Rimworld Guides and Walkthroughs
Much like with all things in Rimworld you have to take a different approach to building residential housing depending on how far into the game you are. When I first start a new colony on Rimworld I typically throw up temporary housing within my base; I make at minimum 5 houses with each room being 4 x 4 or 4 x 3. Usually by the end of year 1 I will have at least 10 temporary houses but sometimes I make up to 12.
A good general rule of thumb is you always want more houses than you have colonists. Sometimes you'll need to convert an extra house to a Prison or a Hospital depending on situations that arise. If you're using the Hospitality mod then you'll need some Guest Rooms too. Up to a dozen or more guests can visit your colony at a time later in the game - don't worry about making beds for them all at the start of the game but you should have individual rooms for most of them and a barracks overflow for the rest.
What size residential area you need to make depends mostly on what AI Storyteller you're using and how many colonists you want. Each AI Storyteller has a different 'colony limit' hardcoded in which means that once your colony reaches a certain threshold the storyteller will keep sending catastrophic events your way until people die and you drop below that threshold. If you'd like to go over the complete list of differences between the storytellers follow the link; I have added the info relevant for this guide below.
Cassandra & Phoebe Max Size: 18 Colonists
Randy Random Max Size: 50 Colonists
Both Cassandra and Phoebe will start throwing catastrophic events at you once you reach 18 colonists but Randy Random waits until you're at 50. Even with Cassandra and Phoebe you can still get well over 18 colonists; it'll just be harder to keep them alive. The same goes with Randy, I have had up to 66 colonists with Randy Random before and I decided that was far too many colonists for me.
If you're playing with Randy Random as your AI Storyteller and you intend to make a giant base - you're going to need a giant residential district to house all your colonists. If you're playing with Cassandra and Phoebe then you'll not need as much space. Since every game is different and every playstyle is different this is something you'll need to figure out on your own.
Below you'll find a couple of residential districts that I have designed in Rimworld. I like to put a rec room in the residential district and a dining table since colonists usually eat immediately after waking up and they do rec before bed/after waking up. My time schedule sometimes gives them 'Anything' hours right when they wake up and before bed. Having this stuff close to where they sleep helps reduce the travel time.
An example of a large Residential District that I made on a Randy Random playthrough.
Residential District that I made on a River map.
Ultimately you should keep in mind there is no 'correct' bedroom size. The Rimworld wiki has an optimal bedroom study which goes over different room sizes and the different materials used to make the rooms if you're really interested in min/maxing. Based on what I have personally experienced and what that wiki page says - I see no reason to make a room larger than 5x5. A 5x5 room can get you to extremely impressive but it ends up taking a lot of space... Especially if your colony is a bit large.
If you're trying to conserve space a 4x4 can be brought up to 'very impressive' or 'somewhat impressive' if you use the right materials to make the room and you put high enough quality statues into the rooms. Keep in mind too that some colonists have a trait where they desire the most impressive bedroom in the colony and some ideologies have requirements where the leaders of your faction want better bedrooms than the riff raff.
Typically I make 3 or 4 bedrooms which are bigger than normal to appease colonists with these traits and desires. If you have two colonists with the 'Greedy' trait it helps to give both of them better bedrooms because if one bedroom gets dirty enough it may stop being the 'best' bedroom. In which case your other colonist with 'Greedy' will have the best bedroom instead of some random person in your colony. Usually I recommend you avoid having any colonists with the 'Greedy' trait though as they're annoying to keep happy.
Only players that have the Ideology or Royalty expansions installed have to worry about pleasing your colony leaders and not all leaders will want a fancy room.
Note: Marble gives the highest beauty modifier of all the stones from both decorations and walls. If you're on a map with Marble use that to build the walls of your bedrooms, as well as the beds, dressers and end tables.
F.A.Q
What size should I make my bedrooms? - The 'min max' answer to this is around 5x5. With the right statues and material used to build the room this can get you 'extremely impressive'. In order to make a bedroom better you need to raise the Impressiveness of the room. You can check the level of Impressiveness as well as Wealth, Space, Beauty and Cleanliness by enabling the 'room stats display' in the bottom right hand corner. Wealth, Space, Beauty and Cleanliness all count towards a room's Impressiveness and you need to raise all 4 of these to improve Impresiveness.
How can I easily improve my bedroom quality? - Put a Masterwork or Excellent statue into your bedroom.