Source: https://guthlabs.ai/docs/instruments/drywall-sheet-calculator/implementation/

instrument implementation / implementation-contract

# Drywall Sheet Calculator implementation

A source-bound implementation contract for Drywall Sheet Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-102

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero sheet dimension produces division by zero and an undefined sheet count. The waste-percent convention also permits a large result discrepancy if the input is interpreted as a fraction instead of a percentage.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "surface": "walls",
    "area": 480,
    "area_unit": "ft²",
    "sheet_width": 4,
    "sheet_height": 8,
    "sheet_dimension_unit": "ft",
    "waste_percent": 10
  },
  "expected_outputs": {
    "sheets": 17
  },
  "working": "sheet_area = 4 × 8 = 32 ft²\nwaste multiplier = 1 + 10/100 = 1.10\nwaste-adjusted area = 480 × 1.10 = 528 ft²\nraw sheets = 528 ÷ 32 = 16.5\nsheets = ceil(16.5) = 17"
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/drywall-sheet-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/drywall-sheet-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/drywall-sheet-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`