Part L1B Compliance - Extensions to existing dwellings

What is Part L1B Compliance?

Part L1B is one part of the four parts to Part L of the Building Regulations – Conservation of Fuel and Power in existing dwellings.


Any new, replaced or refurbished element of a dwelling must achieve minimum thermal standards, and where applicable the total heat loss of the building with extension must be the same or better than a notional building 


I am qualified to produce L1B calculations ae I am a qualified On Construction Energy Assessor & SAP Assessor.


When is Part L1B Compliance Required?

This is required by Building Control in the following circumstances:-

1. Construction of an Extension
2. A material Change of Use, or a change to the buildings energy status, including loft and garage conversions
3. The provision or extension of Controlled Services or Controlled Fittings
4. The replacement of a Controlled Service or Controlled Fittings


Building Control often ask for SAP Calculations instead of Part L1B Compliance - this is the same thing and in most circumstances is triggered due to large glazed areas being added to the building.


What area do we cover?

England and Wales

How Much Will it Cost?    -  from £175.00

Prices reflect the size of property, number of units and information available