Building Layout and Viewing Conventions

This document describes how tilt-up building layouts are represented in plan view and how individual panel elevations are oriented for viewing. These conventions are fundamental to understanding panel books, panel numbering, and the 3D site model in ConstructiVision.

1. Elevation Viewing Convention — Interior View

Tilt-up panel elevations are drawn as viewed from inside the building looking outward at each wall, not from the exterior looking in. This is the opposite of most architectural exterior elevations.

Why interior view? Tilt-up panels are cast face-down on the building slab. The casting slab is the form for the exterior face. When the engineer or detailer drafts an elevation, they are looking at the panel as it lies on the slab — which corresponds to an interior view of the erected wall. Additionally, field crews erecting panels stand inside the building and read panel marks from the interior face. An interior-view convention means the construction documents match the field crew’s physical perspective.

Practical consequence: When reading an elevation from interior view, the left side of the drawing is the observer’s left when standing inside the building. This means:

  • On the Back (north) elevation, the left side of the drawing is the building’s northwest corner and the right side is the northeast corner

  • On the Front (south) elevation, the left side is the southeast corner and the right side is the southwest corner

  • On the Right (east) elevation, the left side is the northeast corner and the right side is the southeast corner

  • On the Left (west) elevation, the left side is the southeast corner and the right side is the northwest corner

This is the reverse of exterior-view conventions. Software that displays tilt-up elevations — including ConstructiVision’s 2D panel editor — must follow interior-view convention to match industry practice.

2. Panel Numbering Sequence — Building Perimeter

Panels are numbered sequentially around the building perimeter, starting from a designated corner (typically the northwest corner of the back elevation) and proceeding clockwise as seen from above. The sequence wraps continuously through all elevations:

            (Back Elevation — Top Side)
          P001  P002  P003  P004  P005  P006  P007  P008
        +------------------------------------------------+
        |                                                | P009
        |                                                |
  P024  |                                                | P010  (Right Elevation)
        |                                                |
  P023  |                  BUILDING                      | P011
        |                   LAYOUT                       |
  P022  |                (Plan View)                     | P012
        |                                                |
  P021  |                                                |
        +------------------------------------------------+
          P020  P019  P018  P017  P016  P015  P014  P013
                (Front Elevation — Bottom Side)

  (Left Elevation)

Key conventions:

  • Numbering runs clockwise around the building perimeter when viewed in plan (from above)

  • No numbering restarts at elevation boundaries — a single continuous sequence wraps the entire building

  • Corner panels belong to whichever elevation they are assigned to by the detailer (typically the continuous panel in a butt-joint corner condition)

  • The starting corner and direction may vary by project or firm practice; clockwise from the northwest corner of the back wall is the most common default

  • When the building has re-entrant corners, jogs, or non-rectangular plan shapes, the numbering still follows the perimeter continuously

Relationship to interior viewing: In the plan-view diagram above, panel numbers along each elevation read left-to-right when looking at that wall from inside the building. For example, the back elevation reads P001→P008 from left to right when standing inside looking north.

3. Plan View Orientation and Compass Mapping

In a standard plan-view building layout drawing:

Drawing Direction

Compass Direction

Elevation

Top of sheet

North

Back

Bottom of sheet

South

Front

Right of sheet

East

Right

Left of sheet

West

Left

This orientation convention carries through to:

  • Panel layout plans in the panel book (Section 4 of panel-book-notation.md)

  • The 3D site model top view in ConstructiVision’s viewer

  • Coordinate systems used in the chain walk algorithm (see Section 4)

4. 3D Site Model Layout — Coordinate Mapping

ConstructiVision’s 3D site model uses a Three.js coordinate system. When viewed from above (top view, camera looking down from +Y):

Three.js Axis

Plan-View Direction

Compass

+X

Right

East

−X

Left

West

+Z

Down (toward viewer)

South

−Z

Up (away from viewer)

North

+Y

Out of screen

Up

The chain walk algorithm places elevations around the building perimeter using a counter-clockwise walk (as seen from above). Starting from the back elevation:

  1. Back — wall extends along +X at Z ≈ −depth (top of plan view, north)

  2. Right — wall extends along +Z at X ≈ +width (right side, east)

  3. Front — wall extends along −X at Z ≈ +depth (bottom of plan view, south)

  4. Left — wall extends along −Z at X ≈ −width (left side, west)

Panel exterior faces point outward from the building center. This means the 3D model shows the building as it would appear from outside, with panel marks visible on the exterior face.

