Part L: Will all housing plots need testing?

In this series of articles, we aim to answer some of your questions about the upcoming changes to Approved Documents L and F, SAP methodology and the Future Homes Standard.

Current proposals suggest these regulations will be coming into force in England from October 2020. Contact us with your own questions about the regulation changes, or to discuss our training seminars and workshops.

Will I need to have more plots tested under the new regs?

Yes. It is proposed that every new dwelling will need to be air tested, and the maximum allowed target is being lowered.

The Future Homes Standard is the Government’s ambitious plan for changing the way we build houses over the next few years. By 2025 the intention is for new homes to be constructed in a far more sustainable way with lower bills, requiring less energy to heat and will in turn produce fewer emissions.

A common theme in the consultation papers is how we prove that completed buildings match their design specification and have been constructed to a high level of quality and skill.

The best way of quantifying this is by carrying out an air leakage test on site. The pressure inside a building is measured to see how quickly air can escape through the building fabric. Less air leakage means a building has been constructed well.

Under current building regulations developers do not have to test every dwelling they build. If they take this approach, they must achieve an air test which both complies with their SAP calculation, and is no higher than 8.

Any plots which are not tested use a worst-case air test assumption known as the ‘Confidence Factor’. This is the average air test result of similar dwellings on the site, plus two.

Developers who opt to test every plot do not need to worry about the Confidence Factor and, providing the SAP calculations comply, they can work to a test result no higher than 10.

The Future Homes Standard is proposing to get rid of this option and suggests every new dwelling should be air tested. This could come into force as early as next year depending on feedback from the Approved Document L public consultation (which is open until February 7^th).

As well as pushing through a 100% testing regime, the maximum air test result allowed will be set to 8 in all cases. We expect most developers will need to aim for a result lower than 8 to ensure they meet compliance with SAP.

When we begin testing every new dwelling there will be no need for the Confidence Factor rule, so it doesn’t feature in the new regulations.