Structural Survey and Underpinning (complete)
Hazard: Structural Collapse and Falling Elements (Category 1)
Deficiency: Structural movement, cracking and instability affecting loadbearing wall(s) and foundations
- Instruct a suitably qualified structural engineer, being a member of Institution of Structural Engineers or Institution of Civil Engineers, to inspect the building and provide a written report identifying:
- a. the nature, cause and extent of all structural movement;
- b. whether movement is historic, progressive or seasonal;
- c. whether defective foundations, ground conditions, drainage failure, water ingress, tree influence, soil shrinkage, heave or other factors are contributing causes;
- d. the full specification of remedial works necessary to remove the hazard.
Install and maintain crack monitoring devices to all significant structural cracks identified by the engineer and monitor movement over a period specified by the engineer sufficient to determine whether movement is active.
Undertake a drainage investigation to all below-ground drainage serving or passing adjacent to the affected structure, including CCTV survey, testing and confirmation of condition, and repair or renew all defective drains, joints, gullies, interceptors or connections found to be contributing to ground instability.
Investigate the influence of nearby vegetation, including trees, hedges and substantial shrubs located within influencing distance of the affected foundations, and were identified by the engineer as causative, undertake appropriate arboriculture measures including pruning, management or removal, together with treatment of roots where necessary.
Expose existing foundations in locations identified by the structural engineer to confirm foundation depth, construction and bearing strata.
Where recommended by the structural engineer, provide permanent structural support to defective foundations by means of reinforced concrete underpinning, installed in sequenced bays and constructed:
- a. to the depth, width and bearing level specified by the engineer;
- b. using reinforcement and concrete grade specified in the design;
- c. in a sequence that prevents destabilisation of the structure;
- d. with temporary support, shoring or propping installed where required during excavation and construction.
All underpinning works shall be carried out under supervision sufficient to ensure that excavations do not exceed safe lengths and that each bay is fully cured before adjacent excavation proceeds.
Following completion of foundation stabilisation, repair all structural cracking to walls, arches, lintels and associated elements by crack stitching, rebuilding, resin bonding, replacement of defective masonry, or other method specified by the structural engineer.
Renew all defective plaster, render, finishes, decorations and disturbed internal or external building elements affected by the structural works.
Obtain all necessary approvals under Building Regulations from Camden’s Building Control before commencement of notifiable works. To include compliance with LOCAL AUTHORITY Planning Conservation Area requirements.
Upon completion, obtain written certification from the structural engineer confirming that:
- a. the works have been completed in accordance with the design;
- b. structural stability has been restored;
- c. the hazard of structural collapse and falling elements has been removed or reduced,
- d. forward copies of the structural engineer’s works completion certificate to LOCAL AUTHORITY environmental health case officer, and the Building Control team.