, humid day.
• Rooms that stay uncomfortable despite new HVAC equipment. We get this call from the Blanco River and Willow Creek subdivisions - homeowners who spent $8,000 on a new condenser and still can’t cool the back bedroom. The unit isn’t the problem; the building envelope is.
• Blower-door readings above 3,500 CFM50 on a home under 2,500 square feet. That’s the measurable threshold where air sealing becomes cost-effective before any insulation upgrade. We’ve tested 1970s slab homes near Texas State that read 5,200 CFM50 before sealing and 2,400 after.

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After

Replacement Cost & What’s Included

Most complete attic air sealing jobs in San Marcos run between $1,800 and $3,400, with smaller partial seals (attic hatch and top plates only) starting around $950. The range depends on attic square footage, accessibility - some of the older homes off Hopkins Street have 18-inch truss spacing that makes crawling miserable - and how many penetrations need treatment. Chimney chase seals with fire-rated intumescent foam add $180-$340 per penetration because the material costs more and the application requires a steady hand.

Every job includes the sealant and foam, labor, cleanup, and our Documented Photo Record showing before-and-after conditions at each penetration. On applicable jobs, we run a blower-door test before and after, then hand you a single printed page with the air-changes-per-hour figure. The 365-Day Done Right Promise covers all workmanship. Your Written Price Before Any Work Starts arrives before anyone lifts a tool - Haven Standard Clause 1.

DIY or Call Us?

There’s safe checking, and then there’s work that belongs to someone who’s done it a few hundred times. You can verify your own symptoms: turn off the AC on a 95°F afternoon, climb into the attic with a flashlight, and look for daylight showing through the top plate or around electrical boxes. If you see it, you’ve found your leak. What you shouldn’t do is start spraying canned foam around recessed can lights or flue pipes - the wrong product near a hot surface is a fire hazard, and most homeowners don’t own a blower door to verify they actually fixed what they found. We’ve cleaned up DIY jobs in San Marcos where the owner sealed the wrong leaks and made the attic humidity problem worse. For a free second opinion on any written estimate, or to get your own blower-door number, call (737) 337-8049.

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