Why Is Air Tightness Testing Important?

Maintaining a continuous and well-sealed air tightness barrier is essential for any building’s energy efficiency. Air tightness testing measures how much air escapes from inside the building to the outside through unintended gaps or leaks. When air leaks occur, they not only cause uncomfortable draughts but also significantly reduce energy performance.

A poorly sealed building can lose up to 50% of its heat through air leakage. This undermines the benefits of investing in energy-saving measures such as additional insulation, high-efficiency boilers, or renewable heating systems like ground source heat pumps.

Prioritising air tightness testing ensures your building performs as designed—helping you save money on energy bills and meet regulatory requirements. In fact, failing an air tightness test could prevent you from achieving Building Control sign-off and handing over the property.

By carrying out a test, you’ll receive a measurable air leakage rate (in m³/hr/m²), which indicates the volume of air lost or gained. This figure is then compared to the limits set by Building Regulations, determining whether the property meets compliance standards.

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What Building Regulations Govern Air Tightness Testing?

Air tightness testing is required under two main parts of UK Building Regulations:

• Part L1A – Governs air tightness for all new dwellings.
• Part L2A – Applies to commercial and public buildings such as offices, schools, and retail spaces.

Compliance with these regulations is enforced by Building Control.

Air tightness testing is also a crucial component of both SAP (Standard Assessment Procedure) calculations for domestic buildings and SBEM (Simplified Building Energy Model) assessments for commercial ones. These assessments determine a building’s overall carbon footprint, which is directly influenced by how airtight the structure is.

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What Happens if the Building Fails the Air Tightness Test?

At Air Pressure Testing, our goal is for your building to pass the first time. However, if the initial test doesn’t meet the required standard, we’ll work with you to identify and resolve the issues quickly to ensure a successful retest.

Some of the diagnostic techniques we use include:

• Commercial Smoke Testing: We fill the building with smoke and then pressurise it to highlight leakage points — the smoke visibly escapes through gaps in the envelope. For smaller properties, we use handheld “smoke pencils” to pinpoint problem areas.
• Thermal Imaging: Using infrared cameras, we can identify hot and cold spots throughout the building, helping locate areas of heat loss and air leakage.

Unlike some testing companies that simply test and leave, we provide a proactive support service, assisting you until your building achieves full compliance and Building Control approval.

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Common Causes of Air Leakage

Air leakage can occur in many areas, often due to construction detailing or poor installation. The most common problem areas include:

• Junctions between external walls and floors
• Behind fitted kitchen or bathroom units
• Around poorly sealed windows and doors
• Around service penetrations (pipes, ducts, cables, etc.)
• Through attic or loft access doors

By addressing these weak points early in the construction process, you can dramatically reduce the likelihood of air tightness test failures later on.

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Need Expert Air Tightness Testing?

If you’d like more information about our air tightness testing and consultancy services, please don’t hesitate to contact Air Pressure Testing on 01525 303905, or visit our website to learn how we can help your project achieve full compliance and energy efficiency.

Why Your Building Needs an Air Tightness Test

When it comes to energy efficiency, keeping a building’s air barrier continuous and leak-free is essential. Air tightness testing measures how much air escapes from inside a building to the outside at low pressure. Even small leaks can create cold draughts and dramatically increase energy use.

Why Air Tightness Matters

Up to 50% of a building’s heat can be lost through an unsealed envelope. That means the money you invest in high-performance insulation, premium boilers, or ground-source heat pumps can be wasted if the structure isn’t airtight. A failed air test can also delay handover, adding cost and frustration to any project.

Testing provides a clear air-leakage figure (measured in m³/hr/m²), which is then compared to the limits set by building regulations. This ensures the property meets efficiency standards and gives you a benchmark for improvements.

Building Regulations to Know

Two main UK regulations govern air tightness:

• Part L1A – for new dwellings
• Part L2A – for commercial spaces such as offices and public buildings

Compliance is checked by Building Control and feeds into energy assessments: SAP (domestic) and SBEM (commercial). Both evaluate a building’s carbon footprint, where airtightness plays a major role.

If Your Building Fails the Test

A first-time pass is the goal, but if your property falls short, targeted diagnostics can identify the leaks:

• Commercial Smoke Testing – Pressurising the building while filling it with smoke reveals hidden gaps as smoke escapes. Smaller properties can use handheld “smoke pencils.”
• Thermal Imaging – Infra-red cameras highlight hot and cold spots, showing exactly where air is leaking.

Unlike companies that simply test and walk away, a good testing service will work with you to plan fixes and retest for compliance.

