Accredited & Registered
ATTMA-accredited air permeability testing to BTS 3/2018 for isolation suites, operating theatres, aseptic pharmacy preparation, and containment facilities. Certificates suitable for commissioning, handover, and periodic verification against HTM 03-01.
BTS 3/2018 testing is required for HTM 03-01 compliance. Early engagement lets us align testing with your commissioning programme.
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Isolation facilities rely on a controlled pressure differential to contain airborne pathogens or protect vulnerable patients. That differential can only be maintained if the room envelope is measurably airtight — BTS 3/2018 sets the target and defines how to prove it.
The BTS 3/2018 recommended limit for overall air leakage of an isolation suite is 2.5 m³/hr/m² at 50 Pa. This is the whole-envelope permeability figure the built room needs to achieve to be considered compliant with the BSRIA methodology referenced by HTM 03-01.
Individual project specifications, infection-control policies, or the client’s estates team may set a tighter limit for particular room types — for example, some high-containment or protective isolation rooms are designed to a stricter figure. Always confirm the target with the design team and infection-control lead before testing.
Alongside the overall envelope test, BTS 3/2018 gives methods for measuring leakage through specific paths — door edges, door grilles, transfer grilles — so that each path can be compared against the design assumptions used by the ventilation designer. Full standard available free from BSRIA.
BTS 3/2018 defines an overall envelope test and, where required, targeted measurements along individual leakage paths. Together they give a complete picture of the room’s air permeability and where any excess leakage is coming from.
The overall envelope test measures total leakage from the isolation suite at a defined reference pressure of 50 Pa (or the pressure specified in the design brief). It gives the headline number to compare against the BTS 3/2018 target of 2.5 m³/hr/m².
Where the design assumes a defined leakage across specific paths — typically the doors, door grilles, or transfer grilles that the ventilation strategy relies on — those paths can be measured individually to compare against the design specification.
Testing is required at commissioning of any new or refurbished isolation facility, and periodically thereafter to verify continued compliance. Both are expected under HTM 03-01 as part of the estates ventilation validation regime.
A BTS 3/2018 test at commissioning demonstrates that the as-built isolation suite envelope achieves the recommended air permeability limit before the room is put into clinical use. Certification is normally required as part of the HTM 03-01 validation package alongside ventilation flow rate testing and other commissioning documents.
Isolation rooms are typically completed by several different trades — carpentry, glazing, ductwork, medical gases, electrical — and each introduces potential leakage paths. The envelope has to be tested as a whole, once complete, because individual component certification does not guarantee an airtight installed system.
We recommend engaging us during design and again before final finishes are applied. Early involvement means design assumptions can be validated, and any remediation is straightforward while penetrations remain accessible.
Over time, minor maintenance, medical gas or IT rewiring, ceiling access, door adjustments, and general wear can all affect envelope integrity. HTM 03-01 and estates governance regimes therefore expect isolation facilities to be periodically re-tested to verify continued compliance.
Retesting is also typically required after any refurbishment, plant replacement, or minor works that penetrate the envelope — even if the works appear cosmetic. A rehung door, replaced ceiling tile, or new data cable can meaningfully change the leakage rate.
Test certificates are retained as part of the facility’s ventilation validation records for audit, inspection, and infection-control governance purposes.
Most BTS 3/2018 failures come down to a handful of recurring paths — nearly all of them straightforward to address before finishes are applied, and disruptive to fix once the room is in clinical use. We provide pre-test guidance at booking and can carry out a walkover inspection to identify likely issues before formal pressurisation.
The core principle: the internal face of the envelope is the primary air seal. Every service penetration, joint, and door/frame junction on the room side must be continuously sealed. Sealing only from the ceiling void or corridor side leaves paths that show up on the test but are hidden until testing exposes them.
Where the design team has specified an infection-control ceiling with sealed access panels, sealed light fittings, and impervious wall linings, this is normally a good indicator that acoustic and hygiene detailing has already been thought through. Where those details are missing, expect a first-pass failure.
BTS 3/2018 sits alongside HTM 03-01 and broader healthcare ventilation guidance. Together they define both the target performance and the estates governance regime around ongoing verification.
Isolation facility testing needs to be booked around clinical availability — we work with estates and infection-control teams to schedule around ward decant, out-of-hours access, and post-refurbishment handover windows.