Camera Presets

Preset Button

Camera Position

What You See

F (Front)

+Z looking −Z

Front (south) elevation exterior

B (Back)

−Z looking +Z

Back (north) elevation exterior

L (Left)

−X looking +X

Left (west) elevation exterior

R (Right)

+X looking −X

Right (east) elevation exterior

TP (Top)

+Y looking down

Plan view — matches panel layout plan

5. Interior View vs. Exterior View — When Each Applies

Context

View Convention

Reason

Panel book elevations

Interior (looking outward)

Matches casting position and field crew perspective

Panel layout plan

Plan view (top down)

Standard construction document convention

3D site model

Exterior (looking inward)

Shows building as-built from outside; natural 3D navigation

2D panel editor

Interior (looking outward)

Matches panel book convention; panel 1 is at left

Important: The 2D editor and the 3D site model show the same panels in reversed left-right order because interior view and exterior view are mirror images. Panel P001 appears at the left end of an elevation in the 2D editor (interior view) but at the right end when viewing that same wall from outside in the 3D model. This is correct and expected behavior - it matches real-world viewing.

6. Construction Layout (Panel Form Placement)

In field and office practice, the phrase construction layout is often used colloquially to mean the slab-based placement plan for panel forms before casting. In this usage, construction layout is not just building control lines; it is the full panel placement strategy that determines how panels are bedded, cast, stripped, and moved for erection.

Typical construction layout decisions include:

  • Interior top-out casting on the building slab (most common baseline)

  • Exterior casting beds (bottom-in) for panels that cannot be efficiently cast in-board

  • Rat slab casting areas where dedicated casting surfaces are created outside the finished floor footprint

  • Stack-cast sequencing where panel families are cast in vertical stacks to save bed area

Construction layout also defines slab timing assumptions. Teams should explicitly note whether the finish slab is expected to be complete before panel casting, whether temporary casting beds are planned, and whether closure strips or delayed slab pours are required to maintain erection logistics.

At minimum, a construction layout package should identify:

  • Panel footprints and panel marks at casting position

  • Form orientation and interior/exterior face indication

  • Required edge offsets and clearances for embeds, reveals, and lifting inserts

  • Crane access, pick corridors, and temporary storage or laydown zones

  • Planned move path from casting position to final erected location

Using this terminology consistently helps align architectural, structural, and field teams when discussing where panels are actually formed, not just where the finished walls end up.

7. Crane Position, Edge Distance, and Lift Logistics

The answers to “how close can the crane get” and “how far from slab edge should panels be cast” are project-specific lift-engineering questions, not fixed code numbers. They depend on crane type, outrigger or track reaction, soil bearing pressure, slab or subgrade capacity, panel weight, and pick radius.

7.1 Inside Pick vs Outside Pick

Two common erection patterns are used:

  • Inside pick (crane inside the building footprint): The crane works from interior slab lanes and sets panels outward to the perimeter line.

  • Outside pick (crane outside perimeter): The crane travels around the exterior and sets panels from outside to inside.

Outside pick is common when interior slab congestion is high, when roof steel sequencing favors exterior access, or when heavy picks require larger crane footprints than interior lanes can provide.

7.2 How Close To Slab Edge

There is no universal minimum that applies to every crane. The enforceable limit is always the crane manufacturer chart plus the geotechnical and erection-engineering plan.

Planning-level guidance:

  • Keep crane travel and setup out of unsupported slab-edge zones unless specifically engineered.

  • For outrigger cranes, the critical point is outrigger pad reaction at the nearest edge, not just tire location.

  • For crawler cranes, track edge proximity still requires bearing and edge-breakout checks even without outriggers.

  • If lift or travel must occur near an edge, use engineered crane mats or temporary ground improvement and document the allowed crane path.

7.3 Panel Placement Distance and Spacing (Planning Bands)

These are planning bands for early layout coordination only. Final values must be issued by the erection engineer.

Layout Item

Typical Planning Band

Why It Exists

Panel casting bed offset from slab/perimeter edge

about 5 ft to 15 ft

Formwork room, strip room, edge safety buffer

Clear spacing between adjacent cast panels

about 3 ft to 8 ft

Form access, reveal protection, rigging access

Crane operating lane beside beds

about 12 ft to 25 ft (or per crane footprint)

Track or outrigger envelope and swing clearance

Tighter spacing may be possible for small panels and small cranes. Large panels, larger inserts, spreader bars, and high boom angles usually push spacing wider.

7.4 Does Crane Size Change Layout?

Yes. Crane class and model can change bed spacing, edge offsets, and pick corridors significantly.

What usually drives crane selection:

  • Load moment, not weight alone: the controlling demand is roughly $W \times R$ (pick weight times radius).

  • Radius growth with erection sequence: as the crane stands farther from the set line, required capacity increases quickly.

  • Boom and height effects: height matters because boom geometry can force larger radii, reduce chart capacity at angle, and add wind sensitivity.

  • Ground pressure and reactions: larger cranes can require much larger support zones and mat systems.

So, height does matter, but mostly through geometry, wind exposure, and radius effects. Weight by itself is not enough.

7.5 Common Crane Types In Tilt-Up Work

Typical crane families seen on tilt-up projects:

  • Crawler cranes (tracked): high capacity and good stability; common on larger panels and repetitive heavy picks.

