Building regulations for roof insulation

Roof insulation thickness for building regulations will vary depending on the type of insulation used. Used within a Bauder waterproofing system our products meet current UK Building Regulations Part B for fire protection.

Different insulants have different efficiencies and performance levels which affects the thickness required to meet building regulations. This table shows a comparison of the insulations when looking to achieve different U-values on a plywood deck.

Warm roof insulations

  0.11W/m²K on a plywood deck 0.13W/m²K on a plywood deck 0.18W/m²K on a plywood deck
Insulation Type Thickness
(mm)
Approx Weight Loading
(Kg/m²)
Thickness
(mm)
Approx Weight Loading
(Kg/m²)
Thickness
(mm)
Approx Weight Loading
(Kg/m²)
BauderPIR FA-TE 200 6 160 4.8 120 3.6
BauderPIR FA 200 6 160 4.8 120 3.6
BauderPIR FA Tapered (average thickness) 200 6 160 4.8 120 3.6
BauderVIP* 110 17.9 80 17 60 13
BauderROCK 335 53.6 290 46.4 200 32
BauderGLAS 310 31 260 26 190 19

*U-value based upon ratio of 80% BauderVIP in combination with 20% BauderPIR FA-TE with an additional 30mm layer of BauderPIR FA-TE for 0.11W/m²K 

 

Inverted roof insulations

 
  0.11W/m²K on a concrete deck 0.13W/m²K on a concrete deck 0.18W/m²K on a concrete deck
Insulation Type Thickness
(mm)
Approx Weight Loading
(Kg/m²)
Thickness
(mm)
Approx Weight Loading
(Kg/m²)
Thickness
(mm)
Approx Weight Loading
(Kg/m²)
BauderJFRI 200 HP (with JFRI WFRL) 300 10.5 255 8.9 185 6.5
BauderXPS 300 (with XPS WFRL) 330 9.9 270 8.1 190 5.7
BauderJFRI 300 (with JFRI WFRL) 320 14.4 280 12.6 200 9
BauderGLAS Inverted (with JFRI WFRL)
two layers
360 36 300 30 220 22

 

England and Wales - Part L of Building Regulations - Convservation of fuel and power

Separate criteria are set out in approved documents; L1 is specific to dwellings and L2 relates to buldings other than dwellings.  These are then split into four sections and for new construction are based on notional buildings:
L1A New Dwellings - 0.13 W/m²K
L1B Existing Dwellings - 0.18 W/m²K
L2A New Buildings other than Dwellings - 0.18 W/m²K
L2B Existing Buildings other than Dwellings - 0.18 W/m²K
More via Government Planning Portal ►
 

Scotland - Section 6 of the Scottish Building Regulations - Energy

Revised target levels for roofs are to be implemented from October 2015 and are approaching or exceeding the passiivhaus standard for buildings.
Domestic buildings - 0.11 W/m²K
Non Domestic buildings - 0.18 W/m²K for heated and naturally vented notional buildings
Non Domestic buildings - 0.16 W/m²K for heated and mechanically vented notional buildings
More via The Scottish Government ►
 

Contact us today about your project

To learn more about building regulations or if you'd like to discuss your flat roof project, get in touch to arrange a meeting with your local area technical manager.