Does the development need to protect neighbours’ sunlight?
A new dual occupancy should not unnecessarily block sunlight to neighbouring homes.
The size, height and location of the new buildings can affect how much shadow falls onto the property next door. We would therefore check the proposed development's shadows to make sure the neighbour continues to receive the required level of sunlight.
This is normally demonstrated using shadow diagrams, particularly for the relevant winter assessment period when shadows are longest.
Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303), Assessment Outcome 15: Solar Access – Planning (Residential Zones) Technical Specifications 2026
Short Answer
Yes. A dual-occupancy development needs to be designed so that it does not cause excessive overshadowing of neighbouring residential properties.
In particular, we would check the proposal against the current solar access and building envelope requirements, including the effect of the proposed building's height, setbacks and building envelope on adjoining properties.
Detailed Explanation
For a dual-occupancy proposal, we would assess overshadowing and solar access against the current Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) and the applicable Residential Zones Policy.
The assessment considers the effect of the proposed development on solar access to adjoining residential land. In practice, the architectural documentation should demonstrate compliance through shadow diagrams and the relevant solar-access calculations, where required.
This means building height, setbacks, orientation and overall building envelope may need to be adjusted where the proposal would otherwise result in unacceptable overshadowing of neighbouring residential properties.
No minimum block size does not remove the need for planning assessment.
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