  • Rough-terrain cranes (wheeled with outriggers): flexible site mobility on prepared ground; common on mid-size projects.

  • All-terrain or truck cranes (wheeled with outriggers): fast mobilization; used where road travel and setup speed matter.

Field slang sometimes says “creeper” for a crane creeping or walking picks, but the equipment class is typically crawler or rough-terrain/truck-mounted.

Representative model families often seen in the market include Grove GMK and RT series, Liebherr LTM/LTR series, and Manitowoc crawler families. Exact model selection is always project-specific.

7.6 Rigging Hardware At The Hook End

The wire rope or sling assembly commonly terminates through one or more of the following:

  • Crane hook block and safety latch

  • Master link or lifting ring

  • Shackles (bow or anchor shackles)

  • Swivels where rotation control is needed

  • Spreader bar or equalizer beam

  • Tilt-up insert clutches compatible with the cast-in lifting insert

  • Chain slings, wire rope slings, or synthetic round slings (as engineered)

  • Tag lines for rotation control during lift

Hardware must be compatible with insert manufacturer requirements, rigging angle, and the planned load share.

7.7 Two-Crane Picks (Tandem Lifts)

Yes, tilt-up teams do use two-crane picks in selected conditions, for example:

  • Very long or unusually shaped panels

  • Asymmetric center of gravity conditions

  • Restricted access where one crane cannot maintain a safe radius through the full rotation

  • Controlled upending where load transfer between cranes is required

Tandem lifts require a dedicated engineered lift plan with explicit load-share assumptions, communication protocol, sequence steps, and stop criteria. They should be treated as higher-risk operations than single-crane picks.

7.8 Documentation Fields To Add In Construction Layout Packages

To make these constraints actionable, include at least:

  • Crane type/class assumption and candidate model class range

  • Maximum planning pick weight and controlling radius by zone

  • Interior and exterior crane travel lanes and no-go zones

  • Required edge-offset notes for crane setup and panel beds

  • Panel bed spacing assumptions and exceptions for heavy panels

  • Tandem-pick flag for panels requiring special lift engineering

This keeps layout drawings, panel books, and erection planning aligned before final stamped lift drawings are issued.

7.9 Planning Size Envelopes By Crane Class (For Initial Placement)

Use these as first-pass planning envelopes to place the crane start station relative to panel beds. Replace with exact vendor submittal dimensions once the crane model is selected.

Crane Class

Typical Lift Class (planning)

Width (travel/transport)

Operating Footprint (setup)

Swing/Tail Clearance Zone

Suggested Initial Lane Width

Rough-terrain (RT) with outriggers

60 to 120 ton

9 ft to 11 ft

about 24 ft x 24 ft to 30 ft x 30 ft

12 ft to 18 ft radius

18 ft to 28 ft

All-terrain/truck crane with outriggers

120 to 300 ton

9 ft to 11 ft

about 28 ft x 28 ft to 40 ft x 40 ft

14 ft to 22 ft radius

22 ft to 36 ft

Crawler crane (tracked)

120 to 300 ton+

16 ft to 30 ft assembled width

about 20 ft x 30 ft to 35 ft x 45 ft

15 ft to 25 ft radius

24 ft to 40 ft

Notes:

  • “Operating footprint” includes outrigger spread for wheeled cranes or track envelope for crawlers.

  • “Lane width” includes crane body/gear plus setup and movement margin; increase where rigging complexity is high.

  • High boom lengths, luffing jibs, and tight swing restrictions can require wider effective envelopes than the planning table.

7.10 Initial Crane Starting Position Method

For first layout pass, place the crane centerline offset from the panel set line using:

$$ O_s = \frac{W_f}{2} + B_s + B_h $$

Planning defaults:

  • Swing Buffer: 4 ft to 8 ft

  • Panel Handling Buffer: 6 ft to 12 ft

Example (mid-size RT crane):

  • Footprint width = 28 ft

  • Swing Buffer = 6 ft

  • Panel Handling Buffer = 8 ft

$$ O_s = 14 + 6 + 8 = 28\ \mathrm{ft} $$

So a first-pass crane centerline about 28 ft off the panel line is reasonable for planning, then adjusted by lift chart checks, pick radius by panel mark, and geotechnical constraints.

7.11 Typical Crane Families To Pre-Plan Around

If the exact crane is not yet procured, layout teams commonly run envelope checks using one model from each likely family:

  • RT check model: Grove RT or similar class

  • AT/truck check model: Grove GMK or Liebherr LTM class

  • Crawler check model: Manitowoc or Liebherr LTR class

The goal is not to lock a brand early; it is to avoid under-sizing crane lanes and setup pads in the panel casting plan.

Sources: TCA panel book conventions; ACI 551.1R tilt-up construction guidance; OSHA 29 CFR 1926 Subpart CC (cranes and derricks in construction); representative crane manufacturer load-chart practice (Grove, Liebherr, Manitowoc); common industry practice from multiple tilt-up detailing firms.