Insulation in San Marcos, TX
Crawl space encapsulation and vapor barrier installation in San Marcos typically runs $2,800-$5,500 for most homes, with full encapsulations on larger crawl spaces reaching $7,500-$12,000. We’re Envelope Insulation Co., and we treat air sealing as a hard prerequisite before any insulation goes in, publishing before-and-after blower-door numbers on every job so you can see the performance change you paid for. Call (737) 337-8049 for a written price before any work starts.
San Marcos sits at a tricky intersection: Gulf humidity meets Hill Country dryness at the Balcones Escarpment, and the result is crawl spaces that stay wet enough to rot floor joists while attics bake at 140°F through four-month summers. The 1970s-1990s rental stock near Texas State University and the newer tract homes on the I-35 corridor face completely different envelope problems, but both need the same thing first - a sealed building envelope, then insulation that actually performs.
Why San Marcos Homes Are Different
San Marcos’s housing market is split down the middle. Near campus, along Sessom Drive and Hopkins Street, sit thousands of 1980s-era apartment complexes and investor-owned duplexes built to minimum code with original fiberglass batts that have settled, compressed, or been shoved aside by decades of HVAC service calls. These units routinely show 40-60% higher cooling loads than their square footage suggests, and landlords often don’t discover the gaps until a summer utility audit shocks them.
On the city’s growth corridor, master-planned developments from the 2010s-2020s received code-minimum insulation at build - typically R-30 blown fiberglass in attics, rarely with proper air sealing - and homeowners are now upgrading after their first few $400+ summer electric bills. The February 2021 Winter Storm Uri freeze hit Hays County hard and exposed how little thermal protection many wall assemblies actually provided. Flash Flood Alley conditions mean crawl spaces and lower attics take on moisture during heavy rain events, degrading batt insulation faster than in drier Texas markets. We dispatch crews from our Austin office and serve San Marcos properties locally.
Our Main San Marcos Services
San Marcos homeowners call us most often for attic work and spray foam upgrades. Here is what those jobs involve locally.
Attic Insulation in San Marcos
Attic insulation in San Marcos means dealing with 98-105°F summer highs from June through September and attics that functionally become solar ovens. We start with a blower-door test to measure air leakage, seal top plates and penetrations, then install Owens Corning or Knauf fiberglass, Rockwool mineral wool, or blown-in cellulose to the correct depth for your roof pitch. Most attic jobs in San Marcos run between $2,200 and $4,800 depending on accessibility and current insulation condition. Attic Insulation in San Marcos
Spray Foam Insulation in San Marcos
Spray foam insulation in San Marcos is the upgrade we recommend for the I-35 corridor’s newer homes with complex rooflines and for any homeowner who wants to condition their attic. We use open-cell Icynene and closed-cell Demilec products, installed after air sealing is complete, with before-and-after blower-door readings provided so you can verify the envelope improvement. Spray foam jobs in San Marcos typically range from $4,500 to $9,500 for attic applications. Spray Foam Insulation in San Marcos
Blown-In Insulation in San Marcos
Blown-in insulation in San Marcos is the workhorse solution for the 1970s-1990s rental stock with settled or displaced fiberglass. We remove compressed batts, seal air leaks at can lights and duct boots, then blow GreenFiber cellulose or Owens Corning fiberglass to R-38 or R-49 depending on your roof structure. This is the most cost-effective upgrade for landlords facing tenant complaints about uneven cooling. Blown-In Insulation in San Marcos
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Before
AfterCrawl Space Encapsulation & Vapor Barrier in San Marcos
Crawl space encapsulation and vapor barrier installation in San Marcos addresses a specific regional problem: the collision of Gulf humidity with Hill Country flash-flood patterns creates crawl spaces that stay damp year-round, accelerating floor joist rot and mold growth in the 1970s-1990s wood-frame rental stock near campus. We install complete vapor barrier and encapsulation systems that separate the crawl space from ground moisture and outside air, always beginning with air sealing of rim joists and penetrations before any barrier goes down. Crawl Space Encapsulation & Vapor Barrier
In San Marcos, we regularly see crawl spaces with standing water after spring storms, fiberglass batts sagging and holding moisture against subfloors, and foundation vents that admit humid summer air directly into the building envelope. Our crews document every stage with photos and provide written scope and warranty before starting.
