When does the as-built get made?

It does not get made. It accumulates. Every epoch is registered into one spatial frame as the job runs, so the state of the works at practical completion is a date on a record that already exists — not a deliverable somebody assembles from photographs in the last fortnight.

What does it take to capture behind the drywall?

One pass per zone before close-up, in the window between services complete and boarding. It is the cheapest capture on the programme and the one that pays for the longest: the alternative is a wall opened on a guess.

One pass per open trench before backfill. The ground is only transparent while it is open — on this specimen the window was 31 hours — and it never comes back on the same terms.

How does a defect close?

On evidence. A directive closes when a capture shows the change, not when somebody ticks a box and not because the period ended. An item still moving at release is stated as still moving, with its rate in units per year.

What happens to the record after the liability period?

It keeps running: the same frame, the same stations, the same measurements carrying their units and their ±, into operation, inspection regimes and refurbishment. The site does not stop existing at handover, so neither does the record.

The organisation that captured it, with access controlled down to the part of the site. What passes at handover is access to what already exists, on the terms written into the contract.

Record · Handover

The as-built nobody had to draw.

A handover pack is usually manufactured — assembled at the end, from memory, by the people least able to remember. Ours is not assembled. It is the record, dated at the epoch the keys changed hands: what was built, what is behind the wall, what is under the ground, and what was still moving when the retention fell due.

Record header · sheet R-04

Record: SPECIMEN SITE 07
Epochs held: 55
Handover epoch: E-42 · 21 APR 2025
Concealed epochs: 31
Liability period: 365 D
Release epoch: E-55 · 21 APR 2026
Stations: ±1.0 M REPEAT

First epoch · 18 Jun 202355 epochs on the recordLatest · 21 Apr 2026

Behind the drywall

The wall remembers what the drawing forgot.

Drag the seam. Left is corridor C2 as it was handed over; right is the same elevation the week before the boarders arrived — duct, tray, sprinkler main, and the chilled-water isolation valve now sitting a metre and a half above the floor behind twelve and a half millimetres of plasterboard. Both states are the same measured setting-out, so every level on the right lands where the left says it should.

Corridor C2 · level 04 · internal elevationHandover epoch E-42 · concealed epoch E-14

AS HANDED OVERE-14 · BEFORE CLOSE-UP

WIPE 44% · DRAG OR USE ARROW KEYS

Concealed elements in corridor C2, level 04, captured at epoch E-14 before the wall was closed up.
Ref	Element	Level	Chainage	Note
MEP-118	Duct, 400 × 250 galvanised	SOFFIT 3,150 AFFL	CH 300 – 8,700	70 mm below rev C. Deviation accepted, VAR-118.
MEP-124	Cable tray, 300 wide	2,950 AFFL	CH 300 – 8,700	Conduit drop to faceplate at CH 6,400.
MEP-131	Sprinkler main, DN80	3,050 AFFL	CH 300 – 8,700	Three pendant drops through the ceiling grid.
MEP-147	Chilled water drop, DN50 pair	VALVE 1,555 AFFL	CH 5,400	Isolation valve concealed behind 12.5 mm board, 640 mm off the door head.

Levels are to finished floor level, taken from the capture, not from the model. Where the two disagree the capture is the record and the difference is stated.

Opening a wall to find a valve costs more than the capture that would have found it.

One pass per zone, between services complete and boarding

Levels taken from the capture, not from the model

Deviations stated with the variation that accepted them

Below the ground

The only day the underground is visible is the day you bury it.

Nobody funds a geophysical survey of their own site. Nobody has to: construction opens the ground for free, once, and closes it within a day or two. Capture at exposure turns that window into a permanent section — invert levels, offsets to the grid, bedding, tape.

Every strike, every exploratory hole and every re-survey after this point is paid for out of the same absence: nobody wrote down what they could see. A section captured at exposure is the cheapest measurement on the job and the one still being read in thirty years.

Section A-A · service trench · CH 240Epoch E-31 · captured at exposure

WATER MAIN: DI DN300 · IL 100.80 · OFFSET 1,550 FROM GRID D
POWER DUCTS: 4 × Ø150 PVC · CROWN 101.20 · SPACER 300 CRS
COMMS DUCT: Ø110 PVC · CROWN 101.40 · DRAW ROPE FITTED

BEDDING: 10 MM SINGLE-SIZE · 100 UNDER · 150 OVER
MARKER TAPE: 101.90 · OVER EACH SERVICE · AT BACKFILL
BACKFILL: AS-DUG · 250 LIFTS · 6 PASSES

Thirty-one hours of visibility, recorded once, worth reading for as long as the pipe is there.

