How Long Does It Take To Replace Cladding

Determining how long does it take to replace cladding requires a detailed understanding of the building’s scale, the complexity of the existing façade system, and the regulatory requirements governing modern external wall remediation. For a standard high-rise residential block, the physical replacement phase typically spans 6 to 18 months, though the entire project lifecycle—from initial investigation to final certification—often extends to 24 months or longer.

At CladdingTesting.com, we recognize that building owners and managing agents need realistic timelines to manage resident expectations and financial planning. The duration is not merely a reflection of how fast panels can be swapped; it involves a meticulous process of pre-construction assessment, technical design, procurement, and safe execution on an occupied site.

Key Takeaways#

• Investigation and Design: The pre-construction phase (surveys, EWS1 assessments, and planning) often takes 6–9 months.
• Physical Works: On-site cladding replacement for a medium-to-high-rise building typically requires 12–18 months of active construction.
• Occupancy Factors: Working on occupied buildings increases duration due to resident safety protocols and restricted working hours.
• Access Logistics: The choice between mast climbers, scaffolding, or cradle systems significantly impacts the daily rate of progress.
• Regulatory Compliance: Time must be factored in for Building Control approvals and final sign-off by qualified fire engineers.
• Remediation vs. Replacement: Targeted remediation of cavity barriers may be faster than a full "strip and replace" program.

Defining the Cladding Replacement Timeline#

In the context of UK construction, cladding replacement refers to the removal of non-compliant or deteriorating external wall systems and the installation of a new, tested assembly. This process includes the outer rainscreen, insulation, fire cavity barriers, and the supporting sub-frame. It is rarely a cosmetic update; rather, it is a fundamental structural and safety overhaul.

When asking how long will it take to replace cladding, stakeholders must account for three distinct stages:

1. Pre-Construction (6–12 months): Detailed cladding testing, intrusive surveys, specialist design, and tender processes.
2. Mobilization (2–3 months): Site setup, material lead times, and the installation of access equipment like scaffolding.
3. Construction and Handover (9–18 months): The phased removal of old materials and the sequential installation of new, compliant systems.

Factors Influencing the Duration of Replacement#

No two buildings are identical. A 10-story residential block in a congested city center presents different logistical challenges than a low-rise commercial unit. To accurately estimate how long does it take to replace dangerous stone cladding or combustible MCM (Metal Composite Material), we must analyze several variables.

1. Building Height and Complexity#

The height of the building dictates the type of access required. For buildings over 18 meters (or 11 meters under newer guidance), safety protocols are more stringent. High-rise structures require wind-load calculations for scaffolding and may necessitate mast-climbing work platforms (MCWPs) which take time to install and move.

Complex geometries, such as curved façades, recessed balconies, or intricate interface details with windows, significantly slow down the installation rate compared to flat, uniform elevations.

2. Occupancy and Resident Safety#

Replacing cladding on an occupied building is considerably slower than on a vacant site. We must implement strict noise curfews, dust suppression, and safe access routes for residents. The sequencing of work must ensure that the building remains weather-tight and fire-safe throughout the transition, often requiring "zone-by-zone" replacement rather than stripping the entire building at once.

3. Material Procurement and Lead Times#

The global supply chain for non-combustible insulation and A1/A2-rated cladding panels can fluctuate. Specialist materials, such as terracotta tiles or specific stone veneers, may have lead times of 12 to 20 weeks. If the project involves bespoke fabrication, these timelines must be baked into the overall schedule before a single panel is removed.

4. Weather and Environmental Conditions#

Façade work is highly weather-dependent. High winds can prevent the use of cranes and mast climbers, while extreme cold or rain can affect the installation of sealants and certain insulation types. In the UK, we typically factor in a 15-20% time contingency for weather-related delays, particularly during winter months.

The Pre-Construction Phase: Why It Takes So Long#

Many building owners are surprised that the "paperwork" phase takes almost as long as the construction itself. However, this stage is critical for ensuring the new system is safe and compliant with the Building Safety Act and updated Building Regulations (Approved Document B).

Initial Investigation and Testing#

Before replacement begins, we must understand the existing wall buildup. This involves intrusive inspections where small sections of the façade are removed to inspect the insulation, sheathing board, and cavity barriers. This data informs the fire engineer's report and the subsequent design strategy.

Technical Design and Specification#

Modern cladding systems are not "off-the-shelf" products. A specialist designer must create interface drawings showing how the new cladding will meet windows, doors, and rooflines. This design must be reviewed and approved by a fire engineer to ensure it meets the required fire performance standards. This iterative process usually takes 3 to 5 months.

Planning and Building Control#

In many cases, changing the external material of a building requires planning permission, especially in conservation areas or for buildings of architectural significance. Furthermore, Building Control must be notified, and they will often perform staged inspections throughout the project, adding administrative time to the schedule.

How Long Does It Take to Replace Dangerous Stone Cladding?#

Replacing stone cladding—such as granite, marble, or limestone—presents unique challenges compared to lightweight aluminum panels. Stone is significantly heavier, requiring a more robust sub-frame and more intensive labor for handling. How long does it take to replace dangerous stone cladding often depends on the condition of the fixings behind the stone.

If the original stone was mechanically fixed but the fixings have corroded, the removal process must be handled with extreme care to prevent falling debris. A typical stone replacement project may progress at a rate of 30-50 square meters per week per team, whereas lightweight rainscreen might progress at double that speed.

• Weight Factors: Heavy stone requires mechanical lifting aids, which require space and careful coordination.
• Structural Integrity: The backup wall (concrete or steel frame) must be assessed to ensure it can support the new, potentially heavier, compliant stone system.
• Fixing Detail: Stone systems often require bespoke stainless-steel brackets that must be precisely engineered, adding time to the procurement phase.