Crawl Space Vapor Barrier
Signs you need it
Your crawl space has visible ground moisture, musty odors rising through floor registers, or fiberglass batts hanging wet from the subfloor.
What it costs in San Marcos
A 6-mil to 20-mil vapor barrier installation in San Marcos typically runs $2,800-$4,500 for an average 1,200-square-foot crawl space.
How we do it
We remove debris and old insulation, grade the ground surface, seam-seal a reinforced polyethylene barrier across the entire floor and 6-12 inches up piers, then seal all seams with pressure-sensitive tape.
Crawl Space Encapsulation
Signs you need it
You have recurring mold on floor joists, buckling hardwood floors, or energy bills that spike despite recent HVAC service.
What it costs in San Marcos
Full crawl space encapsulation in San Marcos, including dehumidification, ranges from $7,500-$12,000 for most residential jobs.
How we do it
We seal foundation vents, install a reinforced vapor barrier across floors and walls, apply closed-cell spray foam to rim joists, and install a dedicated dehumidifier with a condensate pump to maintain 50-55% relative humidity.
What Crawl Space Encapsulation & Vapor Barrier Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Vapor barrier (6-20 mil, floor only) | $2,800 - $4,500 |
| Partial encapsulation (barrier + rim joist seal) | $4,500 - $7,500 |
| Full encapsulation with dehumidifier | $7,500 - $12,000 |
How long does crawl space encapsulation take in San Marcos?
Most vapor barrier installations finish in one day; full encapsulations with dehumidification typically take two to three days depending on crawl space access and existing moisture damage. We provide a written timeline with your written price before anyone starts.
Will encapsulation fix my musty smell?
Yes, when the source is ground moisture or humid outside air entering through vents; we verify this with a moisture meter reading before recommending encapsulation over other solutions. Call (737) 337-8049 for an exact quote - estimates are free.
Radiant Barrier Installation in San Marcos
Radiant barrier installation in San Marcos is one of the most cost-effective envelope upgrades for the 1980s-2000s apartment stock and older single-family homes with dark shingle roofs that absorb relentless summer heat. We install reflective foil or roof-deck barriers that block radiant heat transfer, reducing attic temperatures by 20-35°F and cutting cooling loads measurably. Radiant Barrier Installation
The Hopkins Street corridor complexes we work on were built with zero radiant protection and black asphalt shingles that hit 170°F surface temperatures in August. Landlords who add radiant barrier see immediate tenant comfort improvements and measurable kWh reduction.
Attic Radiant Barrier
Signs you need it
Your attic exceeds 130°F on sunny summer afternoons, your upstairs rooms stay 8-12°F warmer than downstairs, or your AC runs continuously from 2 PM to sunset.
What it costs in San Marcos
Attic radiant barrier installation in San Marcos typically costs $1,800-$3,200 for a 1,500-2,500 square foot home.
How we do it
We staple perforated aluminum foil across rafter bottoms or lay it over existing attic insulation, maintaining proper ventilation channels, then verify attic temperature reduction with an infrared thermometer.
Radiant Barrier Roof Deck
Signs you need it
You’re re-roofing or building new in San Marcos and want permanent radiant protection integrated into the roof assembly rather than added later.
What it costs in San Marcos
Radiant barrier roof deck installation during new construction or re-roofing in San Marcos runs $2,200-$4,000 depending on roof complexity.
How we do it
We install foil-faced roof sheathing or attach radiant barrier directly to the roof deck before shingle installation, ensuring all seams are taped and ventilation pathways remain unobstructed.
What Radiant Barrier Installation Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Attic radiant barrier (foil over insulation) | $1,800 - $3,200 |
| Radiant barrier roof deck (new construction/re-roof) | $2,200 - $4,000 |
| Radiant barrier with attic air sealing package | $3,500 - $5,500 |
Does radiant barrier work with spray foam?
