Sundial House

rootspine:house-on-the-sundial

House on the Sundial

Keys by 17 December 2027, if the brief starts by 1 December 2026.

A four-bed family house, planned backwards from the day its keys change hands and placed on the beach's shared clock: 455 tasks, ten participants, one spine. For keys by Friday 17 December 2027, 200 simulated builds say start by Tuesday 1 December 2026 for nine chances in ten; the plain backcast date, Monday 14 December, is a coin flip.

Start by
Tue 1 Dec 202690% of 200 simulated builds; Mon 14 Dec is a coin flip
On site
Wed 2 Jun 2027after about 15 working weeks with the council
Weathertight
Thu 9 Sep 2027roof on, windows in
Keys
Fri 17 Dec 2027planned handover 23 Nov, then the buffer
The plan
455 tasksten hands, 758 steps
Words used on this page
Beach
a public commons of JSON blocks at beach.happyseaurchin.com, readable by anyone, person or LLM
Block
one named JSON document on the beach, its parts addressed by digits
Spine
the project's block of states: what must be true by each date
Seat
one trade's share of the programme, in a block of its own; a person never speaks through it
Mirror
a participant's own block of commitments, at the same addresses as the spine
Fold
every voice at one address, read together
Sundial address
a date written as ten digits: year, quarter, month of the quarter, seven-day band, day, gathering, beat
Gathering
a ninth of the day, 2 hours 40 minutes; the working day 08:00 to 16:00 is gatherings 4, 5 and 6
Rung (pscale)
the scale a digit stands for, from the beat at 0 to the millennium at 9
Backcast
planning back from a fixed end date to the start it needs

