Facade Retention

Facade Retention

1. Valid Engineering option for

   • Historic/ Listed Buildings
     • Conservation Areas
       • Public face/ Townscape value

2. Detaching facade from structure

   • Can it support its own weight?
   • Surgeons cuts. taking out cross walls
   • Temporary retention located externally or internally

3. Four Phases

   • Erection of support frame
     • Raking shores- triangulated braced supports
   • Connections to wall
     • Horizontal bracing
     • Internal cross bracing
   • Demolition of existing structure
   • Construction of new structure

4. Issues with retention

   • Differential settlement
     • Connections need to allow for some movement as the new construction takes time to settle causing issues
   • Access for construction severely restricted with internal retention system
   • Problems installing the system before demolition can occur

5. External retention

   • Much better option
   • Encroach on pavement/ road
   • Health and safety of public
   • Can be reduced if frames allow walking underneath
   • Proprietary system
     • Easy to install

6. What to check for

   • Appraisal
     • Are there defects internally/externally
     • Is the facade loadbearing or is it the main support for the building a structure frame
     • Have remedial works been undertaken previously
   • New frame will have to be designed accordingly if facade bows or tilts

7. Structural issues

   • 3 sides can be removed without effecting stability of remaining facade
   • In older buildings external walls are often loadbearing and are tied together by the floors
   • If you remove the floors the walls are liable to collapse as loads are transmitted to foundations from the floor and roof via the external walls
     • The new frame must take the structural loads from the building, independant of the facade

8. Types of retention

   • Scaffolding- Used for low level facades 3-4 storeys
   • Proprietary- higher facades, props, ties, braces
   • Fabricated steelwork- Used when cost of proprietary is too much