Marsden Street, NW5

Deep Retrofit Upgrades

INTRODUCTION


A comprehensive deep retrofit project in a conservation area, transforming a cold property with mould issues into an energy-efficient home.

This Camden Council initiative, funded by SHDF at a project value: £31,298.00, was completed in February 2025. The successful implementation

of Internal Wall Insulation, Loft Insulation, Secondary Glazing and ventilation improvements resulted in significantly better heat retention and improved the EPC rating from D to B.

Project Overview & Challenges

Property Issues

Residents reported extreme cold during

winter months and bedroom mould due to inadequate ventilation, requiring comprehensive thermal and air quality

improvements.

Conservation Constraints

Located in a conservation area, requiring

meticulous planning to preserve appearance whilst implementing

modern energy efficiency measures.

Structural Problems

Water ingress in the second-floor bedroom needed resolution before

insulation work could proceed.

The three-storey property required a carefully planned approach to minimise disruption while maximising energy efficiency gains. The ventilation strategy involved a hybrid combination of methods that satisfied both conservation requirements and PAS 2035:2023 standards, including:

Installation of internal wall vents with 100mm core drills


  • Cutting rectangle shapes in the brickwork
  • Installing new black cast iron airbricks at the front
  • Repointing with colour-matching mortar
  • Fitting rectangle to round 100mm duct channel connectors
  • Mounting Glidesvale Fresh 99H ventilators


The conservation approval process took five weeks, delaying the project commencement. Additionally, damp specialists were brought in to rectify the water ingress issue before insulation installation could proceed.

Solutions & Outcomes

These improvements were completed with a total project turnaround time of three months, successfully addressing all identified issues while complying with conservation requirements.


Implemented Measures


  • Internal Wall Insulation (IWI)
  • Loft Insulation (LI)
  • Secondary Glazing (SG)
  • Comprehensive ventilation system


The project demonstrates how effective retrofitting can dramatically improve energy efficiency even in conservation-restricted properties. By proactively managing the conservation application process and promptly addressing structural issues, the team was able to deliver significant improvements to thermal performance and air quality while preserving the property's heritage characteristics.