Trusted Blown-In Insulation for San Marcos Homeowners
Our Blown-In Insulation in San Marcos typically costs $1.20 to $2.80 per square foot of attic floor, with most whole-attic jobs running between $1,800 and $4,500 depending on material choice and whether air sealing is needed first. Most installations finish in a single day, and crews can often be on-site within 48 hours of your call. Call (737) 337-8049 for a written price before any work starts.
We’ve sealed and insulated more than 9,000 homes since 2016, and we’ve learned that blown-in insulation performs poorly when it’s installed over an unsealed attic floor. That’s why every job we take in San Marcos, from the older ranch homes near Rio Vista to the newer builds in Willow Creek, begins with a blower-door test - a pressurization reading that shows, in one number, how much conditioned air your building envelope is losing. We seal first, then insulate. No exceptions. Under Haven Standard Clause 1, you get a flat price, written scope, and written warranty before anyone lifts a tool. Our crews are background-checked and uniformed, and a live person answers our phones 24/7.
What Our Blown-In Insulation Service Includes
Blown-In Cellulose
Blown-in cellulose is ground paper fiber treated with borate fire retardant, and it’s the material we specify most often for San Marcos attics because it settles into irregular joist bays better than batts and performs well in our heat. Cellulose makes sense when your attic has limited headroom, lots of penetrations, or existing insulation that’s compressed or uneven. We source from GreenFiber and other manufacturers, and we install to the depth that achieves your target R-value - typically R-38 to R-60 for attics in this climate zone. Every cellulose job includes air sealing of top plates, can lights, and plumbing penetrations before the blower truck arrives, plus a documented photo record showing coverage depth and any problem areas we found.
Blown-In Fiberglass
Blown-in fiberglass is spun glass fiber that doesn’t absorb moisture and maintains its R-value over decades without settling significantly, which matters in San Marcos where summer attic temperatures exceed 140°F and can degrade lesser materials. We specify fiberglass for homeowners who want maximum longevity with minimal future disturbance, particularly in homes with storage platforms or HVAC equipment in the attic that will need periodic access. We work with Owens Corning and Johns Manville products, installing with dedicated blowing equipment that breaks up clumps and distributes material at consistent density. Your written scope will specify the installed weight per square foot and the target depth, so you can verify what was done.
Dense-Pack Wall Insulation
Dense-pack wall insulation fills closed wall cavities with cellulose or fiberglass at 3.5 to 4.0 pounds per cubic foot - dense enough to resist settling and slow air movement through the cavity, but not so dense that it bows drywall or compresses into useless lumps. This is the service we recommend for San Marcos homes built before 1980 with empty stud bays, or for additions where the builder skipped insulation entirely, and we also provide our Blown-In Insulation in Lockhart for homes in that area. We access walls through exterior siding removal, interior drywall cuts, or existing electrical openings depending on your finish priorities. The blower-door test after dense-packing typically shows a 15 to 30 percent reduction in air leakage, and we publish that number on your job record.
Blown-In Top-Up
Blown-in top-up adds material over existing insulation that’s in decent shape but has settled below current energy code levels, a common situation in San Marcos subdivisions built during the 2000s construction boom when builders often installed minimum R-30. We inspect the existing layer for moisture damage, rodent activity, or compression from storage boards, and we remove and replace sections as needed before blowing new material. A top-up costs less than full removal and replacement, but only makes sense if the original insulation is clean and the attic floor is already sealed. We’ll tell you honestly which category you’re in, and we’ll show you photos of what we found so you can decide with actual information.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Brands We Service for Blown-In Insulation
We specify materials from Johns Manville, Knauf, and Rockwool depending on the application and what we find during inspection. Johns Manville blown fiberglass has been our go-to for high-heat attics in San Marcos because their formaldehyde-free binder holds up to thermal cycling without degrading, and we’ve installed enough of it to know exactly what coverage rates to expect from each bag weight. Knauf’s EcoFill blown fiberglass flows well through long hoses, which matters in the tight attic accesses common in the ranch homes near the university, and their published coverage charts match our field measurements within 5 percent. Rockwool’s blown mineral wool is the choice when fire resistance and sound dampening matter - we’ve used it in homes near the railroad corridor and for homeowners who want the extra hour of fire rating it provides.