Fri 17 Dec 2027

2027 4 3 3 3 00sundial address of the day

PhaseCommissioning and handover

Last gatePlanned handover · Tue 23 Nov

Next gatenone: buffer runs to Fri 17 Dec

Working this week–

From the seats this week–

DecJan 2027FebMarAprMayJunJulAugSepOctNovDecConcept chosen · Fri 15 Jan 2027ConceptBuilding regulations approved · Mon 19 Apr 2027Planning permission granted · Tue 20 Apr 2027PermissionBuilder appointed, contract signed · Wed 21 Apr 2027Pre-commencement conditions discharged · Fri 28 May 2027On site · Wed 2 Jun 2027On siteFoundations in · Thu 17 Jun 2027Ground floor deck complete · Thu 1 Jul 2027Weathertight: roof on, windows and doors in · Thu 9 Sep 2027WeathertightPermanent power on · Wed 29 Sep 2027First fix complete, ready for plaster · Thu 30 Sep 2027External works complete · Tue 5 Oct 2027Plastering complete · Wed 13 Oct 2027Second fix complete · Mon 8 Nov 2027Decoration and flooring complete · Mon 8 Nov 2027Planned handover (end of the chain) · Tue 23 Nov 2027HandoverCritical chainAgree brief, budget and prioritiesAppoint architect and engineerMeasured and topographical surveyTree and ecology walkoverConcept design: three optionsChoose a concept and give commentsDeveloped designPlanning drawings and design statementSubmit the planning applicationCouncil validates the applicationPlanning determination (eight weeks)Submit details to discharge pre-commencement conditionsCouncil discharges the conditionsCommencement notice to Building ControlTwo days' notice before startingSite hoarding and security fencingSite access and hardstandingStrip and stockpile topsoilSet out the buildingExcavate foundation trenchesBuilding Control: excavationsPour trench-fill foundationsFoundation concrete curing (three days)Substructure blockwork to damp-proof courseLay damp-proof course and membraneBuilding Control: damp-proof courseBackfill and compact to formationBeam-and-block floor: lay beamsBeam-and-block floor: blocks and groutBuilding Control: oversiteScaffold: first liftBlockwork inner leaf, ground floor, frontBrickwork outer leaf, ground floor, frontLintels and cavity trays, ground floor, frontBlockwork inner leaf, ground floor, east gableBrickwork outer leaf, ground floor, east gableLintels and cavity trays, ground floor, east gableBlockwork inner leaf, ground floor, rearBrickwork outer leaf, ground floor, rearLintels and cavity trays, ground floor, rearBlockwork inner leaf, ground floor, west gableBrickwork outer leaf, ground floor, west gableLintels and cavity trays, ground floor, west gableSet the steel beam over the rear openingFix first-floor joistsScaffold: second liftBlockwork inner leaf, first floor, frontBrickwork outer leaf, first floor, frontBlockwork inner leaf, first floor, east gableBrickwork outer leaf, first floor, east gableBlockwork inner leaf, first floor, rearBrickwork outer leaf, first floor, rearBlockwork inner leaf, first floor, west gableBrickwork outer leaf, first floor, west gableGable brickwork to the rake, eastGable brickwork to the rake, westBarge boards, west vergeBreathable membrane and battensTile the front slopeTile the rear slopeRidge and dry vergesLead flashingsGutters and downpipes, frontGutters and downpipes, rearStud partitions, first floorSoil stack and waste runsRadiator pipework, first floorCylinder and plant cupboard pipeworkPlumbing first fix, kitchen-dinerPlumbing first fix, utilityPlumbing first fix, cloakroomPlumbing first fix, en-suite 1Plumbing first fix, en-suite 2Plumbing first fix, family bathroomPre-plaster inspection (warranty)Pour liquid screed, ground floorScreed walkable (two days)Plasterboard walls and ceilings, kitchen-dinerSkim coat, kitchen-dinerPlaster drying, kitchen-dinerFit kitchen unitsTemplate the worktopsWorktop fabrication (two weeks)Fit worktopsConnect sink and appliancesFlooring, kitchen-diner: LVTBuilder's cleanSnagging walk-roundSnag fixes: joineryBuilding Control completion inspectionCompletion certificate issuedWalk round with the builder and take the keysProject buffer: 17.6 working days, from the planned handover on Tue 23 Nov to the keys promised on Fri 17 Dec 2027KeysDesign and approvalsDesign and approvals: Mon 14 Dec to Thu 22 Apr 2027Procurement and ordersProcurement and orders: Wed 21 Apr to Thu 9 Sep 2027Site and substructureSite and substructure: Fri 28 May to Thu 1 Jul 2027Shell and roofShell and roof: Thu 1 Jul to Wed 15 Sep 2027First fixFirst fix: Thu 9 Sep to Thu 30 Sep 2027Plaster and screedPlaster and screed: Thu 30 Sep to Wed 13 Oct 2027Second fix and finishesSecond fix and finishes: Tue 12 Oct to Mon 8 Nov 2027External worksExternal works: Wed 15 Sep to Thu 7 Oct 2027Commissioning and handoverCommissioning and handover: Tue 26 Oct to Tue 23 Nov 2027
Drag the slider or press Backcast to watch the plan run from the keys back to the brief. The dashed outline is the reference, the house as it must stand at the end; the solid house is the programme's state on that day. Every element appears on the date its job is scheduled in the levelled plan. In the timeline the amber critical chain ends at the planned handover on Tuesday 23 November; the dashed box after it is the buffer that protects the keys on Friday 17 December.

The full levelled plan, every one of the 455 tasks on a sundial of rings with the 200 simulated builds, is the companion page House on the sundial.

1step 1 of the brief

The house

The test project is a detached four-bedroom house in the West Midlands, built by ten hands in a year: design and approvals through winter and spring, on site from June, keys before Christmas 2027.

What gets built

Two storeys of brick-and-block cavity wall under a tiled, trussed roof, heated by an air-source heat pump. Fifteen rooms and eighteen windows, with a driveway, patio, soakaway drainage and a car charger.

  • Ground floor: hall, living room, kitchen-diner, utility, cloakroom and study.
  • First floor: four bedrooms, two with en-suites, a family bathroom, the landing and a plant cupboard.
  • Structure: trench-fill foundations, a beam-and-block ground floor, engineered first-floor joists, a steel beam over the rear doors and roof trusses.
  • Services: underfloor heating downstairs, radiators upstairs, a heat pump with an unvented cylinder.
  • Finishes: liquid screed, engineered oak, LVT and carpet, tiled bathrooms and a fitted kitchen.

The dates that frame the year

  • Brief agreed: Monday 14 December 2026.
  • Planning permission: Tuesday 20 April 2027, with the builder appointed the next day.
  • On site: Wednesday 2 June 2027.
  • Weathertight: Thursday 9 September 2027.
  • First fix complete: Thursday 30 September 2027.
  • Planned handover: Tuesday 23 November 2027, followed by 17.6 working days of buffer.
  • Keys promised: Friday 17 December 2027.
455tasks: 399 jobs, 40 waits, 16 gates
758steps inside the jobs
2,770crew-hours at median durations
101tasks on the critical chain
17.6working days of project buffer

The ten participants

Each participant has a seat on the beach: a mirror holding its share of the programme. Teams is how many crews that hand can field at once. The strip under each hand shows its crew-hours week by week, from the brief to the keys.

