Tilt-up construction compresses the consequence of grade and layout errors: a slab that is out of flat, an embed that is out of position, or a panel edge line that is off by a fraction of an inch creates problems that are discovered during erection — when the crane is standing by and the fix requires engineering review. Documentation before the pour is the only way to manage these risks.
What grade and layout documentation is required for tilt-up construction?
Tilt-up construction requires documentation at multiple stages: a casting slab surface survey confirming the slab is within the specified flatness tolerance before panels are cast; embed plate location survey (XY and elevation) before the pour with design vs. actual comparison; panel edge line layout verification; a post-pour embed as-built survey for the erector; and a pre-erection documentation package that includes all surveys, any engineer approvals of deviations, and a slab grade summary. The documentation must be complete before erection begins.
The casting slab is the mold for the tilt-up panel. A slab that is out of flat produces panels with variable thickness — which affects the panel's structural properties, its weight calculation for the lift, and its fit against adjacent panels during erection.
Most tilt-up specifications require the casting slab to meet ACI 117 flatness requirements, typically a minimum Flatness Factor (FF) of 25. Some specifications require FF 35 or higher for panels with tight architectural requirements. The F-number survey must be performed within 24 to 72 hours of slab placement — before curling or drying shrinkage affects the result.
| Flatness Level | FF Value | Application |
|---|---|---|
| Minimum for tilt-up casting | FF 25 | Standard industrial tilt-up; basic panel uniformity |
| Typical commercial tilt-up | FF 30–35 | Warehouse, distribution, light manufacturing |
| Architectural panel requirements | FF 40+ | Exposed aggregate, form liner, or smooth architectural panels |
Embed plates are the connection hardware cast into the tilt-up panel that receive structural attachments, dock equipment, roof connections, and mechanical supports after erection. An embed that is out of position by more than the specified tolerance requires an engineering review before the panel can be used — which means delays at the worst possible time.
Required embed documentation steps:
Panel edge lines define the perimeter of each panel on the casting slab. Before casting, a surveyor or qualified layout technician verifies that edge lines are correctly positioned relative to building control lines. The verification record must show:
Panel edge line errors compound during erection — a panel that is 1/4 inch too wide on each side creates a 1/2-inch gap at every joint, which affects weathertightness, sealant performance, and architectural alignment.
The pre-erection documentation package is submitted to the engineer of record and the erection contractor before the crane mobilizes. A complete package includes:
| Document | Required Content |
|---|---|
| Casting slab F-number report | FF and FL values by grid area; compliance statement vs. specification |
| Pre-pour embed survey | All embed plates; design vs. actual XY and elevation; deviations and engineer approvals |
| As-built embed survey | Final embed locations after cure; any movement noted between pre-pour and post-pour |
| Panel edge line verification | All panels; design vs. actual edge line position; pass/fail by tolerance |
| Engineer correspondence on deviations | Written approval or direction for any item outside specification tolerance |
Sitemark captures slab surface surveys, embed locations, and layout verification in the field and assembles the pre-erection package for engineer review — so the documentation is ready before erection day rather than assembled under pressure when the crane is on site.
Sitemark captures casting slab surveys, embed plate locations, and panel layout verification and delivers the pre-erection package before erection day. Avoid crane standby costs from documentation that was not ready.
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