Following the recent update to Part L of Building Regulations we’ve created this simple summary sheet to put the key information at your fingertips
Effective from 15th June 2022
This does not apply to work subject to a building notice, full plans application or initial notice submitted before that date, provided the work is started on site before 15 June 2023
Replacement and Extensions to existing homes
Table 4.2 from Document L
| Product Type | U-value upper limit | or Energy Rating upper limit |
| Windows | 1.4u | B WER |
| Timber Windows | 1.6u | B WER |
| Doors with more than 60% internal face glazed | 1.4u | C DER |
| Doors | 1.4u | B DER |
| External Fire Doors | 1.8u | - |
U-value is W/m2K
- Replacements can’t have worse performance than the element they replace
- If windows or fully glazed doors cannot meet these requirements because of the need to maintain the character of the building, either of the following should be met, either: 1) A centre pane U-value of 1.2 2) Supplemented with low-emissivity secondary glazing
New Homes
Table 1.1 from Document L
| Product type | U-value upper limit | Energy Rating upper limit |
| Windows | 1.2u | |
| Doors with more than 60% internal face glazed | 1.2u | |
| Doors | 1.0u |
Table 4.1 from Document L
| Product type | U-value upper limit | Energy Rating upper limit |
| Windows | 1.6u | |
| Doors | 1.6u |
U-value is W/m2K
- People may specify products with lower U-values than these, as new build thermal performance is calculated on complete building envelopes. Meaning the thermal performance of each element has to be balanced to meet the requirements of Part L. The values shown above are the absolute minimum standards that can be used