The plan tests method and time; cost and ownership come next.

  • Durations are typical medians for a UK build of this kind, not quotes, and not taken from a cited dataset.
  • Safe durations are a flat 1.6 times the median (1.25 times for waits), so the buffer's size follows that choice.
  • A team is one crew of unstated size, so crew-hours are not yet labour-hours or costs.
  • There is no site, client, price or contract yet. Securing a serviced plot, with insurance, the Community Infrastructure Levy, a highways crossover and street naming, comes before the brief and is not in the model.

1.1step 2 of the brief

The method

The plan was built backwards in six steps: fix the outcome, ask what must be true before it, turn each necessity into jobs, find the chain, set the start, and place every job on the clock.

  1. 1

    Fix the reference

    Keys on Friday 17 December 2027, a week before the Christmas shutdown. Every other date derives from this one.

  2. 2

    Work back by necessity

    From the keys, ask what must be true first, and why. Each answer is a because: "Keys wait for the completion certificate, because lenders and the warranty need it." Nineteen such statements carry the logic.

  3. 3

    Turn necessities into jobs

    Each state becomes jobs, each with one owner among the ten, a median duration, a safe duration and its steps. Council periods and lead times become waits; milestones become gates.

  4. 4

    Find the chain and pool the safety

    The critical path gives the logic, and levelling by crew gives the critical chain. The safety hidden in each job is taken out and pooled as one buffer at the end.

  5. 5

    Backcast the start

    Scheduling back from the keys, less the buffer, gives a start of Monday 14 December 2026. Two hundred simulated builds, with weather, lead times, late windows and inspection delays, turn that into start dates by confidence.

  6. 6

    Place every job on the sundial

    Each job sits at the smallest period of the canonical clock that holds both its start and its end. Its steps sit at the gatherings or days beneath; the address is the date and the depth is the scale.

Read it backwards

Ten of the nineteen because statements in the plan, in reverse date order from the keys to the brief. Each state is a necessary condition for some state above it, for the reason given.

  1. Tue 23 Nov 2027Planned handoverKeys wait for the completion certificate, because lenders and the warranty need it.
  2. Mon 15 Nov 2027Completion inspectionBuilding Control won't sign off without the electrical, energy and heat pump certificates.
  3. Wed 27 Oct 2027Heat pump commissionedThe heat pump can't be commissioned on temporary power.
  4. Wed 13 Oct 2027Plastering completeDecoration waits about a week, because paint on wet plaster fails.
  5. Thu 30 Sep 2027First fix completeBoarding waits for first fix and its inspection, because cables and pipes behind plaster can't be checked or changed cheaply.
  6. Thu 9 Sep 2027WeathertightInternal work waits for weathertight, because rain ruins cables, timber and plasterboard.
  7. Fri 11 Jun 2027Windows deliveredWindows can't be fitted until they arrive, and they take seven weeks to make.
  8. Fri 28 May 2027Conditions dischargedStarting before pre-commencement conditions are discharged can make the permission unusable.
  9. Tue 20 Apr 2027Planning permissionNothing is built before permission, because work without it risks enforcement.
  10. Mon 19 Apr 2027Building regulations approvedOrders for structure wait for approved drawings, because trusses, joists and steel are made to them.
  11. Mon 14 Dec 2026The briefBrief, budget and priorities agreed: the start the whole chain backcasts to.
Backcasting asks what must be true first, and why; the dates come from the levelled programme.

1.1.1step 3 of the brief

The theory

Four traditions meet in the method: backcasting sets the direction, Theory of Constraints orders the necessities and finds the bottleneck, the critical path times the work, and Last Planner keeps weekly promises reliable.

Backcasting gives the direction, constraints the focus, the critical path the timing and Last Planner the reliability. The sundial adds a shared address: every participant, and anyone's LLM, reads and writes the plan at the same places, not only those standing at the board.

1.1.1.1step 4 of the brief

The clock and the blocks

Every job lives at an address on the canonical clock, a ten-digit number that is also a date; the plan lives on the beach as one spine and ten seats written at those addresses.

