1.Introduction Part L Changes June 2022 for extensions -Change of Use and Existing Dwellings
The revised (2021 edition) Part L issued in December 2021 came into force in June 2022.
The changes for existing dwellings are significant but not (we think!) complicated.·We have learned this much so far - and hope to update this document as more information becomes available.
Contact [email protected] for any updates or advice on this.
Transition:·Building Regulations applications submitted before 15th June 2022 will not be subject to the changed regulations, provided work is started on site before 15th June 2023.
Key headlines:
Existing dwellings are no longer the subject of a separate approved document (L1b) as they were. Instead, the bulk of the guidance for existing dwellings is in sections 4, 9, 10 and 11 of the enlarged and single – Approved Document L, Conservation of fuel and power, Volume 1: Dwellings
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1057372/ADL1.pdf
As part of the new merged document a lot of the general provisions for new dwellings have been extended to work on existing dwellings.
The 25% glazing rule remains the same for extensions. Where glazing exceeds the 25% of floor area rule , area weighted or full SAP calculations can be used as now to justify the glazing through enhanced U Values elsewhere.
In what looks like a shift in the rules , for ‘change of use’ or change of energy status the 25% rule only seems to apply where new openings are being created or existing ones enlarged.
What were Tables 2 and Table 3 are now Tables 4.2 and 4.3, but U Value targets are more challenging – so better Values will be required.
New elements
Table 4.2 : Limiting Values for new fabric elements in existing dwellings
Element New Maximum U Value Was
Roof (1) 0.15 0.16 / 0.18
Wall (1) 0.18 0.28
Floor (1) 0.18 0.22
Window (3) 1.4 (or WER Band B) 1.6
Rooflight -Lanterns 2.2 2.2
Roof windows (Velux type) (2) 1.4 (as windows) 1.8
Doors with > 60% glazing 1.4 (or WER Band C) 1.8
Other doors (3) 1.4 (or WER Band B) 1.8
Note 1 : Can be area weighted average value
Note 2 : As tested vertically. This is important a it effectively means that you need to specify and buy them up to 0.5 better than the 1.4 maximum figure.
Note 3 : There is an extension on the deadline for the timber window and timber door changes - until June 2023 (!)
5. Retained elements :
This applies to change of use (e.g. office to dwelling), and change of energy status (building not heated to heated dwelling, or one dwelling to two).
It also applies to ‘renovations’ where more than 25% of a thermal element or ‘layer’ is being renewed in existing dwellings. (This includes drylining, cladding, cavity wall insulation, replacing a water proof membrane on a flat roof and replastering where 25%+ of the basic structure is exposed during the process).
If the element has a U Value worse than the threshold U then it shall be renovated to the new ‘improved U’ standard.
Table 4.3 : Limiting Values for retained existing elements in existing dwellings
Element Threshold U Improved U
Roof 0.35 0.16
Wall --Cavity 0.7 0.55
Wall -EWI/IWI 0.7 0.3
Floor 0.18 0.25
The usual caveats about exceptions for technical feasibility, listed / conservation status, loss of floor space / head room and cost still apply.
The standard for existing windows in ‘ change of use’ remains unchanged:
If they have a U Value of higher than 3.3 (3.8 for roof light) (which usually means single glazed), they will need to be replaced to the new elements standard.
6.Other:
There is specific advice about measures to limit air infiltration and reference to detail for continuity of insulation limiting thermal bridging.
All replacement and new light fittings shall have a minimum luminous efficacy of 75 lumens per circuit watt.
There is guidance on heating and replacement services (mostly for manufacturers and installers) - (9.6 to 9.9) :
The ‘consequential improvement’ requirements for alterations to buildings over 1000m2 are unchanged .
The revised (2021 edition) Part L issued in December 2021 came into force in June 2022.
The changes for existing dwellings are significant but not (we think!) complicated.·We have learned this much so far - and hope to update this document as more information becomes available.