Whether you have CertainTeed, Owens Corning, or any other manufacturer in your attic now, we can match or exceed the existing performance. We don’t push proprietary products or exclusive partnerships. Our material recommendation comes from what your home needs, not from a distributor incentive. Bring us a competing quote and we’ll read it with you - our Free Second Opinion applies to every written estimate, no obligation.
Before
AfterSigns You Need Blown-In Insulation Right Now
- Your upstairs rooms are 8 to 12 degrees hotter than downstairs in July. This temperature stratification means conditioned air is escaping through your attic faster than your HVAC can replace it, and your insulation either is missing, compressed, or bypassed by air leaks. We see this pattern constantly in San Marcos homes with original R-19 batts that have settled to R-13 or less.
- Your energy bills spike every summer despite normal thermostat settings. When your attic insulation performs below its rated R-value, your air conditioner runs longer cycles to maintain temperature, and in San Marcos that extra runtime shows up clearly on CPS Energy bills from May through October. A blower-door test will quantify exactly how much air you’re losing.
- You can see floor joists through your attic insulation. Insulation that has settled below the top of joists has lost 30 to 50 percent of its original effectiveness, and any gaps or thin spots create thermal bypasses that render the surrounding material nearly useless. We document this with photos during inspection.
- Your attic has been used for storage or walked on repeatedly. Compressed fiberglass batts don’t rebound, and compressed cellulose loses its trapped air pockets - the actual insulating medium. If you’ve got plywood platforms or walking paths through your attic, those areas need targeted replacement or additional blown-in coverage.
- Ice dams formed on your roof last winter, or your roof deck shows dark staining from moisture. These symptoms indicate warm air reaching the roof deck, either through bypasses around chimneys and light fixtures or through inadequate insulation depth. In San Marcos, this same dynamic creates condensation issues during our brief cold snaps and accelerates shingle degradation year-round.
Our Blown-In Insulation Process - Step by Step
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Schedule and arrival. When you call (737) 337-8049, a live person answers and books your appointment. Under Haven Standard: Arrive on schedule, you get a named technician and a text when they are on the way. Our crew arrives in a marked vehicle, introduces themselves, and lays protective covering before entering your home.
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Attic inspection and blower-door test. We access your attic and photograph existing conditions - insulation depth, signs of moisture, rodent activity, and any electrical or structural hazards. Then we run a blower-door test to establish your baseline air leakage rate in CFM50, a single number that tells us how much conditioned air escapes through your building envelope. This reading drives our air-sealing scope.
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Air sealing before insulation. We seal top plates, wire and pipe penetrations, can light housings, chimney chases, and any other bypasses we find using fire-rated caulk, expanding foam, and rigid baffles. This step is never skipped and never sold separately. In San Marcos, the combination of hill-country wind exposure and summer stack effect makes this sealing critical to performance.
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Blown-in installation to specified depth. We set up our blowing equipment outside, run hoses through a window or door, and install your chosen material to the depth and density specified in your written scope. A crew member remains in the attic to direct hose placement and verify even coverage, particularly around eaves, valleys, and mechanical penetrations.
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Post-installation verification and documentation. We run a second blower-door test to measure your air leakage reduction, photograph the completed insulation depth with a measuring stick visible, and compile your Documented Photo Record. You receive a written summary with before-and-after numbers, coverage verification, and your 365-Day Done Right Promise warranty before we leave.
How Much Does Blown-In Insulation Cost in San Marcos?
A typical blown-in cellulose attic job in a 1,800-square-foot San Marcos home runs $2,200 to $3,800, including air sealing of top plates and penetrations, though you can check our Blown-In Insulation pricing page for more detail on what drives these numbers. Blown-in fiberglass for the same footprint typically runs $2,600 to $4,200 because material costs are higher and the installation requires more bags to achieve equivalent R-value. Dense-pack wall insulation ranges from $1.50 to $3.00 per square foot of wall area, so a 2,000-square-foot home with 1,200 square feet of exterior wall might run $1,800 to $3,600 for walls only. A blown-in top-up over existing insulation in good condition is the least expensive option, typically $1.20 to $1.80 per square foot of attic floor, or $1,400 to $2,500 for that same 1,800-square-foot home.
Several factors move these numbers up or down. Attic accessibility matters: a scuttle hole in a closet costs more in labor than a full staircase in a hallway. Existing insulation condition determines whether we can top up or must remove and start fresh - removal adds $0.80 to $1.50 per square foot. Target R-value drives material quantity; moving from R-38 to R-60 adds roughly 40 percent more material. And air sealing complexity varies: a simple rectangular attic with few penetrations seals faster than one with multiple HVAC platforms, recessed lighting, and a chimney chase.
