Form Stripping Time Calculator

No -- Min Stripping Time is completely independent of the 28-Day Design Strength value. The strength-gain model targets a fixed PERCENTAGE of f28 for each member type, and that percentage target is what determines the timeline, so the actual f28 number cancels out of the time calculation entirely. It does, however, change Required Strength (psi) and Estimated Strength at Strip (psi), which scale directly with f28.

Member Type has the largest effect of any single input across its full range -- switching from vertical forms to a beam/joist soffit moves Min Stripping Time by roughly 12.4x, only modestly more than the swing Ambient Temperature can produce across its own full range (roughly 9.6x) -- but that effect only shows up when you actually switch member categories, since it's a coded 0-2 selection rather than a continuous quantity. Among the continuously-adjustable inputs, Ambient Temperature has the strongest effect, since the calculator adjusts the base strength-gain timeline relative to a 70°F reference — colder curing conditions stretch the wait, warmer conditions shorten it.

Because soffit forms (the formwork under a slab or beam) have to support the member's own weight until the concrete can carry it, so the calculator requires a much higher target strength fraction before stripping — 50% of design strength for slabs and 70% for beams, compared to just 12.5% for vertical wall or column forms, which only need enough strength to hold their own shape once unsupported.

No — it's a simplified maturity-method estimate for planning purposes, built on the form-removal strength-fraction guidance in the American Concrete Institute's formwork guide, ACI PRC-347-14(21) (Guide to Formwork for Concrete). Most project specifications require field-verified cylinder breaks or in-place maturity-meter readings confirming the actual required strength has been reached before structural formwork is removed, regardless of what this calculator's timeline suggests.