TR-20 – Movement Joint in Rendered Blockwork

This rendered blockwork movement joint detail shows a typical vertical joint within the concrete-block outer leaf of a masonry cavity wall.

The detail illustrates a clear joint through the external blockwork and polymer render, filled with compressible material and finished with a flexible weather-resistant sealant. It also shows how the cavity insulation and internal masonry leaf continue behind the joint.

For the equivalent facing-brick construction, see our TB/20 facing-brick movement joint detail. Approved Document A provides the official structural guidance for walls and other building elements.

Supporting notes cover:

• Typical movement-joint width.
• Maximum indicative joint spacing.
• Positioning near corners and changes in wall geometry.
• Compressible closed-cell filler or backing rod.
• Low-modulus weather-resistant sealant.
• Proprietary render movement-joint beads.
• Prevention of render or reinforcement bridging the joint.
• Additional wall ties on each side of the joint.
• Debonded sleeved movement ties where structural restraint is required.
• Continuity of the residual cavity and rigid insulation.
• Flexible continuity of DPCs, cavity trays and airtightness layers.
• Coordination with openings, parapets and structural supports.

The customer receives one downloadable PDF construction detail, drawn at 1:10 and formatted to fit an A3 sheet.

The movement joint shown applies to the outer leaf unless a corresponding inner-leaf joint is required by the structural design. Final joint locations, widths and spacing must be coordinated with the blockwork manufacturer, render-system provider and structural engineer.