Building Regulation Part L Changes: 15th June 2022 Transitional Provisions for Domestic Extensions

BUILDING REGULATIONS

PART L CHANGES 15 JUNE 2022 TRANSITIONAL PROVISIONS

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L

PART L CHANGES

The Government has issued a new Approved Document Part L with guidance on works to existing buildings. The new edition of the Building Regulations Part L will come into force on 15th June 2022.

The new 2022 Part L represents a significant step up from the current (2013) Edition, and includes an uplift in fabric insulation standards, improved U-values and increased thickness of insulation within extensions.

This booklet has been produced by Quadrant Building Control to help builders and designers to understand what the new requirements will be for domestic extensions.

Typical construction details with insulation thickness have been included that should meet the U-values standards contained within the 2022 Edition of Part L. These construction details have been provided for some typical wall, floor and roof details often used within extensions.

Transitional provisions are available for schemes that will start on site before 15th June 2023, but a Building Regulation Application will need to be submitted before 15th June 2022.

U-VALUES FOR DOMESTIC EXTENSIONS New thermal elements should not exceed the U-values listed in the table below.

Element

U-value

Walls

0.18 W/m2.k

Roof

0.15 W/m2.k

Floor

0.18 W/m2.k

Windows

1.40 W/m2.k

KEY DATES WORKS STARTED

APPLICATION RECEIVED

Before 15th June 2022

From 15th June 2022

Before 15th June 2023

Old 2013 Part L applies

New 2022 Part L applies

From 15th June 2023

New 2022 Part L applies

New 2022 Part L applies

For multiple buildings on an application, traditional provisions apply only to the individual buildings where work has commenced by 15th June 2023.

CAVITY WALL CONSTRUCTION Mineral wool insulation

12.5mm plasterboard on dabs

100mm internal lightweight blockwork

U-VALUE: 0.18 W/m2.k

150mm thick cavity wall slab 32 insulation

100mm external facing brickwork

CAVITY WALL CONSTRUCTION Rigid board insulation

100mm external facing brickwork

10mm residual cavity kept clean of mortar droppings

90mm thick rigid board insulation (Thermaclass Cavity Wall 21 or similar)

U-VALUE: 0.18 W/m2.k www.quadrantai.co.uk

Self adhesive breathable tape at all joints and at wall tie locations

100mm internal lightweight blockwork

SLOPING ROOF CONSTRUCTION Rigid board insulation

Roofing tiles Tile battens with roofing felt 100mm rigid board PIR insulation between rafters

50mm rigid board PIR insulation below rafters

12.5mm plasterboard

U-VALUE: 0.15 W/m2.k

FLAT ROOF CONSTRUCTION Rigid board insulation

Flat roofing membrane

100mm rigid board PIR insulation between rafters

Timber decking material

50mm ventilated air gap

50mm rigid board PIR insulation below rafters

U-VALUE: 0.15 W/m2.k www.quadrantai.co.uk

Vapour Control Layer

12.5mm plasterboard

FLOOR CONSTRUCTION Rigid board insulation

Floor screed

Separating layer of polythene DPM

100mm rigid board PIR insulation Damp proof membrane lapped into DPC

25mm perimeter insulation

Concrete floor construction

U-VALUE: 0.18 W/m2.k

Contact

Please contact Quadrant Building Control for further information regarding the transitional provisions.

0345 557 2777 www.quadrantai.co.uk It remains the responsibility of the designer to specify the construction of thermal elements that meet the U-value standards, and it is the responsibility of the contractor to construct the extension in accordance with the U-value standards. The details shown in this booklet are indicative and Quadrant Building Control hold no liability or responsibility for demonstrating compliance with the Building Regulations. Please complete U-value calculations for each thermal element before construction, to ensure the detail proposed meets the U-value standard.