Fence Materials Calculator mechanism

Model scope

The instrument is not ready for an honest production label. It currently supports only basic post and picket estimates under explicit straight-run and unit-consistency assumptions; rail, concrete, panel, and gate-aware outputs are unspecified.

• The post formula is valid only for a straight, continuous fence run with posts at both ends and post_spacing treated as the maximum allowable spacing: ceil(total_length/post_spacing)+1.
• The picket formula is valid only when picket_width_spacing means the center-to-center coverage of one picket plus its gap. It does not account for endpoint conventions, gate openings, corners, or partial-width finishing pieces.
• gate_count is listed as an input but is unused. Gate openings should normally reduce panel/picket coverage, while gate structures may require additional posts.
• The specification promises rail/concrete estimates but provides no formulas for rail count, concrete volume, or concrete bag count.
• The specification claims panels/pickets, but no panel-count formula is provided and panel dimensions are not defined.

Units and conventions

• total_length and post_spacing must use the same length unit before division.
• total_length and picket_width_spacing must use the same length unit before division; mixed units require explicit conversion.
• post_spacing is assumed to be a maximum spacing, not a nominal target that may be exceeded.
• picket_width_spacing is assumed to be picket width plus gap, measured as coverage per picket.
• The post formula assumes one post at each end and no separate treatment for gates, corners, or transitions.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "total_length": 120,
    "post_spacing": 8,
    "picket_width_spacing": 0.5,
    "length_unit": "ft",
    "gate_count": 1
  },
  "expected_outputs": {
    "post_count": 16,
    "picket_count": 240
  },
  "working": "Posts: 120 / 8 = 15; ceil(15) = 15; 15 + 1 = 16. Pickets: 120 / 0.5 = 240; ceil(240) = 240. gate_count is not used by the supplied formulas."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

Zero post spacing or zero picket width-plus-gap produces undefined divisions, so the calculator must reject those inputs. The specification also lacks a formula for rail/concrete estimates and does not define how gate_count affects material counts.

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-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json