Measuring a basement window well cover is the single most critical step in ensuring a safe, secure, and functional upgrade for your below-grade living space. An incorrect measurement leads to frustration, returns, and potentially dangerous gaps that defeat the purpose of having a protective barrier. This process requires precision and a specific method, moving beyond simple length and width to account for the unique geometry of most window wells.
Understanding the Two Primary Measurement Types
Before you retrieve your tape measure, it is essential to distinguish between two fundamental cover types: inside-mounted and outside-mounted. An inside-mounted cover sits within the confines of the window well itself, offering a low-profile appearance that integrates seamlessly with the basement’s aesthetic. Conversely, an outside-mounted cover is secured to the foundation walls surrounding the well, providing maximum clearance and structural stability. The type you choose dictates the exact dimensions you need to capture.
The Critical Inside-Mount Measurement Process
For an inside-mounted cover, accuracy is paramount because the cover relies on the integrity of the well’s existing structure. You must measure the width and length at the top, middle, and bottom of the well. Irregular concrete walls are common, and slight variations can render a cover useless if it only fits tightly at one point. Record the smallest internal dimension for both width and length to guarantee the cover can be physically inserted and sit flush against the surrounding bricks or blocks.
Dimensioning for Outside-Mount Security
Outside-mounted covers provide superior protection because they are not constrained by the well’s interior angles. To measure for this configuration, you need to extend your tape measure beyond the well’s perimeter. Capture the external width and length of the well at its base where it meets the ground. Then, add six to twelve inches to both the width and the length. This extension ensures the cover overlaps the top of the well wall, preventing debris accumulation and eliminating gaps where a child or pet could potentially climb out.
Accounting for Height and Angle
Unlike a standard window in your home, a basement window well often has a slanted profile. The top is wider than the bottom. To determine the appropriate cover height, measure the vertical distance from the bottom of the well floor to the desired top edge of the cover. If you are opting for an outside mount, you must factor in the angle of the well walls. A cover placed too high on a steeply angled wall may not provide adequate head clearance for an adult, while a cover placed too low might channel water toward the foundation.
Tools and Preparation for Success
Relying on an inadequate tool, such as a flimsy sewing tape or a retractable metal tape that bends, will compromise your measurements. Invest in a sturdy, twenty-five-foot fiberglass or metal tape measure for consistent accuracy. Additionally, bring a notepad and pencil to record dimensions directly on your blueprint or scratch paper. Avoid relying solely on memory, as sequential numbers can easily be transposed, leading to a cover that is millimeters off and functionally incorrect.
Verification and Final Checks
Once you have recorded the primary dimensions, treat the measurement phase as if you are verifying a mathematical equation. Physically re-measure at least two of the dimensions to confirm they match your initial readings. If you are measuring for an outside mount, double-check that the added extension creates a symmetrical overhang on all sides of the well. This final verification step is the safeguard against costly errors and ensures the cover will function as intended for years to come.
