Air Tightness Testing

Air Tightness Testing or Air Leakage Testing is a process of measuring the amount of air leaking from a building. Normally though uncontrolled ventilation (e.g cracks, holes, gaps). This is checked by a fan being placed within an opening in the building (normally the front or rear door). Air is either removed from the building (depressurize) or blown into the building  (pressurize). The tester will use calibrated equipment to calculate an air flow either in or out of the property. The amount of air going in or out of the property when subject to a pressure differential is the amount of air leakage. From this information, the software calculates the air permeability of the property.

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We carry out air leakage testing nation wide
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What does the result mean?


Once the tester has completed the test the data is entered into software which will give an air permeability rating. The result will be summarised in this genetic form (5m3/(h.m2@50pa). So in this example the building is losing 5 Cubic metres of air per hour per square metre of building envelope at a pressure differential of 50 Pa).

The envelope in a standard 2 story house would be the ground floor, upstairs ceilings and all external walls. We would determine your envelope area using your own plans prior to coming to the site.



What score does my property need to pass?


The plans for your property will normally have gone through building control prior to it being constructed. As part of this process, SAP calculations are carried out which look at the construction materials being used. E.g (bricks, blocks, windows, insulation, heating, ventilation etc). The U values achieved by the materials being used will determine the energy performance of the building. This will produce an acceptable air permeability for the building. This is known as a target air permeability.

If the air permeability is less than the target air permeability the building will pass and if its above it will fail.


How many dwellings need to be air tested?


Not all dwellings on the same development have to be tested. An air tightness test should be carried on the dwellings as follows:

1 to 2 dwellings: One air test

3 to 4 dwellings: Two air tests

5 dwellings and above : 3 air tests.

If sample air testing is carried out (Eg Not all dwellings are tested). Then on a development a penalty of +2m³/(h.m²)@50Pa is added to the average result of the tested dwellings. This then is taken as the built air permeability of the untested dwellings.

It is important that if sample air testing is being carried out to ensure, the tested dwellings achieve an average of at least 2m³/(h.m²)@50Pa below the target air permeability. Eg: if the target air permeability for that house type was 5m³/(h.m²)@50Pa, the tested dwelling will need to achieve an average of 3m³/(h.m²)@50Pa in order for all the dwellings to pass the air test.

For non-dwellings, all buildings should be tested.


Why use us for Air Tightness Testing?


We are members of ATTMA the Air Tightness Testing and measurement association.

There are a growing number of Air Tightness Testing companies since it was introduced in 2006. So who do you use? It makes sense to us that anyone needing a building testing would want to use a company that understands exactly what forms the air seal on a building and how it is constructed. This is not taught on a course for air leakage testing, neither are the ways to carry out remedial work in what can sometimes be very difficult circumstances. You don't need to have a construction background to become an air tester but without this knowledge of different build types and designs, you could be left with a building not achieving the design air permeability. Scratching your head and not knowing how to put it right. The air tester will be happy though as he will have to come back and charge you again.


It is important during every phase of your build that everyone involved - you, your site manager and all the subcontractors - are aware of what part they play in forming the air seal to a building. Lack of attention to detail in some buildings can be very costly to remedy once the building is complete.


Air Tightness Testing Cost.

We have years of experience in the construction industry. We can generally quickly advise on where the issues may be if your building is not meeting the target air permeability. We will not just do the air test and leave you to it.  What does an Air Tightness Test Cost? Our pricing is very competitive from only £175.00. The price for additional plots of the same type carried out on the same day is from as low as £40. We also give you a generous amount of time for each plot being tested. So over multiple plots, the time saved on ones that require no remedial work, can be used to remedy the ones that are not achieving the air permeability target.

Please give us a call or use the contact us form for any further questions you may have. If you wish to book an Air Tightness Test we will send you a form to fill out with all the information we need.


We are proud to be members of ATTMA. The air tightness testing and measurement association.

We offer Air Tightness Testing in all of these regions:

Greater London| South East| South West| West Midlands| North West| North East| Yorkshire| East Midlands| 

Wales| North West| North East| Mid Wales| South West|South East

We also cover most of Scotland.