Post-Installation Assessment: What It Covers
Post-installation assessment is a critical phase in any retrofit project. It ensures that work has been completed to specification, complies with building regulations and standards, and will deliver the expected energy performance. For housing associations and retrofit coordinators, understanding what post-installation assessment covers is essential for project sign-off and performance verification.
Purpose and Scope
Post-installation assessment serves multiple functions within a retrofit programme:
- Verification that all works have been completed as designed
- Quality assurance against contract specifications and technical standards
- Compliance confirmation with Building Regulations and PAS2035
- Performance baseline establishment for ongoing monitoring
- Client handover documentation and warranties
The assessment typically takes place after all installation work is complete but before the property is formally handed over to the client.
Physical Inspection Checks
A comprehensive post-installation assessment includes detailed physical inspection of all retrofit measures installed:
Insulation measures
- Visual verification of material type and coverage area
- Checks for gaps, compression or settling, particularly at junctions and service penetrations
- Confirmation that insulation meets specified thickness and thermal properties
- Inspection of vapour control layers and breather membranes for correct installation
- Verification of fire safety compliance and certification documentation
Windows and doors
- Installation quality, plumb and level checks
- Air tightness around frames and reveals
- Proper glazing specification and unit identification
- Operation and hardware functionality
- Certification of U-values and acoustic performance
Heating systems
- Correct appliance model installation and positioning
- Proper flue termination and ventilation provision
- Control system installation and commissioning status
- Safety certification and inspection reports
- Commissioning records and performance testing outcomes
Mechanical ventilation
- Ductwork installation, support and sealing
- Fan operation and noise levels
- Commissioning and balancing documentation
- Filter provision and maintenance instructions
Key point: Physical inspection should be carried out by someone independent of the installation team where possible, to ensure objective verification and credibility of assessment outcomes.
Air Tightness Testing
Where air tightness is a project target, post-installation assessment must include pressure testing:
- Blower door testing to BS EN ISO 9972 standard
- Air leakage rate measurement at 50 Pa pressure differential
- Comparison against design target and building regulations minimum performance
- Identification of significant leak pathways for remediation if required
- Retesting following remedial work, if necessary
Air tightness testing should be scheduled after all building work is complete and all service penetrations sealed, but before internal decoration that might conceal problems.
Thermal Performance Verification
Assessment includes confirmation that thermal measures deliver design performance:
- Thermal imaging surveys to identify bridging, voids or installation defects
- Surface temperature monitoring in critical areas
- Condensation risk assessment in high-moisture areas
- Comparison of actual installation against design calculations
- Documentation of any variations or deviations from specification
Thermal imaging is particularly valuable for identifying insulation voids and thermal bridges that might not be visible through standard inspection.
Documentation and Compliance
Post-installation assessment produces substantial documentation requirements:
- Installation completion certificates – from all contractors confirming works completed
- Commissioning reports – for heating, ventilation and control systems
- Building Regulations completion certification – where applicable
- Product certificates – thermal ratings, fire safety, acoustic performance
- Warranty documentation – product and installation warranties
- Test results – air tightness, thermal imaging, pressure testing
- Non-conformance reports – any variations from specification with remediation records
- Operation and maintenance manuals – for all installed systems and appliances
Energy Performance Assessment
Where retrofit work affects Energy Performance Certificate (EPC) rating:
- EPC re-assessment if property characteristics have changed materially
- Comparison of predicted versus modelled energy performance
- Verification that expected carbon savings align with project objectives
- Documentation of actual performance specifications achieved
Quality and Defect Recording
Post-installation assessment must document both compliance and any defects identified:
- Clear photographic evidence of installation quality
- Defect schedule with categorisation by severity
- Remediation actions and responsibility assignment
- Timescale for defect rectification and verification
- Sign-off process confirming all defects resolved
Client Handover
Final post-installation assessment culminates in formal handover:
- Defect-free certification or agreed remediation schedule
- Complete documentation pack for client retention
- Demonstration of system operation to occupants where appropriate
- Training or guidance on new heating or ventilation controls
- Maintenance and servicing schedule for ongoing system care
Thorough post-installation assessment protects all parties: clients receive verified quality and performance, contractors have clear documentation of completion, and housing associations gain assurance that retrofit investment delivers intended benefits.