Metal Foundation Rust: HP, Cost, Raid Cost, Soft Side & Upkeep (2026)

Every sheet metal base in Rust starts with the same block under your feet. The metal foundation is what your walls, floors and Tool Cupboard all stand on, and if a raider takes one out, everything resting on it can come down with it. Getting it right is cheap, and getting it wrong is one of the easiest ways to lose a base.

This metal foundation Rust guide covers what a sheet metal foundation costs, how much health it has, how many C4, rockets and satchels it takes to raid, where its soft side is, what it costs in upkeep, and how it compares with stone and armored.

• What It Is
• Cost
• How to Build It
• Raid Cost
• Soft Side
• Upkeep and Decay
• Stone vs Metal vs Armored
• Tips
• FAQ

What Is a Metal Foundation in Rust?

A foundation is the base building block in Rust. It is the only piece you can place straight onto the ground, and every other piece of your base, from metal walls to floors and roofs, gets its stability from the foundations below it. A metal foundation is simply a foundation upgraded to the sheet metal tier, the fourth of the five build tiers (twig, wood, stone, sheet metal, armored).

There are two shapes: the square foundation and the triangle foundation. Both have the same health and the same raid cost at a given tier. The triangle simply costs half as much and lets you build angled bases and honeycomb layers.

How Much Does a Metal Foundation Cost?

A square metal foundation costs 200 metal fragments, the same as a full sheet metal wall. A triangle foundation costs 100 metal fragments. You also pay 50 wood (25 for a triangle) to place the twig foundation in the first place. Since one metal ore smelts into one metal fragment, each square foundation is 200 metal ore through a furnace.

For a typical 2×2 starter base with four square foundations, that is 800 frags to go metal, which a few metal ore nodes and a furnace run cover easily. If you need more, see our guide to farming metal fragments.

How to Build and Upgrade a Metal Foundation

1. Place it as twig. Equip the Building Plan, pick Foundation (or Triangle Foundation) from the right-click wheel, and place it on flat ground for 50 wood.
2. Place your Tool Cupboard. Put down a Tool Cupboard on the foundation so nobody else can build on or around it.
3. Get 200 metal fragments. Smelt metal ore in a furnace, or loot and recycle for frags.
4. Upgrade with the Hammer. Equip the Hammer, look at the foundation, hold right-click and choose Metal. The foundation becomes sheet metal right away.

How Much to Raid a Metal Foundation?

A metal foundation has the same 1,000 HP as a sheet metal wall, so it takes the same boom. C4 is the cheapest option at 4 charges and 8,800 sulfur. Square and triangle foundations take exactly the same.

In practice raiders almost never blow a foundation. They go through a wall or door, which costs the same or less, and walk in. Foundations get blown when someone wants to collapse a whole section of base, or when the foundation is the only way into a bunker. For every other piece, use our Rust raid calculator.

Metal Foundation Soft Side

Every building piece has a hard side and a soft side. Explosives do the same damage to both, but melee tools do roughly ten times more to the soft side. On a foundation the soft side is the top, and only the middle of the top, not the edges. The outside faces you see from the ground are the hard side.

Metal Foundation Upkeep and Decay

Upkeep is paid from your Tool Cupboard every day. A square metal foundation costs 20 to 67 metal fragments a day and a triangle 10 to 33. The range is because upkeep cost per block goes up as your base gets bigger. If the cupboard runs dry, the foundation starts to decay and goes from full health to zero in 8 hours.

Decay matters most for foundations, because the stability system works from the bottom up. When a foundation breaks, every wall and floor that was resting on it can collapse too, which is why bases left without upkeep fall in big chunks rather than one block at a time.

Stone vs Metal vs Armored Foundation

For most groups sheet metal is the sweet spot. It doubles the raid cost of stone for a resource you are already farming, and it does not touch the high quality metal you need for guns and an armored core. Go armored on the foundations under your loot room once HQM is coming in steadily.

Metal Foundation Tips

• Cupboard before upgrade. Place the TC first so no one can build on your foundations or block your expansion.
• Use triangles. At 100 frags each they are the cheapest way to add an outer honeycomb layer.
• Never leave a top exposed. An open foundation top is a soft side anyone can pick at.
• Keep frags in the cupboard. Eight hours is all a metal foundation lasts with no upkeep, and losing one can collapse the walls above it.
• Defend the outside. An auto turret covering your roof and ledges stops cheap melee raids.
• Upgrade the core later. When HQM comes in, put your loot rooms on armored foundations.

For the full picture of tiers, stability and base layouts, see our Rust building guide.

Metal Foundation FAQ

Sources and Further Reading

• RustClash Wiki, Metal Foundation (health, soft side on top)
• Rustafied, Raiding in Rust (hard side and soft side, explosive damage)
• Raid, melee, upkeep and decay figures from RustLabs data
• Every building piece: Rust raid calculator