Four digits of year, then one digit each for season, month of season, seven-day band, day of band, gathering and beat, in UTC. Friday 17 December 2027 is day 20274333, and its working day, 08:00 to 16:00, is gatherings 4, 5 and 6.

The rungs

Each digit is a rung of scale, from the beat at pscale 0 to the millennium at pscale 9; the root, pscale 10, holds the project's line.

  • Beat, pscale 0: about 18 minutes.
  • Gathering, pscale 1: 2 hours 40 minutes.
  • Day, pscale 2.
  • Seven-day band, pscale 3: days 1–7, 8–14, 15–21, 22–28 and 29–31.
  • Month, pscale 4.
  • Season, pscale 5: a quarter of the year.
  • Year, decade, century and millennium: pscale 6 to 9.

Placement by shared prefix

A job's start and end addresses share a prefix, and the job sits at the node that prefix names. A two-hour job inside one gathering sits in that gathering, a two-day job inside one seven-day band sits in that band, and a job crossing a month end rises to the season. The rule gives orientation, not distance.

The family on the beach

The ten seatsclientarchitectsite-managergroundworkerbricklayercarpenterrooferelectricianplumberplasterer-decorator

The spine voices the states. Each mirror commits what its author will do at future addresses and says done, doing or blocked at past ones. The fold reads every voice per address and rolls each closed span into its parent; this family runs fixed, its spine voiced to the day in advance.

People walk the family at happyseaurchin.com/walk/house-2027. Any LLM can read it without a key at the beach's public endpoint beach.happyseaurchin.com↗.

1.1.1.1.1step 5 of the brief

Ten hands through the year

Ten participants work the plan through three portals: rendered pages to see it, the mirror to write their own commitments, and their own LLM to read and draft at any address.

The three portals

The rhythm

Last Planner's five conversations land on the sundial's rungs.

  1. ShouldSeasonPhase states pulled back from the next gateO-pagesLLM-app
  2. CanNext six weeksDrawings, deliveries, inspections and access made readyLLM-app
  3. WillSeven-day bandEach hand commits at the band's addressMirror
  4. DidDayDone, doing or blocked at today's addressMirror
  5. LearnClosing spanThe fold rolls up: promises kept, and why any slippedO-pages

Who works when

Crew-hours by hand, week by week, with the council and the suppliers as the two outside clocks. The line follows the date in the drawing above.

