# Window Well Drainage Gravel Guide

> Measure a gravel bed and optional drain column while recognizing that gravel quantity alone cannot solve grading, drain connection or waterproofing problems.

- Canonical URL: https://buildmeter.net/guides/window-well-drainage-gravel-guide/
- Category: Excavation & Drainage
- Author: Liron Elimeleh
- Publisher: BuildMeter, developed by ELStudios
- Published: July 19, 2026
- Last reviewed: July 19, 2026

## Direct answer

Calculate the gravel bed as length × width × depth and add any separately defined gravel-filled drain column. Keep the finished gravel below the window opening, but verify the complete drainage route, grading, cover, waterproofing and egress requirements before relying on the well.

## Primary calculator

- [Window Well Gravel Calculator](https://buildmeter.net/window-well-gravel-calculator/)

## Calculate the defined gravel zones

Measure the gravel bed beneath the well as length × projection × depth. If the detail includes a gravel-filled vertical column, calculate that cylinder separately and add it. Multiply by the number of equal wells, then add a settlement and handling allowance.

### Window-well drainage checks

| Element | Question to confirm |
| --- | --- |
| Surface gravel bed | What finished depth and elevation are specified? |
| Drain or gravel column | Where does collected water discharge? |
| Window sill clearance | Will gravel remain below the opening? |
| Well cover and grading | How is roof and surface runoff kept out? |
| Egress dimensions | Does the completed well preserve required access? |

## Worked example

Four wells each have a 4 × 2.5 ft bed that is 6 in. deep. Bed volume is 20 ft³ total. Adding four gravel columns 8 in. in diameter and 2 ft deep adds about 2.8 ft³. With 12% allowance, the order is about 25.5 ft³, or 51 half-cubic-foot bags.

## Gravel is only one part of drainage

A loose aggregate bed can temporarily receive water, but it does not create an outlet in slow-draining soil. The complete detail may connect to foundation drainage, a dry well or another approved discharge. Foundation waterproofing and surface grading remain critical.

## Common mistakes

- Filling gravel above the window sill.
- Assuming gravel alone provides unlimited drainage.
- Directing downspouts toward the well.
- Blocking an egress route with a cover or deep fill.
- Ignoring inspection requirements before backfill.

## Use the calculators

Use the [Window Well Gravel Calculator](https://buildmeter.net/window-well-gravel-calculator/) for bags and weight, the [French Drain Gravel Calculator](https://buildmeter.net/french-drain-gravel-calculator/) for connected drain stone and the [Excavation Calculator](https://buildmeter.net/excavation-calculator/) for the soil removal.

## Sources and professional limits

- [DOE Building Science Education — Foundation moisture flow](https://bsesc.energy.gov/energy-basics/building-enclosure-building-science-intro-moisture-flow)
- [District of Peachland — Window-well inspection bulletin](https://www.peachland.ca/media/file/bulletin-installation-window-wells-requirements)
- [U.S. DOE — Building America resources](https://www.energy.gov/cmei/buildings/building-america-tools-and-resources)

## Related calculators

- [French Drain Gravel Calculator](https://buildmeter.net/french-drain-gravel-calculator/)
- [Drainage Stone Calculator](https://buildmeter.net/retaining-wall-drainage-stone-calculator/)
- [Excavation Calculator](https://buildmeter.net/excavation-calculator/)

## Related guides

- [Drainage Pipe Bedding and Trench Measurement Guide](https://buildmeter.net/guides/drainage-pipe-bedding-and-trench-measurement-guide/)
- [Gravel Types for Driveways and Drainage](https://buildmeter.net/guides/gravel-types-for-driveways-and-drainage/)