What is SAP Air Tightness Certification in the UK?
SAP air tightness certification UK plays an important role when building new homes or converting existing properties. SAP, short for Standard Assessment Procedure, measures the energy performance of a dwelling. Air tightness is a crucial part of this. It checks how much air leaks out of a building through unsealed joints, gaps, or holes. If too much air escapes, your home will lose warmth quickly, meaning you’ll spend more on heating it.
We at Ratio Seven help builders, developers and self-builders across the UK get their dwellings ready for SAP air tightness certification. We know what the regulations expect and how to make sure your property passes the test. With this certification, your property meets environmental and building standards in the UK.
Why Air Tightness is Checked in New Builds
New homes must meet strict guidelines for energy use. The air tightness test checks the home’s envelope, walls, doors, windows, and roofs, and measures how well it prevents air from escaping. If your house is too leaky, it won’t keep heat inside very well. This means more energy will be used, and your energy bills will be higher.
Buildings in the UK must comply with Part L of the Building Regulations, which covers the conservation of fuel and power. To meet Part L, you need to submit a complete SAP calculation, which includes a successful air-tightness test. Without this certificate, it’s nearly impossible to get a sign-off from Building Control.
How Is an Air Tightness Test Completed?
Air tightness testing is not as complicated as it sounds. We use specialist equipment to check for air leakage. A fan is fitted to the external door of the building. The machine increases or decreases the pressure inside, and we measure how much air escapes through unintended gaps.
To get the best result, it’s a good idea to complete any sealing around windows, doors, pipework and floor junctions before the test. Even small gaps can make a big difference. Some homes fail their test for something as small as gaps around sockets in external walls or poorly sealed loft hatches.
Once we’ve completed the test and your building has passed, we provide a certificate that you can use as part of your SAP calculation submission.
What Happens If a Building Fails the Air Tightness Test?
It’s not unusual for a building to fail the first time, especially if work is rushed or sealing details are missed. If the test fails, we’ll go through the results with you and highlight areas that need improvement. From there, sealing work can be done, and a retest booked.
We believe in keeping the retest process stress-free. We don’t want our clients to feel out of their depth. If you want us to be involved earlier in the building stage, we can help identify risk areas and guide your team so your build is ready from the start.
Our experts at Ratio Seven are happy to be called in for early design reviews or pre-test walk-throughs. Sometimes, spotting a careless trade or rushed detail at first-fix can make all the difference in the final air test result.
Where SAP Air Tightness Certification Fits in the Build Process
Timing matters. We recommend doing the air tightness test when the building is almost complete, but before carpets, final decorations, and anyone moves in. This gives you a better chance of achieving a good result and still allows you to fix any minor issues if needed.
At the end of a successful test, you’ll receive the air tightness certificate, which is then included in your SAP assessment report. This report is used to issue an Energy Performance Certificate (EPC), which you must have whether you’re selling, renting or just meeting building regs.
You can read more about the full process and get help from our specialists by visiting our website: Ratio Seven.
Why Choose Ratio Seven’s SAP Air Tightness Certification Services?
We focus on domestic buildings, which means we’re experts in the unique air-tightness challenges that come with homes rather than commercial buildings. We test everything from small self-built bungalows to large housing developments.
What sets our service apart is how we treat our clients. We know house builders are often under pressure. Jobs get delayed, trades overlap, and not everything goes to plan. That’s why we stay flexible and communicate clearly. If you need help understanding failures or prep work, we take the time to talk about it without using technical language.
Our SAP testing services are available across most of the UK. If you’re looking for SAP air-tightness certification UK-wide, click here to find out how we can help.
What Makes a House Airtight?
A truly airtight home isn’t about shutting it up completely. It’s about controlling where air comes in and out. A well-sealed home should still be ventilated, but that ventilation should be planned and mechanical, not escaping through cracks and holes. This lets fresh air in without wasting heat.
The most common leakage points we find in our air tests include:
- Poor sealing at skirting boards
- Unsealed pipe and cable penetrations
- Gaps between window frames and walls
- Poorly fitted loft hatches
- Leaky trickle vents left open during testing
- Loose-fitting meter cupboard doors
- Gaps in plasterboard at wall junctions or between the ceiling and external walls
Fixing these problems not only helps pass your certification, but it also means a warmer, more comfortable home. You’ll find your energy bills are lower, and your home will be a better place to live overall.
FAQs
What is a good air-tightness score?
A good result is often under 5 m³/h/m² at 50 Pa. The building regulations usually require a maximum rate of 10 m³/h/m², but your target may be lower depending on your SAP score or if you’re building to advanced energy standards like Passivhaus.
Can I prepare my building for the test myself?
Yes. We can give you a checklist of sealing tasks before the test. Some clients like to do their prep to keep costs down. Others ask us to do a pre-test walk-through and flag problem areas.
Do all homes need a SAP air tightness test?
Nearly all new dwellings do. Some very small buildings may be given assumed scores, but most homes need a test. If you’re unsure, we can advise based on your architect’s plans.
Can I fail the SAP even if I pass the air test?
Yes. The air test is only one part of the SAP calculation. If your insulation, services, windows or heating system don’t perform well, that might bring your SAP rating down even with a good air test.
How much does the air tightness test cost?
Prices vary based on location and the complexity of your property. Simple one-off homes cost less than multi-plot developments, needing multiple tests. You can request a free quote easily on our website.
Do you offer testing for extensions as well?
Usually, air testing is only required when a new dwelling is created. Most extensions don’t require one unless the entire existing building is being heavily altered; however, we can offer advice if needed.
How long does a test take?
On average, about one hour from set-up to completion. This can vary based on the house size, or if numerous leakage issues are found, we need to investigate further.
Working With Ratio Seven
From our first phone call to issuing your SAP air tightness certificate, our team at Ratio Seven keeps things simple. We know how stressful the final stages of a build can be, and we do everything we can to minimise delays or surprises. We’ll walk your site, carry out a professional air-tightness test, and explain any issues in plain English.
Our support doesn’t stop after your certificate. If something isn’t clear in your SAP breakdown, or you want to improve your energy score in the future to match new standards, we’re here.
We’ve helped hundreds of people across the UK meet their SAP requirements. Whether it’s a self-build project, a residential conversion or a full site of new homes, you’ll find working with us straightforward and reliable.
To explore all the services we offer, including SAP air tightness certification UK, visit Ratio Seven.
Final Thoughts and Next Steps
Getting your SAP air-tightness certification is a big step toward completing your new home project. It can be one of the last tasks on a long list of building jobs, but one that affects energy use and compliance in a real way. Making sure your home is airtight where it should be, while still providing good ventilation, results in homes that are more comfortable and less costly to run.
Choosing the right experts to carry out your tests makes a big difference. We at Ratio Seven enjoy working with both seasoned builders and first-time self-builders, always keeping processes clear and stress-free.
Ready to book your SAP air tightness certification in the UK or need some advice on where to begin? Head over to Ratio Seven and get in touch.