S4Season 1Season 2Season 3Season 4CouncilCouncil validates the application: Fri 5 Feb to Fri 19 Feb 2027Planning determination (eight weeks): Fri 19 Feb to Tue 20 Apr 2027Full plans checked (five weeks): Fri 12 Mar to Mon 19 Apr 2027Council discharges the conditions: Thu 22 Apr to Fri 28 May 2027SuppliersSupplier lead times: Wed 21 Apr to Mon 5 Jul 2027Kitchen manufacture (six weeks): ordered Wed 21 Apr, ready Fri 4 Jun 2027Brick and block lead time (three weeks): ordered Wed 21 Apr, ready Thu 13 May 2027Window manufacture (seven weeks): ordered Wed 21 Apr, ready Fri 11 Jun 2027Joist manufacture (three weeks): ordered Thu 22 Apr, ready Thu 13 May 2027Steel fabrication (two weeks): ordered Thu 22 Apr, ready Thu 6 May 2027Truss design and manufacture (three weeks): ordered Thu 22 Apr, ready Fri 14 May 2027Staircase manufacture (four weeks): ordered Thu 22 Apr, ready Fri 21 May 2027Heat pump lead time (three weeks): ordered Thu 22 Apr, ready Fri 14 May 2027Network operator quote and date (ten weeks): ordered Thu 22 Apr, ready Mon 5 Jul 2027Telecoms lead time (six weeks): ordered Thu 22 Apr, ready Mon 7 Jun 2027Water company quote and date (eight weeks): ordered Fri 23 Apr, ready Mon 21 Jun 2027Supplier lead times: Thu 21 Oct to Thu 4 Nov 2027Worktop fabrication (two weeks): ordered Thu 21 Oct, ready Thu 4 Nov 2027ClientClient, week of Mon 14 Dec: 24 crew-hoursClient, week of Mon 11 Jan: 16 crew-hoursClient, week of Mon 25 Jan: 8 crew-hoursClient, week of Mon 1 Feb: 48 crew-hoursClient, week of Mon 1 Mar: 4 crew-hoursClient, week of Mon 5 Apr: 16 crew-hoursClient, week of Mon 19 Apr: 6 crew-hoursClient, week of Mon 22 Nov: 4 crew-hoursArchitectArchitect, week of Mon 14 Dec: 16 crew-hoursArchitect, week of Mon 21 Dec: 24 crew-hoursArchitect, week of Mon 4 Jan: 40 crew-hoursArchitect, week of Mon 11 Jan: 24 crew-hoursArchitect, week of Mon 18 Jan: 40 crew-hoursArchitect, week of Mon 25 Jan: 40 crew-hoursArchitect, week of Mon 1 Feb: 40 crew-hoursArchitect, week of Mon 8 Feb: 40 crew-hoursArchitect, week of Mon 15 Feb: 40 crew-hoursArchitect, week of Mon 22 Feb: 40 crew-hoursArchitect, week of Mon 1 Mar: 40 crew-hoursArchitect, week of Mon 8 Mar: 32 crew-hoursArchitect, week of Mon 19 Apr: 16 crew-hoursArchitect, week of Mon 8 Nov: 8 crew-hoursSite managerSite manager, week of Mon 8 Mar: 10 crew-hoursSite manager, week of Mon 15 Mar: 30 crew-hoursSite manager, week of Mon 19 Apr: 26 crew-hoursSite manager, week of Mon 3 May: 1 crew-hoursSite manager, week of Mon 10 May: 4 crew-hoursSite manager, week of Mon 17 May: 1 crew-hoursSite manager, week of Mon 24 May: 1 crew-hoursSite manager, week of Mon 31 May: 8 crew-hoursSite manager, week of Mon 7 Jun: 9 crew-hoursSite manager, week of Mon 14 Jun: 3 crew-hoursSite manager, week of Mon 21 Jun: 6 crew-hoursSite manager, week of Mon 28 Jun: 10 crew-hoursSite manager, week of Mon 26 Jul: 10 crew-hoursSite manager, week of Mon 9 Aug: 6 crew-hoursSite manager, week of Mon 6 Sep: 1 crew-hoursSite manager, week of Mon 13 Sep: 14 crew-hoursSite manager, week of Mon 27 Sep: 2 crew-hoursSite manager, week of Mon 18 Oct: 2 crew-hoursSite manager, week of Mon 8 Nov: 36 crew-hoursSite manager, week of Mon 15 Nov: 4 crew-hoursGroundworkerGroundworker, week of Mon 14 Dec: 16 crew-hoursGroundworker, week of Mon 31 May: 17 crew-hoursGroundworker, week of Mon 7 Jun: 32 crew-hoursGroundworker, week of Mon 14 Jun: 38 crew-hoursGroundworker, week of Mon 21 Jun: 