Stirling Council
Retaining wall - Dunblane


Job description/ scope

Following the failure of the existing retaining wall a local structural engineer was engaged to investigate the reason for the collapse and provide rectification requirements. The consequent onsite meeting provided the following information :

  • the original wall was of poor construction
  • low quality materials had been used previously
  • not carried out to the engineers specification.

The construction of retaining walls are primarily used for holding back soil from a building, structure or in our instance a footpath to the adjoining property.

Retaining walls are commonly constructed of concrete, steel and brickwork and their main objective is to prevent a down slope movement of soil or to resist lateral pressure.

Works Completed by Burnbrae Contracts

Following our pre-start meeting with the client and the structural engineer, the procedures below were agreed as safe working practice :

  • removal of existing footpath
  • phased foundation digs and subsequent phased foundation pours after steel cage instalments allowing 7 days between pour
  • retaining wall constructed in phased manner to ensure stability of adjacent ground with temporary propping as required
  • at junction of pours provide dowel bars to ensure continuity between top and bottom base mesh and stem mesh
  • shutter and pour mass concrete block, tied into steel foundation cage to reinforce existing garden return wall
  • 350mm retaining wall constructed with 150mm cavity, wall ties formed using galvanised T6 bar at staggered 450mm horizontal and 900mm vertical centres
  • stem poured in 2 equal lifts, concrete placed no sooner than 5 days after building of brickwork. Pockets at 675mm centres left to allow cleaning of cavity prior to concrete pour
  • repeat retaining wall process to achieve required height
  • cavity fill with concrete, slab and cap off to top of wall allowing 5 day curing time
  • apply 2no coats of R.I.W waterproofing to rear of retaining wall ensuring weep holes are kept clear
  • granular backfill to be contained within a geo textile filter membrane
  • re-build wall profile to match existing, using brick to brick ties to ensure stability
  • clear site
  • handover meeting/ sign-off