Attic Insulation in San Marcos - Same-Day Service, Done Right the First Time

Trusted Attic Insulation for San Marcos Homeowners

Most attic insulation jobs in San Marcos run between $1,800 and $4,200 depending on attic size, existing insulation condition, and whether air sealing is needed first. We’re typically on-site within 24 hours of your call, and we don’t start any work until you have a written price in hand. Call (737) 337-8049 to schedule your free estimate.

Call (737) 337-8049

We’ve sealed and insulated more than 9,000 homes since 2016, and every one started with a written scope and ended with a documented record. In San Marcos, we see the same pattern repeatedly: homes built between 1995 and 2015 with fiberglass batts compressed by summer heat, top plates leaking conditioned air into the attic, and can lights acting like chimneys on 100-degree July afternoons. The result is uneven temperatures between rooms, AC units that run continuously from May through October, and utility bills that climb year after year without explanation.

Our approach is different. We treat air sealing as a hard prerequisite, not an upsell. Before we add a single bag of insulation, we seal every penetration, top plate, and accessible leak point. Then we test with a blower door - a pressurization measurement that shows, in one number, how much air your building envelope was losing before and after. You get the before-and-after readings in writing, along with photos of every critical detail. Under The Haven Standard, every job begins with a written price and ends with documentation. No exceptions.

What Our Attic Insulation Service Includes

Blown-In Attic Insulation

Blown-in insulation - loose-fill cellulose or fiberglass installed with a hose and blower - fills irregular cavities and covers existing insulation without the gaps that batts leave behind. In San Marcos, we use blown-in most often for attics with mixed joist depths, numerous penetrations, or existing insulation that needs an Attic Insulation Top-Up rather than full removal. Our crews measure depth with a ruled probe every 100 square feet and photograph the grid so you can verify coverage. We source blown-in materials from Owens Corning, Johns Manville, Knauf, and GreenFiber, selecting by density and settling rate for each specific attic condition.

Attic Batt Insulation

Batt insulation - pre-cut fiberglass or mineral wool panels sized to fit standard joist spacing - works best in attics with uniform construction, clear access, and minimal obstructions. We install batts when the attic floor is accessible, the joists are regularly spaced, and the homeowner needs a defined thermal boundary with visible inspection points. In older San Marcos neighborhoods like Willow Creek and Blanco Gardens, we’ve found Attic Batt Insulation effective for finishing attics that were never fully insulated during original construction. Every batt is cut to fit around electrical boxes and framing members without compression, which would reduce the R-value you paid for.

Attic Insulation Top-Up

A top-up adds loose-fill or additional batts over existing insulation that has settled, compressed, or simply never reached adequate depth. In San Marcos, we recommend top-ups when the existing material is dry, uncontaminated, and uniformly distributed but has fallen below current energy code levels. We probe the existing depth, check for moisture staining or rodent activity, and document the condition with photos before adding anything. If the existing insulation is clean, a top-up can restore performance at roughly half the cost of full replacement. You’ll get a written depth target and a photo-verified record showing before and after measurements.

Attic Insulation Replacement

Attic Insulation Replacement removes existing insulation down to the attic floor, addresses any air leaks or moisture issues exposed by the removal, and installs new material to a specified depth and density. We recommend replacement when insulation is wet, moldy, heavily contaminated by rodents, or compressed beyond recovery. In San Marcos homes near the San Marcos River and its tributaries, we’ve replaced insulation after roof leaks, plumbing failures, and rodent infestations that rendered existing material unusable. The removal is contained with negative air pressure and HEPA filtration, and we photograph the bare deck before sealing and reinsulating. Replacement costs more than top-up, but it’s the only option when the existing material is compromised.

Attic Baffles & Ventilation Prep

Baffles - rigid foam or cardboard channels that maintain airflow from soffit vents up through the attic - prevent loose-fill insulation from blocking intake vents and causing moisture buildup. We install baffles before blowing insulation in any attic with soffit venting, which describes most San Marcos homes built after 1980. Without baffles, wind pressure and settling can push insulation against the eaves, choking airflow and creating condensation zones that rot roof decking. Our crews staple baffles to the underside of the roof deck, verify clearance with a visual inspection from the attic interior, and photograph every bay before insulation covers the work. Proper Attic Baffles & Ventilation Prep is included in every blown-in quote; we don’t treat it as an add-on.

Brands We Service for Attic Insulation

We’ve installed and serviced insulation systems using Johns Manville fiberglass batts and loose-fill in hundreds of San Marcos-area homes, particularly in subdivisions where builders specified JM during original construction. Their Spider blown-in system, which adds a light adhesive to reduce settling, works well in attics with moderate slope and accessible eaves. We also stock Knauf EcoSeal and Jet Stream products for high-velocity blown-in applications where density and complete cavity fill matter more than initial loft.

