Fysik

Fysik

Structural physics for Valheim building. In vanilla Valheim, a piece only cares about how far it is

from the ground. Fysik replaces that with a force calculation in which the shape of your build

matters, in the spirit of Poly Bridge and Bridge Constructor:

• Arches carry their load in compression and can span gaps that a flat beam cannot.
• Braces and triangles carry load along their length instead of bending: a diagonal under a

balcony halves its stress.

• Cantilevers bend, and the longer they reach, the more they strain.
• An overloaded piece cracks before it falls: it turns red, shakes, creaks and sheds dust, giving

you a few seconds to shore it up. Once something gives way, the collapse follows instantly.

• Building an arch works like the real thing: until the last stone closes it, an unfinished arch is

just two cantilevers and needs scaffolding. Close it, remove the scaffolding, and it stands.

⚠ Before you install

Fysik is on from the start. As soon as a world loads, every building is checked against the

physics Fysik applies, and buildings that do not respect it will crack and fall, including

bases you built before installing it. Back up your world first. We recommend starting a new

world with Fysik, so everything you build is designed for it from the first post.

Status

Early access. Material values are still being calibrated. Back up your worlds before trying

it.

Installation

Install with a mod manager (r2modman, Mod Manager) or manually:

• Install BepInExPack_Valheim

and Jötunn.

• Copy plugins/Fysik.dll into BepInEx/plugins/Fysik.

Fysik must be installed on the server and on every client, with exactly the same version (every

player who owns part of a structure must calculate it exactly as the others do).

Players without it cannot join a server that has it, and vice versa.

Existing buildings follow the new rules as soon as the mod is enabled: back up your world, and

preferably start a new one. To look at an old base before letting it settle, set

Structure.Mode = Sandbox (nothing falls for lack of support) or DisplayOnly (vanilla decides).

Seeing the forces

• Hammer: aim at a piece. It is colored by stress, from blue (relaxed) through green and yellow to

red (at its limit), and the value appears next to the crosshair, e.g. Compression 72%, with its

material and weight. Light blue means the structure is still being calculated; magenta means it has

no path to the ground at all.

• Placing a piece: the ghost is colored by the stress it would have once placed, with the value

next to the crosshair (Preview: Bending 85%). If it would push another piece past its limit, a

second line names that piece. When vanilla says the spot is invalid, the ghost stays vanilla red.

• X-ray (F7): colors every piece within 40 m. Ctrl+F7 widens the radius by 10 m, up to 80 m,

then back to 40 m.

• Cracking: a piece above 100% pulses red, shakes, creaks and sheds dust. You have

CrackWarningSeconds (5 s) to shore it up (add a post, a brace, finish the arch) before it falls. Once something gives way, everything that lost its support comes down with it at

once, as debris that bursts on hitting the ground, like a building being imploded; whatever is left

overloaded follows without warning. A piece left with no path to the ground at all (you removed its

support) has nothing to shore up and falls at once, as in vanilla.

• Furniture: chests, workbenches, torches and similar pieces hold nothing up and add no weight,

but still need something to rest on: they fall when the piece under them goes, as in vanilla.

Building guide

The pictures below were computed with Fysik's own solver and the default materials, using the same

pieces you build with. In game, pieces snap a little differently, so expect similar, not identical,

numbers.

Squeeze, don't bend

A piece is far stronger squeezed or pulled along its length than bent across it. A post under a roof

is squeezed and barely notices; a beam reaching out is bent, a