Expert Pre-Test Sealing for Building Regulations Compliance
Temporary sealing plays a crucial role in preparing buildings for air permeability testing under Building Regulations.
It ensures the defined test envelope is correctly isolated in terms of ATTMA and CIBSE to help avoid invalid test results and unnecessary repeated visits. When delivered correctly, pre-test sealing protects programme timelines and reduces the risk of compliance delays.
Professional Temporary Sealing Services
At Stroma Built Environment, our temporary sealing services are delivered in accordance with ATTMA TSL1, ATTMA TSL2 and CIBSE TM23 guidelines. This ensures that your buildings are adequately prepared for testing, improving the likelihood of first-time compliance and avoiding unnecessary delays.
As our team also delivers air testing services, we understand how sealing decisions directly influence final results. Our joined-up approach provides confidence that all preparation work aligns fully with testing methodology and regulatory expectations.
Why Choose Stroma for Temporary Sealing?
The key difference? Our engineers who test typically do the temporary sealing. This isn't just about taping up openings, it requires a detailed understanding of what is permitted under ATTMA TSL1, ATTMA TSL2, and CIBSE TM23. We know the standards that Building Control are looking for and how sealing decisions influence final test outcomes.
Why professional temporary sealing is more critical than ever:
Since following recent updates to Building Regulations Part L 2021 air permeability requirements have become significantly stricter, leaving less margin for error on test day.
The maximum permitted air permeability was reduced from 10 m³/(h·m²) to 8 m³/(h·m²) at 50Pa representing a 20% tightening of allowable performance.
With notional buildings using 5 m³/(h·m²) as the baseline, proper temporary sealing is essential to achieving first-time test compliance and to protect project programmes.
What sets us apart:
- Testing engineers carry out the sealing – delivered by professionals who understand what is required under ATTMA TSL1, ATTMA TSL2 and CIBSE TM23.
- Comprehensive standards expertise – practical application of ATTMA and CIBSE guidance on live projects.
- Experience-led approach – informed by real-world air testing outcomes and site conditions.
- IRATA Qualified Rope Access Team – within confined spaces and FIRAS training to access otherwise hard to reach complex air barriers.
- Critical timing advice – helping align sealing and testing with commissioning and handover programmes.
- Rapid mobilisation – Same-day or next-day service available when needed
- Professional grade materials – No-residue tape, corex, Polifilm, Celotex, mastic, and specialised sealing equipment.
When is Temporary Sealing Needed?
Temporary sealing is typically required prior to air permeability testing in the following scenarios:
1. Ventilation Systems Before Testing:
- Ventilation openings may require temporary sealing in line with ATTMA TSL1, ATTMA TSL2 and CIBSE TM23 to ensure the correct test envelope is achieved.
- This typically occurs at the last stage of the build when all vents are installed but before final commissioning.
- Testing and commissioning activities should be carefully sequenced to avoid disruption or duplication of works.
2. Extension Openings:
- Openings connecting extensions to existing areas of the building may require temporary sealing to isolate the defined test zone.
3. Smoke Shaft Openings:
- Temporary sealing of smoke shaft openings may be required before integrity or related performance testing (see our Smoke Shaft Testing service).
Standards-Compliant Sealing
Our temporary sealing services strictly follow the guidelines set out in ATTMA TSL1, ATTMA TSL2 and CIBSE TM23. These standards clearly define exactly what can and cannot be temporarily sealed during air permeability testing, and our engineers apply this guidance in practice, not just in theory.
This ensures sealing is compliant, defensible and aligns with Building Control expectations.
Professional Materials & Methods
We use a range of professional-grade materials selected for effectiveness, compliance, and ease of removal:
- No-residue tape – Specialised tape that seals effectively without damaging finishes
- Corex board – Rigid temporary sealing for larger openings
- Polyfilm – Flexible sheeting for irregular shapes and vent systems
- Roll & Stroll – Quick-application temporary sealing membrane
- Celotex – Insulation board for substantial temporary closures
- Mastic – Sealant for joints and critical sealing points
- Specialised sealing equipment – Professional tools and systems for efficient, effective sealing
The Stroma Advantage: Testing Engineers Who Seal
Temporary sealing undertaken without a detailed understanding of testing standards can introduce avoidable risk. At Stroma, our experienced testing engineers carry out sealing to ensure you benefit from:
- Engineers with 20+ years’ combined air testing experience bringing real-world understanding of failure risks and compliance expectations.
- ATTMA TSL1 and ATTMA TSL2 compliant temporary sealing delivered in strict alignment with testing procedures and standards.
- CIBSE TM23 standards and expertise to ensure sealing decisions are technically defensible and inspection ready.
- Professional grade materials and equipment selected specifically for compliant temporary sealing.
- Same day or next day mobilisation available to support programme critical testing requirements.
Critical Timing: Test Before Commissioning
One of the most common and costly sequencing mistakes is commissioning ventilation systems before air-permeability testing has been completed.
Why this matters: Under ATTMA TSL1 and ATTMA TSL2, certain ventilation elements may be temporarily sealed for testing. Once ventilation systems are commissioned, they may no longer be permissible without affecting commissioning status. This can result in expensive programme delays, additional site visits and avoidable rework.
Our advice is clear: Conduct air-permeability testing at the final stage of the build, after all vents are installed but before commissioning.
At Stroma, our experienced engineers provide practical sequencing guidance to align with ATTMA and CIBSE to help project teams protect programme timelines and avoid unnecessary disruption.
Our Temporary Sealing Service
We provide comprehensive temporary sealing services tailored to your project requirements:
- Site assessment – Evaluation of what needs to be sealed and the best approach
- Professional installation – Standards-compliant sealing using appropriate materials
- Timing coordination – Advice on sequencing with construction and commissioning activities
- Rapid mobilisation – Same-day or next-day UK wide service available when needed
- Combined packages – Temporary sealing can be coordinated with air permeability testing for seamless service
- Support across project types – Our temporary sealing services support residential, commercial and mixed-use developments of all scales
- Site-safe delivery – All work is carried out in accordance with site health and safety requirements and coordinated with the wider construction programme.
All services are delivered in accordance with ATTMA and CIBSE, ensuring project teams have confidence that all preparation fully aligns with testing requirements.
Partner with Stroma for Expert Temporary Sealing and First-Time Test Success
Our specialist approach helps improve first-time pass rates on air permeability tests, reduces the need for repeat visits, while delivering services across residential, commercial and mixed-use projects anywhere in the UK with rapid mobilisation.