Sterile tile

Sterile tile is one of the many floors that you can construct. It has the highest cleanliness stat of 0.6. It also takes 60% of the time to clean.

Acquisition

Sterile tiles can be constructed once the Sterile materials research project has been completed. Each tile requires 3 Steel, 12 Silvers, 1,600 ticks (26.67 secs) of work, and a Construction skill of 6.

This tile is relatively slow to construct, taking almost 19x longer than a standard wood floor.

Analysis

Cleanliness is important for a few different types of rooms and buildings. Having a high base cleanliness from sterile tiles means a greater margin before filth accumulation matters and, in some cases, provides additional bonuses. The following are affected:

Hospitals: In a full room of sterile tiles, surgery success is increased by roughly ×1.05 from 0 cleanliness, while tend quality also increases.^{[How much?]} Infection chance per wound is also multiplied by x30%, compared to x50% at 0 cleanliness. While maximum surgery success chance is possible without sterile tile, the extra cleanliness provides a buffer when patients start bleeding all over the floor and the extra tend quality can all save a pawn's life. Sterile tiles should be installed when you can afford it.
Laboratories: Research is accelerated in a clean room by up to +9% in a sterile room, when compared to 0 cleanliness.
Kitchens: Cooking in a dirty room has a chance to give food poisoning. However, the cleanliness only needs to be at -2.0 or higher to avoid the higher chance. Therefore, even dirt floor is sufficiently clean so long as filth is removed. Straw matting is naturally sufficient as well, and prevents 95% of accumulated dirt and trash, which usually makes up for the loss of cleanliness buffer over sterile tile. If your kitchen is sufficiently small, sterile tiles will generally save time in cleaning, but for larger kitchens, straw matting will generally save more time.
Biosculpter pods: Pods run up to +15% faster in a sterile room. As room space doesn't matter, you can make a 2x3 room with just the pod inside it, which is easily affordable.

Cleanliness will also increase room impressiveness, however, sterile tiles also negatively impact beauty, which decreases impressiveness (not to mention also impacting the beauty need!), which makes sterile tiles a very inefficient method for increasing impressiveness. If your only goal is to increase the impressiveness of a room, you should instead use steel tiles, which provide a lesser cleanliness benefit but do not impact beauty; carpets, which provide a substantial amount of beauty, but no cleanliness boost (and, in fact, take substantially longer to clean); or Stone tiles, which provide less beauty than carpets and do not provide a cleanliness boost, but take far less time to clean. Even the humble Wood floor can be preferable for impressiveness, so long as you keep it clean. Sculptures are also vastly more resource efficient at increasing impressiveness than sterile tiles are, providing a 1:1 steel to beauty ratio for a normal-quality sculpture. In short, don't use sterile tiles for impressiveness alone, only use them when the cleanliness itself is important.

In general, sterile tiles aren't an immediate priority to research. Get power, weapons, and enough defenses first so that your colony doesn't fall apart. Then you should get sterile tiles to help save lives and speed up research. The research is also a prerequisite for hospital beds (and by extension Vitals monitors), which provide a further boost to medical success.

Other clean flooring

Steel tiles provide only a third of the cleanliness boost (0.2 versus 0.6), and cost 4 more steel per tile (7 versus 3) than sterile tiles, but are also overall cheaper (value of 16 versus 24), do not require silver to create, do not impact beauty (0 versus -1) and take substantially less research (Steel tiles only require smithing, which is a vital research project anyway, whereas sterile tiles require both the electricity and sterile materials research projects). Both provide the same cleaning speed boost - taking only 60% of the time to clean that wood flooring does. If the player is short in silver and high in steel, or is too early in the research tree to build sterile tiles, this is the best alternative to sterile tiles, and may even be preferable in some situations (e.g. the kitchen, since you only need to be above -2.0 cleanliness).

Gold tiles and Silver tiles generally provide the same benefits as steel tile, but provide a large amount of beauty (+11 and +4, respectively) and are vastly more expensive than any other flooring in the game. Technically these can work in situations where the player has a vast amount of resources but hasn't researched sterile tile, and is technically the "ideal" flooring for the kitchen (setting aside Style bonuses from other floors) as, as mentioned above, kitchens only need to be above -2.0 cleanliness, and the immense beauty is great for someone who sits next to it all day long, but this is an absurd waste of resources.

