We often get asked the series of questions in regards to the air tightness testing of residential and commercial buildings. To try and help our clients better understand this area of works we have highlighted the most common questions and answers below.
What is air tightness?
Air tightness is related to the air permeability through the building fabric. This is not to be confused with the controlled flow of air into or out of the building through purpose built ventilators.
Why we need to construct air tight dwellings?
The energy that we use to heat our homes and offices is primarily created by burning fossil fuels that produce carbon dioxide. By reducing air leakage of a building we also reduce the amount of energy required to maintain comfort levels and in turn reduce carbon dioxide emissions.
Why do we have to undertake air tightness testing in domestic properties?
By proving the air tightness testing of a building is now part of the building regulation process – Part L. Existing houses used to be have an air leakage rate of over
How many air tightness tests are required for a development?
On each development air tightness testing should be carried out on THREE units of each dwelling type or 50% of all the instances of that dwelling type, whichever is less; however a each block of flats should be treated as a separate development irrespective of the number of blocks on the site.
If I don’t undertake the air tightness testing on all the buildings on the development will it affect my SAP report results?
Air pressure testing can be carried out to a ‘sample’ of units; however, if you don’t undertake air testing to all the units the designed air leakage target is automatically lowered by 2m3/hr/m2, i.e. if air leakage rate shown on the SAP is 5m3/hr/m2 (a very common figure) then you will then need to get below 3m3/hr/m2 which is very difficult to attain. If fail any of the units – at the lower sample rate figure) then you are required to test all the units on the development.
Does my buildings extension require air tightness testing?
Where an extension is proposed to an existing building with a total useful floor area over 1000m2 the building is to be upgraded, as far as it is technically, functionally and economically feasible to meet the requirements of Part L.
When should Air Tightness Test take place?
The air tightness testing should take place approx. 1-2 weeks before handover. The actual dwelling needs to be practically complete. To help you know if your building is ready to test we send out a pre-test check list.
How much does an Air Tightness Test cost?
It depends on the location and the number of tests that are required on each site. Please contact us at email@example.com to obtain a no obligation quote.
Will the air tightness test add value to my property?
Several UK studies have shown that improved and demonstrable property air tightness can yield savings of 15% to 30%. This should result in a higher sale price for the property because of on-going reduced energy costs and will be shown on your SAP & EPC assessments.
How long does domestic air tightness testing take?
It depends on a number of factors such as the size of the property, how many apertures need to be taped over. The duration of the actual air test should take no longer than 2 hours.
How long does a Commercial Air tightness Test take?
Should a commercial building fail to meet the required standards of air permeability, then the weakness should be identified (there are a number of particularly common areas). Remedial work should be carried out on the building, then a new test conducted on the building until it achieves the limit value in the TER. the duration of the commercial air test may take up to 4hrs, as the door panel is far bigger and more complex to set up in comparison to our ‘dwelling’ door panel.
How quick can you send us the air test results?
If the property passes the air tightness test, a certificate should be issued within one week which should then be passed to the Building Control Body so it can be signed off.
How long does a typical Commercial Air tightness Test take?
The duration of the commercial air test may take up to 4hrs, as the door panel is far bigger and more complex to set up in comparison to the ‘dwelling’ door panel and there is usually more building preparation on the day of the test.
What happens if I fail the air tightness testing?
Should the dwelling/building fail to meet the required standards of air permeability, then the weakness should be identified (there are a number of particularly common areas) via smoke testing. The air leakage paths can then be recorded and the remedial works can then be carried out on the building. Thereafter a new test conducted on the building until it achieves the limit value in the TER.
What are the common causes of Air Leakage in buildings?
The main areas of air leakage are normally through penetrations in the kitchens, utility rooms and bathrooms and toilets. The other main areas are usually around the wall/floor junctions and doors and windows. It is worth noting that the internal wall should always be used as the air seal line as the external wall is usually ventilated and as a result will not be air tight.
So how do you actually measure the tightness of my building?
The air tightness test is undertaken in-line with Part L and the ATTAMA standard. The pressure differential is measured across the envelope of the building by means of a large fan installed temporarily sealed and a range of static pressures and environmental readings are taken. The fan is switched on and the air pressure in the property is gradually increased or decreased and the differential pressure is recorded at each step. The total air flow required to achieve a pressure differential of 50 Pa is calculated and divided by the total building envelope area to provide the leakage rate in m3/h.m2@50Pa.
Whether you need a full on-going air tightness design/consultancy service, air sealing help, or just an air tightness test we have the knowledge and experience to ensure your building passes first time.
If you need to prepare your building for an air tightness test please visit click here for our Air Tightness checklist.
If you would like more information in regards to our air tightness testing and consultancy services then please contact us at firstname.lastname@example.org.