Choosing the wrong air tightness testing provider can cost you thousands in delays, failed tests, and compliance issues.
But here’s the problem: when you’re comparing providers online, it can be hard to tell which is right for you. So, how can builders, developers and property managers actually tell the difference between a tester who’ll help you pass the first time and one who’ll leave you scrambling to fix problems on test day?
This guide cuts through the noise and shows you exactly what separates professional, reliable air tightness testing companies from the rest.
Need an Air Tightness test?
At Air Tightness Solutions, we offer fast, reliable air tightness testing across the UK – with results and certification typically delivered within 48 hours of testing. Our experienced team holds ATTMA Level 1 and Level 2 certifications and are here to help you meet Part L compliance without delays.Request a free quote today or get in touch to discuss your project.
Why Your Choice of Tester Actually Matters
An air tightness test isn’t just a tick-box exercise it’s a quality checkpoint that affects:
- Your handover date (fail = delays)
- Your project budget (retests + remedial work = unplanned costs)
- Your compliance status (Building Control won’t sign off without a valid certificate)
- Your building’s performance (poor testing = missed opportunities to identify fixable issues)
The difference between a good tester and a mediocre one shows up when things don’t go perfectly and that’s precisely when you need expertise most.
The Non-Negotiables: What Every Provider Must Have
Before you even look at price or availability, check these essentials:
1. Proper Accreditation (Not Optional)
Your tester must be registered with an authorised Competent Person Scheme. In the UK, that means:
- ATTMA (Air Tightness Testing & Measurement Association)
- iATS (Independent Air Tightness Scheme)
- Elmhurst Airtightness Scheme (EAS)
These schemes ensure:
- Testers follow industry-standard procedures (CIBSE TM23 and BS EN ISO 9972:2015)
- Equipment is UKAS calibrated within the last 12 months
- Certificates are accepted by Building Control
- Members undergo regular independent audits
- Test results are accurate and compliant
Why this matters: Non-accredited testers can’t lodge certificates through official channels. Building Control may reject their results, forcing you to retest with a properly accredited provider doubling your costs and delaying your programme.
How to check: Ask for their ATTMA or iATS membership number. You can verify it on the scheme websites. Every legitimate tester will provide this immediately.
2. The Right Level of Certification
Accreditation isn’t one-size-fits-all. Testers hold different levels depending on the buildings they’re qualified to test:
ATTMA Level 1:
- Single dwellings and simple buildings
- Up to 4,000 m³ envelope volume
- Single blower door fan setup
ATTMA Level 2:
- Simple and non-simple buildings
- Up to 80,000 m² envelope area
- Multiple fans or trailer fan setups
Commercial/complex buildings:
- Requires Level 2 certification
- Experience with phased handovers, zonal testing, or large-scale developments
Match the certification to your project. Don’t hire a Level 1 tester for a commercial block or multi-plot development; they’re not qualified for that scope.
3. UKAS Calibrated Equipment
All test equipment must be UKAS calibrated within the last 12 months. This includes:
- Blower door fans or Pulse units
- Pressure sensors and manometers
- Airflow measurement devices
Why this matters: Uncalibrated equipment produces unreliable readings. If Building Control questions your results, calibration certificates are the first thing they’ll ask for.
What a Quality Air Tightness Tester Should Provide
Once you’ve confirmed the basics, look for these differentiators:
Clear, Transparent Pricing
A professional air tightness testing company provides upfront, all-inclusive pricing that covers:
- The test itself
- On-site diagnostics (smoke testing if needed)
- Pass/fail confirmation
- Digital certificate delivery
- Basic remedial advice
Red flags:
- Quotes that seem too cheap (under £120 for a single dwelling)
- Hidden charges for certificates, travel, or diagnostics
- Vague pricing structures that only become clear after booking
What to expect: Single dwellings typically cost £150-£250 depending on location and property size. Multi-plot discounts should be clearly stated (often 50% off for second and subsequent tests on the same day).
Pro tip: Ultra-cheap providers often cut corners uncalibrated equipment, rushed tests, or inexperienced testers. You get what you pay for.
Fast Availability When You Need It
Construction programmes slip. Trades run late. Weather causes delays. Your tester needs to be flexible enough to accommodate this reality.
