Demilec Blown-In Insulation in Sunnyvale: What to Know First
Demilec blown-in insulation service in Sunnyvale typically runs $1,800-$4,600 for a full attic top-up or dense-pack wall job, depending on square footage and whether we’re working around existing Demilec spray foam. We’re an independent Demilec service provider, not a factory-authorized dealer, which means we tell you what’s actually failing and whether it’s worth fixing. Most Sunnyvale jobs take one to two days from assessment to cleanup. This page is for homeowners who own a Demilec product, or are trying to figure out if they do, and want straight answers instead of a sales pitch. Call (669) 215-4805 and a live person answers, any hour.
How Demilec Products Fail - and How We Fix Them
Demilec makes some genuinely good foam and blown-in products. Heatlok, Sealection, and the Agribalance open-cell line all show up in Sunnyvale homes. But we’ve been inside enough attics to know where each one misbehaves. Here’s what we see:
- Heatlok HFO Pro shrinkage around can lights and plumbing penetrations. This is the big one. In Sunnyvale heat, closed-cell Heatlok applied five or more years ago can pull back from the edges of penetrations, leaving a small gap that lets attic air ghost into the living space. We see it most in homes along El Camino Real where the older ranch construction traps roof heat. The fix is typically a targeted blown-in top-up around the affected areas rather than scraping and respraying, which saves you real money.
- Sealection 500 settling in dense-pack wall cavities. Sealection is a great product when installed right, but we’ve opened walls in Sunnyvale’s 1960s Sunset district and found it settled away from the top plate by three or four inches because the original installer rushed the lift. That gap becomes a thermal short. We re-dense-pack with blown-in fiberglass or cellulose to fill the void and restore the wall’s R-value.
- Blown-in over closed-cell foam done wrong the first time. Some homeowners originally did a thin flash coat of Heatlok and paid someone else to blow fiberglass over it. If the fiberglass was installed to the wrong depth, convection currents inside the attic pull heat through it. In Sunnyvale’s cooler winter months, you’ll feel cold rooms even though the thermostat says otherwise. We verify depth and density, then top up to the correct R-value for our climate zone.
- Agribalance open-cell foam losing its air seal at the soffit line. Open-cell products need a continuous air barrier to do their job. In homes near Murphy Avenue where lots of remodels added can lights and bath fans, the soffit area gets chewed up and the air seal disappears. Blown-in insulation alone won’t fix an open soffit path. We identify the gap, seal it, and then blow to specification.
- Rodents chewing through Demilec foam and leaving voids. This is a Sunnyvale reality, not a Demilec defect. Rats and squirrels up here love tunneling through foam. We find foam with golf-ball-sized tunnels and then find the blown-in top-up sitting on top of a compromised air barrier. We address the entry point first, then repair the foam and re-blow the loose fill.
Our Demilec Blown-In Insulation Process
Every Demilec job we take follows the same path, because guessing is what costs you money. Here’s what happens when you call Walt’s Insulation:
- 1
The call. A live person picks up at (669) 215-4805. No voicemail tree. We ask what you’re seeing: a cold room, a hot upstairs, a draft by the baseboards.
- 2
The assessment. A technician comes out, walks the attic and the exterior, and documents what’s actually there. We don’t recommend blown-in top-ups unless we’ve verified the existing Demilec product is sound.
- 3
The honest recommendation. Sometimes the fix is a top-up. Sometimes it’s dense-pack in a wall. Sometimes we tell you to leave it alone. We’ve talked ourselves out of jobs because the honest answer was “your insulation is fine, your windows aren’t.”
- 4
The work. Background-checked, uniformed techs handle the blow-in, masking off the work area and covering your floors. We use manufacturer-spec Demilec-compatible materials, and we document depth and density as we go.
- 5
The test. We use a thermal camera to scan the finished area before we leave. If there’s a cold stripe or an air leak, we find it while we’re still there. Not after you’ve paid.
- 6
The guarantee. Every job is covered by the Done Right Promise. If it’s not done right, we make it right. For life. That’s the whole point of hiring a local owner-operated crew instead of a franchise.
What Demilec Blown-In Insulation Costs in Sunnyvale
No two Sunnyvale houses are the same, but here’s what we typically quote:
- Blown-in top-up over existing Demilec, 1,500 sq ft attic, R-38 to R-49: $1,800-$2,800. Most common job we do.
- Full attic re-blow after foam repair or removal, same footprint: $3,200-$4,600. Higher when we’re cutting out damaged Heatlok first.
- Dense-pack wall insulation for one exterior wall: $900-$1,600 per wall depending on access and whether we’re drilling from inside or outside.
- Spot repair + top-up around penetrations: $450-$850. Small scope, same warranty.
What moves the price: attic access, how much existing foam has to be removed, whether we’re working around old knob-and-tube wiring (common in Sunnyvale’s pre-1950s homes), and whether the attic is walkable. Estimates are free, and if you have a written quote from someone else, bring it. We’ll give you a free second opinion and tell you if their scope is right. And seniors and veterans always get 10% off. Call (669) 215-4805.
Why Sunnyvale Homeowners Call Walt’s Insulation for Demilec Work
Walt Brenner started this company in 2000, and he’s been hands-on since day one. When you call about a Demilec issue in Sunnyvale, the person who answers knows the difference between Heatlok and Sealection and won’t read you a script. We’re the one down the road, with a published address and a real license number. Our techs are background-checked and uniformed, so you know exactly who’s walking into your house. We work on Demilec jobs all the time, and we also service Reflectix radiant barriers and the other major brands: Owens Corning, Rockwool, Icynene, Johns Manville, CertainTeed, Knauf, and GreenFiber. If your house has a mix of products, we can handle it in one visit. Good insulation should be invisible; you only notice it when it’s missing. If you’re noticing, we should talk.
FAQs
Yes. A properly installed blown-in top-up works well with Demilec foam, provided the foam’s air seal is intact. We inspect that first, because blown-in insulation over a failed air seal just hides the problem instead of fixing it. Call (669) 215-4805 and we’ll take a look.
Most top-up jobs get scheduled within a week, and the work itself takes one day for a standard attic. Emergency issues, like a roof leak that soaked your blown-in, get priority. We answer the phone 24/7, so you’ll know today what your timeline looks like.
Topping up is almost always cheaper, usually 40-60% less than a full removal and respray. But if the existing foam has failed, all the blown-in in the world won’t make your house comfortable. That’s why our assessment step is non-negotiable. We’ll show you exactly what’s failing before we quote anything.
We’re an independent Demilec service provider, so we don’t administer their manufacturer warranty. What we do back is our own work: the Done Right Promise covers our labor for life. If our installation fails, we fix it. No prorated nonsense, no runaround.
We can often get a tech out same-day for an assessment, especially if you’re a senior, a veteran, or dealing with an open attic issue. Call (669) 215-4805 and ask. If we can’t make it today, we’ll tell you that up front, not after you’ve waited around all afternoon.
Written by Walt Brenner, Owner, Walt’s Insulation at Walt’s Insulation, serving Sunnyvale and nearby areas.