Radiant barrier is redundant in a fully conditioned spray-foam attic but highly effective in vented attics with fiberglass or cellulose; we recommend it for vented assemblies only. Call (737) 337-8049 for an exact quote - estimates are free.
How much will my attic temperature drop?
Typical attic temperature reduction is 20-35°F on peak summer days, with greater drops on darker roofs and west-facing pitches; we measure before and after with an infrared thermometer and include the readings in your photo record.
Insulation Removal & Replacement in San Marcos
Insulation removal and replacement in San Marcos is most commonly needed in the 1970s-1990s rental stock where decades of HVAC service calls, roof leaks, and rodent activity have rendered existing fiberglass batts useless or hazardous. We remove contaminated or compressed insulation, sanitize the substrate, seal all air leaks, and install new material to the correct depth with documented before-and-after blower-door readings. Insulation Removal & Replacement
Along Sessom Drive, we regularly find original blown-in insulation that rooftop HVAC replacements have displaced entirely, leaving bare drywall directly under black shingles. Property managers typically call us after a tenant complaint or a shocking utility audit.
Contaminated Insulation Removal
Signs you need it
Your attic insulation shows rodent droppings, mold staining, or urine odor; or your HVAC technician has reported biological growth on ductwork.
What it costs in San Marcos
Contaminated insulation removal and disposal in San Marcos runs $1,500-$3,000 for an average attic, before replacement.
How we do it
We set up negative air pressure containment, remove all contaminated material with HEPA-filtered vacuums, apply antimicrobial treatment to exposed surfaces, and provide photos of the sanitized substrate before new insulation goes in.
Insulation Replacement
Signs you need it
Your existing insulation is compressed below its original R-value, has settled unevenly creating thermal bypasses, or was installed before 1990 and likely contains vermiculite or other outdated material.
What it costs in San Marcos
Insulation replacement with new fiberglass or cellulose in San Marcos typically costs $2,500-$5,000 including removal, air sealing, and new material to R-38 or R-49.
How we do it
We remove old material, seal top plates and penetrations with foam and caulk, then blow new Owens Corning or GreenFiber insulation to uniform depth with depth markers every 300 square feet.
What Insulation Removal & Replacement Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Contaminated insulation removal only | $1,500 - $3,000 |
| Insulation removal + replacement (fiberglass/cellulose) | $2,500 - $5,000 |
| Removal + spray foam replacement | $5,500 - $9,500 |
Is it cheaper to remove and replace or just add more?
Adding over contaminated or compressed insulation traps moisture and odor; removal and replacement costs more upfront but prevents callbacks and health complaints that cost far more in tenant turnover. Call (737) 337-8049 for an exact quote - estimates are free.
How do I know if my old insulation is hazardous?
Pre-1990 vermiculite insulation may contain asbestos; we test a sample before disturbing it, and if positive, we refer to a licensed abatement contractor with no markup or referral fee. We document the test result in your photo record either way.
Attic Air Sealing in San Marcos
Attic air sealing in San Marcos is the single most important step we perform, and we do it before any insulation goes in - never after. The 1970s-2000s rental stock and even newer code-minimum builds have hundreds of linear feet of gaps at top plates, wire penetrations, and can light housings that leak conditioned air directly into the attic. We seal these leaks first, verify with a blower-door test, then insulate. Attic Air Sealing
In San Marcos, a typical unsealed attic in a 1,800-square-foot home leaks 3,500-5,000 CFM50 - meaning you’re heating and cooling your attic all year. After our air sealing, we regularly see 40-60% reduction in that number.
Top Plate & Penetration Sealing
Signs you need it
You feel drafts from ceiling fixtures, your attic insulation has dark streaks from dust filtration, or your blower-door test shows excessive leakage despite adequate insulation depth.
What it costs in San Marcos
Top plate and penetration sealing in San Marcos typically costs $1,200-$2,500 as a standalone service, or is included in our attic insulation packages.
