Direct mail might make sense, or flyers at builders trade shows, I know that sounds 'weird' for an online business but it would seem to me that your potential customers are all much too busy to be hanging around on forums.
I am way out of date on this, but vertical specific magazines are hungry for stories. If it is reasonably well written and topical, you are pretty much guaranteed to be published. The only downside is that you should wait until it's published before putting it online. If you have a friend in PR, check to see if this is still true or give one of the mags a call and pitch your idea.
Direct mail might make sense, or flyers at builders trade shows, I know that sounds 'weird' for an online business but it would seem to me that your potential customers are all much too busy to be hanging around on forums.