How do you get the diagonal half tiles for flooring?

I'm working on updating some of my lots for my story, so they don't look nearly so set-like (and I might actually be able to take pictures with them :joy:). However, I'm having difficulty with putting down diagonal half tiles, where they aren't going down with a diagonal wall and room (don't get me started on room functionality >.< I can't even add-on to the room I want to.), so both sides have it. I can't remember if there's a hotkey that I can press when placing the tiles or not.

For those curious, I'm currently updating my vampire council lot and making the outside look kinda like a courthouse. Floor tiles inside the flowerbed with a tree just looks wrong.