38 crew-hoursGroundworker, week of Mon 28 Jun: 23 crew-hoursGroundworker, week of Mon 13 Sep: 19 crew-hoursGroundworker, week of Mon 20 Sep: 40 crew-hoursGroundworker, week of Mon 27 Sep: 40 crew-hoursGroundworker, week of Mon 4 Oct: 17 crew-hoursBricklayerBricklayer, week of Mon 21 Jun: 28 crew-hoursBricklayer, week of Mon 28 Jun: 7 crew-hoursBricklayer, week of Mon 5 Jul: 40 crew-hoursBricklayer, week of Mon 12 Jul: 40 crew-hoursBricklayer, week of Mon 19 Jul: 40 crew-hoursBricklayer, week of Mon 26 Jul: 16 crew-hoursBricklayer, week of Mon 2 Aug: 40 crew-hoursBricklayer, week of Mon 9 Aug: 40 crew-hoursBricklayer, week of Mon 16 Aug: 40 crew-hoursBricklayer, week of Mon 23 Aug: 40 crew-hoursBricklayer, week of Mon 30 Aug: 1 crew-hoursCarpenterCarpenter, week of Mon 12 Jul: 13 crew-hoursCarpenter, week of Mon 19 Jul: 12 crew-hoursCarpenter, week of Mon 26 Jul: 35 crew-hoursCarpenter, week of Mon 9 Aug: 28 crew-hoursCarpenter, week of Mon 23 Aug: 30 crew-hoursCarpenter, week of Mon 6 Sep: 22 crew-hoursCarpenter, week of Mon 13 Sep: 58 crew-hoursCarpenter, week of Mon 20 Sep: 16 crew-hoursCarpenter, week of Mon 11 Oct: 34.8 crew-hoursCarpenter, week of Mon 18 Oct: 80 crew-hoursCarpenter, week of Mon 25 Oct: 37.2 crew-hoursCarpenter, week of Mon 1 Nov: 8 crew-hoursCarpenter, week of Mon 8 Nov: 10 crew-hoursCarpenter, week of Mon 15 Nov: 6 crew-hoursRooferRoofer, week of Mon 9 Aug: 12 crew-hoursRoofer, week of Mon 16 Aug: 3 crew-hoursRoofer, week of Mon 23 Aug: 28 crew-hoursRoofer, week of Mon 30 Aug: 32 crew-hoursRoofer, week of Mon 6 Sep: 29 crew-hoursElectricianElectrician, week of Mon 6 Sep: 11 crew-hoursElectrician, week of Mon 13 Sep: 38 crew-hoursElectrician, week of Mon 20 Sep: 40 crew-hoursElectrician, week of Mon 27 Sep: 27 crew-hoursElectrician, week of Mon 11 Oct: 7.8 crew-hoursElectrician, week of Mon 18 Oct: 32.4 crew-hoursElectrician, week of Mon 25 Oct: 1.8 crew-hoursElectrician, week of Mon 1 Nov: 6 crew-hoursElectrician, week of Mon 8 Nov: 16 crew-hoursPlumberPlumber, week of Mon 19 Apr: 10 crew-hoursPlumber, week of Mon 6 Sep: 3 crew-hoursPlumber, week of Mon 13 Sep: 32 crew-hoursPlumber, week of Mon 20 Sep: 40 crew-hoursPlumber, week of Mon 27 Sep: 27 crew-hoursPlumber, week of Mon 4 Oct: 8 crew-hoursPlumber, week of Mon 11 Oct: 6.7 crew-hoursPlumber, week of Mon 18 Oct: 29.5 crew-hoursPlumber, week of Mon 25 Oct: 25.3 crew-hoursPlumber, week of Mon 1 Nov: 4 crew-hoursPlumber, week of Mon 8 Nov: 4 crew-hoursPlasterer & decoratorPlasterer & decorator, week of Mon 27 Sep: 33 crew-hoursPlasterer & decorator, week of Mon 4 Oct: 120 crew-hoursPlasterer & decorator, week of Mon 11 Oct: 116.5 crew-hoursPlasterer & decorator, week of Mon 18 Oct: 115.5 crew-hoursPlasterer & decorator, week of Mon 25 Oct: 113 crew-hoursPlasterer & decorator, week of Mon 1 Nov: 22 crew-hoursPlasterer & decorator, week of Mon 8 Nov: 18 crew-hoursPlasterer & decorator, week of Mon 15 Nov: 6 crew-hoursDecJanFebMarAprMayJunJulAugSepOctNovDec
Seasons are the sundial's: quarters of the year. The plasterers' peak is three teams at once.
tableCrew-hours by hand and month
Dec 26JanFebMarAprMayJunJulAugSepOctNovDec
Client242448422······4·
Architect401441607216······8·
Site manager···402693014617240·
Groundworker16····31359·9125··
Bricklayer······321391601···
Carpenter·······60589615224·
Roofer········5648···
Electrician·········1114722·
Plumber····10····97758·
Plasterer & decorator·········2647246·

