Dad's Office Building is an office building where Mr. Turner works there.
It is unknown what kind of work is done here but it is likely that is something to do with pencils, in "Nectar of the Odds" the company was destroyed by the Lizard Monster. It was apparently rebuilt, because it appears again in Channel Chasers. Sheldon Dinkleberg also works here, and the boss of the company seems to favor him over Mr. Turner.
The building is purple colored with glass panels running up the side. The top of the building has a sign that reads simply "Dad's Office".
Mr. Turner's workplace has appeared as a minor setting in several episodes, most notably "Mighty Mom and Dyno Dad", where he is seen completing his paperwork at superhuman speeds thanks to a wish for superpowers by Timmy.
It also appeared in "Channel Chasers", where Mr. Turner is seen working hard cleaning up his office in hopes of earning a cleanest office award. However, just moments before his boss arrives to check his office to see if it is clean in order to give him a cleanest office award, Timmy bounces through in a Banzai Bubble, trashing the entire office and causing Mr. Turner's boss to give the cleanest office award to his arch-rival and next-door neighbor, Sheldon Dinkleberg as well as the money that goes with it.
From Season 7 and beyond, Mr. Turner no longer works here, but instead at a similar company with a different building called "Pencil Nexus". It is not explained whether this is the same company, or if Timmy's dad simply got a new job. Most likely, the creators just wanted to give Mr. Turner a more imaginative work place for the episode "The Boss of Me". Therefore, this location is possibly retconned. Another reason why he doesn't work here anymore is possibly because the office building may have gone bankrupt and Mr. Turner had to find a new job and eventually found one at "Pencil Nexus". Another theory is that pencil nexus has 2 branches this and the one in The Boss of Me. Another possible explanation is that in Dread 'N' Breakfast, it was stated Mr. Turner had quit his job to pursue his dream job of selling sock monkeys. Quite possibly, the original company wouldn't hire him back, so he had to go to a different "pencil based" firm.