TideMark is a 3D-printable field tool that helps contractors set formwork to the correct elevation — without a surveyor on site. It's a triangular graduated tower that threads onto a printed ground stake, with an eye bolt for stringline attachment and a sliding lock screw for setting target elevation.
Designed by Oasis Engineering, LLC — a structural engineering firm specializing in wind load analysis, residential permwork, and pre-construction elevation services.
In construction and engineering, teams often deliver the medium instead of the outcome.
The medium is familiar: a plan sheet, a note, or an elevation certificate. Those documents matter, but they are not the end goal.
The real goal is simple: the people in the field need to know the exact elevation of grade, formwork, or finished floor so they can build safely, accurately, and confidently — without second-guessing.
TideMark is designed around that reality. It takes the engineer's elevation intent and turns it into a physical, on-site reference that crews can act on immediately. Traditional exhibits and certificates still have their place; TideMark reduces the friction between "information delivered" and "work built correctly."
Contractors building slabs, accessory structures, and ADUs near flood zones need to hit a specific Finished Floor Elevation (FFE). Today, the typical workflow is:
- Engineer specifies FFE on plans (e.g., "621.25' NAVD88")
- Contractor stares at the number
- Contractor eyeballs it with a tape measure off... something
- Forms get set wrong
- Everyone has a bad day
There is no affordable, standardized field tool that bridges the gap between a PE's elevation determination and the contractor's formwork.
TideMark fixes that.
TideMark is not just a stake — it's a field reference system with three components:
| Component | What It Does | Where It Lives |
|---|---|---|
| TideMark Stake | Physical elevation reference tool | This repo (open source) |
| Formwork Elevation Reference Exhibit (FERE) | PE-stamped elevation determination document | Service from Oasis Engineering |
| Field Methodology Guide | Step-by-step photo-documented workflow | /docs/field-guide.md |
The stake is the delivery mechanism. The exhibit is the product. The methodology ties them together.
┌─────────────────────────────────────────────────────┐
│ ENGINEER SITE VISIT │
│ │
│ 1. PE performs differential elevation survey at │
│ project site, establishes reference elevations │
│ │
│ 2. PE drives TideMark ground stakes at strategic │
│ benchmark locations around proposed structure │
│ │
│ 3. PE threads tower onto each stake, sets lock │
│ screw to required FFE offset, labels elevation │
│ │
│ 4. PE photographs each installed TideMark stake │
│ and surrounding site conditions │
│ │
│ 5. PE produces Formwork Elevation Reference Exhibit │
│ with benchmark data, photos, and offset dims │
│ │
│ 6. PE delivers exhibit to client — TideMark stakes │
│ remain installed on site, ready for use │
└──────────────────────┬──────────────────────────────┘
│
▼
┌─────────────────────────────────────────────────────┐
│ CONTRACTOR EXECUTION │
│ │
│ 7. Contractor locates installed TideMark stakes │
│ using exhibit site plan and photo references │
│ │
│ 8. Contractor confirms stakes are undisturbed │
│ │
│ 9. Contractor ties stringline to eye bolts — │
│ the stakes are already set to FFE │
│ │
│ 10. Contractor sets forms to stringline │
│ │
│ 11. Contractor photographs stakes + forms and │
│ sends to PE for pre-pour verification │
└─────────────────────────────────────────────────────┘
tidemark/
├── README.md # You are here
├── LICENSE # MIT License
│
├── hardware/
│ ├── stl/ # Print-ready STL files
│ │ ├── TrianglePiece.STL # Graduated triangular tower (16")
│ │ ├── GroundStake.STL # Auger-style ground stake
│ │ ├── HookBolt.STL # Eye bolt for stringline
│ │ ├── LockBut.STL # Lock nut for height clamping
│ │ └── TopCap.STL # Triangular cap (bubble + sticker)
│ ├── source/ # Editable CAD source files
│ │ └── TideMark.STEP # Full assembly — all components
│ ├── renders/ # Product renders
│ │ ├── assembly-full.jpg
│ │ ├── assembly-exploded.jpg
│ │ ├── tidemark-iso-1.jpg
│ │ └── tidemark-iso-2.jpg
│ ├── drawings/ # Engineering drawings
│ ├── BOM.md # Bill of materials
│ └── PRINT-SETTINGS.md # Recommended slicer settings
│
├── docs/
│ ├── field-guide.md # Step-by-step field usage
│ ├── photo-verification.md # How to photograph for documentation
│ ├── elevation-basics.md # FFE, BFE, NAVD88 primer for contractors
│ └── faq.md # Common questions
│
├── exhibit/
│ ├── EXHIBIT-SPEC.md # What goes into a Formwork Elevation
│ │ # Reference Exhibit (FERE)
│ ├── SCOPE-OF-SERVICE.md # Standard scope language for proposals
│ ├── general-notes.md # Standard general notes for exhibits
│ ├── elevation-control.md # Elevation control note templates
│ ├── disclaimers.md # Legal disclaimer language
│ └── examples/
│ └── README.md # Description of example exhibits
│
├── branding/
│ ├── color-palette.md
│ └── (logo and label templates coming)
│
├── templates/
│ ├── proposal-template.md # Proposal language for FERE service
│ └── transmittal-template.md # Client transmittal for exhibit + kit
│
└── CONTRIBUTING.md # How to contribute
| Item | Source | Est. Cost |
|---|---|---|
| TideMark Tower (3D printed, triangular) | Print from /hardware/stl/ |
~$3 in filament |
| TideMark Ground Stake (3D printed) | Print from /hardware/stl/ |
~$1.50 in filament |
| TideMark Lock Screw + Nut (3D printed) | Print from /hardware/stl/ |
~$0.50 in filament |
| Eye bolt, 1" loop | Hardware store or printed | ~$1 |
| Hammer | You already have one | — |
| Sharpie | For labeling | ~$1 |
Total cost per stake: ~$7.00
See hardware/PRINT-SETTINGS.md for detailed slicer settings.
