u-values-and-building-regulations-for-insulating-your-home

Building Regulations, Standards and U-Values

The lower the U-Value the more insulation there is in a building element, (e.g a floor, ceiling or wall). Therefore the less heat loss.
Consequently, the higher the U-Value, the more heat loss you have in the home.

U-Values are important because there are certain standards according to the Building Regulations and Standards depending on location.

For example, Scotland buildings will need a lower U-Value due to the colder weather than England. Wales can get away with having a higher U-Value than England and Scotland because it is typically less cold.

u-values demonstration

 

The tables below show the suggested U-values in England, Wales and Scotland. Note the distinction between the domestic and non-domestic columns.

England

Domestic Non-domestic
New Build Existing Buildings New Build Existing Buildings
Best Starting Point (Fabric Only) Extension Refurbishment Best Starting Point (Fabric Only) Extension Refurbishment
Wall 0.16 0.28 0.30 / 0.55 * 0.22 0.28 0.30 / 0.55 *
Floor 0.11 0.22 0.25 0.18 0.22 0.25
Pitched Roof – Ceiling Level 0.11 0.16 0.16 0.14 0.16 0.16
Pitched Roof – Rafter Level 0.11 0.18 0.18 0.14 0.18 0.18
Flat Roof 0.11 0.18 0.18 0.14 0.18 0.18

* A U-value of 0.55 W/m²·K is used for cavity insulation and 0.30 W/m²·K for internal or external wall insulation.

Wales

Domestic Non-domestic
New Build Existing Buildings New Build Existing Buildings
Best Starting Point (Fabric Only) Extension Refurbishment Best Starting Point (Fabric Only) Extension (Domestic in Character) Extension (Other Buildings) Refurbishment
Wall 0.16 0.21 0.30 / 0.55 * 0.22 0.21 0.26 0.30 / 0.55 *
Floor 0.11 0.18 0.25 0.18 0.18 0.22 0.25
Pitched Roof – Ceiling Level 0.11 0.15 0.16 0.14 0.15 0.15 0.16
Pitched Roof – Rafter Level 0.11 0.15 0.18 0.14 0.15 0.18 0.18
Flat Roof 0.11 0.15 0.18 0.14 0.15 0.18 0.18

* A U-value of 0.55 W/m²·K is used for cavity insulation and 0.30 W/m²·K for internal or external wall insulation.

Scotland

Domestic Non-domestic
New Build Existing Buildings New Build Existing Buildings
Best Starting Point (Fabric Only) Extension & Refurbishment * Conversion of Heated Buildings Best Starting Point (Fabric Only) Refurbishment, Extension & Conversion of Unheated Buildings Conversion of Heated Buildings
A B
Wall 0.15 0.17 0.22 0.30 0.18 0.25 0.30
Floor 0.13 0.15 0.18 0.25 0.15 0.20 0.25
Pitched Roof – Ceiling Level 0.10 0.11 0.15 0.25 0.14 0.15 0.25
Pitched Roof – Rafter Level 0.10 0.13 0.18 0.25 0.14 0.15 0.25
Flat Roof 0.10 0.13 0.18 0.25 0.14 0.15 0.25

* Column A is for extensions where the existing dwelling’s walls and roof U-values are worse than 0.70 W/m²·K in the walls and worse than 0.25 W/m²·K in the ceiling. Column B is for other extensions, upgraded existing thermal elements, non-exempt conservatories and conversion of unheated buildings.

For more information on Roofing Insulation, or if you would like to make an order – please email info@coulsy.co.uk or call 07544 030486


 

 Resources

Building Regulations

  • Part A – Structure
  • Part B – Fire Safety
  • Part C – Site preparation and resistance to contaminants and moisture
  • Part D – Toxic Substances
  • Part E – Resistance to the passage of sound
  • Part F – Ventilation
  • Part G – Hygiene
  • Part H – Waste Disposal
  • Part J – Combustion appliances and fuel storage systems
  • Part K – Protection from falling, collision and impact
  • Part L – Conservation of fuel and power
  • Part M – Access to facilities and buildings
  • Part N – Glazing
  • Part P – Electrical Safety
  • Part Q – Security in Dwellings
  • Part R – High Speed Electronic Communications Networks
  • Part 7 – Material and Workmanship

U-values are a measure of thermal transmittance and express the rate of heat transfer through any element of your building, such as the wall, roof, window or indeed any structural component. The higher the figure, the worse the thermal insulation quality. So aim to keep your U-values low.

Because the construction of these elements can vary so much depending on your design and choice of materials, the U-values vary too and hence they need to be calculated specifically for each element. The units used to express U-values are watts per m² Kelvin (W/m²K). This means that if a wall, for example, had a U-value of 1.0 W/m²K, for every degree of temperature difference between the air on the surface inside the wall and the air on the surface outside, 1 watt of heat would pass through any m².

In addition to the Building Regulations, you may be asked to comply with other guidelines including CFSH (Code for Sustainable Homes), SAP (Standard Assessment Procedures), SBEM calculations (Simplified Building Energy Model) and EPC (Energy Performance Certificates).