Imposed and dead loads to SANS 10160-2
An office floor from slab thickness to the ultimate design load: densities from Annex A, the category B1 imposed load, movable partitions (an imposed load, not a dead load), the concentrated load, and the H2 roof formula. Every number comes from the free STATIX quick tools.
1. The problem
An office floor: a 200 mm reinforced concrete slab with a 50 mm screed, finishes and a ceiling, light movable partitions, and a panel of 6 × 6 m = 36 m². What load goes into the slab design, and what goes on the inaccessible roof above it?
2. Permanent load Gk (SANS 10160-2 Annex A)
Self-weight comes from thickness times nominal density. SANS 10160-2 Table A.1 gives 24,0 kN/m³ for normal reinforced concrete and 19,0 to 23,0 kN/m³ for cement mortar (the upper value is used for the screed):
screed 0,050 × 23,0 = 1,15 kPa
finishes 0,50 kPa + services and ceiling 0,50 kPa
Gk = 6,95 kPa
3. Imposed load qk for the office (Table 1)
SANS 10160-2 Table 1 sorts floors by use. An office area for general use is category B1:
The distributed load and the concentrated load are separate checks: the 4,5 kN point load is not added to the 2,5 kPa. It matters for punching and local bending of thin slabs and toppings.
4. Movable partitions (cl. 9.3.1.9)
Partitions that can move are an imposed load in SANS 10160-2, not a permanent one. When the floor can spread the load sideways, they become an extra uniform load added to qk, by their weight per metre of wall:
| Partition self-weight | Extra qk |
|---|---|
| up to 1,0 kN/m of wall | 0,5 kPa |
| up to 2,0 kN/m | 0,8 kPa |
| up to 3,0 kN/m | 1,2 kPa |
Drywall partitions of about 1,5 kN/m give 0,8 kPa, so the office floor carries qk = 2,5 + 0,8 = 3,3 kPa, which is 3,3 × 36 = 118,8 kN on the panel. Heavier partitions are placed where they stand.
5. The inaccessible roof (Table 5)
A roof reached only for maintenance and repair is category H2. Its load depends on the loaded area A of the member. Between 3 m² and 15 m² the footnote formula applies:
Qk = 1,0 kN over 0,1 × 0,1 m
A small loaded area (a single purlin bay) gets up to 0,50 kPa; a large one (15 m² and more) 0,25 kPa. Category H1 (during construction) uses /24 in place of /48 and reaches 0,75 kPa.
6. Into the slab design (SANS 10160-1)
For the ultimate limit state the SANS 10160-1 Table 3 combinations for this floor are STR-P, 1,35 Gk + 1,0 Qk, and STR, 1,2 Gk + 1,6 Qk:
1,2 × 6,95 + 1,6 × 3,3 = 8,34 + 5,28 = 13,62 kPa ← governs
No floor area reduction (cl. 9.3.1.10) is taken here; it may lower qk for large areas carried by one member.
7. Result
| Item | Value |
|---|---|
| Permanent load Gk | 6,95 kPa |
| Office imposed load qk (B1 + partitions) | 2,5 + 0,8 = 3,3 kPa |
| Concentrated load Qk (separate check) | 4,5 kN |
| Inaccessible roof, A = 10 m² (H2) | 0,35 kPa, Qk 1,0 kN |
| Ultimate slab load | 13,62 kPa |
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