How do I prepare for an air test? What needs to be complete before an air test? Can I still air test if the kitchen is not fitted?
These are some of the most frequent questions we hear from clients. So, the compliance engineers at Abbey Consultants took a break from air testing and decided to talk instead! Below the team share some practical advice to help you pass an air test first time round.
Preparation is prevention
Air testing can be a simple and straightforward process. Adopting a fabric first approach is always more reliable than sealing components as a quick fix on the day of testing. If the design of the building is good and airtight, an air test will only be a 45-minute formality.
One of the most common mistakes I see clients make is building without any preparation for an air test. So often, people think it’s OK to start sealing at the last stage. The main reason for failure is a lack of preparation at first and second fix. Ensure that the dry liners have completely boarded the bathroom walls and ceilings. To fit the pipes, cut holes where needed, seal around the pipes, and then build the boxing to cover. This will reduce air leakage and stop the need for last minute foam/mastic work”.
Time your test right
Did you know that the Air Tightness Testing and Measurement Association (ATTMA) recently released guidance that states that 70% of dwelling air tests fail due to early testing? With handover deadlines impending, it can be tempting to get your air test out of the way. But making this mistake often results in higher costs later down the line – you will could end up paying for re-tests, delayed handover and wasted hours.
We always suggest that our clients carry out air testing when building work is 100% complete including snagging. This means windows and doors are fitted and the property is connected to power and water. However, the air test should be carried out without floor finishes and furnishing.
I often see clients booking an air test too early – before the plot is even finished. It is a mistake that almost always requires a revisit as it takes too long to rectify leaks on the day of the air test”.
Windows, Doors and other openings
Before air testing is carried out, all windows and doors need to be fitted and operable. Access doors, such as internal doors to garages, should be airtight because they cannot be temporarily sealed. Trickle vents need to be shut and lofts are to be fitted with the hatch which will be used when the property is handed over.
Pipework (as with any entry or exit to the dwelling) needs to be sealed before the kitchen or bathroom units are placed in the way! It’s good practice to imagine that you’re trying to keep small pests out. I always see boiler flues which are not sealed prior to an air test visit. You must remember to seal the holes above and below the flues, and do not forget to seal parts of the wall where attaching brackets has caused small holes”.
Kitchens
A common air leakage hotpsot is the cavity left behind kitchen cupboards where there are no skirting. We reccomend that clients fit their kitchens before booking an air test with us. However, it is ok to test before kitchens are installed providing that the following requirments are met: the supply and waste pipes for the water are present, no temporary sealing is applied to the walls and that the condition if the kitchen is declared as a deviation (this means it is traceable on the certificate). The ends of the pipes may be taped as these will be sealed with a water trap once the kitchen is complete so this does not artificially improve the air test result.
Bathrooms
Bathrooms are a common air leakage hotspot so take extra care when checking them. All bathrooms need to be fitted and complete before an air test. Seal air leakage paths (like bath panels and pipework) before fitting bath panel, vanity unit covers, extractors and any boxing in.
Skirting and Plaster boards
Skirting is another common leakage point. We recommend sealing above and below skirting boards before any carpeting or floor finishes are in place.
I see sites struggle with skirting all the time. Remember that carpet is very permeable and isn’t airtight. My advice would be to complete external sealing before skirting goes down. Plasterboard needs to be as close to the floor as possible. This greatly restricts the flow of air. If done and sealed before the skirting is down, there will be less future work to do on smaller areas. It’s also an idea to have flooring which goes all the way under units”.
Don’t get caught by the mastic trap
ATTMA have very strict guidelines about what can and cannot be temporarily sealed on the day of testing and if not rigorously followed, the air test result will be void. Below we have listed the rules on temporary sealing as described by ATTMA:
My advice would be generally to have a solid dab on the walls. And, if possible, seal up what you can after first fix, so before the kitchen units/bath go in. Lastly, make sure that the internal/external mastic is completed before the test”.
Mechanical Ventilation (Extractors, MVHR, Air Handling) Mechanical ventilation systems such as bathroom, kitchen and cooker hood extracts must be switched off before being temporarily sealed for the test.
Trickle Vents Trickle vents shall be closed and can be temporarily sealed. It is common practice for temporary sealing not to take place with trickle vents closed. Closed trickle vents have minimal impact on the overall air permeability. Should the building fail to meet its intended DAP, trickle vents shall be sealed.
Air Conditioning Air conditioning grills can be sealed internally. It is important to check and confirm that the air conditioning is switched off during the test.
Passive Ventilation Passive Ventilation, such as air bricks to outside, passive stacks and sub floor ventilation systems should be temporarily sealed for the test. Ventilation grills (leading into boiler cupboards for example) should not be sealed.
Chimney Flues Chimney Flues can be temporarily sealed for the test as these items are accounted for in the SAP calculation.
Door Template There may be occasions where the door template does not fit cleanly into the doorframe. It is acceptable to temporarily seal around the doorframe to ensure there is no leakage through the set up area.
Sockets Electrical sockets should never be temporarily sealed. Any test that has temporary sealing on sockets will be immediately rejected.
Down lights These may be designed to draw in air and must never be temporarily sealed for an air test. Selection of down lights should be considered part of the overall design of the building.
Bath Panel & Shower Trays Bath panels and shower trays are not the air barrier line of a property and must never be temporarily sealed. Areas behind bath panels and shower trays should be permanently sealed before, or during fitting.
Loft Hatches & Access Panels Loft hatches and access panels should be fitted before the test is conducted. It is never acceptable to temporarily seal a mal-fitting loft hatch or access panel.
Doors Cupboards/Storage Areas Doors to unconditioned storage areas should be closed and not temporarily sealed. This includes doors to garages. It is never acceptable to temporarily seal a cupboard door, including boiler cupboard or kitchen cupboard doors. Doing so and declaring the result as final will result in suspension from the Scheme.
External Doors and Windows External doors and windows should seals fitted before the test in conducted. It is never acceptable to temporarily seal a mal-fitting door or window, even if the seal has not yet been fitted, as temporarily sealing will likely be better that the seal itself.
