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Foundation Sheet Drain Drainage Rate Calculator

Calculate the total drainage flow capacity of a dimpled sheet drain across a foundation wall's width.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
65.62 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Total drainage capacity

100 L/s

Check your inputs

Rated flow capacity varies by product and compressive load condition (capacity typically decreases under soil/backfill load) — use your specific sheet drain product's rated capacity under expected field loading, not an uncompressed lab value.

At the values currently entered, the total drainage capacity works out to 100 L/s. Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 100 L/s — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Total drainage capacity = the drain product's rated flow capacity per unit width × total drainage width, the standard method for scaling a manufacturer's per-unit-width flow rating to a full installation

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Frequently asked questions

Why does total drainage capacity scale directly with width?
A dimpled sheet drain's rated flow capacity is expressed per unit width because the dimpled core channels water vertically down the drainage plane — laying more width side by side simply adds parallel drainage channels, so total capacity scales linearly with the total width installed.
Why does the rated capacity depend on compressive load?
Backfill and soil pressure compress the dimpled core, reducing the open channel height available for water to flow through. Manufacturers typically publish flow capacity at one or more compressive load conditions — always use the figure that matches your expected backfill depth and soil load, not an unloaded lab rating.
Does this account for the drain's connection to a footing drain or sump?
No — this only estimates the sheet drain's own flow capacity across the given width. The downstream footing drain, collector pipe, or sump pump must also be sized to handle this flow rate without becoming the bottleneck.