TB/13 – Intermediate Floor Junction with Metal-Web Ecojoists

This metal web joist detail illustrates the junction between an insulated masonry cavity wall and a proprietary Ecojoist intermediate floor.

It is intended for architectural designers, building professionals, contractors, developers and self-builders coordinating floor support, services, fire protection and thermal continuity. For a plain-English introduction, see our related floor-joist guide; Approved Document B provides the official fire-safety guidance.

The detail shows:

• External brickwork and Celcon Solar aircrete block inner leaf
• 75 mm Kingspan Kooltherm K108 partial-fill insulation
• 50 mm clear residual cavity
• Metal-web timber Ecojoist floor construction
• Support using proprietary masonry joist hangers
• Alternative treatment where joists are built into masonry
• Continuity of cavity-wall insulation past the floor zone
• Moisture-resistant tongue-and-groove floor decking
• Acoustic mineral-wool insulation between joists
• Fire-resisting plasterboard ceiling
• Wall restraint straps, noggings and fixings
• Parge coat or airtight membrane behind the floor zone
• Fire stopping and cavity barriers
• Service routes through the open metal webs
• SAP junction reference E6
• Calculated psi value of 0.003 W/m·K

The accompanying notes cover specialist joist design, bearings, hangers, strongbacks, trimming members, floor decking, acoustic insulation, fire resistance, lateral restraint, airtightness and service penetrations.

What This Metal Web Joist Detail Includes

• One downloadable PDF construction drawing
• A3 landscape sheet
• Drawn at 1:10 scale when printed at 100% on A3 paper
• Drawing reference: TB/13
• Detail title: Intermediate Floor

Important Information

This is a standard junction detail and does not constitute a structural design for the floor. Joist depth, chord size, spacing, bearings, hangers, strongbacks, trimming members, concentrated loads and connections must be confirmed by the Ecojoist manufacturer or a suitably qualified structural engineer.

Metal webs and timber chords must not be cut, notched, drilled or altered. Fire, acoustic and cavity-barrier requirements must be coordinated with the project’s approved construction.

The stated psi value applies only where the illustrated geometry, materials and insulation arrangement are followed and should be checked through the project’s thermal assessment.

The drawing does not include a manufacturer’s joist layout, structural calculations, acoustic testing, fire engineering, SAP assessment or Building Regulations approval.

The PDF is supplied for use by the purchaser on their own projects. It may not be resold, redistributed or reproduced for commercial resale without written permission.