Season by season

Where hands meet

Handoffs are where voices converge. Trusses need the carpenter and then the roofer; weathertight needs the roof and the windows; first fix puts electrician, plumber and carpenter in the same rooms. The fold at those addresses shows who meets whom, and when.

An example day

At 07:50 the bricklayer opens the day's address on a phone and sees the courses due. At 16:05 they mark the day done in their mirror, or blocked with the reason. On Friday the site manager's LLM folds the week: promises made, promises kept.

1.1.1.1.1.1step 6 of the brief

What the test found

The method gives a start date for any confidence: Tuesday 1 December 2026 for 90% in the model, Monday 14 December for a coin flip. The buffer is too thin, the council is the constraint, and most short jobs sit a rung too high until aligned.

When to start

December 2026. Each start date gives keys by Friday 17 December 2027 with the confidence shown, across 200 simulated builds. Hatched days are the Christmas shutdown.

Keys across 200 simulated builds

010201 builds finish -22 to -20 working days from the promise2 builds finish -18 to -16 working days from the promise1 builds finish -16 to -14 working days from the promise5 builds finish -14 to -12 working days from the promise5 builds finish -12 to -10 working days from the promise10 builds finish -10 to -8 working days from the promise17 builds finish -8 to -6 working days from the promise15 builds finish -6 to -4 working days from the promise20 builds finish -4 to -2 working days from the promise21 builds finish -2 to 0 working days from the promise19 builds finish 0 to 2 working days from the promise20 builds finish 2 to 4 working days from the promise17 builds finish 4 to 6 working days from the promise20 builds finish 6 to 8 working days from the promise11 builds finish 8 to 10 working days from the promise7 builds finish 10 to 12 working days from the promise1 builds finish 12 to 14 working days from the promise2 builds finish 14 to 16 working days from the promise3 builds finish 16 to 18 working days from the promise2 builds finish 18 to 20 working days from the promise1 builds finish 20 to 22 working days from the promise-20-15-10-50+5+10+15+20working days before or after the promised keys48.5% on time51.5% late

P10 Tue 7 Dec 2027Median Mon 20 Dec 2027P90 Mon 10 Jan 2028

Each build draws its own weather, lead times, late windows and inspection delays. Bars left of the line hand over on or before the promise.

The constraint

Validation2 working wkDetermination8 working wkConditions5 working wk
condition details sent with the application can remove most of this wait
About 15 working weeks of the chain sit with the council between Friday 5 February and Friday 28 May 2027, before a spade goes in. Conditions are modelled at five weeks; the statutory period is eight.
Nine results from the levelled plan and two hundred simulated builds.
Start by, backcastMonday 14 December 2026
Start by for 80% and 90% confidenceThursday 3 December and Tuesday 1 December 2026
Keys across 200 simulated builds7 December 2027 (P10), 20 December 2027 (median), 10 January 2028 (P90)
On time with the root-square buffer48.5% of builds
Buffer used by the median build106%
Cost of levelling by crew35 working days (199.4 to 234.5)
The council's share of the chainAbout 15 working weeks
Rung fit before and after alignment43.1% and 87.7%, for 4.4 days
Simulated Percent Plan Complete86.9%, optimistic

The buffer

The root-square rule assumes risks are independent; weather and supply delays are not, so the buffer under-protects. Only 1 build in 200 meets the chain's own end, 23 November, and 51.5% overrun the promise. Goldratt's rule of thumb, half the work on the chain, would give 66.2 days instead of 17.6; the simulation says starting about nine working days earlier gives 90% in the model.

The constraint

The council holds about 15 working weeks of the chain: two to validate, eight to determine and five to discharge conditions. Five is the model's assumption; the statutory period for conditions is eight weeks, which would move every start date about three weeks earlier. Theory of Constraints says exploit the constraint first: submit the condition details with the application, which can remove most of that wait.

Rung fit

85% of misfits are jobs of a day or less: short jobs that cross a gathering boundary, and half-day and day jobs that run past 16:00 into the next day. A day and a half of blockwork from Thursday 29 July to Monday 2 August sits at the season node, two rungs above its seven-day band, because it crosses a month end. Letting the scheduler spend up to two days of float lifts fit to 87.7%; declaring Monday-to-Friday weeks barely helps.

Promises

The simulated weekly PPC is 86.9% because the model re-plans perfectly every week. The Lean Construction Institute reports that only 54% of planned work gets done in a typical week; Ballard treats 70% as the level where gains begin.

The last critical run

The kitchen worktop closes the chain: templated once the units are fixed and level, two weeks of fabrication, then fitting.

What the simulation leaves out

A planning refusal, council delays beyond a fifth, no-shows, rework and client changes; it also re-plans perfectly each week. The confidence figures are upper bounds.

1.1.1.1.1.1.1step 7 of the brief

Loosening the plan

A house fixes its plan to the day; the same method loosens by raising one dial, the finest rung the spine voices in advance.

reference · 10millennium · 9century · 8decade · 7year · 6season · 5termmonth · 4week · 3day · 2gathering · 1beat · 0the referenceA social venturethe termA maths syllabusthe dayA houseevery stepA Lego model
Solid: fixed in advance. Thin: voiced as it arrives. The dot is each project's fixity rung.

The fixity rung

The beach's backcast law voices only the reference and the live path, which is fixity at the top. A construction programme voices every rung down to the day. One number separates them: the finest rung written in advance.