Contact [email protected] for any updates or advice on this.
Transition:·Building Regulations applications submitted before 15th June 2022 will not be subject to the changed regulations, provided work is started on site before 15th June 2023.
Key headlines:
Existing dwellings are no longer the subject of a separate approved document (L1b) as they were. Instead, the bulk of the guidance for existing dwellings is in sections 4, 9, 10 and 11 of the enlarged and single – Approved Document L, Conservation of fuel and power, Volume 1: Dwellings
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1057372/ADL1.pdf
As part of the new merged document a lot of the general provisions for new dwellings have been extended to work on existing dwellings.
The 25% glazing rule remains the same for extensions. Where glazing exceeds the 25% of floor area rule , area weighted or full SAP calculations can be used as now to justify the glazing through enhanced U Values elsewhere.
In what looks like a shift in the rules , for ‘change of use’ or change of energy status the 25% rule only seems to apply where new openings are being created or existing ones enlarged.
What were Tables 2 and Table 3 are now Tables 4.2 and 4.3, but U Value targets are more challenging – so better Values will be required.
New elements
Table 4.2 : Limiting Values for new fabric elements in existing dwellings
Element New Maximum U Value Was
Roof (1) 0.15 0.16 / 0.18
Wall (1) 0.18 0.28
Floor (1) 0.18 0.22
Window (3) 1.4 (or WER Band B) 1.6
Rooflight -Lanterns 2.2 2.2
Roof windows (Velux type) (2) 1.4 (as windows) 1.8
Doors with > 60% glazing 1.4 (or WER Band C) 1.8
Other doors (3) 1.4 (or WER Band B) 1.8
Note 1 : Can be area weighted average value
Note 2 : As tested vertically. This is important a it effectively means that you need to specify and buy them up to 0.5 better than the 1.4 maximum figure.
Note 3 : There is an extension on the deadline for the timber window and timber door changes - until June 2023 (!)
- Apart from the U Values getting more demanding, it also means that where there is ‘excess’ glazing, there is less scope to compensate for it by improving the U values in other elements of the extension. Effectively this means that closer adherence to the 25% will be needed.
5. Retained elements :
This applies to change of use (e.g. office to dwelling), and change of energy status (building not heated to heated dwelling, or one dwelling to two).
It also applies to ‘renovations’ where more than 25% of a thermal element or ‘layer’ is being renewed in existing dwellings. (This includes drylining, cladding, cavity wall insulation, replacing a water proof membrane on a flat roof and replastering where 25%+ of the basic structure is exposed during the process).
If the element has a U Value worse than the threshold U then it shall be renovated to the new ‘improved U’ standard.
Table 4.3 : Limiting Values for retained existing elements in existing dwellings
Element Threshold U Improved U
Roof 0.35 0.16
Wall --Cavity 0.7 0.55
Wall -EWI/IWI 0.7 0.3
Floor 0.18 0.25
The usual caveats about exceptions for technical feasibility, listed / conservation status, loss of floor space / head room and cost still apply.
The standard for existing windows in ‘ change of use’ remains unchanged:
If they have a U Value of higher than 3.3 (3.8 for roof light) (which usually means single glazed), they will need to be replaced to the new elements standard.
6.Other:
There is specific advice about measures to limit air infiltration and reference to detail for continuity of insulation limiting thermal bridging.
All replacement and new light fittings shall have a minimum luminous efficacy of 75 lumens per circuit watt.
There is guidance on heating and replacement services (mostly for manufacturers and installers) - (9.6 to 9.9) :
- Replacement heating shall be no worse than existing.
- Minimum boiler efficiencies specified.
- Heat loss standards for replacement HW cylinders
- All accessible pipes to be insulated when a boiler or HW cylinder is being replaced.
- Operating and maintenance instructions to be given to owners of the dwelling.
The ‘consequential improvement’ requirements for alterations to buildings over 1000m2 are unchanged .