Precast detailing services for elements that cast, lift and fit.

What a precast package has to carry

A precast element is manufactured once and delivered to a slot in a sequence. Everything that governs whether it casts, strips, lifts, travels and fits has to be on the drawing before the mould is set, because there is no adjusting it afterwards.

A package normally carries:

• Element drawings for every unit type — solid and insulated sandwich wall panels, tilt-up panels, hollowcore and plank, double tees, rectangular and inverted-tee beams, columns, stairs, landings, retaining and basement units, and architectural façade elements.
• Mould and formwork drawings, dimensioned to the plant's standard beds and side forms, with stop-ends, magnets, chamfers and finish faces identified.
• Reinforcement and mesh for each element, coordinated with everything cast into it.
• Cast-in items — lifting anchors, sockets, connection hardware, bearing plates, electrical boxes, conduit, window and door frames — positioned and scheduled.
• Marking plans and general arrangements that tie every element mark to its position in the building, so the yard, the trailer and the crane are all naming the same unit.
• Erection drawings with element marks, levels, bearings, grout and ferrule locations, temporary propping and connection details.
• Element schedules and bills of material by unit, by load and by production week.

Element marks follow your numbering, not ours, and stay stable from the model through production to the erection sequence on site.

Detailed on your moulds and your shop rules

Precast detailing that ignores the plant produces drawings that are correct and unbuildable. The rules that actually decide a drawing are local to the factory: which beds and side forms exist, the standard chamfer, the demoulding method, what the crane in the yard can lift, how units are stacked and how they travel on a trailer.

Those rules are captured once, as your own detailing standard, and then applied to every element. Handling and demoulding conditions are considered where the element geometry makes them critical. Finish faces, tolerances and joint widths follow the plant's practice. Where an architect's geometry cannot be produced in your moulds, that comes back as a question with an option, early, while it is still a design conversation and not a change order.

The result is a package that reads like it was drawn by someone who has stood in your factory — because the rules that produced it came from your factory.

How the work runs, element by element

Intake fixes the element breakdown, the connection concept, the tolerance and joint strategy, the mould library and the production programme. Nothing is modelled before those are agreed, because every one of them changes the drawings.

Then the elements are produced. The AI-driven part of the work is the repetition — and precast is repetition: the same wall type at forty positions, each with different openings, embeds and edge conditions. The system builds them, places the standard cast-in items, generates the reinforcement, dimensions the sheets, marks the elements and builds the schedules. Senior engineers work on the units that are genuinely different, on the connections, and on the sequence.

Issue follows the production programme, release by release. Each release is a decision someone signed, with a change list against the previous revision, so the plant knows exactly which moulds are affected.

Machine-checked before the mould is set

The automated checks run on the model, the drawings and the schedules together, before a reviewer sees them. In precast the cost of a missed check is a cast element, so the check list is long on purpose:

• element marks unique across the model, and consistent between the element drawing, the schedule and the erection set;
• every cast-in item present in the model appears on the drawing and in the schedule, positioned to the same coordinates;
• reinforcement clear of inserts, sockets and openings, with cover maintained to every face;
• element weights and centres of gravity recomputed from geometry and reconciled with the lifting arrangement shown;
• openings and penetrations reconciled against the architectural and services models where those are available;
• element dimensions against the mould they are assigned to, including length, depth and side-form availability;
• drawing revisions against the register, and the schedule against the drawing set it was cut from.

A senior engineer reviews the package with those results in front of them and signs it. Production runs against a signed set, not against the latest file in a folder.

Lifting, handling and the loads that are not in the design

A precast element is designed for the load it will carry for sixty years. It is very often governed by the twenty minutes before that: stripping from the mould, turning, stacking in the yard, riding a trailer, and hanging from a crane.

So the handling case is detailed as its own problem. Element weight and centre of gravity are recomputed from the geometry — including openings, recesses and every cast-in item — rather than taken from a typical. Lifting anchors are selected against the concrete strength on the day of stripping, not the twenty-eight-day figure, with edge distances and reinforcement around the anchor shown on the drawing. Sling angle is stated, because a rigging arrangement that closes to forty-five degrees loads an anchor far harder than the vertical lift someone assumed.

The rest follows the same logic. Panels that have to be turned are detailed with the rotation method and the anchors it needs. Storage is drawn with support points and stacking limits so a stack does not crack the units at the bottom of it. Transport support positions, dunnage and the overhang the trailer allows are shown, because a bearing point moved half a metre for convenience is a crack that appears at the yard gate. Temporary propping, bracing and stability during erection are detailed with the connection that eventually replaces them.

Where a handling case cannot be made to work — a panel too slender to strip, a lift the plant's crane cannot take, a unit that will not sit on the trailer — that comes back as a query with an option while the element can still change shape.

Erection, sequence and the site set

The site receives a different document to the factory, and it has to agree with it exactly. Erection drawings carry element marks in the erection sequence, setting-out and levels, bearing details, joint and grouting details, temporary propping and stability requirements, and the connection hardware in the order it is installed.

Load lists are built to the delivery sequence rather than to the element schedule, because a trailer arriving in the wrong order costs a crane day. Where the programme changes, the sequence is re-issued and the affected loads are identified, instead of the site working out the difference for itself.

Standards for precast concrete

Precast sits under both product and execution standards, and the detailing changes with them.

• Europe — EN 13369 for the common rules for precast concrete products, with the product standards that sit under it: EN 1168 for hollow core slabs, EN 13224 for ribbed floor elements, EN 13225 for linear structural elements, EN 13747 for floor plates with in-situ topping, EN 14992 for wall elements and EN 14843 for stairs. EN 1992 and its National Annex govern design, EN 13670 execution.
• North America — ACI 318 for design, with the PCI Design Handbook for element and connection design and PCI plant quality practice for structural and architectural manufacture, handling and erection. ACI 551 where the work is tilt-up.
• Australia and New Zealand — AS 3600 with the national guidance on precast concrete handling and erection.
• Information management — ISO 19650 where the project runs a formal common data environment, with element data delivered in a structure the plant's production system can read.

Where a project spans two of these, the standard is set per package at intake and the checks are configured to match it.

One partner, one signature

BuildTwin produces the precast package, checks it and signs it. One delivery lead, one register, one production programme to report against, one company answerable for the drawing the mould was set from — not a pool of people you have to manage.

The work runs on data centres, residential and commercial frames, manufacturing plants, car parks, stadiums and infrastructure elements, and it runs inside your systems: your mould library, your element numbering, your common data environment, and your production planning. When the plant's programme accelerates, the system produces more elements per week; the review and the signature stay with the same senior engineers.