Paved tiles don't increase cleanliness and take a bit longer to clean than sterile tiles (80% versus 60% cleaning time, which is still an improvement over the norm), but take only 2 steel per tile, and, like steel tiles, have no beauty impact. These combine to make paved tile a fine early-game alternative to sterile tiles.

Concrete is almost strictly inferior to sterile tiles, providing no cleanliness boost, the same -1 beauty penalty, and taking longer to clean (80% versus 60%). However, they're incredibly cheap, costing a mere 1 steel per tile. However, as it does not give a yield on deconstruct, it's generally a poor idea to place concrete in rooms where you plan to use sterile tile in the future. Paved tile deconstructs for 1 steel (providing the same net cost when upgrading) and has no beauty penalty. In situations where materials is scarce, though, concrete is the best option available.

Room creation

As sterile tiles are relatively expensive, you may want to initially combine hospitals and research rooms to make the most out of the buff. Otherwise, you may want to make hospitals small, to save on resources. The smallest room size to maintain cleanliness for triage is 4x5, but a single blood spill will make it dirty every time, not to mention the small size of the room reducing patient capacity. Increasing the size of the room will proportionally reduce the cleanliness impact from each individual pile of filth. You can increase the size, which increases room Impressiveness, patient capacity, and the buffer against filth, as you can afford it.

Note that the floor under a door doesn't count for Cleanliness, so you don't need to place sterile tiles on a doorway. However, filth under a door does count, and colonists stepping from dirt or sand to flooring have a high chance to create filth, so players should still place some flooring under doors.

In combination with straw matting

Combining sterile tiles with straw matting can increase the cleanliness of a room, while decreasing the amount of filth. Put sterile tile under objects that won't be walked over, such as beds, tables, and shelves, and put straw matting elsewhere. Flower pots or sculptures will offset the beauty from both tiles. Straw matting under the door is ideal as it won't reduce the cleanliness of the room but will prevent filth on that spot that can.

Another strategy is to use short entryways (roughly 3-4 tiles long) made of straw. Separate the entryway from the main room with doors so that the cleanliness and beauty penalties of straw don't hurt the room's impressiveness (the doors between the entryway and main room don't need to remain closed, however, as their only purpose is to create a separate room).

Version history

0.12.906 - Added
1.4.3523 - Beauty decreased from 0 to -1. Cleaning time factor added. Description changed from Sterile tiles with special cleanliness-enhancing properties. Extra-clean rooms improve outcomes in hospitals and research labs. This tile is very slow to build. to Sterile tiles with special cleanliness-enhancing properties. Extra-clean rooms improve outcomes in hospitals and research labs. This tile is very slow to build, but quick to clean.

Architect

Floors: Burned floors (Carpet, Straw matting, Wood floor, Bioferrite plate) • Concrete • Flagstones (Sandstone, Granite, Limestone, Slate, Marble) • Gold tile • Paved tile • Silver tile • Steel tile • Sterile tile • Straw matting • Wood floor • Fungal gravel • Hex tile • Spikecore plates • Totemic boards
(research): Carpet • Stone tiles (Sandstone, Granite, Limestone, Slate, Marble) • Fine carpets • Fine stone tiles (Sandstone, Granite, Limestone, Slate, Marble) • Hex carpet • Mindbend carpet • Morbid carpet • Morbid stone tiles (Sandstone, Granite, Limestone, Slate, Marble) • Spikecore stone tiles (Sandstone, Granite, Limestone, Slate, Marble) • Totemic stone tiles (Sandstone, Granite, Limestone, Slate, Marble) • Bioferrite plate
Floor coverings: Animalist slab (Medium, Broad) • Morbid slab (Medium, Broad) • Rustic rug (Medium, Broad) • Spikecore floor-star (Medium, Broad) • Totemic slab (Medium, Broad)
Related: Bridge • Smooth stone • Void metal