Good providers:
- Offer same-week availability
- Communicate proactively if delays occur
- Have buffer capacity for urgent tests
Warning signs:
- Lead times of 3+ weeks (suggests poor capacity management)
- No communication between booking and test day
Experience With Your Type of Build
Not all buildings test the same. Common leakage points vary dramatically between:
- Timber frame vs masonry construction
- New builds vs conversions
- Standard compliance vs Passivhaus/high-performance
- Single dwellings vs multi-plot developments
- Residential vs commercial buildings
Why experience matters:
An experienced tester will:
- Know the typical problem areas for your construction type
- Spot issues during the pre-test walk-through (before the fan goes on)
- Provide targeted advice that’s relevant to your build method
- Understand realistic expectations for your target
Comprehensive Diagnostics (Not Just Pass/Fail)
A professional test should include diagnostic capability, not just a number at the end:
Smoke testing: Uses theatrical smoke to visually identify air leakage paths during the test. Essential for failed tests but valuable even for passes (shows you where your weak points are).
Thermal imaging (optional but valuable): Identifies temperature differentials that indicate air leakage routes, especially useful for complex failures.
Live feedback during testing: Good testers explain what they’re finding as they go, rather than disappearing for an hour and returning with a number.
Why this matters:
If you fail and the tester just hands you a certificate saying “12 m³/h·m² failed,” you’re left guessing where the problems are. That means:
- Your trades can’t start remedial work immediately
- You might fix the wrong things first
- Delays extend while you troubleshoot
A diagnostic-focused tester pinpoints exactly where air is escaping “gaps around window reveals, unsealed loft hatch, poor sealant behind skirting in bedroom 2” so remedial work is targeted and efficient.
Preparation Support (The Best Prevention)
Professional testers don’t just show up on test day. They help you prepare properly to maximise your first-time pass rate.
Look for providers who offer:
Pre-test checklist: A detailed, project-specific list covering everything that needs to be complete before testing (windows sealed, penetrations dealt with, wet trades dried, etc.).
Site readiness consultation: A phone call or site visit to review your preparations and flag potential issues.
Ongoing communication: Regular reminders about what needs to be done and when to book relative to your programme.
Why this matters:
Buildings that follow a preparation checklist have dramatically higher first-time pass rates typically 90%+ vs 30-40% for unprepared sites.
A tester who provides this support is invested in your success, not just collecting a test fee.
The Practical Considerations
Certificate Turnaround Time
You need your certificate quickly to keep your programme moving.
Warning: Providers who take 5-7 days to issue certificates may be outsourcing or lack proper systems. This slows your compliance process.
Multi-Plot Capabilities
If you’re a developer or contractor working on multiple units, your testing provider needs to handle volume efficiently:
Look for:
- Bulk testing capability (test several plots in a single site visit)
- Volume discounts (substantial savings for 2nd, 3rd, 4th+ tests)
- Coordinated scheduling (one engineer, multiple units, single day)
- Individual certificates for each unit (issued promptly, not weeks later)
Why this matters: Testing 10 units individually over 10 separate visits costs far more than batch testing. Good providers structure their service around developer needs.
Reputation and Track Record
Before committing, check:
Google reviews: Look for recent reviews (last 12 months) and consistent themes. Watch for:
- First-time pass rates
- Communication quality
- Problem-solving when issues arise
- Punctuality and professionalism
Testimonials: Look for project-specific testimonials from builders, developers, or self-builders similar to your situation.
Case studies: Do they showcase projects similar to yours? This demonstrates relevant experience.
Red flags:
- No reviews or testimonials
- Only generic positive reviews (suggests filtering or faking)
- Recent negative reviews mentioning failed equipment, missed appointments, or unhelpful attitude
Geographic Coverage
Air tightness testing requires physical presence. Make sure your provider actually services your area:
Why this matters:
Providers stretching beyond their normal coverage area may:
- Charge premium travel fees
- Offer poor availability (they’re only in your region once a week)
- Be less familiar with local Building Control requirements
Red Flags: When to Walk Away
Watch out for these warning signs:
❌ No accreditation or can’t provide membership numbers
❌ Unusually cheap pricing (under £120 for single dwelling)
❌ Can’t provide UKAS calibration certificates
❌ Vague about qualifications or experience level
❌ No pre-test support or preparation guidance
❌ Long lead times with no flexibility
❌ Poor communication before booking
❌ Reviews mentioning equipment failures or rejected certificates
❌ No diagnostic services included
❌ Pressure to book immediately without proper consultation
What a Professional Testing Experience Looks Like
Here’s what you should expect from a top-tier air tightness testing provider:
Before the test:
- Clear quote with no hidden extras
- Detailed preparation checklist sent in advance
- Confirmation call a few days before test
- Exact appointment time (not vague windows)
On test day:
- Punctual arrival with professional demeanor
- Pre-test walk-through to identify potential issues
- Clear explanation of what they’re doing and why
- Live updates if problems are emerging
- Diagnostic smoke testing if needed
After the test:
- Immediate pass/fail confirmation on-site
- Clear explanation of results and what they mean
- Specific remedial advice if you’ve failed
- Digital certificate within 48 hours
- Follow-up support if you have questions
Why Partner with Air Tightness Solutions Testing
Value-Engineered Expertise You Can Trust
With more than 50 years of combined industry experience, our team has seen every type of build, challenge, and compliance requirement. We’ve also spent over a decade training others in the industry, which means the advice we give is practical, proven, and engineered to deliver the best results for your project. When you work with us, you’re not just booking an air tightness test, you’re gaining the insight of true specialists.
