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Before completion
Book when the property is nearly finished and external openings can close fully.
Part L Building Regulations
Part L is the part of the Building Regulations concerned with conservation of fuel and power. Air tightness testing helps demonstrate how well a building limits uncontrolled air leakage.
Plain English
Part L sets standards for energy efficiency in buildings. In simple terms, it is about reducing wasted energy, improving building performance and supporting lower running costs.
For new dwellings, airtightness is an important part of the overall energy performance calculation alongside insulation, thermal bridging, heating systems and ventilation.
Part L & Testing
A test measures how much air leaks through the building fabric. A better airtightness result usually means less uncontrolled heat loss, provided the property also has suitable ventilation.
When To Book
Air tightness testing is often needed near completion, but it should be considered much earlier so key details are not missed during construction.
Book when the property is nearly finished and external openings can close fully.
Allow time to review the result before project handover.
Have the property address, type and floor area available when requesting a quote.
Check what evidence is required for your specific project.
FAQs
Air tightness is linked to Part L energy performance requirements for many new buildings. The exact requirement depends on the project, location and Building Control route.
England and Wales have separate Approved Documents and update timelines. Always check the applicable guidance for the nation your project is in.
SAP is the calculation method used to assess the energy performance of dwellings. Air permeability is one of the inputs that can affect the calculation.
No. Airtightness reduces uncontrolled leakage. Ventilation should still be properly designed to provide healthy air exchange.
Not always. Requirements vary depending on the project and Building Control requirements. Ask your architect, energy assessor or Building Control if unsure.
It can affect the completion process, so it is sensible to plan airtightness details during construction and avoid leaving testing too late.
Send the project details and preferred test date.
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