How much insulation should be up there?
ENERGY STAR's benchmark for Climate Zone 5 homes, which covers Longmont, puts attic insulation at R-49 to R-60 for optimal performance. That's a useful target to check existing insulation against, but the exact depth that gets a homeowner to that R-value depends on which material is up there — fiberglass, cellulose, and rigid foam all perform differently per inch.
Because of that, eyeballing depth alone can be misleading without knowing the material. A quick, low-stakes way to get a real answer is to have someone who does this regularly look at what's actually installed and compare it against the target, rather than guessing from a tape measure and a general rule of thumb.
What does 'settled' insulation actually mean?
Loose-fill cellulose insulation is common in older Longmont attics, and it doesn't stay at the depth it was installed at forever. According to the Building America Solution Center, loose-fill cellulose will settle 10 to 20 percent over time due to gravity and vibration — meaning an attic insulated to a given depth ten or fifteen years ago may be noticeably thinner, and therefore under-performing, today.
Fiberglass batts don't settle the same way, but they compress if anything gets stored on top of them, and blown fiberglass can shift or thin out in spots too. Either way, "installed depth" and "current depth" aren't always the same number.
What non-visual signs point to failing insulation?
Depth is one signal, but it's not the only one. Rooms that run noticeably warmer or colder than the rest of the house — upstairs especially — can point to insulation or air-sealing gaps in the attic floor or walls, separate from anything happening with the HVAC system.
Recurring ice dams along the eaves in winter are another. They usually mean heat is escaping into the attic and melting snow unevenly, which points back to gaps in insulation or air sealing rather than a one-off weather event.
Is a rising heating bill actually a reliable signal on its own?
A rising heating or cooling bill is worth noting, but it's not proof of failing insulation by itself — utility rates change, household habits change, and equipment ages, all of which move a bill independent of the attic. It's a more useful signal when it shows up alongside one or two of the other signs here, like uneven room temperatures or visible settling.
What is a reasonable next step if several of these signs show up?
If several of these signs are showing up together — thin or settled insulation, uneven rooms, a climbing bill, maybe a recent ice dam — it's reasonable to get a professional opinion rather than keep guessing. EPA estimates homeowners save an average of 15% on heating and cooling costs by air sealing and adding insulation in attics, floors over crawl spaces, and basements, which is roughly the upside available when insulation that's actually failing gets replaced.
It's also worth checking whether current utility or state rebate programs apply to the work before assuming the full cost is out of pocket — a licensed contractor can typically tell you what's available at the time of the estimate.
Sources
What the data says
According to ENERGY STAR, “Climate Zone 5 homes need attic insulation rated R-49 to R-60 for optimal performance.”
According to the Building America Solution Center, “loose-fill cellulose will settle from 10 to 20 percent over time due to gravity and vibration.”
According to ENERGY STAR, “EPA estimates homeowners save an average of 15% on heating and cooling costs by air sealing their homes and adding insulation in attics, floors over crawl spaces, and basements.”
Take the next step
What happens after you request a quote?
An independent local insulation contractor will follow up to schedule a visit, check current insulation depth and condition against the target for this climate zone, and provide a written estimate.
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We've got your info and are routing it to a local pro. When they call, here's what to look for in the quote you receive: (1) R-value target — the model energy code for Climate Zone 5 calls for R-49 to R-60 attic insulation; ask what your contractor is quoting to. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first, and Xcel requires a blower door test to rebate it. (3) Rebate handling — ask which programs your specific address qualifies for. Xcel and Efficiency Works are separate programs with separate paperwork, and not every address qualifies for both. (The federal IRA Section 25C tax credit ended December 31, 2025 — no federal insulation credit applies to 2026 work. Xcel Energy's insulation and air-sealing rebate remains active for its gas and electric customers. Longmont Power & Communications electric customers may separately qualify for an Efficiency Works rebate — check your bill to see which utility serves your address. Boulder County EnergySmart pays a third, income-qualified-only rebate as of January 1, 2026.) (4) Removal scope — older homes often need old insulation removed before new install. If a quote skips all four, get another quote.
Frequently asked
What do homeowners ask about failing attic insulation?
How can I check my attic insulation depth myself?
Open the attic hatch, use a flashlight, and look at the depth of the insulation relative to the ceiling joists — if joists are clearly visible above the insulation line, it's likely below target. This is a rough check, though; a professional visit gives a more reliable read, especially on what material is up there.
Does insulation ever need full replacement, or can it just be topped up?
It depends on condition. Insulation that's just thin but otherwise dry and undamaged can often be topped up. Insulation that's wet, moldy, compressed by rodent activity, or contaminated needs removal first — topping up over a damaged layer doesn't fix the underlying problem.
Is 20-year-old insulation automatically failing?
Not automatically — age alone isn't the test. Fiberglass and cellulose don't have a hard expiration date, but they can lose performance through settling, compression, moisture exposure, or pest damage, so condition matters more than age by itself.
Can I tell if insulation is failing just by feeling drafts?
Drafts point more toward air-sealing gaps than insulation depth specifically, though the two problems often show up in the same house. Both are worth checking together rather than assuming one explains the other.
Does this apply the same way in Lafayette, Louisville, and Niwot?
Yes — the diagnostic signs here are general building science and apply to any home in this climate zone, not just Longmont specifically.
Is a home energy audit worth it before replacing insulation?
It can be, especially if several signs are present but the cause isn't obvious. An audit typically identifies specific air-leakage points and insulation gaps rather than relying on visual inspection alone.
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