Tayross Associates Chartered Building Surveyors | Party Wall Rates London | Party Wall Surveyor West London | Building/Structural RICS Survey London

As London’s property landscape continues to evolve, the demand for converting commercial buildings into high-quality residential spaces is rising. At Tayross Associates, we are proud to be at the forefront of this transformation—most recently through a detailed and technically rigorous window survey for a prominent multi-block development in Central London.

The Project: Assessing 900+ Windows Across Nine Blocks
The scope of this ambitious project was to evaluate over 900 windows across nine building blocks, in preparation for the change of use from commercial to residential and the addition of two new storeys.

Our objective was clear: to determine, for each window, whether it should be retained, refurbished, or replaced, ensuring that all openings would meet the demanding regulatory and user requirements of residential accommodation in England.

A Strategic, Data-Driven Sampling Approach
We deployed a stratified sampling strategy to ensure comprehensive coverage across:
- Each block (A–I)
- Window orientation and elevation
- Floor level
- Frame material and glazing build-up
- Exposure level (flush vs setback)
- Physical condition (initially assessed as Good/Fair/Poor)

Initial Sampling covered 10% of units per stratum (minimum 5), escalating to 25% or even 100% where defect thresholds were exceeded. This risk-based methodology allowed us to deliver robust insights efficiently and cost-effectively.

No sampling was used for:
- Bedroom windows (for fire escape and ventilation compliance)
- Easily accessible windows (security risk)
- Interfaces with the new upper storeys
- All window system variants (to ensure representation)

What We Measured and Why It Matters
Each sampled window was carefully assessed and documented, including:
- Photos (internal and external), ID tags, and dimensions
- Opening size and angle – crucial for egress and ventilation
- Frame material, thermal breaks, glazing spec (e.g., low-E coatings, safety markings)
- Condition indicators – decay, draughts, condensation, or hardware failure
- Perimeter interfaces – flashings, DPCs, cavity barriers
- Security features – PAS 24 compliance, locks, restrictors
- Acoustic performance potential – glazing build-up and sealing

Residential Suitability: Going Beyond the Surface
Each window was assessed against all relevant residential standards for England, including:

Fire (Part B)

Escape window dimensions and placement

Fire spread risk and cavity barriers

Ventilation (Part F)

Purge and background ventilation viability

Feasibility of retrofitting trickle vents

Thermal (Part L)

U-values, thermal bridging, condensation risk

Overheating (Part O)

Orientation, shading, and mitigation checks

Security (Approved Document Q)

PAS 24 compliance for ground/accessible windows

Acoustics (Part E)

Glazing and sealing adequacy, particularly for bedrooms

Daylight & Outlook

Internal daylight factor and room layout implications

Interfaces with New Storeys

Wind load and structural capacity of existing frames

Tools and Testing: Our Technical Edge
To ensure accuracy and insight, our survey team employed:
- Glass specification tools to verify thickness, coatings, and safety compliance
- Endoscopes to inspect hidden interfaces and cavity barriers
- Thermal imaging and smoke pencils to identify draught paths
- Visual checks and detailing review for signs of water ingress
- Health & Safety vigilance – flagging asbestos risk zones for R&D survey

Deliverables: From Raw Data to Actionable Advice
Our client received a suite of actionable, design-informed reports:
1. Window Type Register – distinct systems with typical photos and specs
2. Sampling Results – pass/fail by stratum and defect severity
3. Suitability Matrix – clear "Retain / Refurbish / Replace" outcomes with reasoning
4. Cost Plan – budgetary ranges for refurbishment vs replacement
5. Risk Log – highlighting any triggers for further investigation
6. Design Recommendations – including secondary glazing needs, compliance strategies, and interface challenges

Why Choose Tayross Associates?
At Tayross Associates, we combine deep technical knowledge, attention to regulatory detail, and a strategic, risk-based approach to surveying. Whether you're a developer, architect, or project manager navigating a complex commercial-to-residential conversion, we bring clarity, compliance, and confidence to your decision-making.