July 21, 2004—More than a third of buildings tested by the UKs Building Research Establishment (BRE) are failing the airtightness test, two-and-a-half years after the introduction of Approved Document L2.
“A large number of companies still appear to be unaware that Building Control have to be satisfied that a building is airtight before it can be signed off,” says Mike Jaggs, Head of BRE’s Airtightness Service. “This means designers and contractors are not addressing the issue at the start of a project when it is very often quite simple to put in place the right design and workmanship principles.
“Failing the test means having to go back and re-do work in the final stages of construction,” says Mike Jaggs, “and this is very costly, both in time and money. It comes as quite a shock to clients when they suddenly realize they havent designed or built for airtightness.”
According to Jaggs, the ruling is quite straightforward. All commercial and public buildings over 1000m2 have to demonstrate they are airtight either by reviewing designs and workmanship with building control, or by putting the building through an airtightness test in the final stages of construction. “ODPM recommends the test option, unless the building is very large or being built in stages.”
In BRE’s experience, companies that manage the process properly have no problem in getting their buildings through the test. “It’s a matter of attention to detail; everyone needs to know what has to be done and why. And, success doesn’t depend on building type—complex buildings can pass while simple buildings fail.”
However, there does seem to be a discrepancy between building control offices—some are lenient and approve air permeability levels of 14 when it should be below 10, while others will fail a building at 10.2. BRE feels some improvement could be made here. “Airtightness plays an important part in the fight to reduce carbon emissions. It is important to iron out these differences and have everyone working towards best practice levels,” say Jaggs. “They aren’t difficult to achieve, its just a matter of learning what to do on your first building and then rolling the process out on following projects.”
For more information, visit the BRE.
