Steelwork

Also see:
6.1
6.3
6.4

6.5.2Design guidance

Steelwork shall be designed to support and transmit loads to the supporting structure without undue movement or deflection. Issues to be taken into account include:

  1. support of masonry partitions
  2. support of timber floors, including trimmed openings.

Support of masonry partitions

Masonry partitions may be supported by steelwork selected in accordance with this chapter. Care should be taken to avoid masonry supported by steelwork being partially supported or out of true.

Conditions for Tables 1 and 2

Steel beams in accordance with Tables 1 and 2 of this chapter will generally be acceptable for the support of masonry partitions where the following conditions are met:

  • the partition is of one of the types detailed in Table 1.
  • the partition is built centrally on the steelwork beam and is less than 2.7m in height.
  • the span of the steel beam is less than 4m.
  • steel beams only support the weight of the partition and self-weight.
  • brickwork or blockwork (workface size 440mm x 215mm) supporting the steel beam has a minimum strength of 2.8N/mm² and the beam supports do not occur over a door or window opening.
  • padstones are provided where required, in accordance with Table 6.

Where any of the conditions are not met, steelwork should be designed in accordance with Technical Requirement R5.

Method of applying tables:

  • ensure that all conditions apply.
  • identify the masonry partition construction and thickness.
  • use Table 1 to establish the load per metre run.
  • check the span of the beam(s).
  • use Table 2 to determine a suitable steel section size.
  • use Table 6 to determine if padstones are required.

An example is provided at the end of this chapter.

Table 1: Load of partition to be supported

Table 2: Size of steel beam supporting partition

Partition load (from Table 1) (kN/m run)Clear span of beam (m)Smallest suitable universal beam size (mm x mm x kg/m)
Less than 3Up to 4
Over 4
127 x 76 x 13
(2)
3 to 5Up to 3
3 to 3.5
3.5 to 4
Over 4
127 x 76 x 13
152 x 89 x 16
178 x 102 x 19
(2)
5 to 7Up to 2.5
2.5 to 3
3 to 4
Over 4
127 x 76 x 13
152 x 89 x 16
178 x 102 x 19
(2)

Notes

1 For spans up to 4m, universal column 152mm x 152mm x 23kg/m (smallest size available) may be used.
2 For spans over 4m, beams should be designed by an engineer in accordance with Technical Requirement R5.

Support of timber floors, including trimmed openings

Timber floors may be supported by steelwork selected in accordance with this chapter and should include full allowance for the shrinkage of timber joists.

Conditions for Tables 3 and 7

Steel beams in accordance with Tables 3 and 7 will be acceptable to NHBC for the support of floors, where the following conditions are met:

  • the floor construction is of decking (softwood boarding, chipboard, oriented strand board or plywood) on timber joists and the ceiling is plasterboard with a plaster skim coat or a plastic finish (Artex or similar).
  • aAllowance has been made of 0.5kN/m2 for self-weight (floor and ceiling load).
  • the floor does not support masonry partitions.
  • any lightweight partition, such as plasterboard on timber studwork or proprietary product, is non load-bearing.
  • padstones are provided where required in accordance with Table 6.
  • clear span of beam does not exceed 4.4m.
  • connections between steelwork beams are in accordance with Clause 6.5.6, or are designed by an engineer.
  • the floor support is one of the methods shown in Figure 1.

Where any of the conditions are not met, steelwork should be designed by an engineer in accordance with Technical Requirement R5.

Method of applying tables:

  • use Figure 1 to determine the area supported by the beam(s).
  • check the span of the beam(s).
  • use Table 3 to determine a suitable steel section size.
  • use Table 7 to determine if padstones are required.
  • where steel beam-to-steel connections are required, refer to the connections in Clause 6.5.6.

Ensure that all conditions apply.

Figure 1: Effective areas supported by steel beams

Where any area shown as ‘void’ contains a staircase, add 2m2 to the effective area supported by any beam which fully or partially supports that staircase.

Table 3: Size of steel beam supporting timber floor