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Gantt & critical path templates

Six-Day Site Week — The Calendar Is Not An Assumption

The same durations under a Monday-to-Saturday working week, which is what a construction site runs. The working week is declared, not assumed, so "12 days" means one unambiguous thing and the engine says which — and the non-working days are shaded, so a bar that takes twelve days and spans fourteen is legible as such rather than mysterious. Reports clean.

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Roof replacement — Gantt chart with critical path9 tasks; from 2026-04-06 to 2026-05-18, 36 working days; 8 on the critical path; every check ran and found nothing.Roof replacementMo 6 Apr 2026 → Mo 18 May 2026 · 36 working days · 43 calendar dayscritical path: scaf → strip → deck → felt → tile → rain → down → doneshorten first: strip (up to 6d) · deck (up to 5d) · tile (up to 5d)Apr 2026May 2026Mo6Tu7We8Th9Fr10Sa11Su12Mo13Tu14We15Th16Fr17Sa18Su19Mo20Tu21We22Th23Fr24Sa25Su26Mo27Tu28We29Th30Fr1Sa2Su3Mo4Tu5We6Th7Fr8Sa9Su10Mo11Tu12We13Th14Fr15Sa16Su17Mo18EnablingNew roofOff siteSS+3d▲ Scaffold4d · shorten → 4d▲ Strip existing covering6d · shorten → 6d▲ Deck repairs5d · shorten → 5d▲ Underlay and battens4d · shorten → 4d▲ Tiling12d · shorten → 5dLeadwork4d · float 5d▲ Rainwater goods3d · shorten → 3d▲ Scaffold down2d · shorten → 2d▲ Practical completion2026-05-18critical — zero floatnear-criticalhas floattotal floatmilestonenon-working daybaselineEvery check ran, and none of them found anything.·Mo 6 Apr 2026 to Mo 18 May 2026 — 36 working days across 43 calendar days, on a Mo–Sa week with 1 holiday·one critical path, through 8 tasks — shortening any one of them shortens the project, up to the point another path becomes binding·to finish sooner, shorten `strip` by up to 6 working days (the whole task); `deck` by up to 5 working days (the whole task); `tile` by up to 5 working days (then the next-longest path becomes binding).Anything beyond those figures moves nothing — the gain from taking δ days off a task is min(δ, the figure above), and it is zero for every critical task not listed here.

Make it your own.

title "Roof replacement"
start 2026-04-06
calendar mon-sat
holiday 2026-05-04 "Early May bank holiday"

section "Enabling"
  task scaf  "Scaffold" 4d
  task strip "Strip existing covering" 6d after scaf
  task deck  "Deck repairs" 5d after strip

section "New roof"
  task felt  "Underlay and battens" 4d after deck
  task tile  "Tiling" 12d after felt
  task lead  "Leadwork" 4d after ss:tile +3d
  task rain  "Rainwater goods" 3d after tile, lead

section "Off site"
  task down  "Scaffold down" 2d after rain
  milestone done "Practical completion" after down