Demilec Attic Air Sealing in Morgan Hill: What to Know First
Demilec attic air sealing in Morgan Hill typically runs $1,800-$3,400 for a complete attic-floor seal on a home with Demilec spray foam or hybrid insulation systems, and most jobs finish in one day. As an independent Demilec service provider, we work on the building envelope - not the foam chemistry - so we seal the gaps the Demilec system was meant to close but didn’t. This page is for Morgan Hill homeowners who found cold spots, high PG&E bills, or drafty rooms after a Demilec install and need someone who understands where the air is actually getting through. Call (669) 280-8103 for a free estimate with a written price before any work starts.
How Demilec Products Fail - and How We Fix Them
- Demilec SEALECTION 500 open-cell foam shrinkage at top plates. SEALECTION 500 is a water-blown open-cell that can pull away from framing members as it cures, especially in the temperature swings Morgan Hill sees between 40°F winter nights and 90°F summer afternoons. We find gaps up to 3/8 inch along top plates in homes built 2017-2021. Our fix: remove the failed bead, seal with acoustical sealant or closed-cell foam at the critical junction, then verify with smoke pencil and blower-door.
- Demilec Heatlok Soya HFO shrinkage around duct boots and penetrations. Heatlok Soya HFO is a high-performing closed-cell, but its rapid rise can leave voids where round ducts or electrical penetrations pass through the foam field. In Morgan Hill’s older ranch homes near Oakwood Avenue, we’ve found these voids channeling attic air straight into conditioned space. We cut back to sound substrate, fill with two-part closed-cell, and seal the perimeter with foil tape rated for the temperature range.
- Demilec Agribalance settling in vaulted ceiling assemblies. Agribalance is an open-cell with a distinctive tan color, and in sloped attic applications common in the East Main corridor builds, gravity and thermal cycling compress it at the eaves over 5-7 years. The foam itself isn’t the air barrier anymore - the cracks are. We remove the compressed material, re-establish the air barrier with targeted closed-cell at the eave junction, then blow in new insulation to restore R-value.
- Hybrid Demilec-and-fiberglass jobs with unsealed transitions. Some Morgan Hill contractors sprayed Demilec on the roof deck and laid batts on the floor, treating the attic as “conditioned” but never sealing the floor penetrations. The result: a wind-washing loop where house air escapes through the floor, gets pulled across the foam, and recirculates. We seal every top plate, wire penetration, and can-light boot with the floor as the primary air barrier, because the foam on the roof doesn’t stop stack effect.
- Demilec foam degradation from rodent activity in Morgan Hill’s hillside homes. Near the foothills, roof rats and mice tunnel through open-cell Demilec for nesting material, leaving channels that bypass the air barrier entirely. We don’t just patch the foam - we seal the entry points with steel mesh and foam, restore the air barrier with compatible closed-cell, and document the repair with photos for your records.
Our Demilec Attic Air Sealing Process
- 1
Call and schedule. A live person answers 24/7. We book a diagnostic visit at your Morgan Hill home, usually within 48 hours.
- 2
Blower-door test and thermal imaging. We pressurize the house - a blower-door test that gives us one number for how much air the envelope is losing - and run a FLIR camera to find where Demilec foam has separated, shrunk, or been compromised.
- 3
Written scope and price. Before anyone lifts a tool, you get a written price, a written scope, and a written warranty. No exceptions. This is Haven Standard Clause 1.
- 4
Seal first, then insulate. We seal every top plate, can-light boot, duct penetration, attic hatch perimeter, and wire chase with the right material for the Demilec substrate - never generic caulk over foam. Seal the leaks first. The insulation just holds what you’ve already captured.
- 5
Post-seal blower-door test. We run the blower door again and publish the before-and-after CFM50 numbers so you can see the performance change you paid for.
- 6
Documented Photo Record and cleanup. You get photos of every sealed penetration, the blower-door readings, and a clean attic floor. We leave nothing behind but the work.
