Hi all,

This query follows on a similar theme to the previous topic.

We are working on an existing building that is intending to improve the envelop performance by internally adding insulation to all external walls.
There will be no other alterations to the envelope.

1) Given that we are altering and thermally improving the existing external wall - do we have to also install an air barrier per 5.4.3.1.2?
2) Are the other envelope elements that remain unchanged such as the floor/roof exempt from air barrier requirements?

Thanks!