At its core, Valheim is an immersive survival game, and though exploration is important, a player's primary goal will need to be staying alive. One of the key components of survival in Valheim is building a base that can protect the player's character from the weather and provide a safe place to rest and recover. Campfires and bonfires are great ways to keep warm, and some kind of fire is required near or inside a shelter for players to be able to use their beds.
As soon as poor weather hits, players will lose their source of warmth and heat. Players can build a fire in their homes, as long as they have proper ventilation. While away from the base, this can get trickier, but players can use a similar strategy of building a protective awning to keep their fire going even in bad weather.
Building A Fire Inside Your House
By far the easiest way to protect a fire in Valheim is to build it inside a house. This way, it can be used to cook, will keep the player character warm, will address the need for a bed to be near a fire, and will allow the player to monitor and refuel it easily. To build a fire inside, players will need to remove a piece of the floor using a hammer. They will then need to select the campfire in the Build menu which requires 5 Stone and 2 Wood materials to craft.
Next, players will need to build some sort of ventilation system. This is usually a decent-sized hole in the roof. Too small of a gap will often still cause the house to fill with smoke that can easily kill the character. Too wide of a hole will fail to protect the player from rain or cold while indoors and can still allow a shower or thunderstorm to put the fire out.
There are a few options for players to get creative about their ventilation system. One option might be to build a small room around the fire on three sides, creating a fireplace and chimney, and stack the walls on top of each other and through a gap in the roof. Players can then use angular roof tiles to keep out the rain and let the smoke escape easily.
Other players have decided to fully embrace the Valheim Viking theme and build a longhouse with a fire in the center. Players can then create a gap in the roof right in the center of the fire and use the thatched roof pieces at 45 or 26 degrees. This will allow the smoke to escape in a single column at the center of the house, preventing the cloud from spreading too far, and preventing rain from getting in.
When players are adventuring, if they build a lean-to or smaller base in the various biomes, they may include a campfire. To protect this fire from inclement weather, players can use the same process to make sure it is also enclosed in some kind of structure with a roof, but with enough ventilation to avoid dying.