Can you install an egress window in winter in Fort Collins? Frost line, freeze dates and the smart off-season plan

September 21, 2026

Sometimes, but usually you should not want to. Fort Collins and Larimer County both set the design frost depth at 30 inches below grade, and an egress well digs four to six feet down through ground that spends the winter freezing and thawing above that line. Winter excavation is slower, dirtier, and harder on the drainage bed than the same dig in May. The full install still runs $3,800 to $7,000, but the schedule risk is on you. The smarter winter plan is paperwork: the engineer’s letter, the permit, and the window order, so the cut happens in the first dry week of spring.

Here is what the local climate record says, what the codes require before anyone can dig, and how to use the cold months well.

The Fort Collins winter, by the numbers

The weather station on the Colorado State University campus, northwest of the Lory Student Center, has been recording since January 1, 1889. NOAA’s 1991 to 2020 normals for that station, at 5,004 feet, give this picture:

Two things stand out for excavation. First, the frost-free window is short, about five months from the first of May to the first week of October. Second, most of the moisture that falls here falls as snow, and it arrives on top of the clay soil that this city sits on. A hole opened in January sits under snowmelt on frozen ground. That is the worst environment for setting a gravel drainage column that has to work for 25 years.

What the 30-inch frost depth means for the dig

The City of Fort Collins lists a 30-inch frost depth in its building code page, and Larimer County’s structural design sheet for the 2024 residential code says the minimum frost depth is 30 inches below grade countywide. That number sets how deep footings have to go so the ground under them does not freeze and heave.

For an egress well, it matters two ways:

• The dig goes well below it. The bottom of a code well sits under the window sill, which sits up to 44 inches below the floor, which is already several feet below grade. Then the gravel column goes deeper still. So the crew is working through the entire frost zone and below it.
• Frozen ground does not drain. From roughly November through March the top of that 30-inch zone is frozen for stretches. Water that lands in an open excavation cannot soak away. It sits, refreezes, and expands against the fresh anchors and the new well. The heaving well page describes what that looks like a year later.

Contractors can and do dig in winter with a machine and a warm spell. It costs more in time, and the drainage bed is set into ground that is not behaving the way it will in April. We will do it when a closing date demands it. We will also tell you that it is the second-best option.

What has to happen before anyone digs

This is the part that makes winter useful. Fort Collins requires more paperwork for a foundation opening than most people expect, and all of it can be done while the ground is frozen.

The engineer’s letter. The city’s emergency escape window guide is explicit: for new or altered windows in foundation walls, submit a letter or drawings evaluated and stamped by a Colorado licensed engineer. The residential basement finish guide repeats it, listing installation of a new window in an existing foundation wall as a condition that requires engineered and stamped structural plans or a letter. That letter runs $300 to $700, and it takes an engineer’s site visit and turnaround time, which is easier to schedule in February than in the spring rush.

The permit. Cutting a new window opening in a foundation is a permitted job in Fort Collins. Since April 1, 2026, permits submitted to the city fall under the 2024 International Codes with the city’s local amendments, and the 2021 editions stay posted for reference only until October 1, 2026. The fee runs off the city’s valuation table and typically lands at $150 to $300 for an egress job. We pass it through at cost. The permits and inspections page explains which office covers which address, because Loveland, Windsor, Wellington, Timnath, Greeley and Berthoud each handle their own.

The bedroom permit, if that is the goal. The city guide also says something most homeowners do not know: installing an egress window does not by itself create a legal bedroom. A remodel or basement finish permit is required to create or relocate a bedroom. If the point of the window is a fourth bedroom on the listing, the basement finish permit is part of the winter to-do list too. The basement bedroom conversion page covers what that permit checks.

The window order. Egress units sized to beat the net clear opening are not always on the shelf. Ordering in winter means the unit is on hand the day the saw arrives.

The off-season plan

Here is the sequence that gets a Fort Collins basement bedroom finished by early summer without paying for a frozen dig:

1. December to January: measure. Free on-site measure. We confirm the wall, the footing depth, the joist bearing, the utilities in the wall cavity, and where the well can go with a clear path to the street or sidewalk, which the city requires.
2. January to February: engineer and permit. Engineer’s site visit and stamped letter. Permit application through the city’s online portal with the letter and the plan attached. If a basement finish permit is also needed, it goes in at the same time.
3. February to March: order the window. Unit sized backward from the code numbers, well and ladder ordered to match the depth.
4. April: watch the ground. The median last freeze is May 1, but the soil is usually workable in April between storms. First dry week, the machine comes.
5. April to May: cut, set, drain, backfill, inspect. One to two days on site. Final inspection scheduled before the finish crew touches drywall.

That plan puts you at the front of the spring queue instead of behind everyone who called in April.

What runs year-round

Not every job needs a hole in the yard. A basement window replacement in an existing opening is interior work with no excavation. It runs $450 to $1,200 per window and we do it straight through the winter. The city requires replacement windows to keep the same operation and a clear opening at least as large as before, and never smaller than 22 inches high, 20 inches wide and 4 square feet, so a swap can also fix a draft without touching the well.

Well covers, ladder retrofits, and liner work in a well that is not frozen solid are also winter-friendly. The window well calculator prices those on their own.

The honest answer on winter installs

If you have a closing date in February and a buyer’s inspector who flagged the basement bedroom, call. We will look at the wall, check the forecast, and tell you whether the dig is workable and what it costs to do it right in the cold. If you have any flexibility at all, spend the winter on the engineer, the permit, and the window, and let the ground thaw before the saw comes out. The price is the same either way, and the well you get in May is the better well.

The egress window calculator gives you the range now, from the same table we quote from on the phone.