What is being measured?
The UGF approach gives different forms of surface cover different weightings rather than treating every green-looking area as equivalent. The GLA's published explanation combines the areas and relevant factors into a score for the site. It is a design and assessment tool, not a statement that a particular percentage of the site must simply be planted. [1]
The GLA explanatory page is labelled as a 2021 consultation draft. It is useful for understanding the method, but its historic tables should not be treated as proof of today's applicable factor values or borough target. Use the current submission calculator and guidance agreed for the application. [1]
When does the council ask for it?
For example, Westminster's 2026 validation list requires a UGF assessment for all major applications. It asks for a scaled landscape plan, colour coding by surface type and a completed calculation table. A general landscaping illustration alone does not provide the same evidence. This is a local requirement, not a claim that every home extension across London needs a UGF report. [2]
Check the Local Plan, validation list and any relevant landscape guidance at feasibility stage. Where the position is unclear, ask the council which target, calculator and drawing information it expects for the specific proposal.
Who should prepare it?
A landscape professional, working with ecological and architectural input, is well placed to coordinate the greening proposal. The GLA's explanatory guidance encourages suitably qualified landscape and ecological involvement early in design. [1]
Ask the team to distinguish the calculation from the detailed landscape specification and maintenance arrangements. A score based on an ambitious planted roof is not enough information to procure or maintain that roof. Request clear identification of what is proposed, where it is shown and who will develop its technical detail.
Do not confuse UGF with Biodiversity Net Gain
The statutory BNG metric addresses biodiversity value under a separate framework. Meeting a UGF target should not be described as automatically meeting a BNG obligation, and a BNG exemption does not itself answer whether a local UGF submission is required. [3] [2]
Coordinate the ecological and landscape work so that the same retained trees, habitat areas and proposed planting are represented consistently. Also ask the drainage designer to review any greening intended to perform a water-management function.
Keep the proposal achievable
Use the assessment while layout choices remain open. Before submission, check that the calculation, landscape plan and architectural drawings describe the same scheme. Record who will review the assessment if roof plant, access routes or other design elements change.
The draft new London Plan is under consultation until 15 October 2026. Future greening policies may change the assessment framework, but the consultation draft is not an adopted replacement. [4]