TR-01 – Trench Fill Foundation, Cavity Wall and Ground-Bearing Slab

This detailed construction drawing shows a typical junction between a rendered masonry cavity wall, trench-fill foundation and insulated ground-bearing concrete floor slab.

The drawing illustrates the relationship between the foundation, inner and outer wall leaves, cavity insulation, damp-proof course, damp-proof/radon membrane, floor insulation, perimeter insulation, concrete slab and compacted hardcore. It also shows how the wall and floor insulation should be coordinated to reduce thermal bridging at the perimeter junction.

Supporting notes cover:

• Typical trench-fill foundation dimensions and construction requirements.
• Ground-bearing slab build-up.
• Damp-proof and radon-barrier continuity.
• External cavity-wall construction.
• Wall ties, mortar and cavity control.
• Perimeter insulation and airtightness.
• Typical thermal-performance targets.
• Junction SAP reference E5 and the calculated PSI value shown on the drawing.

The customer receives one downloadable PDF construction drawing, prepared at a scale of 1:10 and arranged to fit an A3 sheet.

This is a standard construction detail intended to assist architects, architectural designers, technicians, builders and self-builders when preparing construction and Building Regulations drawings. Foundation sizes, depths, materials and thermal specifications must be checked and adapted to suit the particular project, ground conditions, structural design and Building Control requirements.