Transparency · Contract 2026-08-20.2
Methodology
Every calculator on this site is governed by a written content-and-calculation contract (version 2026-08-20.2). This page describes what each sheet computes, what its results are allowed to say, and — just as importantly — the questions it refuses to answer.
What the sheets are
| Sheet | Classification | What it does |
|---|---|---|
| Area & solution | Transparent arithmetic · planning estimate | Sums pane areas, applies your margin, and converts area to solution volumes using only the application rate and dilution ratio you enter from a product label. |
| Pole reach | Transparent geometry · hard stop states | Computes √((H−P)² + S²) + A and compares it with your entered usable pole length. Site-condition answers can stop the plan regardless of geometry. |
| Access decision | Conservative decision composer | Composes one of four planning states from eight answers. It is not a compliance checker and never selects equipment. |
| Time planner | Transparent arithmetic · planning estimate | area ÷ your productivity + setup + moves. No default productivity is authoritative. |
Result vocabulary
Tool results use planning vocabulary only: planning estimate, geometric reach, entered values, stop and reassess, ground-based method fits the entered geometry, competent access planning required, check the product or film manufacturer’s instructions, insufficient information. A companion list of terms is banned from every result, interpretation, warning and assumption a sheet can emit — words that assert safety, compliance, approval, guarantees or suitability — and an automated scanner enforces the ban in the test suite and against the built site. A geometric margin is a length, never a safety margin.
Fail-closed rules
Each sheet refuses to produce a result rather than guess. Concretely:
- Blank, non-numeric, non-finite, zero-where-positive-required and negative-where-forbidden inputs invalidate the calculation.
- Editing any input after a successful calculation immediately clears the result, interpretation, notes and print availability — there is no stale output state.
- If a form control is missing from the page (a broken browser extension, a partial load), the sheet reports it and refuses to calculate.
- Optional inputs never get invented defaults: without an entered application rate there is no solution volume; without a rate and ratio there is no concentrate split.
- Numeric overflow to infinity fails closed with an out-of-range message.
How “unknown” answers are treated on the pole reach planner
The contract makes electrical hazards and thunder stop conditions when answered yes or unknown, and visibility a stop condition when answered no or unknown. For the remaining conditions — high wind, pole defect, obstructions, and control of the working area — an answer of yes (or no for area control) stops the plan, and an answer of unknown fails closed as Insufficient information: an unknown decisive condition never falls through to a geometric interpretation. Geometry values are withheld entirely in stop and insufficient states.
How the access decision composes its states
Order: (1) any unresolved hard hazard — electrical not verified absent, weather/control not acceptable, site not controlled, including “unknown” — returns STOP; (2) a practicable inside method returns the inside-first planning state; (3) complete ground-method evidence (glass in view, an entered checked method, operator competence) returns the ground-method planning state; (4) anything else — including an existing place of work that still needs site-specific confirmation — returns “Competent access planning required”. The tool’s verdict line is restricted to four fixed sentences; the inside-first and ground-method states share the ground-based verdict sentence and are distinguished in the planning notes beneath it.
Display rounding
- Areas: two decimals (m²).
- Litres: three decimals below 10 L, otherwise two.
- Millilitres: nearest 1 ml, display only.
- Geometry: three decimals on screen; print records also carry the six-decimal unrounded value.
- Times: rounded to the minute on screen, with the unrounded hours and minutes shown alongside.
- All chained calculations use unrounded values throughout.
Without JavaScript, and on paper
Every sheet ships as static HTML showing a labelled worked example — “Worked example — fixed entered values” — with its formula written out in words and a blank worksheet. JavaScript upgrades the sheet to a live calculation (“Current calculation from entered values”) and enables printing; a printed sheet is a plan record carrying the route, date, contract version, inputs, outputs, assumptions, stop state, disclaimer and source keys. While a sheet is edited or invalid, printing is unavailable and the record marks itself as having no current calculation.
Evidence and citations
Consequential claims link to the source registry, which records publisher, URL and the date each document was captured. The hierarchy: legislation and HSE guidance for work-at-height principles; the HSE/FWC best-practice guide for water-fed pole hazards and stop conditions; manufacturer documents for product-specific film care (labelled as product-specific, never universal); Kärcher’s guidance as general method context; and transparent arithmetic over your entered values for everything numeric. Where a source does not state a publication date, the registry says so rather than inventing one.
Corrections log
- 2026-08-20 — First publication of the site under content contract 2026-08-20.2. Changes to formulas, decision order, source boundaries or result vocabulary will be listed here with dates and the nature of the change.
This site is an independent information project. It is not a window-cleaning contractor, shop, training provider or compliance checker, and its sheets are planning aids over your entered values — not professional advice.