Window/Door Rough Opening Calculator mechanism

Model scope

The arithmetic is valid only when the clearance is explicitly defined as a per-side clearance. The honest label correctly requires verification against the specific manufacturer's installation specification; the implementation should display that warning and identify the clearance unit and whether the entered value is per side or total.

• The formula is ambiguous about whether standard_clearance is the clearance for one side or the total clearance for both sides. If it is per side, the correct formulas are rough_opening_width = unit_width + 2 * clearance_per_side and rough_opening_height = unit_height + 2 * clearance_per_side.
• There is no universal standard clearance value; the required rough opening depends on the specific manufacturer's installation instructions and may require different width and height clearances.
• The specification does not state whether width and height may have separate clearance values, which is necessary for products with asymmetric installation requirements.

Units and conventions

• Each dimension and its corresponding clearance must use the same unit before addition.
• The inch vectors assume unit dimensions and per-side clearances are in inches.
• The metric vector assumes dimensions and per-side clearances are in millimetres; 12.7 mm equals 0.5 in.
• The calculations assume standard_clearance means clearance per side, not total clearance.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "unit_width_in": 36,
    "unit_height_in": 48,
    "clearance_per_side_in": 0.5
  },
  "expected_outputs": {
    "rough_opening_width_in": 37,
    "rough_opening_height_in": 49
  },
  "working": "Width: 36 + (2 × 0.5) = 36 + 1 = 37 in. Height: 48 + (2 × 0.5) = 48 + 1 = 49 in."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

Extreme but representable numeric inputs overflow to Infinity in JavaScript, zero dimensions can produce numerically valid but physically invalid openings, and an unlabeled clearance value is conventionally ambiguous and can change the result by 1 inch in each dimension.

Other records

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
• BOUNDARY_HAZARD_CATALOG.json