New Building Regulations


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)
  • 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)
  • 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.