What is air sealing, and why does it come before insulation?
Insulation and air sealing solve different physics. Insulation slows conduction — heat moving through solid material. Air sealing stops convection — conditioned air physically leaving the building and outside air replacing it. R-value does almost nothing about the second, which is why a deep attic over a leaky ceiling still underperforms.
The leaks are not where most people look. Windows and doors are the usual suspects and are usually minor. The significant paths are the top plates where interior walls meet the attic, penetrations for wiring and plumbing, recessed light housings, bath fan boxes, the attic hatch, the chase around a chimney or flue, and the rim joist down at the foundation. Nearly all of them are invisible from inside the finished house.
The ordering argument is practical rather than theoretical. Sealing the ceiling plane requires being able to see it, and once fresh insulation is down that access is gone. Air sealing after insulation means moving the insulation. That is the concrete reason it goes first, ahead of any argument about which delivers more.
Scope here is retrofit work on homes that are already built and lived in: assessment, removal where the existing material has to come out, air sealing, and installation. New construction runs on a different process and is normally handled through the builder — and it is worth knowing that Atmos excludes residential new construction from these rebates outright, so a new build does not have this money available to it in the first place.
How does the Atmos air sealing rebate actually work?
Differently from the insulation rebates, and in a way that is worth understanding before scoping the job. It is a flat $575 rather than a percentage. It requires a blower door test showing at least a 20% reduction in CFM(50) leakage — meaning a measurement before the work and a measurement after, with the difference documented.
The consequence people miss: the test is the rebate. Sealing work that is not measured before and after does not qualify no matter how well it was done. If air sealing is on your scope, the blower door has to be in the plan from the start, and it is worth confirming that explicitly rather than assuming it is included.
The second consequence is more useful. This measure carries no starting-R-value condition, unlike the attic rebate with its below-R-20 threshold and the wall rebate with its R-5. So a home whose attic is already at target — and therefore does not qualify for the insulation money at all — can still qualify for this. For a well-insulated but leaky Greeley home, air sealing is frequently the only rebate on the table, and it happens to be the measure that home actually needs.
Atmos rebate amounts verified August 5, 2026 against Atmos Energy's Colorado residential rebate page. Atmos states amounts are subject to change and that rebates are available until funding is fully allocated — confirm current amounts before scoping work.
Does the wind here really change the case for air sealing?
It does, though not for the reason the regional marketing copy usually gives. Greeley sits on open plains roughly 40 to 45 kilometres east of the foothills. NOAA research on Front Range windstorms finds that chinook downslope events concentrate their strongest winds within 10 to 20 kilometres of the foothills, while cold-air-advection windstorms spread strong winds across a much wider area of northeastern Colorado.
So the honest local story is not foothills wind-washing borrowed from a market closer to the mountains. It is open-exposure plains wind, and the concrete local number is the City of Greeley's own published design wind speed of 115 mph. Wind pressure on a building envelope drives air through every unsealed path in it, and a site with little natural shelter sees that more often than a sheltered one.
Elevation contributes a smaller, real effect. Greeley sits at roughly 4,675 feet, where air is thinner than at sea level. That is a modest adjustment to heat transfer and combustion air rather than a dramatic one, and it is worth stating at its actual size — the number that matters far more for infiltration here is the wind exposure, not the altitude.
Sources
What the data says
According to the Atmos Energy, “the Atmos Energy residential air sealing rebate pays a flat $575 and requires a blower door test documenting a minimum 20% CFM(50) leakage reduction.”
According to the ENERGY STAR, “air sealing alone — before insulation upgrades — can reduce energy bills by up to 15% in older homes.”
According to the NOAA, “chinook downslope windstorms concentrate their strongest winds within 10 to 20 kilometers of the foothills, while cold-air-advection windstorms spread strong winds over a much wider area across much of northeastern Colorado.”
Take the next step
Want a number instead of a draught?
The assessment locates where the house is actually leaking rather than where it feels like it is. Because the Atmos rebate is defined by a measured 20% reduction, getting the before-number on the record is also the first step of qualifying for it — and it works on homes whose attics are already too good to qualify for anything else.
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We've Got It. Here's What Happens Next.
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 — Greeley builds to the 2021 IECC, which puts attics at R-49 to R-60; anything less is under-spec. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first, and Atmos requires a blower door test to rebate it. (3) Rebate handling — ask who files the Atmos paperwork and confirm it goes in within 60 days of the install. (The federal IRA Section 25C tax credit ended December 31, 2025, and Colorado's HEAR program is closed. Atmos Energy's residential rebates are the primary insulation rebate stack for Greeley-area projects in 2026, and income-qualified households can get insulation work done at no cost through the state Weatherization Assistance Program.) (4) Removal scope — older homes often need old insulation removed before new install. If a quote skips all four, get another quote.
Frequently asked
Questions about air sealing
What is the difference between air sealing and insulation?
Insulation slows heat conducting through material. Air sealing stops air physically moving through gaps. They solve different problems, and R-value does almost nothing about air movement, which is why a well-insulated house with a leaky ceiling plane still feels draughty and still costs too much to heat.
How much does air sealing save?
ENERGY STAR puts air sealing alone, before any insulation upgrade, at up to 15% off energy bills in older homes. Your number depends on how leaky the house is now, which is exactly what the blower door test measures — and on this measure the measurement is required for the rebate anyway.
Do I really need a blower door test?
For the Atmos rebate, yes, and not as paperwork. The rebate is defined by a documented minimum 20% reduction in CFM(50), so it requires a measurement before the work and another after. Sealing done without those two measurements does not qualify however well it was performed.
Can I air seal the house myself?
Some of it, genuinely. Caulking around window and door trim, weatherstripping, and sealing obvious gaps are reasonable homeowner jobs. The high-value work is in the attic — top plates, penetrations, light housings, the hatch — which means working in a confined space around wiring, and the rebate needs a documented before-and-after in any case.
My attic is already well insulated. Is there anything for me?
This is the measure for you. Air sealing carries no starting-R-value threshold, unlike the attic rebate at below R-20 and the wall rebate at R-5 or less. A home that is well insulated and leaky often does not qualify for insulation money at all, and this is both the rebate it can get and the work it actually needs.
Will sealing the house too tightly cause problems?
It is a real consideration and a manageable one. A house needs a known ventilation path, and the right approach is to seal deliberately and ventilate deliberately rather than rely on random leakage. Combustion appliances need checking as part of the work, which is standard practice on a properly run air sealing job.
When is air sealing not worth doing?
Rarely on its own merits, which is unusual for anything on this site. The case where it does not pay is a house that has already had thorough sealing done and measured tight — there is no 20% reduction left to document, so the rebate is unreachable and the remaining gains are small. A blower door number tells you which side of that line you are on before you spend anything.
Does duct sealing count as part of this?
It is a separate Atmos measure with its own terms: $663, requiring a minimum 20% CFM(25) reduction, measured on the duct system rather than the house. If ducts run through an attic or crawl space, it is worth scoping alongside the envelope work, since much of the access overlaps.
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