Better airtightness – A builder’s choice.

It’s a rewarding experience when working with a builder who is engaged in the building performance process, and is willing to set the bar higher as a starting point.

This year I have had discussions about building performance and best practices with Shannon at Evoke Building Group in Ballarat. The discussions centered around how to achieve a higher performance house without radically changing construction methods and without causing cost blow-outs. True to his word, Shannon applied the principles of good building science and, as part of the process, was keen to test one of his houses for air tightness.

We did a blower door test, and achieved a great result. NCC maximum permeability is 10 m3/hr.m2 at 50Pa. Our test result was 4.1 m3/hr.m2 at 50Pa. = nearly two and a half times better than code.

It was pleasing to see Shannon’s reaction during the test. He checked the whole house for leaks, identified some seals that he missed, noted areas that he would improve upon in the future, and correctly suggested that he probably would have achieved an air permeability of around 3 m3/hr.m2 at 50Pa if these items were rectified.  The conversation also lead into 24hr ventilation strategies.

The lesson here, for airtightness, is that when a builder knows what to do, and why they are doing it, they start aiming higher.

Evoke are going to apply their new strategy to all of their houses as a base starting point. Seeing Shannon in action, there is no doubt that he will be continually improving and fine-tuning along the way.

The good news is that knowledge and attention to detail is all you need to achieve a good result without having to re-invent the construction process.

LESSON: There is no need to wait for building codes to change to start building better.