128 Thirlmere Drive St Albans Hertfordshire Al1 5Ql

1. 7 Apr 2026

   Received by St Albans

2. 8 Apr 2026

   Validated

   Checked as complete and ready for consideration.

3. 7 Jul 2026

   Decision issued: Certificate of Lawfulness Approved

4. 7 Sep 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

• 117 Cell Barnes Lane St Albans Hertfordshire Al1 5Pu

  5/2021/1554 Submitted 23 May 2021 145m away

  Prior Notification - Single storey rear extension 2.9m in height x 5.5m in depth and 2.9m in height to the eaves

  Granted Prior approval Extension 10 docs
  Small domestic

• 58 Windermere Avenue St Albans Hertfordshire Al1 5Qn

  5/2026/1056 Submitted 1 Jun 2026 148m away

  First floor rear extension

  Decided Householder Extension 11 docs
  Domestic

• 58 Windermere Avenue St Albans Hertfordshire Al1 5Qn

  5/2016/1955 Submitted 23 Jun 2016 148m away

  Prior Notification - Single storey rear extension 4.2m depth x 3.64m height x 2.5m in height to the eaves

  Granted Prior approval Extension 26 docs
  Small domestic

• 34 Thirlmere Drive St Albans Hertfordshire Al1 5Qr

  5/2026/0897 Submitted 6 May 2026 267m away

  Prior Notification - Single storey rear extension 2.95m in height x 4.00m in depth with 2.95m height to eaves

  Granted Prior approval Extension 9 docs
  Small domestic

• 34 Thirlmere Drive St Albans Hertfordshire Al1 5Qr

  5/2026/0043 Submitted 9 Jan 2026 267m away

  Single storey rear extension with raised patio (replacing existing conservatory)

  Refused Householder Extension 9 docs
  Small domestic

• 118 Cell Barnes Lane St Albans Hertfordshire Al1 5Qe

  5/2016/1908 Submitted 19 Jun 2016 306m away

  Prior notification - Single storey rear extension 3m in height by 6m in depth with 3m in height to the eaves.

  Refused Prior approval Extension 6 docs
  Small domestic

• 5/2026/1607 Decided

  5 Flavian Close St Albans Hertfordshire Al3 4Jx

  Certificate of Lawfulness (proposed) - Construction of single storey rear extension with tiled lean to roof fitted with 3no. roof lights

  1 Sep 2026 Lawful development
• 5/2026/0951 Refused

  23 Clarence Road St Albans Hertfordshire Al1 4Np

  Certificate of Lawfulness (proposed) - New single storey garden room and close boarded access gates

  15 May 2026 Lawful development
• 5/2026/1558 Granted

  31 Highfield Avenue Harpenden Hertfordshire Al5 5Ub

  Certificate of Lawfulness ( Proposed) - Proposed rear single-storey extension, side single-storey extension and removal of rear chimney stack

  20 Aug 2026 Lawful development
• 5/2026/0291 Refused

  66 Pondfield Crescent St Albans Hertfordshire Al4 9Pf

  Certificate of Lawfulness (proposed) - Hip to gable and new dormer

  16 Feb 2026 Lawful development
• 5/2026/1252 Refused

  7 Palfrey Close St Albans Hertfordshire Al3 5Re

  Certificate of Lawfulness (proposed) - Single storey/ground floor extension to dining room, to extend as far as kitchen rear/outside wall across to party wall. Repositioning French windows to new rear of room, and repositioning downpipe and soak away in r

  30 Jun 2026 Lawful development