How this list works
How were these companies chosen?
This list is compiled from publicly available signal — service focus, certifications, tenure, and Google ratings as listed — not paid placement and not a personal endorsement. Denver Colorado Insulation is a homeowner information resource that connects you with local installers. It does not perform installation work itself, and a spot on this list is not a guarantee of any company's work.
Who's best for a whole-home energy audit in Denver?
An audit-led approach diagnoses the whole envelope — not just the attic — before recommending work.
REenergizeCO
Denver, CO
BPI-certified and LEED-accredited, with over 15 years of audit-first experience. Their own site names them a Top Producing Contractor with Xcel Energy, built around the home energy audit rather than insulation alone.
Which company is strongest on Xcel rebate handling?
Confirmed directly on their own site as an authorized Xcel Energy Trade Ally contractor — eligible to file the rebate paperwork on your behalf, not just eligible to install.
Insulation Nation
Denver, CO
An authorized Xcel Energy Trade Ally contractor with a dedicated rebate-processing service — the paperwork is a named line item, not an afterthought.
Who does spray foam well in the Denver metro?
Four companies list spray foam as a named, dedicated service line.
Koala Insulation of Denver
Commerce City, CO
Offers the full insulation-material menu — spray foam, blown-in, and batt — plus solar attic fans and crawl space encapsulation, under one Commerce City-based crew.
Koala Insulation of SE Denver
Englewood, CO
Sister location to Koala Insulation of Denver, based in Englewood and covering southeast-metro homes with the same spray foam, blown-in, and crawl space encapsulation lineup.
NetZero Insulation
Denver, CO
BPI-certified, covering everything from spray foam to rim joist sealing to blower door testing in one operation.
Level Up Insulation Co.
Denver / Colorado Front Range
Covers spray foam, blown-in, attic, and crawl space work across the Front Range.
Which contractors focus on attic insulation and air sealing?
Air sealing has to happen before or alongside insulation to actually hold — these three name it as a distinct service, not a footnote.
Koala Insulation of Denver
Commerce City, CO
Offers the full insulation-material menu — spray foam, blown-in, and batt — plus solar attic fans and crawl space encapsulation, under one Commerce City-based crew.
NetZero Insulation
Denver, CO
BPI-certified, covering everything from spray foam to rim joist sealing to blower door testing in one operation.
Bestway Insulation LLC
Denver, CO
Over 47 years insulating Colorado homes, with home energy audits and air sealing built in alongside attic, wall, and vaulted-ceiling work.
Who specializes in blown-in and cellulose insulation?
The two companies below name blown-in or cellulose as a core service.
Koala Insulation of SE Denver
Englewood, CO
Sister location to Koala Insulation of Denver, based in Englewood and covering southeast-metro homes with the same spray foam, blown-in, and crawl space encapsulation lineup.
Denver Insulation, LLC
Denver, CO
Over 20 years serving Denver, Aurora, Lakewood, and Boulder, with spray foam and blown-in cellulose covering both residential and commercial jobs.
Which companies have been in Denver the longest?
Tenure isn't the only signal that matters, but these three have the longest publicly stated track records on this list.
Mucilli Brothers Insulation
Denver, CO
Denver's longest-tenured name on this list, serving the metro since the 1970s, with a service range that extends beyond insulation into soundproofing and fireproofing.
Bestway Insulation LLC
Denver, CO
Over 47 years insulating Colorado homes, with home energy audits and air sealing built in alongside attic, wall, and vaulted-ceiling work.
Denver Insulation, LLC
Denver, CO
Over 20 years serving Denver, Aurora, Lakewood, and Boulder, with spray foam and blown-in cellulose covering both residential and commercial jobs.
Sources
What the data says
According to the Xcel Energy, “to receive a rebate, all insulation and air sealing upgrades must be completed by a participating contractor.”
According to Xcel Energy’s insulation and air sealing rebate program rules, a blower-door-verified reduction in air leakage of at least 20% is required to qualify for the full air-sealing rebate.
According to the Department of Energy, “adequate insulation and air sealing can reduce heating and cooling costs by 10% to 20% in typical homes.”
Get organized before you call anyone
Know your numbers first.
Two free tools turn "get a few quotes" into an informed conversation, with any company on this list or off it: the cost calculator gives you a real price range for your home size before the first call, and the rebate eligibility checker tells you which Xcel programs actually apply. For the full vetting checklist — insurance, scope of work, red flags — see how to choose a Denver insulation contractor.
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.
Your info is in. Denver Colorado Insulation refers your request to an independent local insulation contractor — not necessarily one of the companies compared on this page — and may be compensated for that referral. There's no fixed timeline for when they'll reach out. While you wait, here's what to look for in the quote you receive: (1) R-value target — current Colorado code is R-49 to R-60 for attics, anything less is under-spec. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first. (3) Rebate handling — Xcel rebate paperwork should be handled for you, not by you. (The federal IRA Section 25C credit expired in 2025 and Colorado HEAR closed for the Front Range — Xcel programs are now the active rebate stack.) (4) Removal scope — pre-1990 homes often need old insulation removed before new install. If a quote skips all four, get another quote.
Frequently asked
What do Denver homeowners ask before hiring an insulation contractor?
How were the companies on this list selected?
From publicly available signal only — service focus, certifications, tenure, and Google ratings as listed. No company paid for placement, and inclusion isn't an endorsement or a guarantee of workmanship.
Do these companies handle Xcel Energy rebate paperwork?
Some do, some don't — it's called out per company above. Xcel's rebate requires the work to be completed by a participating contractor (Xcel's current term; it used to say "Trades Ally"), so confirm that status directly with whichever company you contact, even if it's listed here.
What makes a good insulation contractor in Denver?
Proof of insurance on request, a quote based on an actual attic inspection — not a guess from the driveway — and a written scope naming your current and target R-value. The full vetting checklist, including the questions to ask before signing, lives on the choosing-a-contractor guide below.
Is this list ranked first to last?
No. Companies are grouped by what they're strongest at — energy audits, rebate handling, spray foam, blown-in, or tenure — because a single 1-to-9 ranking would hide the fact that different homes need different things. A 1970s general insulator and a 15-year audit-focused specialist aren't competing for the same job.
Does Denver Colorado Insulation install insulation?
No. Denver Colorado Insulation is an information and lead-connection resource — this list, the cost calculator, and the rebate eligibility checker exist to help homeowners get organized before calling anyone, including the companies named here.