Responsive, Reliable, and Built Around Your Schedule
Construction timelines are tight, and delays are costly. That’s why we prioritise short lead times and a genuinely reactive service. Whether you’re approaching a Building Control deadline or juggling multiple plots, we respond quickly and work around your needs to keep your project moving without interruption.
Fully Accredited for Complete Peace of Mind
Every test we carry out is completed by ATTMA-accredited engineers, ensuring your results are fully compliant, recognised by Building Control, and delivered in line with the latest technical standards. You can trust that your certification will be accurate, accepted, and ready when you need it.
Read our case studies to learn more about who we’ve worked with.
Key Takeaways for a Find the Right Provider
- Be properly accredited (ATTMA/iATS/EAS with verifiable membership)
- Hold the right level of certification for your project type
- Use UKAS calibrated equipment with certificates to prove it
- Offer transparent, all-inclusive pricing
- Provide fast availability and flexible scheduling
- Have relevant experience with your building type
- Include diagnostic services (smoke testing, thermal imaging)
- Support your preparation with checklists and guidance
- Deliver certificates quickly (48 hours standard)
- Have a strong track record with verified reviews
Remember: The cheapest provider is rarely the best value. A professional tester who helps you pass the first time saves far more than you’ll pay in the test fee.
Ready to Book With Confidence?
Don’t gamble with your compliance or your programme. Our ATTMA-registered engineers deliver Part L-compliant air tightness testing with:
- Full ATTMA Level 1 and Level 2 certification
- UKAS calibrated equipment (certificates provided)
- Same-week availability across the UK
- 48-hour certificate turnaround
- Comprehensive preparation support to maximise first-time pass rates
- Diagnostic smoke testing included
- Multi-plot discounts for developers
👉 Get in touch today for a no-obligation quote and discuss your project requirements.
FAQs
What qualifications should an air tightness tester have?
A qualified air tightness tester in the UK must be registered with an authorised Competent Person Scheme such as ATTMA, iATS, or Elmhurst Airtightness Scheme (EAS).
They should hold the appropriate level certification for your project:
Level 1: Single dwellings and simple buildings up to 4,000 m³ envelope volume
Level 2: Complex buildings and non-simple structures up to 80,000 m² envelope area, requiring multiple fans
The tester must also:
Have completed formal training and passed competency assessments
Use UKAS calibrated equipment (within the last 12 months)
Follow ATTMA Technical Standards (TSL1/TSL2) and BS EN ISO 9972:2015
Undergo regular independent audits to maintain certification
Always ask to see their membership number and verify it directly with the scheme operator.
How do I verify an air tightness tester is properly accredited?
You can verify accreditation in three ways:
1. Ask for their scheme membership number and check it directly:
ATTMA member verification
Elmhurst Airtightness Scheme tester search
2. Request UKAS calibration certificates for all equipment they’ll use on your project. These must be dated within the last 12 months and issued by a UKAS or ILAC-accredited calibration laboratory.
3. Check they can lodge certificates through official channels. If they’re properly accredited, they should be able to issue an official lodgement certificate accepted by Building Control.
Red flag: If a tester hesitates to provide this information or can’t produce evidence immediately, walk away. Legitimate testers provide this documentation routinely.
What’s the difference between ATTMA, iATS, and Elmhurst schemes?
