Foundation Waterproofing Calculator

Two of this calculator's six inputs are walled off from outputs a reader might expect them to touch. Form Tie Spacing only ever changes Form Ties to Seal -- it has no path into Material Quantity at all, since the coating/membrane volume is driven purely by wall area (Total Application Area), not by how the concrete forms were tied together. And Include Footing Detail, despite adding real area to Total Application Area and therefore to Material Quantity and cost, never touches Drainage Board Sheets: that output is sized off Net Wall Area alone, with no footing wrap included, so toggling the footing detail on or off leaves the drainage board line item exactly where it was.

Perimeter and wall height both raise Material Cost and Total Estimated Cost monotonically across their full declared ranges, but which one moves Total Estimated Cost more depends on the rest of the inputs -- at the default footing-detail setting, Perimeter is the larger factor, but turn footing detail off and Wall Height becomes the larger factor instead, so no single input safely "wins" independent of how the calculator is configured. Cost Per Sq Ft does not share that clean monotonic behavior: because it's Total Estimated Cost divided by Net Wall Area, and each material line item is rounded up (Math.ceil) to whole gallons, rolls, or sheets before pricing, a one-foot increase in Perimeter can occasionally land just above a rounding threshold and nudge Cost Per Sq Ft down even while every underlying cost total keeps rising -- e.g. sweeping Perimeter from 150 to 156 ft at default inputs gives Cost Per Sq Ft of 4.18, 4.26, 4.25, 4.27, 4.25, 4.24, 4.22, reversing direction three times, even though Material Cost and Total Estimated Cost rise every single step. Window/Opening Deductions works by simple subtraction: it reduces Net Wall Area directly, and everything downstream of that area -- material quantity, drainage board sheets, labor cost -- shrinks with it, though the effect is easy to miss near a deductions value of zero, since an input that starts at zero has no small nudge to probe; you have to actually raise it to see the area shrink.