  • A house: fixed to the day. Necessity is physical, durations are known, inspections are mandatory.
  • A maths syllabus: fixed to the term. Necessity is conceptual: fractions before ratio, ratio before proportion.
  • A social venture: fixed to the reference. Only the far aim is fixed; each voice writes its own path.
  • A Lego model: fixed to every step. One builder and one numbered sequence: it fits trivially and tests nothing.

A maths syllabus

A syllabus fixes the term and voices weeks and days as teacher and pupils arrive at them. Its necessity tree is the curriculum's prerequisites, and Theory of Constraints thinking tools are already taught to children.

What the beach still lacks

Last Planner's Can: a make-ready log of constraints cleared ahead of the work. Without it, a mirror can only report BLOCKED after the fact.

1.1.1.1.1.1.1.1step 8 of the brief

Ownership and funding

The plan already says when money and hands are needed; who owns the house is the next calculation, comparing four routes.

When money is needed

A dated need for every resource: design and surveys from December to March, council fees in February and March, deposits for windows, trusses, joists, steel, kitchen and heat pump in late April, and trades from June. Each gate is a natural point to pay for completed stages, and the hours by hand are known.

Design, surveys, drawingsDesign, surveys, drawings: Mon 14 Dec to Thu 11 Mar 2027Council and regulation feesCouncil and regulation fees: Fri 5 Feb to Thu 11 Mar 2027Deposits on long-lead ordersDeposits on long-lead orders: Wed 21 Apr to Thu 22 Apr 2027Trades on siteTrades on site: Wed 2 Jun to Mon 22 Nov 2027Certificates, warranty, handoverCertificates, warranty, handover: Mon 15 Nov to Mon 22 Nov 2027DecJanFebMarAprMayJunJulAugSepOctNovDec
Each bar runs from the first to the last day that kind of spending falls due in the levelled plan. Amounts are the next calculation.

Four routes

Four ways the house could be owned, to be costed side by side.

Precedents

UK law already supports parts of this. Councils keep self-build and custom housebuilding registers and must permission enough serviced plots to meet them. Community land trusts hold land for a local community and are controlled by their members.

Fulcrum's proposal

Fulcrum's Volume 3 treats money as a vector: directed by people towards future objectives, it makes intentions visible. Volume 2 proposes that money converted into living credits buys conjoint ownership of land and buildings, which turns ownership into stewardship.

In an AI-saturated world

Coordinating many small owners used to cost more than it saved. With each hand's LLM keeping its mirror and anyone able to compute the fold, that cost falls.

The next calculation

  • Cost by phase, and the land.
  • Who holds title, and how a share is earned.
  • How an hour of work compares with a pound.
  • What a backer receives, and when.
  • Who carries the 51.5% chance of an overrun.

Not an offer

This document describes a plan. No money is sought, and nothing in it is an offer or an invitation to invest.

beachwhere the project lives

Open it yourself

The house is a family of blocks on a public commons. People read it on rendered pages, participants write to it from their own mirror, and any LLM can read it without a key.

With your own eyes

Walk the programme month by month at happyseaurchin.com/walk/house-2027. The full levelled plan, with its dial and the 200 simulated builds, is a companion page, House on the sundial.

As a participant

Take up a trade by writing your own mirror, house-2027:<your handle>, at the same addresses as its seat, in your own words, at mirror.onen.ai. A seat is the plan's word for a trade, never a person's.

Through your LLM

Paste this into any assistant that can read the web.

Read this building programme from the beach, keyless:
https://beach.happyseaurchin.com/.well-known/pscale-beach?block=spine:house-2027
Each ten-digit address in it is a date (year, quarter, month of the quarter, seven-day band, day, gathering, beat). If this brief is also there, read it down digit 1:
https://beach.happyseaurchin.com/.well-known/pscale-beach?block=spine:house-on-the-sundial
Tell me whether the plan is feasible, what it leaves out, what the main risks are, and what I would need to know before taking part.

This page carries its own copy of the brief block. Served from happyseaurchin.com, it reads the block live from the beach.

8a side-room of the root

Sources

The references this brief stands on, grouped by tradition, each with its link; opened and checked on 17 October 2026.

Backcasting

Theory of Constraints

Last Planner System

Critical path and linear programming

UK rules and routes

Fulcrum and the beach

All the animations · House on the sundial, the full levelled plan with its dial