All three are authorised Competent Person Schemes recognised by UK Building Control, but they operate independently:
ATTMA (Air Tightness Testing & Measurement Association): The largest and most established scheme, recognised across England, Wales, Scotland, and Northern Ireland. Sets industry technical standards (TSL1 and TSL2).
iATS (Independent Air Tightness Scheme): Another authorised scheme with its own membership base and audit processes.
Elmhurst Airtightness Scheme (EAS): Operated by Elmhurst Energy, the UK’s largest energy assessment accreditation body. Often chosen by testers who also provide SAP assessments and EPCs.
Important: All three are equally valid for compliance purposes. What matters is that your tester is registered with one of them and maintains their accreditation through regular audits.
Can I use a non-accredited tester?
Technically, Building Control can accept evidence from non-accredited testers, but they must provide:
Evidence that their equipment is UKAS calibrated within the last 12 months
A full test report complying with ATTMA TSL1, TSL2, or BS EN 13829:2001
Evidence of compliance with National Occupational Standards
However, this is extremely risky for several reasons:
Your risk, not theirs: Building Control may reject the results, forcing you to retest with an accredited provider doubling your costs
No oversight: Non-accredited testers aren’t independently audited, so there’s no quality assurance
Insurance issues: If problems arise, you have no recourse through a scheme operator
Hidden costs: Proving competency to Building Control’s satisfaction takes time and creates delays
Bottom line: Using an accredited tester costs £150-£250. Using a non-accredited tester who fails or gets rejected could cost you £3,000-£5,000 in delays and retests. The savings aren’t worth the risk.
What should be included in an air tightness testing quote?
A comprehensive, transparent quote should itemise:
The test fee:
Single dwelling test
Additional tests on same site (discounted rate)
Travel charges if outside core coverage area
Included services:
Pre-test preparation checklist
On-site test execution (60-90 minutes)
Pass/fail confirmation on-site
Diagnostic smoke testing if issues identified
Digital certificate delivery (timeframe stated)
Basic remedial advice
Equipment details:
Confirmation of UKAS calibration
Type of equipment (blower door or pulse)
Exclusions and extras:
Thermal imaging
Return visit for retest (typically 50% of original fee)
Site preparation work (if tester needs to seal temporary gaps)
Terms:
Payment terms (usually invoice on completion)
Cancellation policy
What happens if weather prevents testing
Warning: Quotes that seem too simple (just a number with no detail) often hide additional charges that appear after booking.
What questions should I ask a tester before booking?
Ask these specific questions to separate professional testers from the rest:
Credentials:
“What’s your ATTMA/iATS/EAS membership number?” (Verify it online)
“Are you Level 1 or Level 2 certified?”
“Can I see your equipment’s UKAS calibration certificates?”
“How many [your building type] have you tested?”
“What’s your first-time pass rate?”
“Can you provide references from similar projects?”
“What’s your current lead time for booking?”
“How quickly will I receive the certificate?”
“Do you provide a pre-test preparation checklist?”
“What diagnostic services do you include if we fail?”
“What exactly is included in your quoted price?”
“Are there any additional charges I should know about?”
“What’s your retest fee if we don’t pass the first time?”
“Will you be the actual tester on-site, or will you send someone else?”
“What happens if weather prevents testing on the scheduled day?”
Red flag responses:
Vague or defensive answers
Can’t provide membership number immediately
Won’t commit to certificate timeframes
Pressure to book without answering questions
How can I reduce the risk of choosing the wrong provider?
Follow this systematic approach:
Step 1: Verify credentials first
Check scheme membership (ATTMA/iATS/EAS)
Confirm Level 1 or Level 2 as appropriate
Request UKAS calibration certificates
Step 2: Research reputation
Read recent Google reviews (last 12 months)
Look for project-specific testimonials
Check for consistent themes (good or bad)
Step 3: Assess communication
How quickly did they respond to your inquiry?
Did they ask relevant questions about your project?
Did they provide clear information without pressure?
Step 4: Compare value, not just price
Get 2-3 detailed quotes
Compare what’s included, not just the bottom line
Factor in experience and service quality
Step 5: Confirm preparation support
Ask about the pre-test checklist
Understand what you need to complete before they arrive
Clarify who’s responsible for site readiness
Step 6: Understand the retest policy
What happens if you fail?
What’s included in diagnostic services?
How quickly can you rebook?
Final check: Trust your instincts. If a provider feels unprofessional, unreliable, or unclear during the booking process, they’re unlikely to improve on test day.
For more guidance on avoiding common air test mistakes, preparation is your best defence against problems.