Construction projects in Malta are increasing in complexity, but recent collapses show that the frenetic pace of construction has not been accompanied by adequate checks and balances.
The current situation contrasts significantly with the diligent approach taken by other countries such as the UK, where stringent processes are imposed to protect neighbouring buildings during construction works. Malta would benefit considerably from the introduction of similar processes, at least for the more complicated projects involving multi-storey basements adjoining third-party properties.
Recently, my practice provided structural engineering services for the construction of a 6.5 metre deep basement and five-storey rear extension as part of the refurbishment of a listed townhouse in Brompton Square, central London. The six-storey townhouse was adjoined by third-party buildings on either side and a scheduled church seven metres behind the site.
The comprehensive system of rules and procedures with which we were expected to comply can serve as a case study which could be useful to Malta’s policy makers.
The most difficult part of the works consisted of forming the deep basement. Extensive temporary works were required to ensure safety during construction.
Planning application requirements
As part of the planning documentation, we were required to compile a construction-method statement (CMS) report which included findings from a site investigation carried out to record geotechnical information. The report included a proposed sequence of construction outlining how the works were assumed to be carried out safely.
The ground conditions on site were particularly challenging, with the existing building founded on topsoil, lying above silt and clay with a perched water table. The report was therefore complemented by a study of the ground movements expected during the works to demonstrate that negligible damage would be caused to the existing and adjoining third party properties. A strategy for monitoring of movements during the works was also set out in the report.
Given the technical nature of such reports, the planners engaged third-party structural engineers to check that the documents submitted were technically satisfactory.
In addition to other planning criteria, the planners requested the basement footprint to be limited to half the garden area not to significantly affect existing local groundwater flow paths.
Planning permission was only granted after this process was completed and all other planning criteria satisfied.
Implementing similar requirements in the planning process in Malta for projects with deep basements would discourage abusive speculators and help focus minds early on.
Before starting the works, 34 monitoring stations were installed on the walls of the existing and adjoining properties
Party wall legislation
Once planning was granted, the developer had to appoint a party-wall surveyor to make sure that all the criteria set out in the UK Party Wall Act were abided to.
A notification of the proposed works was initially sent to all affected third-party properties covered by the Act (i.e properties whose foundations lie within a 45-degree zone from the lowest perimeter of the proposed excavation). In our case, this involved four neighbouring properties.
Each affected neighbour had the right to appoint an independent party-wall surveyor and an independent structural engineer at the expense of the developer in order to safeguard their respective interests. As part of this process, we had to submit structural engineering drawings and calculations to the structural engineers representing the third-party properties affected.
Party-wall agreement was only obtained once all requirements identified by the third parties’ consultants were integrated in the project designs. Furthermore, frequency of monitoring of movement throughout the works was agreed in the party- wall award. The developer was also obliged to place bank guarantees to be accessed by the third parties in case of any damage caused to their properties. No works could commence on site until the party-wall award was granted.
Implementing a similar Party Wall Act in Malta would take time but would enshrine these requirements in law. Following the above steps, the completed project designs were submitted to the building control body for building regulations approval.
No works could commence on site before building regulations approval was obtained, and a building-control officer visited the site regularly to check that the main works were being carried out as documented, with authority to stop works otherwise.
This is another important safeguard to enhance safety in construction.
Temporary works
The contractor had clear responsibility for the temporary works on the project and had to prepare his detailed method statement for the works. This involved engaging a temporary-works engineer to design, detail and prepare drawings for all the temporary works (shoring, propping, etc).
This temporary-works design package was sent to the design team for review and was also sent to the party-wall surveyors and to building control for approval. Works could not commence before these were approved.
Having the contractor responsible for the temporary works reduces ambiguity of responsibilities which sometimes seems to exist in Malta between the contractor and project architect in this regard. The site technical officer (STO) would in this context form part of the contractor team.
This approach also incentivises contractors to employ workers having the right skill sets and discourages them from taking any risks that may jeopardise safety.
Monitoring of building movements
Before starting the works, 34 monitoring stations were installed on the walls of the existing and adjoining properties facing the basement, as agreed with the party-wall surveyors.
Readings were taken every fortnight and these were sent to the project team, building control, and party-wall surveyors and structural engineers representing the third-party properties. A mitigation strategy was agreed beforehand should limits of movements be exceeded (yellow, amber and red limits).
In this project, monitoring of movements commenced before excavation works started and continued up to six months after the basement works were completed, as agreed with party-wall surveyors. The maximum movement recorded was 2mm, with recorded ground movements satisfying the damage-limitation category stipulated by the planners.
Monitoring of movement allows the contractor and project teams to react fast if unexpected movements occur on site, before these become excessive and potentially cause serious damage to third parties.
Implementing the above measures in Malta would invariably increase construction costs. However, the status quo is not acceptable, and these measures would encourage safety on site while diminishing the risk of damage to third party properties.
Konrad Xuereb is director at KonceptX