BTS 3/2018 testing for NHS trusts and independent hospitals across Birmingham, Solihull, Coventry, Wolverhampton, and the wider West Midlands — including UHB, SWBH, and Sandwell & West Birmingham estates. Isolation suites, operating theatres, and containment facilities.
Isolation facility testing for hospitals and specialist units across Bristol, Bath, South Gloucestershire, and the surrounding South West. HTM 03-01 validation for new build and refurbishment projects.
Based in Worcester — BTS 3/2018 testing across Malvern, Droitwich, Evesham, Bromsgrove, and Redditch. Rapid mobilisation for local hospitals and pharmacy aseptic units.
Isolation facility air permeability testing across Cheltenham, Gloucester, Stroud, Tewkesbury, and the Cotswolds. Certificates accepted for HTM 03-01 estates validation records.
BTS 3/2018 testing across Oxford, Banbury, Bicester, Witney, and the wider Oxfordshire area — NHS trusts, university teaching hospitals, and specialist research facilities.
BTS 3/2018 testing delivered nationally where project scale or programme justifies the travel. Regularly working with NHS trusts and independent hospital groups outside our core regions.
Looking for BTS 3/2018 testing near you? Whether it’s a new isolation suite at commissioning, an operating theatre refurbishment, a pharmacy aseptic room, or periodic HTM 03-01 revalidation. We deliver clear reports with the certificate you need for the estates record. Call 01386 365145 or email us to book.
BTS 3/2018 is a technical standard published by BSRIA in December 2018, titled “Air permeability testing of isolation facilities”. It sets recommended air leakage limits for isolation suites and other healthcare facilities where infection control depends on maintaining pressure integrity.
It also describes how to measure whole-envelope leakage as well as leakage through specific paths such as doors and door grilles. Referenced by HTM 03-01 as the accepted methodology for validating air tightness of isolation suites, operating theatres, aseptic pharmacy preparation rooms, and containment facilities.
BTS 3/2018 recommends an overall envelope air leakage limit of 2.5 m³/hr/m² at 50 Pa for isolation suites in healthcare facilities. The standard also gives guidance on measuring leakage through specific paths so those individual routes can be compared against design specifications.
Individual project specifications, HTM addenda, or the client’s estates and infection-control team may set a tighter target — the applicable value should always be confirmed in the design brief before testing.
An isolation suite works by controlling the direction and rate of air movement between the suite and adjacent spaces — a negative-pressure infection isolation room contains airborne pathogens, while a positive-pressure protective isolation room keeps them out. Both depend on a well-defined envelope with predictable leakage.
Excessive or unaccounted-for leakage means the room’s ventilation system cannot achieve the design pressure differential, air can bypass HEPA filtration, and airborne pathogens can migrate to or from other clinical areas. BTS 3/2018 testing verifies that the built envelope will support the intended airflow strategy.
BTS 3/2018 testing is typically carried out at commissioning, once the envelope is sealed and services are terminated but before final finishes are applied. Testing at this stage means any leakage found can be traced and sealed while penetrations, ceiling grids, and joints are still accessible.
Repeat testing may then be required after finishes, after handover, and periodically through the building’s operational life to verify continued compliance following maintenance or minor works.
A failure result identifies the total leakage rate exceeding the BTS 3/2018 target. Remediation involves locating the leakage paths — typically door seals, glazing perimeter seals, ceiling grid junctions, service penetrations (medical gases, data cables, sprinkler pipework), and any transfer grilles or observation windows — and sealing them individually. We then re-test the envelope to confirm compliance.
Where practical, we recommend a preliminary walkover and thermal or smoke-pencil survey before formal pressurisation so that obvious paths can be sealed in advance.
They use similar equipment — a calibrated fan and pressure gauges — but measure different things. Part L air tightness testing (to ATTMA TSL Issue 1) measures whole-envelope leakage of a dwelling or non-domestic building for energy compliance.
BTS 3/2018 testing measures the air permeability of a single isolation suite or room within a larger building, to verify infection-control performance rather than energy compliance. The same accredited team can perform both, but the test procedures, reporting, and pass criteria differ.
Engaging us before final finishes go in gives the best chance of a first-time pass. We work around clinical availability and estates handover windows.
Tell us about your project and we'll confirm our availability, provide a quote, and advise on the optimal testing programme for your schedule.
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