What Demilec Attic Air Sealing Costs in Morgan Hill
Most Demilec attic air sealing jobs in Morgan Hill fall between these ranges:
- Partial seal (targeted repairs): $1,200-$1,800 - one or two failure zones, SEALECTION 500 top-plate gaps or single duct-boot voids, no insulation replacement.
- Full attic-floor seal on Demilec hybrid system: $1,800-$2,800 - all top plates, penetrations, can lights, and hatch sealing; assumes accessible attic with standard pitch.
- Full seal plus insulation restoration: $2,600-$3,400 - adds blown-in cellulose or fiberglass to restore R-value after compressed or contaminated Agribalance removal.
What moves the price: attic accessibility (cathedral ceilings add labor), square footage, whether we need to remove degraded foam first, and how many can-light boots need fire-rated covers. We also service Reflectix systems and can quote hybrid repairs if your home has mixed materials. Every estimate is free, written, and delivered before work starts - call (669) 280-8103.
Why Morgan Hill Homeowners Call Topside Attic Insulation Morgan Hill for Demilec Work
Wes Okafor has spent over a decade running air-sealing crews across Santa Clara County, from the older homes near Oakwood Avenue up to the newer builds off East Main in Morgan Hill. His rule - learned at Olive-Harvey College in front of blower-door equipment before he ever touched a bag of blown-in - is that installing R-38 over an unsealed attic floor is expensive decoration. We don’t upsell air sealing; we require it. Every job gets a written price first, a 365-Day Done Right Promise, before-and-after blower-door numbers, and a Documented Photo Record you keep. Our technicians are background-checked and uniformed. Calls are answered by a live person, 24/7. And because we’re independent - not affiliated with Demilec, Owens Corning, or any manufacturer - we choose the right material for your specific failure, not the product we’re pushed to move.
FAQs
No. Demilec’s warranty covers foam defects in material and application, not subsequent building-envelope work performed by independent contractors. As an independent Demilec service provider, we work on the air barrier adjacent to your foam, not the foam chemistry itself. We document our scope with photos so any future warranty claim on the original spray is unaffected. Call (669) 280-8103 if you want us to review your warranty paperwork before we start.
We use compatible closed-cell or open-cell foams from Icynene, Johns Manville, or other manufacturers, selected for the specific repair - adhesion to your substrate, fire rating, and vapor permeability. We don’t stock Demilec-branded two-part kits; the OEM product is sold in bulk to licensed applicators only. Our repairs are mechanical and air-barrier-focused, not cosmetic color matches. The performance metric that matters is your post-repair blower-door number, not the brand on the can.
If the foam is intact but separated from framing - shrinkage gaps, pulled top plates - air sealing targeted repairs usually solve it. If the foam is chemically degraded, heavily rodent-damaged, or compressed below half its original thickness, removal and replacement is the honest call. We make that distinction with a blower-door test and thermal imaging, not a sales pitch. Our written scope specifies which approach we’re recommending and why.
We typically schedule diagnostics within 48 hours of your call. Most Demilec attic air sealing jobs in Morgan Hill are completed in one day once scheduled. Emergency calls - active water intrusion through a foam failure, for example - get same-day response. A live person answers (669) 280-8103 24/7 to book your slot.
Canned “great stuff” foam is open-cell, low-density, and not rated for the temperature cycling or fire exposure of attic assemblies. We’ve pulled out hardened yellow globs that did nothing but block visual inspection of the real leak. For a Demilec repair that actually holds, you need compatible chemistry, proper substrate prep, and a blower-door test to prove it worked. The cost of fixing a bad DIY patch usually exceeds doing it right the first time. Call (669) 280-8103 for a free estimate - estimates are free, and the price is written before any work starts.
Written by Wes Okafor, Owner & Lead Insulation Technician, Topside Attic Insulation Morgan Hill at Topside Attic Insulation Morgan Hill, serving Morgan Hill and nearby areas.