Common Air Leakage Points

Addressing these trouble spots early can prevent failed tests:

• External wall/floor junctions
• Behind fitted kitchen or bathroom units
• Around poorly sealed windows and doors
• Around service penetrations (pipes, cables, vents)
• Through attic hatches or loft doors

Bottom Line

Air tightness testing is more than a regulatory checkbox, it’s key to comfort, lower bills, and a reduced carbon footprint. By planning for airtight construction from the start and working with a proactive testing team, you’ll protect your investment and ensure your building performs as efficiently as possible.

For expert testing or consultancy, visit the Air Pressure Testing website or call 01525 303905.

Why Air Tightness Testing Matters

In an era where energy efficiency and environmental responsibility are top priorities in the construction industry, air tightness testing has become an essential part of building compliance. Since 2006, it has been a legal requirement in England and Wales under Building Regulations Part L. But beyond legal obligations, air testing plays a crucial role in reducing energy consumption, minimising environmental impact, and improving indoor comfort.

At APT Sound Testing, we offer professional and reliable Air Tightness Testing services across the UK, working with a wide range of clients, from private homeowners and developers to large-scale commercial contractors. What sets us apart is our commitment to quality, our comprehensive services, and our status as one of the few UKAS-accredited companies able to carry out both air and sound testing under one roof.

The Importance of Air Tightness Testing

Air tightness refers to how well a building can prevent the uncontrolled flow of air through gaps and cracks in its structure. In layman’s terms, it’s about reducing draughts and unwanted ventilation that leads to energy loss. Building Regulations refer to this as “air leakage,” and the more airtight a building is, the more energy efficient it becomes.

If a building isn’t airtight, heated or cooled air can escape, making heating and cooling systems work harder. This not only increases energy bills but also contributes to higher carbon emissions. In response, regulations now require new developments to meet specific air permeability rates, usually around 5.0 m³/hr/m² for residential dwellings. Commercial properties often face even stricter standards, with targets as low as 3.0 m³/hr/m².

But airtightness isn’t just about energy efficiency. It also affects the long-term health of a building. For example, in colder months, moist indoor air can escape into the walls and cause condensation within cavities. This can lead to mould, damp, and even structural rot, all of which are expensive and disruptive to fix.

Comprehensive Testing Packages

APT Sound Testing is uniquely positioned to help developers meet their compliance goals efficiently and cost-effectively. We provide combined Air, Sound, and Vent Testing packages, often completing all three during a single site visit. This streamlined approach not only saves money but also improves on-site coordination and reduces delays.

We believe in doing the job properly, so unlike many other providers, we never subcontract our work. Our in-house team of multi-skilled, UKAS-accredited engineers carry out all testing to the highest professional standards.

Many of our clients take advantage of our three-step pre-completion package, which includes:

1. Air Tightness Testing – to assess and reduce air leakage.
2. Sound Insulation Testing – to ensure acoustic performance between walls and floors meets regulatory standards.
3. Ventilation Testing – to verify that airflow systems meet design specifications and building codes.

This all-in-one solution means fewer contractors to manage, fewer appointments to schedule, and faster results.

Support from Design to Completion

Achieving air tightness begins long before the test itself. At APT Sound Testing, we provide design-stage consultancy to identify potential problem areas before construction even begins. Our experienced consultants review architectural drawings and offer expert advice on construction techniques and materials that will help your project meet its targets.

This early intervention helps avoid costly delays or retesting later on. We also conduct on-site inspections and walkthroughs to ensure the building is prepared before the final air test, significantly increasing the chance of a first-time pass.

Flexible Testing to Suit Your Schedule

We understand that construction sites are busy places, often running on tight deadlines. That’s why we offer flexible scheduling, including weekend and out-of-hours testing. This ensures your project stays on track without disrupting other critical work during normal hours.

Whether you’re managing a small residential build or a major commercial development, our goal is to make the compliance process as smooth and stress-free as possible.

Expert Advice and Friendly Service

Our clients appreciate our professional yet approachable service. We’re always happy to answer questions, explain procedures, and work closely with your site team to ensure successful outcomes.

Whether you’re new to air testing or an experienced builder looking for a reliable partner, we’re here to help. Our team of air tightness experts can provide tailored advice based on your project’s unique needs.

Get in Touch

If you need assistance with air tightness testing, or would like to explore our full suite of compliance services, contact APT Sound Testing today. Use our simple online contact form or call our offices at 01525 303905 to speak with one of our knowledgeable consultants.

We’re ready to support your project from planning through to completion with professional service, competitive pricing, and industry-leading expertise.