Insulation is an increasingly important part of any building job. As we seek to use less energy – both for the planet and our wallets – good insulation in every part of a building becomes vital.
Regulations around insulation in the UK have been updated fairly regularly over the last few years as new materials, technologies and best practices emerge. Here is the latest information on what insulation requirements are for contractors in the UK.
What are the Minimum Insulation Requirements in the UK?
As with other areas of UK building regulation, the rules around insulation are slightly different across the nations. Here are the different documents outlining the rules in various regions:
- England: Approved Document L
- Scotland: Technical Handbook Section 6
- Wales: Approved Document L (different standards to the English version)
- Northern Ireland: Technical Booklet F1
While the specifics are different, the general principles behind most of these documents are the same.
U-Values
All parts of a building where heat could be lost must be insulated to a certain U-value to ensure a minimal level of insulation and energy efficiency.
U-values are a common measurement of a material or building’s ability to resist heat loss. Materials that conduct less heat have a lower U-value, and as a result, are better at keeping heat in place (e.g. indoors).
UK building regulations outline maximum U-values permitted in various parts of a building, from roofs to floors. Details on how U-values are measured in each instance are provided in the relevant documents highlighted above.
Insulation Requirements for New Builds vs Existing Buildings
As with other building regulations, such as accessibility regulations, rules around insulation mention that any work on existing buildings must ensure that insulation is taken into account. This point is important to consider when doing work on things such as loft conversions or windows.
Insulation requirements for existing buildings can vary depending on the nature of the job. Generally, there’s an expectation that the level of insulation will be improved compared to previously if it didn’t meet the new standards being set before the work commenced. However, some mitigations are permitted, such as if installing adequate insulation would be economically unfeasible or cause other issues in the building.
Areas of Insulation Covered by UK Building Regulations
As mentioned, UK insulation requirements outline specific expectations for U-values in different areas of a build. Here are some of the areas that frequently come up across all areas, although there can be some discrepancies in various regions.
Roofs
The roof is the biggest area for heat loss in a building, so it’s crucial that this is insulated. As roofs can come in many shapes, sizes, and with different uses, there is room for contractors to use whatever materials and thicknesses they see fit, so long as the U-value is achieved.
The long-term protection of roof insulation should be considered while also allowing for any future maintenance.
Walls
Another big area for potential heat loss. Most expectations for wall insulation concern external walls. There are different expectations for cavity insulation walls when working on existing dwellings.
For existing buildings, if providing the required level of insulation would cause a notable reduction in the floor space (due to expanding the wall), then a lower standard than required can be accepted.
Floors
As heat can be lost through the ground, there are insulation expectations for flooring to also consider. Generally, the U-value of flooring is expected to be at a similar level to that of the roof, while there is added emphasis on moisture-resistant insulation materials due to its location.
Similar to walls, if insulation on an existing floor would cause problems with adjoining floors (for example, by forcing the floor level to be raised), then lesser standards can be accepted.
Boilers & Pipework
Building regulations also stipulate that boilers and pipework must be adequately insulated. Doing so ensures the heating system works to a good level of efficiency, further saving money and emissions.
Unlike other insulation areas, pipework insulation is measured in thickness, with higher thicknesses for wider pipes (assuming the insulation used is of a good standard). Hot water cylinders, or other products that store hot water for domestic use (e.g. boilers) must fall below a maximum daily heat loss figure.
Other Areas
UK building regulations also outline insulation and heat-loss expectations for other areas in buildings. Some of these can be more job-specific and include:
- Swimming Pool floors
- Rooflights
- Doors
Other UK Insulation Regulations
UK building regulations not only set out minimum expectations regarding heat loss from various areas. The regulations also set out further best practices when it comes to the quality of insulation across a whole building.
Airtightness
Keeping a building sealed is crucial to ensuring minimal heat loss. Just putting quality insulation inside a wall won’t help if it’s not been adequately inserted and isn’t supported by insulation in other areas.
Expectations around airtightness include:
- Ensuring any insulation is adequately packed and sealed.
- Taking care to minimise and seal penetrations (for passage of pipes, wires etc.) both inside the insulation and passing through the building.
Thermal Bridging
Similar to airtightness, thermal bridging occurs when there are differences in insulation levels across various aspects of the building, causing heat to leave through specific areas. This should be minimised wherever possible.
Suggested actions highlighted by the regulations concerning thermal bridging include:
- Ensure plans for new dwellings are adequately audited to flag potential problem junctions and minimise thermal bridging.
- Consider the continuity of insulation (for example, roof insulation stretching down to meet wall insulation).
- Take care around windows and doors to ensure their impact on insulation is minimised.
Hopefully, this guide helps you to understand more about the various UK regulations concerning building insulation. For further details on requirements and to understand what’s expected of your project, we recommend reading the relevant documents yourself or speaking to your local authority, who should be able to advise.
