whilst testing this week we came across houses that could have done a lot better if they sealed more holes. One interesting place to check is under the bath or behind the bath
panel. Often developers think that holes under there dont matter because no one will see them. truth is the fan will still pull air from there if there is a hole. It is best to seal every where as you go. The picture speaks a thousand words. You can see under this bath there was a massive hole where the air was been pulled from.
If you look carefully you can also see that part of the floor has been removed for plumbing pipes and it has been left unsealed. This property passed the air leakage test after these holes were sealed.