According to the City of Louisville Building Safety, the City of Louisville has adopted the 2024 International Code Council codes, including the 2024 International Residential Code and the 2024 International Energy Conservation Code, along with local amendments, effective December 6, 2025.
Why insulate
Why do Louisville homes need insulation attention?
Louisville's housing-age numbers are genuinely mixed, and not in the usual way. Close to half of Louisville housing units (46.0%) predate 1990, and the median home dates to about 1991 (Census Bureau American Community Survey 5-year estimates, 2020-2024) — on paper, one of the older housing stocks in this service area. But the December 2021 Marshall Fire destroyed several hundred Louisville homes, concentrated in 1970s-80s subdivisions, and much of that lost stock has been rebuilt since. A home that reads as 'built in the 1970s' in some records may in fact be a 2022-or-later rebuild sitting on an older lot.
What that means practically: we won't assume your Louisville home's age from its neighborhood or its lot without asking. If your home was rebuilt after the fire, it was very likely built to a recent code edition with insulation well above older baselines — a different conversation than a pre-1990 original-stock home.
Utility-wise, Louisville is simpler than Longmont: Xcel Energy is confirmed as both the gas and electric utility here, so there's one insulation rebate program to check, not two.
According to the U.S. Census Bureau, the ACS 5-year estimates are available for the nation, all states, and places (i.e., towns or cities) — the geography behind this site's town-by-town housing-age figures, drawn from the 2020-2024 release, table B25034 for year structure built and table B25035 for median year structure built.
Rebates & credits
What rebates can Louisville homeowners claim?
Xcel Energy — the gas and electric utility here:
- Xcel Energy Insulation and Air Sealing Rebate — pays a percentage of project cost for gas-heat customers against per-measure caps; ask your contractor for the current rate. A reduced tier applies to Xcel electric customers with central air conditioning whose heating fuel is not provided by Xcel Energy. Requires a participating contractor and, unless a first blower door test already finds the home tight enough by Xcel Energy's own measure, a documented 20% reduction in CFM50.
Xcel's rebate excludes new construction, additions, garages, sheds, and mobile homes. Ask your contractor to confirm your project scope and heating fuel qualify before assuming a figure.
For current Xcel rebate amounts and program rules, see the Xcel Energy insulation and air-sealing rebates page. Eligibility may depend on program funding levels and qualifying product specifications.
Get a quote
Tell Us About Your Home
30 seconds to fill out. Free quote, no high-pressure follow-up.
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 — ask what R-value your contractor is quoting to, in writing, and confirm the figure your permit is reviewed against with the City of Longmont's building department. (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 whether your project qualifies for Xcel's gas-heat tier or the reduced tier, which is open only to homes on Xcel electric service that have central air conditioning and whose heating fuel is not provided by Xcel Energy. (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 here.) (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 Louisville homeowners ask most about insulation and rebates?
My home was rebuilt after the Marshall Fire — do I still need this?
Probably not yet, if the rebuild was recent. Homes rebuilt after the December 2021 Marshall Fire were built to a recent code edition, with attic insulation well above older baselines. If your bills are normal and comfort is fine, hold the money — this page is aimed at Louisville's pre-1990 original-stock homes, not fire rebuilds.
How do I know if my Louisville home is original stock or a rebuild?
Check your county assessor record for the actual year built and any recent permit history — that's more reliable than assuming from the neighborhood or the lot. A 2022-or-later built date means recent code, not the older baseline this page discusses.
Does Louisville have its own separate electric-utility rebate, like Longmont does?
No. Louisville is confirmed Xcel-electric — Xcel Energy serves both gas and electric here, so there's a single insulation rebate program to check. Longmont's situation (a second, Longmont Power & Communications-only rebate) doesn't apply in Louisville.
What does Xcel's rebate actually pay for a Louisville attic project?
For gas-heat customers, Xcel pays a percentage of project cost against per-measure caps — ask your contractor for the current rate. A reduced tier applies only where Xcel provides the electric service, the home has central air conditioning, and the heating fuel is not provided by Xcel Energy. Xcel requires a participating contractor and, unless a first blower door test already finds the home tight enough by Xcel Energy's own measure, a documented 20% reduction in CFM50.
Do you serve all of Louisville?
Yes — all of Louisville, plus Longmont, Lafayette, and Niwot. Service areas listed at the bottom of this page show where we work regularly.
Service area
Where do you provide insulation services in and around Louisville?
- Louisville
- Old Town Louisville
- greater Louisville area