Basement Window Replacement in Fort Collins

A basement window replacement swaps a failing single-pane, hopper, or rotted-frame basement window for a modern, efficient unit in the existing opening, with no concrete cutting. In Fort Collins it runs $450 to $1,200 per window installed, and because there is no dig it runs year round. It is the right job when the opening is fine and the window is not. It is the wrong job when someone needs an egress window and is hoping a swap will get them there.

What the city requires on a replacement

Fort Collins lists window replacements among the projects that need a permit, and its Emergency Escape and Rescue Windows guide has a specific rule for a replacement in an escape opening: same operation and same clear opening size or larger, but not less than 22 inches high, 20 inches wide, and 4 square feet of net clear opening. That is the existing-window allowance under the city’s code. It is smaller than the 5.7 square feet a new window needs, which is what makes replacement a real option in a lot of older basements.

The city’s basement finish guide also sets the energy line: U-factor 0.28 maximum, SHGC 0.35 maximum, labeled on every new or replaced window. And it reminds owners that if you are re-using an existing window as the escape opening for a bedroom, it has to meet the sill height and well depth standard in force when the house was built. The city’s own chart puts a 48 inch sill on homes permitted after November 1966 and 44 inches after December 1977; the 36 inch well with ladder arrived in May 1998.

What we replace and what we install

What comes out. Original single-pane hoppers on steel or wood frames, sashes that no longer latch, frames rotted from years of a wet well, and units whose seals failed and fogged. In the older blocks of Fort Collins the city’s historic districts date to the 1870s through 1930s, and a fair number of those basements still have their original small windows.

What goes in. Vinyl or fiberglass sliders, hoppers, or casements, double-pane low-e glass at the city’s energy line, foam-insulated and sealed to the buck. Sliders are the value pick. Casements give the most net clear opening per rough opening, which matters when the replacement is also the escape window.

Replacement or enlargement?

The tape measure decides. With the sash fully open, measure the clear height and width of the hole and multiply.

• 4 square feet or more, at least 22 by 20 inches, in an escape opening: a replacement window meets the city’s existing-window allowance.
• Under 4 square feet, or the sill is above the height allowed for the house’s era: a replacement cannot fix it. The opening needs to be enlarged, which is a cut, an engineer’s letter, and a permit, priced on the egress window installation page at $2,800 to $5,000 for an enlargement.
• The room is going to be a bedroom for the first time: the city’s guide is explicit that a window alone does not create a legal bedroom. See basement bedroom conversion.

The failed inspection page walks the tape through the whole check.

If the house is a rental

The City of Fort Collins Landlord-Tenant Handbook sets its own floor for rental housing, and it is worth knowing before you order a window for a rented basement. The required emergency escape and rescue opening must be maintained to the code in effect when the house was built, or provide a net clear opening of at least 720 square inches, whichever is greater, with a sill no higher than 48 inches above the interior floor. The handbook also requires smoke alarms in each room used for sleeping, outside each sleeping area, and on every story including the basement. A replacement that meets the city’s 22 by 20 inch, 4 square foot existing-window allowance may still fall short of the rental standard, so on a rental we size the replacement to clear both. Since January 1, 2025 most long-term rentals in the city must register annually and self-certify to the property maintenance code, which makes this the wrong place to guess.

Outside city limits

Unincorporated Larimer County treats a replacement differently: the county’s permit-requirements page says that replacing a window with one the same size or smaller than the existing window does not need a county permit. A larger opening does, and the county takes residential permit applications on paper rather than through its online portal. Loveland, Windsor, Wellington, Timnath, Greeley, and Berthoud each have their own office, and the permits page lists them.

Fix the well first

A new window sealed into a well that holds water will fail the same way the old one did. Before setting a replacement we look at the well: standing water, silt at the bottom, rust at the soil line, grade tipping toward the house. On the swelling clays the Colorado Geological Survey maps under Fort Collins, a well without a gravel drainage column is a bucket, and the window seal is the bucket’s weakest point. If the well needs a drainage rebuild or a replacement, we quote it in the same visit rather than sell you a window that will be staining in two springs. The leaking window page explains why the water is usually not the window’s fault.

Pricing

Every line matches the pricing page. Colorado labor runs above the upper Midwest, and these ranges reflect it.

How the job goes

1. Measure the true net clear opening and the well, and confirm which era of the city’s sill-height chart the house falls under.
2. File the permit through the city portal, or the county or town office for addresses outside Fort Collins.
3. Pull the old unit, clean and repair the buck, and set the new window plumb and square.
4. Foam, flash, and seal, then label for the inspector.
5. Correct anything obvious in the well while we are there: a downspout dumping beside it, a missing cover, grade tipping in.

Send a photo of the window from inside and one of the well from outside. That is enough to tell you whether a swap is the whole job or the start of one. Free measure, flat quote, across Fort Collins, Loveland, Greeley, and Berthoud.