Load Paths: How a Building Carries Weight to the Ground

Structure is the art of getting every load safely to the ground. If you can trace an unbroken path from where a load lands to the soil that finally carries it, the building stands up. Break the path anywhere and something fails.

Thinking in load paths

Follow the weight downward:

1. Floor → slab. People, furniture, and the floor’s own weight press on the slab.
2. Slab → beams. The slab spans the short way and hands its load to the beams.
3. Beams → columns. Beams collect the slab load and deliver it to the columns at their ends.
4. Columns → footings. Columns carry it straight down.
5. Footings → soil. Footings spread the concentrated column load over enough area that the soil can bear it.

Why it matters for design

• Everything below carries everything above. A column on the third floor must carry every floor stacked on it — loads accumulate on the way down. To size a member you start from how much floor it carries: the Tributary Area & Load Takedown calculator does that.
• No path, no support. Remove a column for a nicer plan and the load above it needs a new route — usually a bigger transfer beam, which is expensive. Spot the load path early and you avoid late surprises.
• Lateral loads have paths too. Wind and earthquakes push sideways; that load also needs a continuous path (through floors acting as diaphragms into walls or braced frames) down to the foundation. Same idea, different direction.

Once you see a building as a set of load paths, structural decisions stop feeling arbitrary — each member is just a link getting weight one step closer to the ground.