Dead load is the permanent weight of the structure and everything fixed to it; live load is the movable, variable weight the structure carries while it is in use. StructLoads asks you for both as pressures on each floor, then turns them into support reactions, because the split decides how each load is factored and whether it can be reduced. Getting the two buckets right is the first move in any load takedown.
What counts as dead load
Dead load is the self weight of the building: the slab, beams, columns and walls, plus permanent finishes, screeds, ceilings, cladding and fixed services. It is predictable because it does not move and you can compute it from geometry and material density. A reinforced concrete slab, for example, weighs about 24 kN/m3, so a 150 mm slab contributes about 3.6 kN/m2 of dead load on its own, a figure you can confirm from published concrete properties. Add finishes and services and a typical office floor dead load lands near 4.5 kN/m2.
What counts as live load
Live load, called imposed load in Eurocode, is the variable weight from occupancy and use: people, furniture, stored goods, vehicles and equipment. It is uncertain in both magnitude and position, so codes set conservative minimum values by occupancy. The same idea appears in guidance on imposed load: you design for a sensible worst case, not the load present on an average day. The gap between the two is well documented; the National Bureau of Standards measured real office floors in its survey of fire loads and live loads in office buildings, the field data behind the conservative code minimums used today.
Dead vs live load at a glance
The two differ in what they are, how predictable they are, and how the code treats them.
| Property | Dead load | Live load |
|---|---|---|
| What it is | Permanent self weight and finishes | Movable occupancy and use |
| Predictability | High, from geometry and density | Low, set by code minimums |
| Typical office floor | About 4.5 kN/m2 | About 2.5 to 3.0 kN/m2 |
| Load factor (ASCE 7 strength) | 1.2, or 1.4 alone | 1.6 |
| Reducible over large areas | No | Yes, by tributary area |
The pattern is consistent: dead load is certain and lightly factored, live load is uncertain and heavily factored.
How partitions and services are handled
Fixed, permanent partitions are dead load, counted by their real weight. Movable partitions are usually covered by a live load allowance instead, because their future position is unknown. This is why a floor that looks lightly loaded on paper still carries a partition allowance: the layout can change over the building’s life.
Why the split changes the numbers
The dead and live split is not bookkeeping for its own sake; it changes the design reaction. Strength design multiplies dead and live by different factors and takes the worst combination, so two floors with the same total weight but a different dead to live ratio produce different factored loads. Live load can also be reduced on members that support a large area, because it is unlikely to be fully present everywhere at once, a credit explained in ASCE 7 live load reduction. Dead load is never reduced this way.
Key takeaways: dead vs live load
Dead load is the permanent, predictable self weight; live load is the variable, code-set occupancy load. The split decides the load factors and whether a reduction applies, so it is the first thing to get right before a load takedown turns the pressures into reactions. Enter both per floor in StructLoads and it carries them, separately, all the way to the foundation. Final values must follow your governing code and a qualified engineer’s review.
Related guides
More in this series: area, line and point loads, how to calculate a wall line load, roof live load vs snow load and superimposed dead load. It also connects to the partition load allowance.
Also: the dead and live load calculator.
Quick answers
What is the difference between dead load and live load?
Dead load is the permanent weight of the structure itself, the slab, beams, columns, finishes and fixed services. Live load is the variable, movable weight the structure carries in use, the people, furniture, storage and equipment. Dead load stays constant; live load changes. Both are entered as pressures and then carried through a load takedown.
Is a partition wall a dead load or a live load?
A fixed, permanent partition is a dead load, counted by its actual weight. Movable partitions are usually covered by a separate live load allowance instead, because their position is not known in advance. Codes give a minimum partition allowance to add to the floor live load when the layout can change.
What are typical dead and live load values for a floor?
A 150 mm concrete slab weighs about 3.6 kN/m2, and with finishes and a partition allowance a typical office dead load is around 4.5 kN/m2. Office and residential live loads are commonly 2.5 to 3.0 kN/m2. Always take the governing values from your code and project.
Why do dead and live loads have different load factors?
Dead load is known and constant, so it is multiplied by a smaller factor. Live load is uncertain and rarely at full value everywhere at once, so it carries a larger factor and, over large tributary areas, can be reduced. The factors come from the code load combinations.