How we do it
We access the attic floor, seal all top plate gaps with expanding foam, caulk wire and pipe penetrations, install fire-rated covers over can lights, and retest with the blower door to verify leakage reduction.
Can Light & Duct Boot Sealing
Signs you need it
Your recessed can lights flicker in wind, your duct boots show dust accumulation on the attic side, or rooms farthest from the air handler never reach set temperature.
What it costs in San Marcos
Can light and duct boot sealing in San Marcos runs $800-$1,800 depending on the number of fixtures and accessibility.
How we do it
We install pre-formed fire-rated enclosures over each can light, seal duct boots with mastic and mesh tape, and pressure-test the duct system if leakage is suspected.
What Attic Air Sealing Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Top plate & penetration sealing | $1,200 - $2,500 |
| Can light & duct boot sealing | $800 - $1,800 |
| Full attic air sealing with blower-door verification | $2,000 - $4,000 |
Can air sealing alone lower my bill?
Yes, 15-25% cooling cost reduction is typical in San Marcos homes with significant leakage, though we recommend pairing sealing with insulation upgrade for maximum performance; we provide both options in writing. Call (737) 337-8049 for an exact quote - estimates are free.
How do you prove the sealing worked?
We provide before-and-after blower-door readings in CFM50 - a single number showing exactly how much less air your home loses after our work - plus timestamped photos of every sealed penetration in your Documented Photo Record.
Wall Insulation in San Marcos
Wall insulation in San Marcos addresses a specific vulnerability exposed during Winter Storm Uri: the 1970s-1990s wood-frame rental stock and many 2000s-era builds have empty or poorly filled wall cavities that offer minimal thermal protection during freeze events. We install dense-pack cellulose or injection foam without removing interior drywall, improving R-value and air tightness simultaneously. Wall Insulation
The February 2021 freeze burst pipes in hundreds of San Marcos homes with uninsulated or under-insulated exterior walls. Properties we retrofitted with injection foam before that storm had zero freeze damage in walls, even with extended power outages.
Injection Foam Wall Insulation
Signs you need it
Your exterior walls feel cold to the touch in winter, you have visible thermal bypasses around outlets and switches, or your home was built before 2000 with empty wall cavities.
What it costs in San Marcos
Injection foam wall insulation in San Marcos typically costs $3,500-$6,500 for a 1,500-2,000 square foot home depending on wall area and cavity condition.
How we do it
We drill 2-inch holes through exterior siding or interior drywall at stud-bay spacing, inject slow-rise foam until the cavity is full, patch all access points, and verify fill with thermal imaging.
Drill & Fill Wall Insulation
Signs you need it
Your walls have some existing batt insulation that has settled or compressed, leaving gaps at the top and bottom of cavities that show as cold stripes on thermal imaging.
What it costs in San Marcos
Drill and fill with dense-pack cellulose in San Marcos runs $2,800-$5,000 for typical residential wall area.
How we do it
We remove a row of siding or drill through drywall, blow cellulose to 3.5 pounds per cubic foot density to prevent settling, patch access holes to match existing finish, and provide thermal images showing before and after wall performance.
What Wall Insulation Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Drill & fill (dense-pack cellulose) | $2,800 - $5,000 |
| Injection foam (full cavity fill) | $3,500 - $6,500 |
| Exterior wall insulation with air sealing | $4,500 - $7,500 |
Will wall insulation help with summer cooling?
Yes, though the primary benefit is reduced heat conduction through walls; the bigger summer gain comes from combining wall insulation with attic air sealing and radiant barrier to address the full envelope. Call (737) 337-8049 for an exact quote - estimates are free.
Do you have to remove my drywall?
No, we access wall cavities from exterior siding or through small interior patches; for homes with brick or stucco exteriors, we work from inside with strategic furniture placement to minimize disruption.
