Documentation Guide
How a NeXTimber mass timber project is documented and delivered: responsibilities, drawing requirements, tolerances and the three-issue approval process.
Introduction and glossary
This guide outlines the documentation and approval process, including the development of the Project Data, and the documentation standards NeXTimber needs to produce the Manufacturing Documentation. Following it helps ensure a smooth process from receipt of the design documents through to manufacture.
| Term | Definition |
|---|---|
| Billet | Large format CLT element from which individual panels are machined |
| BIM | Building Information Modelling |
| CLT | Cross-Laminated Timber (panels) |
| CNC | Computer Numerical Control (timber processing machine) |
| Design Documentation | Documents prepared by the engineer, architect or other consultants necessary to complete NeXTimber deliverables |
| DfMA | Design for Manufacturing and Assembly |
| GLT | Glue-Laminated Timber (beams and columns) |
| LOD | Level of Development (the accuracy of a model) |
| Manufacturing Documentation | Digital documentation produced by NeXTimber to manufacture the project: the 3D digital model, CNC files and QA documentation |
| Panel | Components cut or machined from a CLT billet |
| PIR | Project Information Requirements |
| Project Data | All information produced by NeXTimber to execute the project: Manufacturing Documentation, programs and timelines, logistics and loading plans, material take-offs and procurement |
Documentation and responsibility matrix
The matrix indicates which party develops and supplies each output on a standard engagement. It may vary if a different agreement is negotiated with NeXTimber.
| Deliverable | Architect | Engineer | Contractor | NeXTimber |
|---|---|---|---|---|
| Frozen geometric model | Yes | |||
| Panel sizes / specification | Yes | |||
| Penetration size and locations (holes, rebates) | Yes | Yes | ||
| Indicative panelisation / breakup | Yes | |||
| Connection and fixing details / specification | Yes | |||
| Fully coordinated design documents for construction | Yes | Yes | ||
| Development of LOD 400 manufacturing model | Yes | |||
| Fixing and CLT BOM | Yes | |||
| Machine and manufacturing files | Yes | |||
| Pre-manufacture approval & signoff | Yes | Yes | ||
| QA documentation | Yes | |||
| Temporary works / lifting certification | Yes | |||
| Truck loading and despatch drawings | Yes |
For items relating to the supply of elements within NeXTimber supply scope only. Fixing and CLT bill of materials applies if fixings are supplied by NeXTimber.
Project delivery
Each project is assigned a Project Coordinator who is the primary point of contact and manages delivery on behalf of NeXTimber. Once the contract is signed, all communication should be directed through the Coordinator.
End-to-end detailing, including documentation coordination and development of the Final Project Data, typically takes in the order of 12 weeks, depending on the size and complexity of the project. Engaging NeXTimber early, with a DfMA mindset, reduces rework, optimises panelisation and aligns logistics and assembly.
Incoming drawings and quality
NeXTimber prepares its Manufacturing Documentation in the HSBCad platform, which integrates with Revit and AutoCAD. The preferred input is a 3D digital model, with detailed 2D drawings an option for less complex jobs. The minimum BIM level is LOD 350 (LOD 300 may be evaluated in some cases). Documentation must be issued and certified 'For Construction' and coordinated across all disciplines before manufacturing modelling begins.
| Interface | Tolerance |
|---|---|
| CLT to CLT | 2 mm |
| GLT to GLT | 2 / 5 mm* |
| CLT to GLT | 2 mm |
| CLT/GLT to other timber | 2 / 5 mm* |
| CLT/GLT to steel | 10 mm |
| CLT/GLT to concrete | +/- 25 mm |
Approval process: three issues
NeXTimber uses a three-issue design approval process. The customer must formally approve each phase in writing before the next begins.
- Issue 1 - Pre-approval (massing and setout). 3D model in IFC/hsbShare with primary geometry, thicknesses, CLT grain directions, treatment areas and visual aspect.
- Issue 2 - For approval (draft project data). Updated model plus 2D assembly drawings with connection, panelisation and joint details for the nominated installation sequence.
- Issue 3 - For manufacture (final project data). Final 3D model for manufacture plus lifting, fixings and truck loading drawings. On approval, panels are nested in billets, tooling is assigned and production begins.
Revit families and downloads
NeXTimber provides a free Revit BIM library: a CLT template file with the families in place, and a GLT beam and column family file.