Joseph,

Here is what a completed Census page for 1840 can look like. Your Joel House should be listed an Part I with all of the other persons enumerated on that page. If he is/was a FPOC his family structure should be on Part II under the heading of Free Persons of Color.

In the below example note Lewis Adams & Jeffery Thompson (lines 5 & 6) are listed with all others, but their family structure is under "Free Colored Persons". they are the only two FPOC on this Census page.
Click the magnify glass icon for an enlarged image.

http://artthomasfamily.tribalpages.com/tribe/browse?userid=artthomasfamily&view=62&sort=0&albumid=2&photoindex=86&rand=568175552

This seems to be the rule for annotating FPOC, but I'm sure there are exceptions.

Hope this helps answer your Census question.

Art Thomas