To avoid overpaying, get any competing quote in writing and bring it to us for a Free Second Opinion - we’ll read it with you line by line and explain where the scope differs from ours. Our price includes the blower-door testing, air sealing, material, installation, cleanup, and documentation. No separate charges for “prep work” or “disposal fees” appear after you approve the scope. Call (737) 337-8049 for your written price - estimates are free, and no work starts until you’ve seen and approved the full number.
Blown-In Insulation Near San Marcos - Our Service Area
We work throughout Hays County and into surrounding markets, with typical drive times of 20 to 45 minutes to Blown-In Insulation in Redwood, Blown-In Insulation in Kyle, Lockhart, Buda, and the Austin metro fringe including Shady Hollow and Lost Creek. Homes in Lago Vista, Lakeway, and Hornsby Bend fall within our service radius for building envelope work, though response times may extend to 60 minutes for those outer reaches. We’ve also completed jobs in Bastrop for homeowners who wanted our documented process and published blower-door numbers. Wherever you are in this corridor, the same Haven Standard applies: written price first, documented record last, live person on the phone throughout.
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.
Frequently Asked Questions - Blown-In Insulation in San Marcos
Blown-in insulation is loose fiber material - cellulose, fiberglass, or mineral wool - installed with a blowing machine that propels it through a hose into attic floors, wall cavities, or irregular spaces. It conforms to joist bays and around obstructions better than batts, and when paired with proper air sealing, it reduces both conductive heat transfer and air leakage through your building envelope. We use blown-in methods for most San Marcos attics because they deliver consistent coverage without the gaps and compression common with hand-placed batts.
Most residential attic jobs in San Marcos finish in four to six hours, with dense-pack wall work adding another day if interior access cuts are needed. The air sealing phase typically takes longer than the blowing itself - two to three hours for a thorough seal of an average attic - because we work methodically around every penetration. You’ll know your specific timeline before we start; it’s written into your scope.
Attic jobs typically run $1,800 to $4,500 depending on material and whether removal is needed, wall dense-packing runs $1.50 to $3.00 per square foot of wall area, and top-ups over existing insulation start around $1,400 for smaller homes. Your exact price depends on attic accessibility, existing conditions, and target R-value. Call (737) 337-8049 for a written estimate with no obligation - we’ll inspect, measure, and price before you decide.
Yes, we install and specify all three brands regularly, along with Owens Corning, CertainTeed, and others. We don’t have exclusive arrangements with any manufacturer, so our recommendation is based on your home’s specific needs - fire resistance, moisture tolerance, sound dampening, or budget - not on a distributor quota. Your written scope will name the exact product and bag weight we’re installing.
We don’t treat insulation as an emergency trade - there’s no burst pipe scenario - but we do answer calls 24/7 and can often inspect within 48 hours if your situation is urgent, such as insulation removal after a roof leak or rodent contamination. A live person will answer when you call (737) 337-8049, and we’ll schedule the earliest available crew. For true building envelope emergencies like active roof leaks, we’ll help you triage and schedule the insulation work for when the structure is dry and safe.
Every job is backed by our 365-Day Done Right Promise - if it’s not done right, we make it right - plus the manufacturer’s material warranty, which ranges from limited lifetime to 30 years depending on product. Your written warranty document, delivered before work starts, specifies what’s covered, the claims process, and our response commitment. Haven Standard: Have it in writing.
Clear a path to your attic access and remove any stored items from the attic floor that you want to keep; we can move light items, but heavy storage should be handled before we arrive. Ensure we have access to an exterior door or window for our blowing hose, and keep pets in a separate room during the installation. We’ll bring protective coverings for floors and furniture, and we’ll handle all cleanup. Your technician will call the day before to confirm any site-specific needs.
Schedule Your Blown-In Insulation Service in San Marcos Today
Call (737) 337-8049 now and speak with a live person who can book your inspection. You’ll receive a written price before any work starts, a documented photo record when the crew leaves, and published before-and-after blower-door numbers on every applicable job. The 365-Day Done Right Promise applies to everything we do. No obligation, no voicemail loops, no callback windows measured in business days.
Written by Wes Okafor, Owner at Envelope Insulation Co., serving San Marcos since 2016.