Air Tightness Consultancy

It is critically important to design air tightness into a building from the very start of a project. In most cases, air pressure testing is carried out only on completion of a build – meaning leakage problems are identified too late. Remedial work is costly, time-consuming and often technically difficult to achieve once construction is complete.

An integrated approach links air tightness requirements to other Building Regulations obligations, particularly those relating to energy efficiency. Build Energy provides air tightness consultancy services throughout the project lifecycle, from detailed design through to construction completion, to help your team deliver airtight buildings to whatever target specification is required.

For on-site testing once construction is complete, see Air Tightness Testing. For pressurisation testing in smoke control shafts, see Smoke Shaft Testing. For underfloor plenum systems, see Plenum Testing. Return to the Air Tightness services hub.

What is air tightness consultancy?

Air tightness consultancy is a proactive advisory service provided during design and construction to help project teams achieve their target air permeability before the mandatory pressure test. Unlike air testing (which only confirms whether a building passes or fails), consultancy identifies potential leakage paths early so they can be addressed in the design and construction process.

When should I appoint an air tightness consultant?

Ideally at RIBA Stage 3, before detailed design is finalised. Early engagement allows Build Energy to review drawings while changes are still straightforward to make. Appointing a consultant after construction has started significantly reduces the opportunity to address high-risk details and increases the likelihood of costly remedial work.

What is a target air permeability and who sets it?

Air permeability is a measure of the rate at which air leaks through the building envelope, expressed in m³/(h·m²) at 50 Pa. Part L of the Building Regulations sets a maximum acceptable value, but many projects specify a tighter target – particularly those seeking BREEAM credits or Passivhaus certification. The design target is agreed with the client and design team at the outset.

What happens if a building fails its air pressure test?

A failed air pressure test means the building does not comply with Part L of the Building Regulations and cannot be signed off. Remediation requires locating and sealing air leakage paths – often at junctions, penetrations and interfaces between elements. This can be expensive and disruptive after construction is complete. Build Energy’s consultancy service is designed to prevent failures before testing takes place.

Does Build Energy also carry out the air pressure testing itself?

Yes. Build Energy offers both air tightness consultancy and air permeability testing. Combining both services under one consultant ensures that the design strategy, construction inspection and final test are fully aligned – and that any issues identified during consultancy are directly reflected in the testing programme.