In Bloxburg, floor refers to the lower surfaces of a building. You are able to buy this one from Build Mode for $3 per square of floor. Similar to roofs, you are able to automatically place floors in a room. However, for further precision, you are able to manually select points to place down a piece of custom floor.
Talking about the floor, some people love to place something that looks like a floor to camouflage something. If you want to make a fake floor in Bloxburg, there are two gamepasses required for this.
The first one is Advanced Building Placement or Advanced Placing. It is a really good help if you like to build often or are really into it at all. This one allows you to place objects without collision checks in Build Mode. It means they are able to be placed inside each other. As you probably know, players without this gamepass will always have collision checks toggled on. The price of this gamepass is R$200.
The second gamepass that you need to purchase to make a fake floor in Bloxburg is called Basements. Basements is the name of a gamepass and a feature that was added in the game version of 0.7.4. This one allows players to build underneath the first level in Build Mode. If you want to access the basement feature, you must purchase this gamepass in order to build basements, which is currently the cheapest one in the game, costing only R$100.
If you want to insert a basement, you first need to go into the Build Mode option and then open up the Build section. Then, choose the Basement tab. Apparently, placing a basement is similar to placing a pool, and you will be able to choose how big your basement is.
For your information, a 1×1 square of basement costs $25. If you want to go down to the basement level, you have to press the down arrow on the bottom right area of your screen. This allows you to place items, walls, and so on in the basement. Please take a note that basements cannot be colored and need walls or floors to have items placed on them.
Aside from the two gamepasses called Advanced Building Placement or Advanced Placing and Basements, you will also need to purchase carpet. Carpets are the main thing to make a fake floor in the game. There are a few kinds of carpet in the game but you only need to purchase the Simple Carpet. Simple Carpet can be described as a simple and abstract rectangular carpet. This one is available in any color. How much does it cost to get it? According to Wiki, it costs $40. The Simple Carpet is usually used as a decoration for your home but in this case, it is able to be used to make a fake floor. For a better explanation of how to make a fake floor in Bloxburg, it is better for you to watch the tutorial on Youtube.