Retention and the liability period

A year measured, not argued.

Practical completion is the start of the most expensive year of the job to get wrong. Scroll it. Each defect is a longitudinal object: first observed at an epoch, re-measured at every epoch after it, closed only when a capture shows the change. At day 365 the balance of retention is due against measured condition — including the two items that are still moving, stated with their rate.

Defects liability · 365 days from practical completionDay 365 / 365 · open 2 · closed 2

Defect register at the end of the liability period: two items closed by capture, two measured open at release.
Ref	Location	Measured	First seen	Latest	Growth	Status
D-07	South abutment, wall 3Resin injected day 251. Arrested: no growth across two epochs.	Crack width	DAY 0	1.6 mm	+0.7 mm/yr	CLOSED · E-52
D-12	Plant room 04-P2Roof outlet re-formed day 201. Closed on the capture that showed it dry.	Damp staining	DAY 92	0.0 m²	-2.9 m²/yr	CLOSED · E-49
D-19	Apron slab, bay 6Open at release. Still moving: growth measured across four epochs.	Settlement	DAY 182	11.0 mm	+14.0 mm/yr	OPEN
D-23	Parapet, joint J-14Open at release. Raised on the penultimate epoch.	Sealant failure	DAY 306	3.1 m run	+4.3 m run/yr	OPEN

Balance DUE · 2 ITEMS MEASURED OPEN

Retention is released against measured condition, not against an opinion of it.

Release epoch walks the handover epoch's stations, ±1.0 m

Growth quoted per year, from the readings that produced it

An item still moving is stated as still moving

What changes hands

Six things, none of them assembled at the end.

Each one exists because the record was running while the work happened. Nothing here is produced for the handover; the handover is a date applied to what is already held.

As-built geometry

Not a drawing redrawn from memory at the end of the job. The measured state of the works at the handover epoch, at the same stations the next capture will use.

Concealed services

Everything the finishes now hide, captured the week before they hid it: levels to finished floor, chainages, deviations against the coordination model, accepted variations named.

Below-grade services

Every trench captured at exposure, before backfill. Invert levels, offsets to the grid, bedding and tape depths — recorded during the one window in which they were visible.

Component identity

Serial and batch numbers bound to the position each unit was installed in, so a warranty claim, a recall or a replacement starts from a location rather than a search.

Witnessed hold points

The moments somebody had to see before the work was covered: witnessed on a dated epoch, released under delegated authority, and readable years later as the epoch they were witnessed on.

The defect register

Every item a longitudinal object with its own measurements — first observed, measured at each epoch, growth rate, closed only when a capture shows the change.

Questions of record

The prerequisites, in the headline register.

What it costs in capture time, when it has to happen, and what carries on afterwards.

01When does the as-built get made?: It does not get made. It accumulates. Every epoch is registered into one spatial frame as the job runs, so the state of the works at practical completion is a date on a record that already exists — not a deliverable somebody assembles from photographs in the last fortnight.
02What does it take to capture behind the drywall?: One pass per zone before close-up, in the window between services complete and boarding. It is the cheapest capture on the programme and the one that pays for the longest: the alternative is a wall opened on a guess.
03And below ground?: One pass per open trench before backfill. The ground is only transparent while it is open — on this specimen the window was 31 hours — and it never comes back on the same terms.
04How does a defect close?: On evidence. A directive closes when a capture shows the change, not when somebody ticks a box and not because the period ended. An item still moving at release is stated as still moving, with its rate in units per year.
05What happens to the record after the liability period?: It keeps running: the same frame, the same stations, the same measurements carrying their units and their ±, into operation, inspection regimes and refurbishment. The site does not stop existing at handover, so neither does the record.
06Who holds it?: The organisation that captured it, with access controlled down to the part of the site. What passes at handover is access to what already exists, on the terms written into the contract.

One record. Every phase. Decades.

The as-built is a byproduct of having captured at allConcealed and buried work recorded while it was visibleThe liability year measured epoch by epoch