Shadow Diagrams & Overshadowing Studies
for UK Planning.
Planning-focused shadow studies and overshadowing visualisation for UK projects. Formal daylight and sunlight assessment (VSC, APSH, NSL) is scoped and quoted separately — from £450.
We read your local planning authority brief before we model a single shadow
Shadow diagrams built for clear planning review.
Most shadow diagram rejections in UK planning come from the same three sources: wrong reference dates, missing BRE 209 methodology statements, and diagrams that don't match the scale or orientation of the submitted drawings. We eliminate all three before your application is lodged.
What's Included in Your Shadow Diagram Set
One fixed price for the confirmed scope. Additional requirements or design changes outside that scope are reviewed and quoted before work proceeds.
Shadow Footprints at Required Dates
Shadow diagrams at the equinox (21 March / 21 September) and winter solstice (21 December) at the times required by your LPA — typically 8am, 10am, 12pm, 2pm and 4pm. Existing and proposed shadows distinguished by colour.
BRE 209 Methodology Statement
Written methodology note confirming software and sun-path model, site coordinates (OS grid reference), applicable BRE 209 criteria, reference dates and times, and true north basis. Ready to include in your Design and Access Statement or planning report.
VSC / APSH / NSL Analysis
Where required by your LPA brief — full Vertical Sky Component, Annual Probable Sunlight Hours and No Sky Line calculations join the service line late August 2026 for affected neighbouring windows. Window-by-window results with interpretation against the applicable BR 209 (2022) criteria.
True North & OS-Accurate Geometry
True north confirmed against OS map data. Site boundaries, neighbouring property footprints and street alignment verified against your planning drawings before work starts. Scale bar, north point and title block consistent with your submitted drawing set.
Print-Ready PDF + DWG / ArchiCAD Source
A1/A3 print-ready PDF formatted for planning submission, plus full DWG and/or ArchiCAD source files. No locked files, no watermarks. Your architect or planning consultant can incorporate the drawings directly into the submission set.
One Free Planning Amendment
If your LPA requests amended shadow diagrams as a planning condition, one amendment round is included at no additional charge. We review the officer's comments, update the analysis and re-issue the amended set within 48 hours.
The key BRE 209 thresholds explained
BRE 209 (Site Layout Planning for Daylight and Sunlight) is the primary guidance document used by UK planning authorities to assess daylight and sunlight impacts. Here are the three main criteria.
Measures the amount of skylight reaching a window from the sky vault. BRE 209 suggests a window receiving a VSC of 27% or more receives adequate skylight.
If a proposed development reduces a neighbouring window's VSC by more than 20% of its former value (e.g. from 30% to below 24%), the impact may be noticeable. Both the absolute value and the percentage reduction are considered.
BRE 209 §2.2Measures the number of hours of direct sunlight a window receives over the year. BRE 209 recommends that main living room windows facing within 90° of south should receive at least 25% of annual probable sunlight hours (APSH), including at least 5% in the winter months (21 September to 21 March).
A reduction of more than 20% of either the annual or winter figure may be considered a significant impact.
BRE 209 §3.2The No Sky Line divides the working plane of a room into areas that can and cannot receive direct skylight. BRE 209 suggests that if the NSL moves so that the area of the working plane receiving direct skylight is reduced to less than 0.8 times its former value, the occupants will notice the reduction in the quality of their daylight.
BRE 209 §2.3BRE 209 thresholds are guidance, not mandatory standards. Local planning authorities apply them with varying degrees of flexibility. We confirm the applicable approach with your LPA before commencing.
Why shadow diagrams get rejected at planning.
The same issues appear repeatedly in UK planning officer comments. We eliminate all three before submission.
- ✕No BRE 209 methodology statement
Submitting shadow diagrams without a written methodology note — confirming sun-path model, OS grid reference, reference dates and applicable BRE 209 criteria — is the most common reason planning officers request further information. Without it, the results are unverifiable.
- ✕Wrong reference dates or missing time-points
Most LPAs require shadow analysis at the equinox (21 March or 21 September) and winter solstice (21 December). Some require additional dates or specific hourly intervals. Using the wrong dates or omitting a required time-point triggers a Further Information request.
- ✕Scale or north point inconsistency
Shadow diagrams that use a different scale or north point from the submitted site plan cannot be cross-referenced by the planning officer. This is treated as an error in the submission, not a minor omission, and typically requires a full re-submission.
- ✓Full BRE 209 methodology statement included
Every deliverable includes a written methodology note confirming the software and sun-path engine, OS grid reference for the site, applicable BRE 209 section, reference dates and times, and basis for true north. Written for planning officers, ready to paste into your DAS or planning statement.
- ✓LPA brief confirmed before work starts
We confirm the required reference dates, time-points and any LPA-specific requirements in writing before modelling begins. For standard applications: equinox and winter solstice. For LPAs with additional requirements, those are identified and included in scope before commencing.
- ✓Scale and north point matched to submitted drawings
True north confirmed against OS map data. Scale, north point and title block are matched to your submitted site plan before any shadows are generated. The planning officer can overlay our diagrams directly on the site plan.
From brief to planning-ready shadow diagrams in four steps
Send Your Brief
Share your planning drawings, OS map extract, and the LPA name or planning reference. We confirm the required reference dates, time-points and any specific LPA requirements before starting.
LPA Brief & Scope Confirmed
We confirm the applicable BRE 209 criteria, reference dates and any LPA-specific requirements in writing. OS grid reference verified. Scale and north point matched to your submitted drawings.
First Draft in 48 Hours
3D model built from your drawings. Shadow footprints generated at all required times. BRE 209 methodology statement prepared. First working draft delivered within 48 hours of confirmed project start.
Print-Ready & Submission-Ready
After review and one amendment round, final print-ready PDF, DWG and ArchiCAD source files delivered. Methodology statement included. Ready to submit with your planning application.
Transparent pricing. No surprises.
Every quote is fixed price — not hourly. Invoiced in GBP. No VAT applicable (invoiced from North Macedonia).
Extensions, single dwellings, rear additions — standard shadow diagram for householder planning application.
- Shadow footprints at equinox & solstice
- All required LPA time-points
- Existing vs proposed shadows
- BRE 209 methodology statement
- True north & OS-accurate geometry
- Print-ready PDF + DWG source
- 1 free planning amendment · NET 14
Multi-unit residential, commercial developments and complex sites. Full BRE 209 VSC/APSH/NSL reporting joins the line late August 2026.
- Everything in Householder package
- Full VSC / APSH / NSL analysis — from late August 2026
- Multiple affected neighbours assessed
- Window-by-window interpretation against the applicable criteria
- Extended time-point coverage
- Priority 48-hour turnaround available
- Quoted per project scope
All prices in GBP. No VAT — invoiced from KAS STUDIO DOOEL, Skopje, North Macedonia. Fixed quotes within 24 hours of brief received.
UK cities we regularly work in
We deliver shadow diagrams for planning authorities across England, Wales and Scotland. Not in the list? Get in touch — we work with any LPA.
Common questions about shadow diagrams for UK planning
Also need shadow diagrams for Australia?
Fixed-price quote within 24 hours.
- £280 householder / single dwelling
- £450+ multi-unit / commercial
- 48-hour first draft
- 1 free planning amendment included
- No VAT · NET 14 payment terms
Prefer to email directly? info@casstudio.com