Glossary · Two-word term
Construction Phase
In short
the period during which a building or structure is being erected or modified
The construction phase is the period during which a building is erected or modified, encompassing the physical installation of cladding systems and the transition from design to the finished external wall structure.
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Construction Phase
Definition and Technical Scope
In the context of the UK built environment, the construction phase is defined as the period during which a building or structure is being erected or modified. While this definition encompasses the physical assembly of a project, in the cladding and remediation sector it specifically denotes the duration between the formal handover of the site to a principal contractor and the point of practical completion. It is a critical stage where theoretical designs, fire strategies, and material specifications transition into physical installation.
For external wall systems (EWS), the construction phase is not merely a logistical exercise but a period of intensive quality control. It involves the sequential installation of various components, including the inner leaf, vapour barriers, thermal insulation, cavity barriers, and the outer rainscreen or masonry leaf. Each element must be installed in accordance with the manufacturer's instructions and the specific design intent to ensure the system functions as a coherent whole.
The Cladding and Remediation Context
When addressing cladding testing, repair, or replacement, the construction phase is the point at which latent defects are often uncovered or where new, compliant systems are integrated. In many contemporary remediation projects, this phase is preceded by a significant pre-construction period involving intrusive surveys and EWS1 (External Wall System) assessments.
During the construction phase of a recladding project, the building’s fabric is frequently exposed. This allows for the inspection of substrate conditions and the verification of existing fire-stopping measures which may have been obscured previously. The process typically involves:
- The systematic removal of existing non-compliant or damaged materials.
- The inspection and, if necessary, repair of the underlying structure.
- The installation of new components, such as non-combustible insulation and specified cavity barriers.
- Ongoing inspections by Building Control or independent clerks of works to verify that the installation matches the approved plans.
Regulatory Framework in England and Wales
The regulatory landscape for the construction phase has undergone significant transformation, particularly following the introduction of the Building Safety Act 2022. For high-risk buildings (HRBs), which are defined as being at least 18 metres tall or having at least seven storeys, the construction phase is governed by a stringent 'Gateway' process.
Gateway 2 must be passed before the construction phase can commence, requiring the Building Safety Regulator (BSR) to be satisfied that the design meets all functional requirements of the Building Regulations. Once construction begins, the project enters a period of heightened oversight. Any significant changes to the design or materials during this phase must be managed through a formal change control process and may require further approval from the BSR. This ensures that the 'as-built' structure does not deviate from the 'as-designed' safety parameters without rigorous technical review.
Building Fabric and External Wall Systems
The integrity of the building fabric during the construction phase relies heavily on the sequence of operations. For cladding systems, the management of the "Golden Thread" of information is vital during this period. This involves recording exactly what materials were installed, where they were placed, and who performed the installation.
Key technical considerations during the construction phase include:
| Aspect | Technical Requirement |
|---|---|
| Cavity Barrier Alignment | Must be positioned to close the gap between the cladding and the structure in the event of a fire. |
| Moisture Management | Ensuring the building remains weather-tight while the external leaf is removed or replaced. |
| Material Substitution | Strictly prohibited without professional reassessment and regulatory notification. |
| Site Records | Digital photographic evidence of concealed elements before they are covered by the final cladding panels. |
Effective management of the construction phase ensures that the technical performance of the external wall system—including its thermal efficiency, weather resistance, and reaction to fire—is realised in practice.
Construction Phase
Responsibilities for Building Owners and Managers
Building owners, managing agents, and directors of Residents' Management Companies (RMC) or Right to Manage (RTM) companies hold specific duties during the construction phase, even if they are not physically performing the work. Under the Construction (Design and Management) Regulations 2015 (CDM 2015), the 'Client' must ensure that suitable arrangements are in place for managing the project.
During cladding remediation, this includes ensuring that the principal contractor provides a construction phase plan. This document outlines how health and safety risks will be managed while residents may still be in occupation. Managers must also facilitate access for surveyors and contractors while ensuring that the "Golden Thread" of information is being updated. It is essential to understand that the construction phase is the period of highest operational risk, requiring clear communication channels between the project team and the building’s occupants regarding scaffolding, noise, and site security.
Common Misunderstandings
A frequent misconception is that the construction phase begins only when the first new cladding panel is fixed to the building. In technical and legal terms, the phase begins as soon as construction work, including site set-up and demolition or stripping of existing materials, starts.
Another misunderstanding involves the scope of changes allowed during this period. It is often incorrectly assumed that a contractor can substitute a specified material for a "similar" product due to supply chain issues without formal re-approval. In the current UK regulatory climate, particularly for HRBs, such deviations during the construction phase can lead to significant delays, as the Building Safety Regulator may require the work to stop while the change is assessed for compliance. Finally, it is often wrongly believed that the end of the construction phase is defined by the removal of scaffolding; technically, it concludes only when the building reaches practical completion and, for HRBs, when a completion certificate is issued by the BSR.
Related Terminology and Definitions
Understanding the construction phase requires familiarity with several adjacent terms used in the UK cladding industry:
- Practical Completion: The point at which the works are sufficiently finished for the building to be handed over to the client, marking the end of the construction phase.
- Gateway 3: The stage at the end of the construction phase where the BSR reviews the as-built information before the building can be occupied or re-occupied.
- Principal Contractor: The organisation appointed to plan, manage, and monitor the construction phase.
- Clerk of Works: A professional whose role is to inspect the quality of work on site during the construction phase, ensuring adherence to specifications.
- Latent Defects Period: The timeframe following the construction phase during which the contractor remains liable for defects that were not apparent at completion.
By maintaining a rigorous focus on the construction phase, the industry aims to bridge the gap between design intent and the reality of the finished building fabric.
Construction Phase