Live loads for houses in Pakistan (Building Code of Pakistan 2021)

The Building Code of Pakistan (BCP) 2021 is published by the Pakistan Engineering Council (PEC). It revises the Building Code of Pakistan – Seismic Provisions 2007, which was notified by S.R.O. 971(I)/2008, and it is based on the 2021 International Building Code (IBC), used under a licence from the International Code Council. It keeps the IBC's chapter and section numbers, so Chapter 16 (Structural Design) reads like IBC Chapter 16, with Pakistan's own ground snow, wind speed, rainfall, flood and earthquake maps added.

Section 1607 and Table 1607.1 give the minimum uniformly distributed live loads, Lo, and the concentrated loads for each occupancy or use. Use the larger of the load the intended use is expected to cause and the table value (1607.3). The table is in pounds per square foot (psf), with the SI note 1 psf = 0.0479 kN/m². This page gives kN/m² first and the psf table value in brackets, as the app does.

For load combinations, wind, snow and earthquake, BCP 2021 points to ASCE/SEI 7-16 (Minimum Design Loads and Associated Criteria for Buildings and Other Structures), as the IBC does. Section 1605.1 lets you use the strength combinations of ASCE 7 Section 2.3, the allowable stress combinations of ASCE 7 Section 2.4, or the alternative allowable stress combinations printed in BCP Section 1605.2.

Detached one- and two-family houses and townhouses of up to three storeys above grade, with their own exit, may comply with BCP 2021 or with the International Residential Code (101.2, exception). Where a house is designed by an engineer to BCP Chapter 16, the values below apply. Check with the local building control authority which rules it applies.

These are minimums (1607.3). Floors must also carry the concentrated loads of Table 1607.1 where the table gives one, whichever has the worse effect (1607.4); for dwellings the table gives none except 300 lb on stair treads. Floor live loads may be reduced for large tributary areas by 1607.12; no reduction is applied on this page.

In buildings where partition positions may change, BCP 2021 treats partitions as a live load: allow at least 0.72 kN/m² (15 psf) uniformly distributed, whether or not partitions are shown on the drawings, unless the specified live load is 4.79 kN/m² (80 psf) or more (1607.5). The house live load of 1.92 kN/m² is below that limit, so the allowance applies to light partitions that could be moved.

Fixed brick or block partitions are not movable, so take them as dead load at their actual weight (1606.2), placed where they stand. A 115 mm brick partition on a slab is much heavier than 0.72 kN/m² spread over the floor, so model it as a line load on the slab or on the beam or wall below.

Interior walls and partitions over 1.83 m (6 ft) high must also resist a horizontal load of at least 0.240 kN/m² (5 psf) (1607.16).

A flat RC roof that nobody uses takes the ordinary roof live load of 0.96 kN/m² (20 psf), on the horizontal projection, which 1607.14.2.1 lets you reduce for large tributary areas or steep slopes. Most flat roofs on Pakistani houses are reached by a stair and used for sleeping, drying clothes and water tanks: treat them as occupiable and use the load of the occupancy served, 1.92 kN/m² (40 psf), as floor live load L. Add the weight of water tanks as dead load. Snow is only a design load where BCP Figures 1608.2(1) and 1608.2(2) or a site study give a ground snow load; it may be taken as zero where no snow is reported, as the authority approves (1608.2).

A two-storey house of load-bearing brick walls with cast-in-place RC slabs, a common form in Pakistan. A 225 mm (9 in) interior brick wall runs the length of the house. The first-floor slab and the roof slab each span 3.6 m one way from the exterior walls onto this wall, on both sides, so the wall's tributary width is 3.6 / 2 + 3.6 / 2 = 3.6 m (simple spans; continuity over the wall would raise this). The roof is reached by a stair and used by the household. Wall height between slabs 3.0 m in each storey.

Assumed dead loads (check them for the actual build-up; BCP 2021 asks for actual weights, 1606.2, and gives no table of material weights): RC slab 150 mm at 24 kN/m³ = 3.6 kN/m²; floor finish, screed and ceiling plaster 1.2 kN/m²; roof insulation and waterproofing (mud phuska and brick tiles) with ceiling plaster 2.4 kN/m²; 225 mm brick wall plastered both sides 4.8 kN/m² of wall area. Live loads from Table 1607.1: first floor 1.92 kN/m² (40 psf, item 26, all other areas); roof used by the household 1.92 kN/m² (40 psf, item 27, same as the occupancy served).

Strength combinations from ASCE 7-16 Section 2.3, which BCP 1605.1 refers to (BCP itself does not print them): 1.4D = 1.4 × 67.68 = 94.8 kN/m. 1.2D + 1.6L = 1.2 × 67.68 + 1.6 × 13.82 = 81.2 + 22.1 = 103.3 kN/m. The second governs. Its 0.5(Lr or S or R) term is zero here, because the used roof carries floor live load L, not roof live load Lr. Use 103.3 kN/m to check the brickwork in compression to TMS 402, which BCP 2101.2 refers to, and the strength design of the footing.

Service load, BCP 1605.2 Equation 16-1, D + L + (Lr or S or R): 67.68 + 13.82 = 81.5 kN/m. Use it with the soil's allowable bearing pressure to size the strip footing.

Add the plinth wall and the footing's own weight below ground-floor level. This is a gravity check only: brick walls in Pakistan must also be checked for earthquake load under BCP Section 1613 and ASCE 7, which this example does not cover. No live load reduction is applied.

• Using the 2007 code's live load table. BCP 2021 Table 1607.1 replaces it; take values from the 2021 table.
• Designing a flat roof that the household uses for 0.96 kN/m² (20 psf). A used roof takes the load of the occupancy served, 1.92 kN/m² (40 psf) for a house.
• Spreading fixed brick partitions as the 0.72 kN/m² (15 psf) allowance. That allowance is for movable partitions; heavy fixed partitions are dead load at their actual weight and position.
• Using 1.92 kN/m² for a balcony. Balconies and decks take 1.5 times the load of the area they serve, 2.87 kN/m² (60 psf) off a house's rooms.
• Mixing units: Table 1607.1 is in psf. 40 psf is 1.92 kN/m², not 4 kN/m² or 40 kN/m².
• Checking footing bearing pressure with factored loads, or the brickwork with service loads. Keep factored (ASCE 7 Section 2.3) and service (BCP 1605.2) totals apart.