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New Building Regulations

Did you submit a building regulations application before 15th June 2022, if so, you will be affected by the ending of the transitional provisions for new Building Regulation requirements F, L, O and S?

At the end of 2021, the government published new Approved Document F (covering ventilation) and L (covering energy efficiency). Both were in two volumes with 1. dealing with dwellings and 2. covering buildings other than dwellings. They were accompanied by an all-new Approved Document O (covering overheating in dwellings). New homes meeting the new standards should produce 31% less CO2 compared to those built to current standards. They also introduced Approved Document S (Infrastructure for charging electric vehicles).

The latest changes for new residential buildings are a step on the way to the Future Homes and Future Building Standards 2025, which are a set of standards that will complement the Building Regulations to ensure new homes built from 2025 will produce 75-80% less carbon emissions than homes delivered under current regulations.

When Approved Documents are updated or introduced, the Government puts in place Transitional Provisions specifying when the new regulations come into force. The regulations covered by these transitional arrangements are Parts F, L, O and S. This applies only to projects in England. The Transitional Provisions mean that projects where a building regulations application was made before that date must be started on site before the 15th of June 2023 or the new regulations will apply.

Do all plots have to be commenced?

Where multiple dwellings or buildings are on a single application, work on each unit must have commenced for transitional provisions to apply - so for an application for 100 dwellings, work on all 100 units must have commenced before 15 June 2023.

If only 10 of these 100 dwellings have started, only these 10 can be built to the previous standards, the remainder must meet the new 2022 standards.

Foundations for blocks of flats is considered a start on all units within that block.

In the case of Part S (Infrastructure for charging electric vehicles) however, where multiple dwellings or buildings are on a single application, work on just one unit must have commenced for transitional provisions to apply to all units.

To demonstrate commencement, you must have started one of the following for each plot:

  • excavation for strip or trench foundations or for pad footings
  • digging out and preparation of ground for raft foundations
  • vibro-compaction (stone columns) piling, boring for piles or pile driving
  • drainage work specific to the building(s) concerned.

The Government has confirmed that the following would not constitute a commencement for the purposes of building regulations:

  • removal of vegetation
  • demolition of any previous buildings on the site
  • removal of top soil
  • removal or treatment of contaminated soil
  • excavation of trial holes
  • dynamic compaction
  • general site servicing works (e.g. roadways).

The Government is introducing new building regulations requirements in June 2022 as follows: -

New dwellings - Full Plan and Building Notice submissions after 15th June 2022 or previously submitted and not started by 15th June 2023:

Approved Document Part F: Ventilation - Requirements revised.

Approved Document Part L: Conservation of fuel and power - Requirements revised.

Approved Document Part O - New requirements considering overheating. 

Approved Document Part S - New requirements requiring electric car charging points.  

Extensions and alteration Full Plan and Building Notice submissions after 15th June 2022 or previously submitted and not started by 15th June 2023:

Approved Document Part F: Ventilation - Requirements revised. (Including replacement windows) 

Approved Document Part L: Conservation of fuel and power - Requirements revised. (including new U-values)

To assist with new Part L requirements, please see the following guide:

Part L Insulation Guide – Dwellings 2022

(K. value in brackets)

Floors - 0.18W/m²K (P/A = 0.5 - 1.0)

Concrete slab

  • 120 - 150mm Jabfloor HP 70/100 (0.032) 
  • 150 - 200mm Jabfloor 70 (0.038)
  • 90 - 100mm PIR insulation (0.022)

Beam & Block

  • 120 -150mm Jabfloor HP 70/100 (0.032) 
  • 150 – 200mm Jabfloor 70 (0.038)
  • 90mm – 100mm PIR (0.022)

Timber suspended (joists@400c/cs)

  • 200mm Glass fibre slab (0.035)
  • 130 - 150mm PIR (0.022)


Walls - 0.18W/m²K

Dense Block or Brick, Cavity, Aerated (0.15-0.24) Block (Inner)

  • 100 mm Dritherm 37 batts (0.037) (+ 62.5mm Insulated Plasterboard on dabs)
  • 100mm Dritherm 32 batts (0.032) (+ 52.5mm Insulated Plasterboard on dabs)
  • 150mm Dritherm 32 batts (0.032) (Wet plaster)
  • 100mm PIR (0.022) (with 50mm clear cavity)

Block, Cavity, Block (Aerated 0.15-0.24)

  • 100 mm Dritherm 32 batts (0.032) (+ 32.5mm Insulated Plasterboard on dabs)
  • 125mm Dritherm 32 batts (0.032) (only with blockwork combinations with K values of 0.11-0.15)
  • 150mm Dritherm 37 batts (0.037) (Wet plaster)
  • 85mm PIR (0.022) (with 50mm clear cavity)

Medium Dense Block, Cavity, Medium Dense Block

  • 180mm Dritherm 37 batts (0.037) (Wet plaster)
  • 100mm PIR (0.022) (with 50mm clear cavity)

Brick, Cavity, Studwork

  • 100mm stud regularised -> 90mm PIR (0.022) (between) + 40mm (internal)
  • 150mm stud regularised -> 110mm PIR (0.022) (between) + 25mm (internal)

Solid blockwork (Aerated)

  • 215 mm thermal blocks (0.11)
    • 70mm PIR (0.022) (On battens, + Plasterboard)
    • (52.5mm on dot and dab only achieves a max of 0.30W/m²K)
  • 265 mm thermal blocks (0.11) (reduce PIR by 10mm)

Solid brickwork (215 mm)

• 100mm PIR (0.022) (On battens, + Plasterboard)

Timber walls (studs @, 400c/cs)

Tile hung, or render on ply

150mm studs regularised

  • 140 mm Dritherm 37 (0.037) (Between studs)
    • +50mm PIR (0.022) (Over studs)
  • 110mm PIR (0.022) (between) + 25mm (to internal face)

100mm studs regularised

  • 90mm Dritherm 37 (0.037) (Between studs)
    • + 70mm PIR (0.022) (Over studs)
  • 90mm PIR (0.022) (between) + 40mm (to internal face)

Roofs (joists/rafters @, 400c/cs)

Flat roof - 0.15W/m²K
Warm Deck (Insulate Perimeter)

  • 150mm PIR (0.022) (Includes 6mm ply)

Cold Deck (Allow 50mm airflow above insulation)

  • 150 + 25mm PIR (Between and under joists)
  • 120 + 40mm PIR                      “
  • 100 + 50mm PIR                    “

Pitch roof (@400 c/cs)
Insulation at ceiling level - 0.15 W/m²K

(Between and over joists)

  • 150mm x2 (300mm) Fibre glass (0.044)
  • 150mm PIR (0.022) (between) 40mm PIR (0.022) (over joists)

Insulation at rafter level 0.15W/m²K

  • 215mm PIR (0.022) (Between rafters)
  • 140 mm PIR (Between) + 40mm PIR (under)
  • 120mm PIR (Between) + 50mm PIR   “
  • 100mm PIR (Between) + 60mm PIR   “
  • 90mm PIR (Between) + 70mm PIR     “
  • 75mm PIR (Between) + 75mm PIR     “ 
  • 50mm PIR (Between) + 90mm PIR     “ 

(*** At 600c/cs, insulation can be reduced a little***)

Note. This information is produced as an 'on-site' guide and manufacturers data should be used where possible.