TB/12 – Internal Loadbearing Wall Junction with External Wall

This loadbearing wall junction detail illustrates the connection between an internal masonry wall and the inner leaf of an insulated external cavity wall.

It is intended for architectural designers, building professionals, contractors, developers and self-builders preparing a Building Regulations drawing package or project specification. It can be used alongside the corresponding foundation-support drawing, while Approved Document A provides the official structural guidance.

The detail shows:

• 102 mm external brickwork
• Clear residual cavity
• Rigid cavity-wall insulation
• Celcon Solar aircrete block inner leaf
• 100 mm dense concrete block internal loadbearing wall
• Bonding to the inner leaf where walls are built concurrently
• Alternative proprietary stainless-steel wall-starter connection
• Starter ties in alternate bed joints
• Maintenance of the full cavity width
• Continuity of cavity-wall insulation
• Prevention of ties or masonry bridging the cavity
• Requirements for wall support, lintels and lateral restraint
• Indicative 30-minute fire resistance with finishes to both sides

The accompanying specification notes cover block strength, mortar, wall support, bonding, starter systems, tie spacing, cavity continuity, lintels, lateral restraint and fire resistance.

What This Loadbearing Wall Junction 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/12
• Detail title: Internal Loadbearing Wall Junction with External Wall

Important Information

This is a standard construction detail intended to provide general design and specification guidance. The internal wall thickness, block strength, support, connections, lintels and restraint must be suitable for the actual loads and building arrangement.

The wall must be supported by a suitable foundation, thickened slab or other purpose-designed structural support. Project-specific requirements should be confirmed by a suitably qualified structural engineer where necessary.

The drawing does not include structural calculations, foundation design, lintel calculations, fire engineering or Building Regulations approval. Purchasing or using the detail does not guarantee approval by Building Control.

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.