On 24 March 2026 the Ministry of Housing,Communities & Local Government published the Future Homes Standard impact assessment. Policy comes into force on 24 March 2027. If you build, design, or specify new homes in England, airtightness is now a legal requirement. Here's what you need to know...
The Future Homes Standard amends Part L of the Building Regulations to require that every new dwelling in England is built to a zero-carbon ready standard. New homes must be so energy efficient that once the electricity grid decarbonises, they will produce zero carbon emissions in use with no retrofit needed.
To define what compliance looks like, the government has set a notional building which is a reference specification that all new homes must match or exceed. That notional building includes a heat pump, wastewater heat recovery, improved airtightness and decentralised mechanical extract ventilation. Airtightness performance required under the FHS is more demanding than anything previously required under Building Regulations.
Why airtightness specifically
A building loses heat two ways: through its materials by conduction, and through gaps and leaks by infiltration. Insulation handles the first problem. Airtightness handles the second. You cannot compensate for one with the other as a well-insulated wall with a poorly sealed junction is still a leaking building.
Every new home will be subject to an air permeability test to verify the building envelope performs as designed. Retrofitting a building to correct failures costs around 66 to 80% more than getting it right during construction. So it pays to get it right the first time round. Airtightness must be planned before construction begins and not during or after.
When does it apply to you
The regulations come into force on 24 March 2027. There is a transitional provision: developers have 12 months after the legislation is laid to submit an initial notice, a building notice or full plans application to the local authority, and a further 12 months to commence construction. If they meet both deadlines, they are permitted to continue building to the 2021 standards for that specific building. If they do not meet these deadlines, they are required to meet the FHS.
In practice this means architects specifying projects today are already specifying to the new standard. Contractors pricing 2026 work are pricing jobs that will be tested under FHS requirements. The government expects that by 2030 the vast majority of dwellings completed will be FHS-compliant.
What this means in practice
Getting airtightness right is not too complicated but it does require the right materials and consistent attention to detail throughout the build. Every junction where different elements meet, every window reveal, every service penetration through the envelope needs to be properly sealed and taped. Standard construction tape will not achieve the performance levels required. Products need to be specified for performance, installed correctly, and maintained continuously across the envelope.
The bottom line
March 2027 is twelve months away. An airtightness failure does not show up during the build but at the end, when the blower door test gives a result nobody wants, on a house that is otherwise finished.
If you are getting to grips with the new requirements, we are happy to help you work out which products you need for your build. Browse our full range of airtightness tapes and membranes here or get in touch and we will talk you through it.
sales@airtightsupply.co.uk
Airtight Supply Ltd is an authorised UK distributor of Siga airtightness products, supplying contractors, architects and self-builders across the UK.
Sources:
- Future Homes Standard Impact Assessment, MHCLG, 24 March 2026 assets.publishing.service.gov.uk
- Future Buildings Standard Impact Assessment, MHCLG, 24 March 2026 assets.publishing.service.gov.uk
- Building Circular 01/2026, MHCLG, 24 March 2026 — gov.uk