Attic Cleaning & Rodent Proofing in San Marcos
Attic cleaning and rodent proofing in San Marcos is a frequent need in the 1970s-1990s rental stock where roof leaks, fruit trees, and proximity to the San Marcos River corridor create sustained rodent pressure. We remove contaminated insulation and debris, sanitize all surfaces, seal every entry point, and restore the attic to a clean, inspectable condition before any new insulation goes in. Attic Cleaning & Rodent Proofing
Property managers near campus call us after tenants report scratching noises or musty odors; we often find years of accumulated droppings, compressed trails through fiberglass batts, and chewed wiring that creates fire risk.
Attic Sanitizing & Decontamination
Signs you need it
Your attic has visible rodent droppings, urine staining on insulation or drywall, or a persistent organic odor that HVAC circulation distributes through the house.
What it costs in San Marcos
Attic sanitizing and decontamination in San Marcos typically costs $1,800-$3,500 depending on contamination extent and attic square footage.
How we do it
We remove all contaminated material under negative pressure, HEPA-vacuum every surface, apply enzyme-based sanitizer to break down organic residue, and provide photos of the cleaned substrate before any restoration work.
Rodent Proofing & Exclusion
Signs you need it
You hear scratching in walls or ceiling, find droppings in the attic, or have had recurring pest control treatments that never fully solve the problem.
What it costs in San Marcos
Rodent proofing and exclusion in San Marcos runs $1,200-$2,800 for a typical home, with complex rooflines or multiple entry points at the higher end.
How we do it
We inspect every roof and soffit intersection, seal all gaps larger than 1/4 inch with steel mesh and foam, install chew-proof vent covers, and provide a written exclusion map showing every entry point found and sealed.
What Attic Cleaning & Rodent Proofing Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Attic sanitizing & decontamination | $1,800 - $3,500 |
| Rodent proofing & exclusion | $1,200 - $2,800 |
| Full attic restoration (cleaning + proofing + re-insulation) | $4,500 - $8,500 |
How do I know rodents are gone before you re-insulate?
We set monitoring devices, seal all entry points, and wait 7-14 days to confirm no new activity before installing new insulation; we document this waiting period and final inspection in your photo record. Call (737) 337-8049 for an exact quote - estimates are free.
Will my insurance cover rodent damage?
Most homeowner policies exclude rodent damage to insulation and wiring; we provide detailed documentation and photos that help if you’re filing a claim for related structural damage, but we do not bill insurance directly.
Home Energy Audit in San Marcos
A home energy audit in San Marcos gives landlords and homeowners a documented baseline of exactly where their building envelope is failing and what fixes will deliver measurable return. We perform blower-door testing, thermal imaging, and insulation inspection to produce a prioritized scope with written pricing for each recommendation. Home Energy Audit
For the Sessom Drive and Hopkins Street apartment complexes, our thermal imaging regularly reveals insulation displacement from old HVAC replacements that property managers had no idea existed; the audit becomes an easy, high-conversion sales conversation because the images show the problem in color.
Blower Door Test
Signs you need it
Your energy bills are 30% or more above similar homes, rooms have uneven temperatures, or you’re considering insulation upgrades and want to prioritize air sealing versus insulation.
What it costs in San Marcos
A standalone blower-door test in San Marcos costs $350-$600; we credit this toward any work we perform.
How we do it
We install a calibrated fan in an exterior door, depressurize the house to 50 Pascals, measure total leakage in CFM50, then use a smoke pencil to locate major leaks while the fan runs.
Thermal Imaging Inspection
Signs you need it
You suspect missing or displaced insulation, have rooms that never cool evenly, or need documentation of envelope condition for a property sale or refinance.
What it costs in San Marcos
Thermal imaging inspection in San Marcos runs $400-$750 as a standalone service, or is included in our full energy audit package.
How we do it
We scan every exterior wall and ceiling surface with a FLIR infrared camera, identify thermal anomalies indicating missing insulation or air leaks, and provide annotated images with temperature readings and recommended fixes.
What Home Energy Audit Costs in San Marcos
| Item | Typical range in San Marcos |
|---|---|
| Blower-door test | $350 - $600 |
| Thermal imaging inspection | $400 - $750 |
| Full home energy audit (all tests + written report) | $650 - $1,200 |
How long does a full energy audit take?
