Building regulations

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.

  0.16W/M³K on a plywood deck 0.18W/M³K on a plywood deck
Insulation Type Thickness
Approx Weight Loading
Approx Weight Loading
BauderPIR FA-TE 140 4.2 120 3.6
BauderPIR Flatboard 160 4.8 140 4.2
BauderPIR Tapered 150 4.6 130 3.9
Expanded Polystyrene 210 4.9 180 4.2
BauderROCK 230 33.1 200 27.2
BauderXPS CO2 (with Umax) 230 8.1 200 7.0
BauderJFRI 200 (with JFRI VPM) 225 6.75 200 6.0
Cork 240 24.0 210 21
Cellular Glass 240 30.0 210 26.3

England and Wales - Part L of Building Regulations - Conversation 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.