Quick reference:
- Material: PETG for tower (UV/impact), PLA for threaded parts (sharper threads)
- Layer height: 0.2mm
- Infill: 50% gyroid
- Walls: 4 perimeters
- Print plates: 3 separate plates (tower, hardware, ground stake)
- Color: Safety orange or bright yellow for tower, contrasting for lock hardware
- Avoid: PLA for the tower (warps in sun, brittle on impact)
- Tower body: 16" tall, equilateral triangular cross-section, 3" per face
- Connection: Female thread (1" × 2") at tower base, mates to male thread on ground stake
- Graduations: Embossed inch marks on one face, 1" major / 0.25" minor ticks (1/4" resolution)
- Stringline attachment: 1" eye bolt threaded into top of tower
- Height lock: Sliding lock screw through tower wall — threaded bolt + nut clamps position
- Label window: Flat area on one face for Sharpie notation
- Branding: "TIDEMARK" and "OASISENGINEERING.COM" embossed on one face
- Ground stake: 8" driven section + 2" handle/grip + 1" male thread (11" total)
The Formwork Elevation Reference Exhibit is the engineering document that makes TideMark useful. Without it, TideMark is just a ruler on a stick. With it, it's a precision field reference system.
A FERE includes:
- Site plan with proposed building location and benchmark positions
- Observed reference elevations (field-measured benchmarks in NAVD88)
- FEMA FIRM map exhibit showing flood zone and BFE (if applicable)
- Photo exhibits of physical benchmark locations
- Foundation detail showing FFE relationship to existing grade
- Elevation control notes specifying FFE, tolerances, and contractor responsibilities
- General notes and disclaimers clarifying scope limitations
See exhibit/EXHIBIT-SPEC.md for the full specification.
- ❌ Not a boundary survey
- ❌ Not a topographic survey
- ❌ Not a construction survey
- ❌ Not a substitute for field verification by the contractor
It is a reference tool based on limited field observations and publicly available GIS/FEMA data, prepared by a licensed Professional Engineer, intended to assist the contractor in establishing formwork elevation.
Need a FERE for your project?
Oasis Engineering provides Formwork Elevation Reference Exhibits as a standalone service for contractors, builders, and homeowners working on:
- Accessory structures (barndominiums, workshops, detached garages)
- ADUs (accessory dwelling units)
- Residential additions in or near flood zones
- Slab-on-grade structures requiring FFE compliance
What's included:
- Site visit or remote assessment (GIS/photo-based)
- PE-stamped Formwork Elevation Reference Exhibit
- TideMark stake kit (4 stakes + lock hardware)
- Field methodology guide
📞 813-694-8989 🌐 oasisengineering.com 🌐 windcalculations.com
See CONTRIBUTING.md for guidelines.
We welcome:
- CAD improvements and ergonomic refinements
- Field testing feedback and photos
- Alternative print material recommendations
- Translations of the field guide
- Integration ideas (QR codes, NFC tags, digital level adapters)
The TideMark hardware designs are released under the MIT License.
TideMark™ is a trademark of Oasis Engineering, LLC. The open-source hardware license covers the physical designs. The TideMark name, logo, and branding are not included in the open-source license.
The Formwork Elevation Reference Exhibit service, methodology, and associated professional engineering deliverables are proprietary services of Oasis Engineering, LLC.
Designed in Tampa, FL by Oasis Engineering — Structural Engineering · Wind Load Analysis · Elevation Services