Air Tightness Testing Services

An air tightness test, commonly known as a blower door test, involves temporarily sealing a building’s main entrance with a frame-mounted fan. This fan pressurises or depressurises the building to 50 Pascals, allowing measurement of air leakage through the building envelope. All intentional openings, such as vents and flues, are sealed during the test to ensure accuracy. The resulting air permeability rate, expressed in m³/h·m² at 50 Pa, indicates the building’s airtightness. Testing is carried out in accordance with BS EN ISO 9972 and CIBSE TM23.

The cost varies depending on the size, complexity, and location of the building. For single dwellings, prices typically start from £190, with bulk discounts available for developments with multiple units. Larger or more complex buildings may be priced individually. It’s recommended to request a tailored quote to ensure accurate pricing.

An air tightness test, also known as a blower door test, measures how much uncontrolled air leaks through a building’s fabric.
A standard air tightness test measures uncontrolled airflow through a building’s fabric. Using a calibrated fan system, the building is pressurised or depressurised to a set level (typically 50 Pa), and air leakage is measured. Testing follows BS EN ISO 9972 and CIBSE TM23 methodologies to ensure reliable and consistent results across different project types.

In England and Wales, Approved Document L sets a maximum air permeability of 8 m³/h·m² at 50 Pa for new dwellings. Most developers aim for lower targets, typically 5 m³/h·m² or below, to improve energy performance. Scotland applies similar requirements under Section 6 of the Building Standards.

Yes, an air test for new builds is a legal requirement under current UK regulations. All new homes and most commercial properties must undergo testing to demonstrate compliance with Part L or Section 6.

A compliant test result is required before Building Control sign-off. Without a compliant test result, final approval may be delayed and remedial works may be required before occupation or completion.

Learn more about the testing process on our What Is Air Tightness Testing? page.

Yes. Air tightness testing plays a key role in improving a building’s overall energy performance. By identifying uncontrolled air leakage, the test allows developers or property owners to address heat loss through the building fabric. The benefits of air tightness testing include reduced air leakage means less reliance on heating systems, lower energy bills, and improved SAP (Standard Assessment Procedure) scores. It also contributes directly to meeting energy efficiency targets under Part L and achieving higher EPC ratings.

We carry out air tightness testing across a wide range of buildings, from individual houses and flats to offices, retail units, warehouses, care homes, leisure facilities, and large commercial developments. Each test is tailored to the building’s specific construction and compliance needs, ensuring accurate results and a smooth path to certification.

An air tightness test should be carried out once the building envelope is complete but before internal finishes are applied. This allows any air leakage issues to be identified and resolved without delaying completion or requiring costly remedial work.

If a building fails, a detailed report is provided, outlining where excessive air leakage was detected. Common reasons a building may fail an air tightness test include unsealed service penetrations, gaps in plasterboard, or poorly fitted doors and windows. Our team can advise on cost-effective remedial measures and provide prompt retesting.

For a standard single dwelling, testing typically takes 1 to 2 hours. This includes setup, sealing, data collection, and preliminary feedback. Larger or more complex buildings may require more time. Certification is usually issued within 48 hours.

A good air tightness test result for new dwellings in the UK is typically 5 m³/h·m² at 50 Pa or lower. Building Regulations allow a maximum of 8 m³/h·m² under Approved Document L, but lower results improve SAP scores, EPC ratings, and overall energy efficiency. Find a detailed explanation on our What Is Air Tightness Testing? page.

Air tightness testing in the UK is carried out by approved testing organisations using calibrated equipment and recognised methodologies. Air Tightness Solutions provides compliant air tightness testing nationwide, including London and Oxford, with results accepted by Building Control and SAP assessors. Our qualified engineers deliver fast and compliant testing for residential and commercial projects across the UK.