Building Construction Trigger

Is there any way for an integer condition checking the amount of units owned by a player to not include buildings currently under construction?
If the trigger requires two of a building and I have one, the minute I begin construction on a second it activates the trigger.

I assume I'll end up using unit groups but at the moment I'm still really new to the extent of WC3's triggers.
I've also looked around the forums and haven't found anything that matches this so help would be awesome.