In Rimworld, will a fire always destroy your base? Or is there some better way to put fires out in the game?
Always set firefighting to priority 1.
Use the tool to define your home area to cover everything you want to protect, or else your colonists won't even bother.
Build stone walls (I used granite, use whatever is most available and not flammable) all around your base.
Add a several meters layer of stone floor around your wall can help too.
Kill boomrats when it's raining. Kill 'em all.
Don't rely too much on batteries, the more you have, the biggest explosion/fire it creates.
Firefoam poppers are great too, but costly and need some advanced research. I didn't bother to much with it (except in my boomrat farm of firedeath, for obvious security reasons), the above tips should largely suffice.
Now, depending on the source of your fires, some more techniques can be useful. So what causes fires in the first place ?
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EDIT : So, it looks like lightning is your main source of fire.
Lightning mostly occurs when it's raining, but sometimes the rain stops a bit early. You can even have dry thunderstorms, and these are a real pain. For the latter, these is not much to do, and the best defense are stone walls (but expect to lose some vegetation around).
However, when you have only one fire still going on after the rain stops, you can deal with it : just follow rule 1 and 2, and expand temporarily your home area on and around the fire. Then select all of your colonists and draft then undraft them to make them stop immediately their job. If you don't, some may finish what they were doing instead of putting out the fire.
Absolutely.
You have a few options so I'll list them in the order that I think is most effective.
If you look in the menu, you should see a zone option, this is usually where you go to create growing areas. There is a zone type in there called "home area". If you click on it you can see your current home area, this area basically specifies the area that you consider your home, as such any cleaning/repairs and fires in this area will be put out. I would recommend putting a home area a few blocks further than your walls to prevent structural damage. The catch with this is only people assigned to the firefighting role in jobs will actually put out fires. Wiki
Place a ring of non-burnable flooring around your base. This prevents fires from spreading far enough to cause you damage, fires can spread with any grass/plants but can't burn stone. This is arguably the best method but it can be time consuming and resource intensive.
Using firefoam poppers. These are research unlocked devices that explode when fire touches them, instead of causing further damage it sends out a decent sized circle of foam which instantly puts out fires and prevents more fire from entering those tiles. Wiki
I forgot to mention, you're not barred from using all 3 of the methods described above, if you want to 99% safe then you can implement all 3.