Retrofit guides

What PAS 2035:2023 is, when it applies, the roles and stages it defines, what changed in the 2023 edition, and what it means for your project.

The difference between surface and interstitial condensation, the methods used to assess each (fRsi, BS EN ISO 13788, BS EN 15026), and which you need for a retrofit.

When a retrofit coordinator is required, when it is optional but worthwhile, what the role does, and what to ask before you appoint one.

What an air tightness test measures, what counts as a good result for a new or existing home, how to prepare, and what affects the cost.

Why damp and mould sometimes appear after energy improvements, how to tell condensation from other damp, the ventilation rules, and what Awaab’s Law means for landlords.

The current permitted development rules for air source heat pumps in England, the Boiler Upgrade Scheme, and why a proper heat loss calculation matters.

What leaseholders need to check before insulating, replacing windows or changing heating in a London flat – the lease, freeholder consent, planning and building safety rules.

How internal and external wall insulation compare for solid-walled London homes – planning permission, Building Regulations, moisture risk and fire safety.

What the temperature factor fRsi measures, how it is calculated, the critical values in BRE IP 1/06, and what it does not tell you about moisture.

Heat loss (kW) and heat demand (kWh) answer different questions. This guide explains each, how they are calculated and when you need them.