A complete audit takes 3-4 hours for a typical single-family home; large or complex properties may require a full day, and we schedule accordingly with your written confirmation. Call (737) 337-8049 for an exact quote - estimates are free.
What do I get after the audit?
You receive a written report with blower-door readings, thermal images with annotations, a prioritized scope of recommended work with flat pricing for each item, and our Free Second Opinion on any competing quote you bring us.
Brands We Service in San Marcos
We install and service materials from Owens Corning, Knauf, Rockwool, CertainTeed, Icynene, Demilec, and GreenFiber - no proprietary lock-in means we specify what’s right for your home, not what we’re obligated to sell. Our crews carry common Knauf and Rockwool stock locally for fast turnaround on standard jobs. our brands
Pricing for Insulation in San Marcos, TX
| Service | Typical range in San Marcos |
|---|---|
| Vapor barrier (crawl space) | $2,800 - $4,500 |
| Full crawl space encapsulation | $7,500 - $12,000 |
| Attic radiant barrier | $1,800 - $3,200 |
| Radiant barrier roof deck | $2,200 - $4,000 |
| Contaminated insulation removal | $1,500 - $3,000 |
| Insulation removal + replacement | $2,500 - $5,000 |
| Top plate & penetration sealing | $1,200 - $2,500 |
| Can light & duct boot sealing | $800 - $1,800 |
| Drill & fill wall insulation | $2,800 - $5,000 |
| Injection foam wall insulation | $3,500 - $6,500 |
| Attic sanitizing & decontamination | $1,800 - $3,500 |
| Full home energy audit | $650 - $1,200 |
Prices in San Marcos push higher for limited attic access, active moisture remediation needed before encapsulation, or homes with vermiculite requiring asbestos testing. Every job still begins with a written price before any work starts - Haven Standard Clause 1 - and includes a Documented Photo Record when the crew leaves.
Neighborhoods We Serve in San Marcos
We serve properties throughout San Marcos with crews dispatched from our Austin office, typically arriving same-day or next-day for scheduled assessments. These are representative neighborhoods we work in regularly.
- Historic Downtown San Marcos
- Sessom Drive / Hopkins Street corridor (TXST campus area)
- Willow Creek / Blanco River area
- I-35 growth corridor (newer master-planned developments)
- San Marcos Hills / ranch-style properties
Service Area - Cities Near San Marcos
Envelope Insulation Co. serves the full I-35 corridor between Austin and San Antonio, with local crews available in Kyle, TX, Buda, TX, Lockhart, TX, and throughout the greater Austin, TX metro. Scheduling and dispatch are coordinated from our Austin office; San Marcos properties receive local crew assignment with same-day or next-day availability for most services.
Serving San Marcos, TX - Our Local Coverage Area
We’re based in the San Marcos area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Insulation in San Marcos
Most attic and wall insulation upgrades in San Marcos do not require a permit if you’re not altering structure or electrical; crawl space encapsulation and spray foam may need Hays County review depending on scope. We handle permit research as part of our written scope when required, at no additional fee.
We schedule assessments within 24-48 hours for most San Marcos locations, with emergency calls for active leaks or HVAC failure answered by a live person 24/7; our Austin dispatch office coordinates crew routing for same-day service when available.
Yes, roughly half our San Marcos volume is rental property and student housing; we provide written scopes suitable for owner approval, coordinate tenant access, and deliver documentation that satisfies most property management compliance requirements.
What happens when you call
- 1A real person answersNo phone trees - talk to a local insulation pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3A background-checked tech heads outLicensed & insured, typically within 60-minute.
- 4You approve before work beginsNothing starts until you say go.
What San Marcos Customers Say
"The winter gas bill dropped by about a third. They had estimated a quarter, so they under-promised."
- Genevieve R."Crawl space encapsulation done properly. Photographs of the vapour barrier at every seam, and the damp smell in the hallway is gone."
- Ainsley P."Fixed price, clean work, and they hauled the old material away as agreed."
- Todd M.