Part L · As Built Testing

Air Tightness Testing
in Birmingham & the West Midlands

ATTMA-accredited blower door testing across Birmingham, Solihull, Coventry, Wolverhampton, Dudley and Walsall. Regular testing slots available with fast report turnaround.

Book an Air Test How the test works

ATTMA

accredited testers
certificates accepted nationwide

24 hr

report turnaround
after test

From £95

+VAT per dwelling
no hidden fees

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Regular slots across Birmingham & the West Midlands

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Air tightness testing in Birmingham

ATTMA-accredited testing across the West Midlands' largest development market.

Air tightness test blower door equipment in Birmingham

Birmingham and the wider West Midlands represent one of the UK's most active development markets, with large-scale residential schemes, commercial builds, and urban regeneration projects across the conurbation. We maintain regular testing slots across the region and travel from our Worcester base in under an hour, meaning we can respond quickly to both planned programmes and urgent last-minute requests.

Air tightness testing — also called air leakage testing or a pressure test — measures the amount of uncontrolled air escaping through gaps, poor seals, and penetrations in a building's envelope. It is expressed as cubic metres of air per hour per square metre of envelope area at 50 Pascals of pressure (m³/h.m² @50Pa).

Part L of the Building Regulations requires all new build residential and commercial properties in England and Wales to demonstrate an acceptable air permeability result as part of achieving building control sign-off. The result is also a direct input into your as-built SAP calculation — a poor result can push a dwelling below its compliance threshold.

Beyond compliance, a well-sealed building retains heat more effectively, reduces energy bills for occupants, and minimises the risk of condensation and moisture ingress through the building fabric. Air tightness is one of the highest-impact, lowest-cost improvements available during construction — the detail work costs little; a failed test and retesting does.

Current pass benchmark

8 m³/h.m²

maximum air permeability at 50 Pascals — Part L 2021, England & Wales

Your SAP target may be tighter. The notional dwelling in SAP 10 assumes a design air permeability of 5 m³/h.m². If your design stage SAP used a tighter figure to achieve compliance, the as-built test must match or beat it — or your EPC will fail. We flag this risk before we test.

Commercial buildings (Part L Vol. 2) have a default maximum of 10 m³/h.m², though your SBEM calculation may require a lower target.

The test process

What happens on the day of your air test.

A typical single-dwelling test takes around 90 minutes on site. We work with your site team to minimise disruption and move efficiently through the process.

Pre-test preparation check

We walk the building with your site team, confirming all vents are temporarily sealed, internal doors are open, and the envelope is ready. We flag any obvious problem areas before the fan is fitted.

Blower door installation

A calibrated fan unit is fitted to an external doorframe. The fan depressurises the building to a series of reference pressures, typically between 10–60 Pa, while airflow and pressure readings are recorded.

Measurement & analysis

BSRIA TM23 methodology is used to calculate the air permeability from the pressure and flow readings. Results are compared against your Part L compliance target and SAP design value.

Report & certificate

Test report issued within 24 hours. If the building passes, a compliance certificate is provided for Building Control submission. If it fails, we provide a written list of likely causes and remediation advice.

Preparation

Getting your building ready — and avoiding a re-test.

The most common cause of a failed air test isn't poor construction — it's poor preparation on the day. Unsealed service penetrations, open trickle vents, and incomplete mastic around window reveals are the usual culprits, and all are fixable before we arrive.

We provide all clients with a pre-test preparation checklist at the point of booking. For larger developments, we strongly recommend a pre-test inspection once the building is watertight but before internal finishes are applied — at that stage, any leakage paths are still visible and accessible, making remediation cheap and fast.

For projects targeting very low air permeability (under 3 m³/h.m²), or those pursuing Passivhaus certification, early-stage pressure testing during construction is standard practice. We can advise on a testing programme appropriate for your project.

Pre-test checklist

All doors & windows fitted and closedExternal openings must be fully operational and properly weather-sealed.

Service penetrations sealedPipes, cables, and ducts passing through the envelope must be sealed with appropriate materials.

Skirting & architraves fittedJunctions between floor, wall, and ceiling finishes should be complete and sealed.

Trickle vents & extract fans temporarily sealedIntentional ventilation openings must be closed or blocked for the duration of the test.

Internal doors fixed openAllows even air distribution throughout the building during pressurisation.

SAP design value confirmedWe need to know your design stage air permeability target to check the result against it.

Towns we cover in the West Midlands

Air tightness testing across Birmingham & the West Midlands.

Regular testing slots available across the West Midlands for new build residential, apartments, and commercial properties.

Birmingham City Centre & Edgbaston

Air tightness testing for city centre apartments, commercial units, and residential developments.

Solihull, Shirley & Knowle

Covering Solihull borough including new housing developments and commercial properties.

Coventry, Kenilworth & Bedworth

Testing across Coventry and surrounding areas.

Wolverhampton, Dudley & Walsall

The Black Country and north-west West Midlands.

Sutton Coldfield, Tamworth & Lichfield

North Birmingham and south Staffordshire border areas.

Wider England & Wales

As ATTMA-accredited testers, our certificates are valid nationally. Contact us wherever your site is.

We also cover: Worcestershire, Gloucestershire, Bristol & Somerset, Warwickshire

FAQ

Common questions about air tightness testing in Birmingham.

Pricing starts from £95+VAT for a single dwelling. Larger or multi-unit developments across Birmingham, Solihull, Coventry, Wolverhampton and the wider West Midlands are quoted based on the number of units, construction type, and location.

There are no hidden fees — the quoted price includes travel, the test, and the compliance certificate or failure report.

If the result exceeds your compliance target, we provide a written report identifying the most likely causes of the excess air leakage and recommended remedial actions. Common causes include unsealed service penetrations, gaps around loft hatches, poorly sealed window reveals, and incomplete floor-to-wall junctions.

Once remediation has been carried out, a re-test is arranged. We try to accommodate re-tests quickly to minimise delays to your completion programme.

Your air permeability test result is a required input for the as-built SAP calculation. The design stage SAP will have assumed a target air permeability value — if your tested result is worse than that assumed value, the as-built SAP score will be lower, and may push the dwelling below its compliance threshold.

This is why we always check your design stage SAP assumptions before testing. If there is a risk of non-compliance, we flag it so you can investigate potential remediation before the formal test is conducted.

Yes. We test residential buildings under Part L Volume 1 and commercial buildings under Part L Volume 2. Birmingham and the West Midlands have a large commercial development market and we regularly test offices, retail units, warehouses, and mixed-use schemes across the region.

Commercial permeability requirements are set at 10 m³/h.m² by default, but your SBEM calculation may require a tighter target. We confirm the applicable target before testing.

Yes. We cover the entire West Midlands conurbation including Birmingham, Solihull, Coventry, Wolverhampton, Dudley, Walsall, Sandwell, and Sutton Coldfield. We also cover surrounding areas such as Tamworth, Lichfield, and Cannock. We maintain regular testing slots across the region.

We maintain regular testing slots across Birmingham and the West Midlands, with same-week availability frequently offered. Our base in Worcester is under an hour from central Birmingham, meaning we can respond quickly to urgent requests. Contact us on 01386 365145 to check current availability.

Yes. For projects with a tight permeability target, or where the client wants confidence before the formal test, we can carry out a pre-test inspection and informal pressure check during construction — typically once the building is plastered and before floor finishes are laid.

At this stage any leakage paths are still accessible, and remediation is straightforward and inexpensive. This is particularly valuable on Passivhaus or near-Passivhaus projects, or on first-of-type plots on a larger development.

Air Tightness Testingin Birmingham & the West Midlands