Basement Window Replacement Cost in 2026

By HomeCost Guide · Updated October 2026 · Angi 2026 national average; typical range $400–$1,000 per window with $150–$600 in labor.

Replacing a basement window costs $400 to $1,000 per window installed in 2026, with Angi's 2026 data putting the national average at $700. Basement windows live a harder life than any other window in the house: they sit at or below grade, fight moisture from both sides, and are often neglected for decades until a leak, a break-in concern, or a finishing project forces the issue. The good news is that basement windows are small and mostly standard-sized, so prefab units from any hardware store fit — vinyl hoppers, sliders, and awnings dominate because they are cheap, weather-resistant, and simple. The costs that surprise people are not the windows but the surroundings: concrete cutting for larger openings, window wells and covers, and waterproofing. This guide prices the window styles, the well work, and the concrete realities unique to below-grade openings.

1. Basement Window Replacement Cost in 2026 cost breakdown

Angi's 2026 basement data ($400–$1,000, avg $700, labor $150–$600) aligns with prefab unit pricing of $100–$800 and custom units at $150–$1,200. Quotes above $1,000 per window almost always include concrete cutting, well replacement, or waterproofing — ask which.

Where the money goes: labor vs materials vs fees

• Labor$150–$600 per windowOld window removal, fitting the new unit, sealing against the foundation, and waterproofing. Concrete cutting or well work is extra.
• Materials$100–$800 per windowPrefab vinyl units are cheap and plentiful; custom sizes, glass block, and egress units cost more.
• Permits & fees$0–$200Same-size swaps rarely need permits. Enlarging openings or adding egress triggers permits and inspections.

Sources: Angi, HomeYou, Thumbtack. Figures are national averages compiled from published industry data; your price will vary by home and location.

2. Signs your basement windows need replacing

Signs your basement windows need replacing

• Water staining on the wall below the window or puddles on the floor after rain — the seal to the foundation has failed.
• Rusted-out steel frames or crumbling concrete around the opening, common on 40-plus-year-old basement windows.
• Single-pane glass with heavy winter condensation, or frames cold to the touch — the basement's heat is pouring out.
• Windows painted shut, swollen shut, or with broken latches that will not secure — a security risk at grade level.
• A finishing project that needs code-compliant egress in a bedroom — small hoppers will not qualify.
• Visible mold or musty smell concentrated around the window area, signaling chronic moisture intrusion.

3. How basement window replacement works

How basement window replacement works

1. Opening and foundation assessment. The installer measures the opening, checks the surrounding foundation for cracks or deterioration, and inspects the window well's condition and drainage. Below-grade openings get a moisture history review — past leaks predict future ones.
2. Window style selection. Hopper, slider, awning, or casement is chosen based on the opening size, well depth, ventilation needs, and whether egress sizing is required. Prefab stock sizes keep costs down; odd old-foundation openings may need custom units.
3. Old window removal. The old unit — often a rusted steel frame set directly in concrete — is cut or chiseled out. The opening is cleaned to sound concrete or block, and any deteriorated mortar or concrete is patched.
4. Setting and waterproofing. The new window is set level, anchored to the foundation, and sealed with masonry-appropriate sealants and flashing. This joint is the entire waterproofing system — below grade, there is no forgiveness for a sloppy seal.
5. Well, cover, and grading check. The window well is cleaned or replaced, a cover is fitted, drainage stone is refreshed, and the exterior grade is verified to slope away from the well. The installer water-tests the seal before leaving.

4. What affects the cost

Hopper vs. slider vs. awning vs. casement

Hopper windows (hinged at the bottom, tilt inward) are the cheapest basement option ($300–$600 installed) and the most secure — the small inward tilt ventilates without creating a climb-through opening. Sliders ($400–$900) give more airflow but have more seal area to fail. Awnings ($400–$800) shed rain while open, a real advantage at grade. Small casements ($500–$1,000) seal best but need well clearance to crank outward. Match the style to the well depth and your security comfort, not just the price tag.

Prefab vs. custom sizing

Most basement openings accept stock prefab vinyl units ($100–$800 for the unit alone) — this is the great cost advantage of basement work. Old stone or block foundations with odd-sized openings force custom orders ($150–$1,200 per unit, 25–50% premium) with weeks of lead time. Measure every opening; in pre-1950s foundations, no two are alike, and assuming uniformity is how projects stall waiting on one custom unit.

Concrete cutting for larger openings

Upgrading from a tiny hopper to an egress-compliant window means cutting concrete — $600–$1,500 depending on poured vs. block construction, plus dust control. This single item can double the project cost, which is why 'just make it bigger' is never casual below grade. If egress is the goal, price the cut, the well enlargement, and the drainage together — the window unit is the smallest line.

Window wells: condition and covers

A rusted, collapsed, or undersized well undermines a new window — replacement wells run $300–$1,000 installed, and covers add $50–$250. Covers are cheap insurance: they keep rain, leaves, and animals out while still allowing emergency exit from inside. Egress wells have code minimums (9 sq ft, 36-inch projection, ladder if deeper than 44 inches) that old wells often miss.

Waterproofing and drainage

Below-grade windows live or die by water management. The seal between window and foundation, the well's gravel base and drain, and the exterior grade slope form one system. Skipping drainage work to save $200–$600 is the most expensive saving in basement remodeling — the resulting leak repair costs thousands. If the old window leaked, the new installation must address why, not just replace the unit.

Glass block as an alternative

Glass block windows ($400–$900 installed) trade ventilation for security, privacy, and near-zero maintenance — popular in urban basements and utility areas. Vented glass block units with a small operable center add airflow for $100–$200 more. They are mortared in like masonry, so installation is a different trade skill than vinyl retrofits; hire someone who has set block before.

Security considerations at grade

Basement windows are the most burglar-accessible openings in the house. Hoppers and glass block are inherently resistant; sliders and casements should get upgraded locks, and security bars or laminated glass ($100–$300 add) are worth considering on hidden sides of the house. A $50 window lock upgrade is the cheapest security improvement in homeownership.

Egress requirements for finished basements

Any basement bedroom needs a code-compliant emergency escape: 5.7 sq ft of clear opening (5.0 at grade), 20 inches wide, 24 inches tall, sill within 44 inches of the floor. Standard basement hoppers do not come close. If finishing the basement is in the plan, install egress-sized windows now — retrofitting after drywall is finished costs far more and makes a mess of completed work.

Foundation condition around the opening

Spalled concrete, crumbling mortar, or step cracks around the opening must be repaired before the new window goes in ($150–$500). Setting a precision vinyl unit into a deteriorating opening guarantees a bad seal and a short service life. The foundation repair and the window installation are one job below grade, even if two trades perform them.

Ventilation and moisture balance

Basements need controlled ventilation, not just sealed windows. An operable hopper or awning that you actually open in dry weather does more for basement air quality than any dehumidifier marketing claim. When replacing, keep at least one operable window per basement zone — sealing every opening tight trades water intrusion for stale, musty air.

5. Saving money & hiring right

Questions to ask your contractor

• Will a stock prefab unit fit my openings, or do I need custom sizes?
• What is the condition of the foundation around each opening, and is repair included?
• How will you waterproof the joint between the new window and the foundation?
• What is the well's drainage situation, and do I need a new well or cover?
• If I finish the basement later, will these windows meet bedroom egress code?
• What locks or security upgrades do you recommend for ground-accessible windows?

6. How costs vary by state

Basement window work is concentrated in regions with basements — the Northeast, Midwest, and Mid-Atlantic. Pricing follows foundation labor and how much concrete work each job needs.

7. Frequently asked questions