Demilec Radiant Barrier Installation: The Los Angeles Owner’s Guide
Demilec radiant barrier installation in Los Angeles typically runs between $2,800 and $4,600 for a 1,200-2,000 square foot attic, and we stock Demilec-compatible reflective insulation systems for same-day or next-day installation. Most homeowners in Los Angeles discover their radiant barrier is failing when second-floor rooms stay hot past 7 p.m. despite the AC running, or when summer electric bills jump 30-40% year-over-year with no rate change. We carry Demilec’s Heatlok HFO-based spray foam pairing and standalone radiant barrier rolls; our crews measure attic deck temperatures with infrared guns before quoting so the price reflects what your roof assembly actually needs.
Which Demilec Models This Applies To
Demilec does not sell a standalone “radiant barrier” product line under consumer-facing model numbers. Instead, their reflective insulation work pairs with two product families: Heatlok HFO closed-cell spray foam, which we use to air-seal and insulate the roof deck before laying reflective sheeting, and Demilec’s Agribalance open-cell foam for unvented attic applications where the foam itself becomes the air barrier and the radiant barrier hangs as a separate reflective layer below the rafters. The compatibility question is not “which Demilec part number” but which assembly type your attic was built for: vented (radiant barrier on the attic floor or stapled to rafter bottoms) or unvented (foam against the roof deck, reflective layer optional below).
To identify what you have, check the roof deck in your Los Angeles attic. If you see silver reflective sheeting stapled to the underside of rafters with visible air gaps above it, that’s a vented assembly. If the roof deck is fully covered in yellow-tinted foam with no visible gaps, you likely have Demilec or similar spray foam and may be adding radiant barrier as a retrofit below the rafters. We do not install Demilec foam over existing radiant barrier that has degraded; we remove failed reflective layers, seal the deck, then reinstall. OEM Demilec foam paired with third-party radiant barrier sheeting (Reflectix, LP TechShield) is standard practice and carries the same thermal performance warranty as all-Demilec assemblies. We stock both approaches on our trucks.
Signs Your Demilec Radiant Barrier Installation Is Failing
- Attic air temperature exceeds outdoor ambient by less than 10°F on a 95°F day. A functioning radiant barrier in a Los Angeles attic should drop deck surface temperatures 20-30°F below unprotected sheathing. When the reflective surface oxidizes or collects dust, that delta shrinks and your AC works harder for the same thermostat setting.
- Visible dust coating on reflective surfaces that wipes off as gray residue, not silver. Demilec-compatible radiant barriers in Los Angeles fail first from particulate accumulation - wildfire ash, freeway particulate, and Santa Ana dust settle on horizontal attic-floor installations and cut reflectivity by half within 7-10 years.
- Peeling or delaminating edges, especially within 18 inches of gable vents or turbine openings. The marine layer moisture that rolls through Los Angeles coastal neighborhoods corrodes aluminum-facing adhesive at cut edges; we see this first in Venice, San Pedro, and Manhattan Beach homes where overnight humidity hits 80% even in summer.
- Hot spots on the ceiling directly below ridgelines or west-facing roof sections. This indicates either radiant barrier gaps where sheets were never overlapped properly, or foam failure in unvented assemblies where Demilec spray foam has pulled away from the deck and lost its air-seal.
- Blower-door test shows minimal improvement after prior “insulation upgrade.” We have tested homes in Los Angeles where a previous contractor stapled radiant barrier over unsealed top plates and can-light penetrations; the barrier reflects heat but the assembly still leaks 3,000+ CFM50. Seal the holes first. Then measure the R-value. In that order.
Before
AfterReplacement Cost & What’s Included
Most Demilec-compatible radiant barrier replacements in Los Angeles run $2,800-$4,600 for attics between 1,200 and 2,000 square feet. The lower end covers vented attics with open rafter bays and good access; the upper end covers unvented retrofits where we remove degraded foam, recondition the deck, and reinstall both air barrier and reflective layer. That price includes removal of failed material, blower-door-guided air sealing of top plates and penetrations, installation of new radiant barrier sheeting with proper 3/4-inch air gaps, and a documented photo record of deck condition before and after.
What moves the number: attic square footage, roof pitch (steeper than 8/12 adds labor hours), whether we are working around existing HVAC ducts or storage decking, and whether the prior installation left nails or staples that must be extracted before new material goes in. We publish the before-and-after blower-door numbers on every job where air sealing is performed; in Los Angeles, we typically see pre-work readings of 3,500-5,500 CFM50 drop to 1,800-2,800 after sealing and barrier installation. Our 365-Day Done Right Promise applies. Under Haven Standard Clause 1, you get a written price before any work starts - no exceptions.
DIY or Call Us?
An owner can safely check whether their radiant barrier is dusty, peeling, or has visible gaps - use a flashlight, wear a respirator, and step only on joists or a secured walkboard. Do not compress fiberglass below to reach rafters; you’ll destroy the insulation that is still doing work.
Where DIY goes wrong: radiant barrier installation without air sealing is cosmetic. Stapling Reflectix to rafter bottoms while can lights and top plates leak conditioned air is like wearing a raincoat with the zipper open. In unvented assemblies, Demilec foam application requires controlled thickness, temperature, and substrate moisture - off-ratio foam traps water against roof decking and voids manufacturer warranties. We have removed 4-inch waves of failed DIY foam from Los Angeles attics where the homeowner saved $800 upfront and paid $4,200 to fix it. For a written price on proper installation, call (628) 226-1097. Estimates are free, and we stock Demilec-compatible materials for same-day scheduling.
FAQs
In Los Angeles conditions, a properly installed radiant barrier lasts 15-25 years in vented attics with minimal dust exposure, and 10-15 years in coastal zones where salt air and marine-layer humidity accelerate oxidation. Horizontal attic-floor installations fail faster than vertical rafter-mounted sheets because dust settles and stays. We inspect barrier condition during every energy audit and tell you whether cleaning or replacement is the better value. Call (628) 226-1097 for an exact assessment - estimates are free.
Spot repairs work only for small, accessible areas with localized peeling or punctures; we patch with matching material and foil tape. If dust accumulation covers more than 30% of the surface, or if adhesive failure is widespread at edges, full replacement costs less than repeated service calls and restores the original reflectivity rating. We document the coverage area with photos so you can see what we see. Call (628) 226-1097 for a written scope.
Most Demilec-compatible radiant barrier installations in Los Angeles finish in one day for attics under 2,500 square feet. Two-day jobs involve unvented retrofits with foam removal, deck reconditioning, or extensive storage relocation. We arrive with materials on the truck, run the blower-door test first, seal air leaks, then install barrier - in that sequence every time. You get a text when the crew is en route and a photo record before we leave.
We stock Demilec-compatible spray foam, reflective sheeting, and fastening systems on every Los Angeles service vehicle; we do not stock Demilec-branded standalone radiant barrier rolls because Demilec’s core product is foam, with radiant barrier as an assembly pairing. We source reflective insulation from Reflectix and other manufacturers that meet the same emissivity specs (0.05 or lower) and install to Demilec assembly standards. Same-day availability is standard. Topside Attic Insulation Los Angeles is an independent service provider, not affiliated with Demilec.
Written by Wes Okafor, Owner & Lead Insulation Technician, Topside Attic Insulation Los Angeles at Topside Attic Insulation Los Angeles, serving Los Angeles and nearby areas.