​​How does airtightness smoke testing work?

During the investigation, the building or enclosure is placed under controlled positive or negative pressure using specialist fan equipment. Smoke is then introduced at selected locations or released within the test area.

The pressure difference causes the smoke to move through gaps, cracks and unsealed penetrations. This makes otherwise invisible air-leakage routes easy to locate and record.

Depending on the building and the purpose of the investigation, smoke may be used internally to identify air being drawn into the building or externally to show where smoke escapes through the building envelope.

Smoke testing equipment for every application

Airtightness UK has four professional smoke machines in different sizes, allowing us to select the most suitable equipment for each project.

Our smaller smoke machines provide controlled smoke for detailed investigations around individual components and confined areas. Our larger machines can rapidly generate a much greater volume of smoke for large buildings, industrial spaces, service voids, plenums and specialist enclosures.

Having several machines also allows us to introduce smoke at multiple locations where required, making it possible to investigate complex or larger leakage paths efficiently.

What can smoke testing identify?

Smoke testing can help locate air leakage around:

• Windows and external doors

• Roofs, eaves and loft hatches

• Suspended floors and floor-to-wall junctions

• Skirting boards and internal finishes

• Service penetrations and pipework

• Electrical sockets and consumer units

• Ductwork and ventilation systems

• Wall-to-roof and wall-to-floor junctions

• Service risers, shafts and boxed-in areas

• Plenums and ceiling voids

• Fire-suppression and specialist enclosures

• Poorly sealed construction joints

• Gaps hidden behind fitted units or finishes

The test can also demonstrate whether air is passing between rooms, floors, adjoining properties or separate areas of a building.

When is smoke testing useful?

Smoke testing is particularly valuable when a building has failed an airtightness test or achieved a higher air-permeability result than expected. It can also be used during construction, before finishes are completed, when leakage points are generally easier and less expensive to seal.

Typical applications include:

• Investigating failed airtightness tests

• Pre-test inspections and diagnostic testing

• Staged testing during construction

• New-build dwellings and developments

• Large residential and commercial buildings

• Passive House and low-energy projects

• Industrial buildings and warehouses

• Smoke shafts, plenums and service risers

• Gas fire-suppression enclosures

• Identifying air movement between adjoining spaces

• Checking completed remedial work

Find leaks before they become expensive

Air leakage is often hidden behind plasterboard, ceilings, service boxing and fitted finishes. Once construction is complete, these areas can be difficult and costly to access.

Carrying out smoke testing at the right stage gives contractors the opportunity to locate and seal leakage paths before they are covered. This can reduce the risk of a failed final airtightness test, minimise disruption and help avoid unnecessary remedial work.

Smoke testing can also be used after sealing work has been completed to confirm whether the identified leakage has been successfully reduced.

Clear evidence and practical advice

Where appropriate, we can provide photographs and video evidence showing the air-leakage locations identified during the investigation. Our engineers will explain the findings on site and provide practical guidance on the areas that should be investigated or sealed.

Smoke testing is primarily a diagnostic service. Where a formal airtightness result or certificate is required, the smoke investigation can be carried out alongside a calibrated airtightness test.

Book an airtightness smoke investigation

Whether you need to investigate a failed test, locate difficult air leakage or check the building envelope before work is covered, Airtightness UK has the equipment and experience to help.

With four smoke machines of varying capacities, we can support everything from detailed investigations in individual rooms to large-volume smoke testing in commercial, industrial and specialist buildings.

Contact Airtightness UK to discuss your building, the issue you are experiencing and the most appropriate testing method.