Phases of On-Site Work#

Once the project moves to the construction phase, the timeline is driven by the work sequence. A methodical approach ensures the building remains protected from the elements and fire risks are managed.

Step 1: Access Installation (4–8 Weeks)#

Depending on the building's footprint, erecting scaffolding around a high-rise can take two months. If using mast climbers, the process is faster, but it requires solid ground-level foundations (sole boards or concrete pads) which must be surveyed and prepared.

Step 2: Removal of Existing Cladding (Variable)#

The removal of the old system is often faster than the installation of the new one. However, if the building contains hazardous materials (like asbestos or highly combustible insulation), disposal protocols will slow the process. We generally strip the building in sections to minimize the time the inner structure is exposed.

Step 3: Remediation of the Sub-structure (2–4 Weeks per Section)#

Once the cladding is off, we often find that the underlying steel or timber studs require repair, or the sheathing board has suffered water damage. Rectifying these hidden defects is essential for the long-term health of the building but can add weeks to the timeline.

Step 4: Installation of New System (12–24 Weeks)#

This is the most labor-intensive phase. It involves:

• Installing new non-combustible insulation.
• Fitting intumescent cavity barriers (essential for fire safety).
• Installing the rail system and brackets.
• Affixing the final cladding panels.

Common Challenges That Delay Projects#

Understanding the risks of delay can help managing agents provide more accurate updates to leaseholders. In our experience at CladdingTesting.com, the following issues are the most frequent causes of extended timelines:

1. Discovery of Unforeseen Defects#

It is common to find that the original fire stopping was missing or that the building’s substrate is not as expected. If the structural deck is compromised, work must pause while a structural engineer provides a new design for the fixings.

2. Regulatory Changes#

The UK regulatory landscape for façades is currently dynamic. Changes in government guidance or insurance requirements midway through a project can necessitate design revisions to ensure the building remains insurable and compliant upon completion.

3. Site Logistics and Access Restrictions#

In dense urban environments like London, Manchester, or Birmingham, pavement licenses and delivery schedules are tightly controlled. If we can only receive one delivery per day or have limited hours for crane use, the project duration will inevitably extend.

The Role of EWS1 and Fire Safety Certification#

The physical completion of the work is not the final step. For residential buildings, the ultimate goal is often obtaining a satisfactory EWS1 (External Wall System) form or a final Building Control completion certificate. This allows residents to sell or remortgage their properties.

The process of final inspection, where a qualified professional verifies that the installation matches the approved design, can take 4 to 8 weeks after the scaffolding has come down. This involves reviewing "as-built" drawings, photographic evidence of cavity barriers, and material data sheets.

Repair vs. Full Replacement: Impact on Time#

Not every building requires a total strip-down. Where a façade investigation identifies that only specific elements—such as the insulation or the cavity barriers—are defective, targeted remediation may be possible.

Remediation projects are typically 30-50% faster than full replacements. By retaining the existing outer rainscreen and only replacing the internal components, we reduce the time spent on material procurement and minimize the visual impact on the building. However, this is only an option if the outer panels are non-combustible and in good structural condition.

Frequently Asked Questions#

How long does it take to replace cladding on a 15-story building?#

For a 15-story building, you should expect the physical on-site works to last between 14 and 20 months. This accounts for the time needed to safely install access equipment, the phased removal of materials, and the weather-sensitive installation of the new façade system.

Does the building need to be empty during the replacement?#

No, most cladding replacement projects in the UK are carried out while the building remains occupied. While this extends the project duration due to safety protocols and noise restrictions, it avoids the massive cost and disruption of decanting hundreds of residents.

Can weather stop work for long periods?#

Yes. High-rise projects are particularly sensitive to wind. If wind speeds exceed safe limits (usually around 35-40 mph depending on the equipment), mast climbers and cranes cannot operate. We typically build weather contingency into our schedules to account for the UK climate.

Why is the pre-construction phase so long?#

The pre-construction phase ensures the new system is legally compliant and safe. It includes fire engineering, structural calculations, and planning approvals. Rushing this stage often leads to delays later in the project when materials don't fit or fail to meet building regulations.

Does replacing dangerous stone cladding take longer than aluminum?#

Generally, yes. Stone is a heavy-set material that requires more specialized handling, heavier-duty fixings, and often more precise craftsmanship than lightweight aluminum composite or rainscreen panels. How long does it take to replace dangerous stone cladding depends heavily on the weight of the stone and the complexity of the fixing system.

Will replacing the cladding affect my building insurance?#

During the works, your insurance premiums may stay elevated. However, once the project is completed and a new EWS1 form or compliance certificate is issued, most building owners find it significantly easier to secure competitive insurance rates, as the fire risk is drastically reduced.

Planning Your Remediation Strategy#

If you are responsible for a building with identified cladding issues, the first step is a comprehensive technical assessment. Knowing how long will it take to replace cladding on your specific asset starts with understanding exactly what is behind the panels.

At CladdingTesting.com, we help property professionals navigate the complexities of façade remediation. From the initial cladding inspection to the final sign-off, our approach focuses on safety, compliance, and logistical efficiency. We provide realistic timelines and clear communication, ensuring that your remediation project is delivered with minimal disruption to residents and maximum protection for your investment.

Every building is unique, and a successful project relies on a tailored strategy. Whether your building requires localized repairs or a full-scale recladding program, identifying the specific needs of the building envelope early is the best way to ensure the project stays on schedule and within budget.