Part L · England · Free to use
Limiting U-values check (Part L)
Check walls, roofs, floors, windows and doors against the limiting fabric values in Tables 4.1 and 4.2.
Approved Document L Volume 1 (2021, including 2023 amendments)
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Part L · Result
1 element over the limit
New and replacement elements in existing homes. Windows may instead meet WER Band B, doors DSER Band B or C.
Check failed- External wall: Checks passedmax 0.180.18
- Roof: Checks passedmax 0.150.15
- Floor: Checks passedmax 0.180.18
- Windows: Checks passedmax 1.41.4
- Rooflights: Checks passedmax 2.22.2
- Doors: Check failedmax 1.41.6
- Renovated elements use the Table 4.3 threshold and improved values instead.
Clauses this relies on
Source edition and scope
Approved Document L Volume 1 (2021, including 2023 amendments).
Uses the 2021 edition including 2023 amendments. These are limiting values, not a calculation of a construction’s U-value or the dwelling’s overall energy performance. Check the applicable standards and transition dates for your project.
This is a preliminary check of the conditions shown. Confirm the edition, project circumstances and any additional requirements with your architect or building control.
A design aid, not legal advice. Checked against the Building Regulations 2010 for England; confirm with building control.