18 Sycamore Avenue Hatfield Hertfordshire AL10 8LZ

1. 21 Nov 2022

   Received by Welwyn Hatfield

2. 16 Jan 2023

   Decision issued: Granted

3. 9 Aug 2026

   Added to PlanIndex

Permission has been granted, usually subject to conditions listed on the decision notice, some of which must be discharged before work starts. The decision notice on the council portal sets out exactly what was approved.

Work must normally begin within three years of the decision or the permission lapses. Neighbours cannot appeal a grant; challenging one means judicial review of how the decision was made, within tight time limits.

A lawful development certificate is a legal determination, not a planning judgement. It asks the council to confirm either that existing use or works are lawful, often through the passage of time, or that a proposal would not need planning permission at all. The applicant must prove the facts; the merits of the scheme are not considered.

More on lawful development applications in our guide

• 12 Sycamore Avenue Hatfield AL10 8LZ

  6/2024/2005/PN8 Submitted 18 Oct 2024 55m away

  Prior approval for the erection of a single storey rear extension measuring 5.9m in depth, 3m in height and 2.6m to the eaves

  Refused Prior approval Extension
  Small domestic

• 12 Sycamore Avenue Hatfield AL10 8LZ

  6/2024/1548/HOUSE Submitted 14 Aug 2024 55m away

  Erection of part single, part two storey rear extension

  Refused Householder Extension
  Domestic

• 96 Briars Lane Hatfield AL10 8EY

  6/2021/1146/HOUSE Submitted 8 Apr 2021 72m away

  Single storey front extension and alterations to fenestration on existing first floor front elevation

  Granted Householder Extension Windows or glazing
  Small domestic

• 17 Sycamore Avenue Hatfield AL10 8LZ

  6/2026/1031/HOUSE Submitted 12 Jun 2026 84m away

  Erection of a part single storey, part two-storey rear extension, garage conversion, front porch extension, alterations to fenestration and external materials

  Withdrawn Householder Extension Windows or glazing
  Small domestic

• 71 Briars Lane Hatfield AL10 8EX

  6/2026/1336/HOUSE Submitted 30 Jul 2026 124m away

  83% historically approved · decision due ~28 Sep

  Erection of a single storey side extension

  Awaiting decision Householder Extension
  Small domestic

• 2 Sycamore Avenue Hatfield AL10 8LZ

  6/2026/1160/HOUSE Submitted 3 Jul 2026 124m away

  Raising the roof height and converting the garage into habitable use, installation of a pergola to the rear elevation of the dwelling and alteration to fenestration.

  Granted Householder Windows or glazing
  Domestic

• 6/2026/0735/LAWE Refused

  1 Northaw Place Coopers Lane Northaw Potters Bar EN6 4NQ

  Certificate of lawfulness for the existing use of the land as residential garden land ancillary to the dwellinghouse continuously since 2012

  27 Apr 2026 Lawful development
• 6/2026/1132/LAWE Refused

  19 Cunningham Avenue Hatfield AL10 9LR

  Certificate of existing lawfulness of a 5 person HMO since 6 April 2006

  30 Jun 2026 Lawful development
• 6/2026/1506/LAWP Awaiting decision

  Gosmore Brocket Road Welwyn Garden City AL8 7TT

  Erection of single storey side extensions x 2 and two storey rear extension

  27 Aug 2026 Lawful development
• 6/2026/1503/LAWE Awaiting decision

  27 Batterdale Hatfield AL9 5JG

  Certificate of lawfulness for the existing like-for-like replacement of damaged and aged windows on the front and rear elevations

  26 Aug 2026 Lawful development
• 6/2026/1044/LAWP Granted

  5 Peartree Court Welwyn Garden City AL7 3XN

  Certificate of lawfulness for the change of use from C3 (dwellinghouse) to C4 (HMO for up to 6 unrelated residents)

  15 Jun 2026 Lawful development