Timber Joist & Rafter Advisor
Preliminary Section Sizing
Returns the minimum compliant solid softwood section for a given span, use type, and member spacing. Covers floor joists, ceiling joists, flat roof joists, and rafters for UK domestic construction. Derived from TDUK Knowledge Library span tables (C16 and C24 grades).
What it does
Pure lookup engine against TDUK/Eurocode 5 span tables (Bartosz Belch for TDUK, 1 July 2023). Accepts span, use type (floor/ceiling/flat roof/rafter), timber grade (C16 or C24), and joist spacing (400/450/600mm c/c). Returns the minimum compliant section from 17 standard softwood sizes. Sweep mode compares all three spacings in a single call to find the most efficient combination.
Disclaimer
STRICTLY NOT FOR CONSTRUCTION. Results are preliminary guidance only, derived from TDUK span tables for solid softwood. Cannot be used for structural design, building control, hardwoods, or engineered timber. Always engage a structural engineer before proceeding.
Use cases
- —Preliminary joist sizing at RIBA Stage 1–2 without engaging a structural engineer
- —Quick span feasibility check for domestic floor, ceiling, or roof member
- —Comparing C16 vs C24 timber grade for a given span and loading
- —Spacing optimisation — sweep 400/450/600mm in one call to find the most efficient section
Autodesk Revit AI Assistant
Revit 2027 introduces native MCP server support, connecting AI assistants directly to your BIM model via the open MCP standard. Datatreehaus tools are built to this standard — Revit AI Assistant integration is planned for a future release.
Quick start
// Claude Desktop — claude_desktop_config.json
{
"mcpServers": {
"datatreehaus": {
"url": "https://timber.datatreehaus.com/mcp",
"headers": {
"X-DTH-Key": "dtk_live_YOUR_KEY_HERE"
}
}
}
}Get started
Sign up for a free API key to use this tool.
Sign up free →MCP SERVER URL
https://timber.datatreehaus.com/mcp
(API key required)