Rockwool - mineral wool made from basalt and recycled steel slag - is our choice for fire-resistant assemblies and sound-dampening applications in homes near I-35 or the railroad corridor. CertainTeed’s Optima and InsulSafe lines round out our batt and blown-in inventory for homeowners who want a specific manufacturer for warranty or color-coding reasons. Whether you have Johns Manville, Knauf, Rockwool, CertainTeed, or any other make, we can match the existing product or recommend a compatible replacement based on your attic conditions and performance goals. No proprietary lock-ins, no brand exclusions.

Before

After

Signs You Need Attic Insulation Right Now

• Your upstairs rooms are 8-12 degrees hotter than downstairs in summer. This temperature stratification is the classic signature of an under-insulated or unsealed attic in Central Texas heat. Hot air radiates through the ceiling assembly faster than your AC can push conditioned air upward, and the system runs longer to compensate. We’ve measured ceiling surface temperatures above 110°F in San Marcos attics with inadequate insulation during July afternoons.
• Your electric bill spikes every June and stays elevated through October. When insulation is thin, compressed, or bypassed by air leaks, your HVAC system loses the battle against attic heat gain. The compressor runs more cycles, draws more amps, and ages faster. If your summer bills have climbed 30% or more over five years without a rate increase, the attic is the first place to investigate.
• You can see floor joists through the insulation in your attic. Current Texas energy code calls for R-38 to R-60 in attles depending on construction date, which translates to 12-18 inches of fiberglass or cellulose. If joists are visible, you have less than half the recommended depth. We probe and photograph depth on every estimate so you know exactly where you stand.
• Your attic hatch has no weatherstrip or insulation cover. An unsealed attic hatch is a 2-3 square foot hole in your thermal boundary, often leaking more air than all the recessed lights combined. We see this constantly in San Marcos homes where the original builder never finished the hatch detail. It’s a quick fix that pays for itself immediately.
• You feel drafts near interior walls and ceiling fixtures in winter. These drafts aren’t from windows; they’re from top plates and electrical penetrations that connect your conditioned space directly to the attic. Air sealing stops them. Insulation alone won’t, because fiberglass doesn’t block airflow. That’s why we seal first, then insulate.

Our Attic Insulation Process - Step by Step

1. 1
   Schedule and arrival. You call (737) 337-8049 and speak to a live person, 24/7. We book a two-hour arrival window, send a text when your technician is en route, and arrive in a marked vehicle with a uniformed, background-checked crew. Under Haven Standard: Arrive on schedule, you get a named technician and a text when they are on the way.
2. 2
   Attic inspection and blower-door test. We access the attic, photograph existing conditions, measure insulation depth at multiple points, and identify air leaks, moisture staining, and ventilation deficiencies. On applicable jobs, we run a blower-door test - a pressurization reading that shows, in one number, how much conditioned air your home is losing through the envelope. This baseline reading becomes your benchmark for improvement.
3. 3
   Written price and scope. Before any work begins, you receive a flat price, a written scope of work, and a written warranty. This is Haven Standard Clause 1: no work starts without it. The scope specifies materials, depths, air-sealing details, and the blower-door target. If you have a competing quote, we offer a Free Second Opinion - we’ll read it with you and explain where the differences are.
4. 4
   Air sealing first, then insulation. We seal top plates, can lights, plumbing and electrical penetrations, chases, and any accessible bypasses using foam, caulk, and rigid blocking as appropriate. Only after sealing is complete do we install insulation to the specified depth. For blown-in, we mark depth targets on framing members and verify with probed measurements every 100 square feet. For batts, we cut around obstructions without compression gaps.
5. 5
   Documentation and final test. We photograph the completed work, run a final blower-door test on applicable jobs, and compile your Documented Photo Record with before-and-after readings. You get this record before we leave, along with your written warranty under the 365-Day Done Right Promise. If it’s not done right, we make it right.

How Much Does Attic Insulation Cost in San Marcos?

Attic Insulation Near San Marcos - Our Service Area

We serve San Marcos and surrounding communities with typical response times under 24 hours for estimates and same-day or next-day scheduling for most work. Our crews regularly work in Redwood, where older ranch homes often need full replacement of settled fiberglass, and Kyle, where new construction frequently leaves attics under-insulated to code minimum. We also cover Lockhart, Buda, Shady Hollow, Lost Creek, Austin, Hornsby Bend, Lakeway, Lago Vista, and Bastrop. Travel beyond San Marcos city limits may affect scheduling slightly, but we don’t charge mileage premiums within our standard service radius.

Frequently Asked Questions - Attic Insulation in San Marcos

Schedule Your Attic Insulation Service in San Marcos Today

Call (737) 337-8049 to speak with a live person and schedule your free estimate. You’ll get a written price before any work starts, a Documented Photo Record when we’re done, and before-and-after blower-door numbers on every applicable job. The 365-Day Done Right Promise applies to all work. No obligation, no pressure, no surprises.

Written by Wes Okafor, Owner at Envelope Insulation Co., serving San Marcos since 2016.