Planning Permission for House Extensions in 2026: What You Need to Know
A guide to permitted development rights for homeowners planning a house extension or loft conversion in 2026.
One of the most common questions we get from homeowners planning a house extension or loft conversion is whether they'll need planning permission. In many cases, the answer is no — thanks to permitted development rights.
Current permitted development limits: for detached houses, extensions can go up to 4 metres deep under standard permitted development, or up to 8 metres via the Prior Approval process. For semi-detached and terraced houses, the limit is 3 metres under standard rules, or up to 6 metres via Prior Approval. Extensions must stay within 50% of the original land area, height restrictions still apply, and materials should match the existing property in appearance.
When you'll still need permission: listed buildings, conservation areas with an Article 4 Direction, National Parks, Areas of Outstanding Natural Beauty, and flats or maisonettes don't benefit from permitted development rights, so planning permission is required regardless of size. No changes to permitted development rules have taken effect as of 2026, although a government consultation on relaxing the 50% curtilage rule and extension depth limits closed in 2024, with no formal response published yet.
Not sure whether your project qualifies? L.A.R. Property Extensions & Loft Conversions can assess your plans and handle the process from design through to build.
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