KENYA STANDARD  DKS 2972 :2022  
ICS 77.140 
First  Edition  
  
 © KEBS 2022   
 LIGHT STEEL FRAME BUILDING  - 
SPECIFICATION  
 
 
 DKS 2972 : 2022  
ii © KEBS 2022  – All rights rese rved 
 TECHNICAL COMMITTEE REPRESENTATION  
The following organizations were represented on the Technical Committee:  
Kenya Industrial Research and Development Institute  
Space and Style Ltd.  
Blackberry House Ltd.  
Consumer Informatio n Network  
Edge & Atelier Ltd.  
Kangemi Jua Kali Association  
Edge & Atelier Ltd.  
Kepsa/Kenya National Federation of Jua Kali  
Sub County Health Services, Kamukunji  
Dedan Kimathi University  
Aluglass Ltd.  
Mabati Rolling Mills Ltd.  
Tile and Carpet Centre Ltd – Top frame Division  
Zenith steel Fabricators -Light Frame  Division  
Kenya Bureau of Standards — Secretariat   
REVISION OF KENYA STANDARDS  
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed.  Suggestions 
for improveme nts to published standards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
© Kenya Bureau of Standards, 2022  
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of  the Laws of Kenya , copyright 
subsists in all Kenya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bure au of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior p ermission in writing 
from the Managing Director.KENYA STANDARD  
 
  DKS 2972 :2022  
ICS ##.###  
First  Edition  
 
© KEBS 2022  – All rights reserved  iii 
   
 LIGHT STEEL FRAME BUILDING    
 
Kenya Bureau of Standards, Popo Road, Off Mombasa Road,  
P.O. Box 54974 - 00200,  Nairobi, Kenya  
 +254 020 6948000, + 254 722202137, + 254 734600471  
 info@kebs.org  
 @KEBS _ke 
 kenya bureau of standards (kebs)  
  
iv © KEBS 2022  – All rights rese rved 
 Foreword  
This Kenya Standard was prepared by the Construction Technology Technical Committee under the guidance 
of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya Burea u of 
Standards  
In development a lot was borrowed from SANS10162 -2: The Structural Use of Steel Part 2: Limit -states 
design of cold -formed steelwork and SANS517: Light steel frame buildingDKS 2972 : 2022     
 
© KEBS 2022 – All rights reserved   
 LIGHT STEEL FRAME BUILDING  
1 Scope  
This standard specifies requireme nts for fabrication and construction of buildings with light steel frames, clad 
and insulated with appropriate materials, including the roofs , walls, floors & foundations  of such 
buildings .  
This standard does not cover doors, windows, services, finishes o r other elements of buildings that are either 
not peculiar to light steel frame buildings or do not have a direct interface with the steel frame.  
2 Normative references  
The following referenced documents referred to in the text in such a way that some or a ll of their content 
constitutes requirements of this document. For dated references, only the edition cited applies. For undated 
references, the latest edition of the referenced document (including any amendments) applies.  
 
3 Terms and definitions  
3.1 Defi nitions  
For the purposes of this document, the following definitions and symbols apply.  
3.1.1 Acceptable  
Acceptable to the parties concluding the purchase contract, as relevant.  
3.1.2 Acoustic Insulation  
Insulation material installed to reduce the transmit tance of sound from one side of the insulation to the other.  
3.1.3 Air Infiltration  
Air movement through a material, component or an assembly into a building  
3.1.4 Roof Batten  
Member fixed to roof trusses or rafters to support roof tiles  OR ROOF SHEETS  
3.1.5 Beam  
Horizontal structural member that supports vertical loads and is subject to flexural stresses.  
3.1.6 Bottom Wall Plate  
Bottom plate: member running along the bottom of a wall frame and resting directly on a foundation wall, 
foundation beam or floor  slab.  
3.1.7 Bracing  
Diagonal members, or diaphragms, that resist lateral movement of members or racking forces (or both).   
ii © KEBS 2022  – All rights rese rved 
 3.1.8 Brandering  
Member fixed to roof trusses or rafters to support the ceiling, and which does not apply to suspended 
ceilings  
3.1.9  Brick Veneer  
Single leaf non -load-bearing brick wall serving as exterior cladding.  
3.1.10 Building Envelope  
Exterior skin of a building, consisting of the floor, external walls, ceiling under roof overhangs, and roof 
cladding.  
3.1.11 Bulk Insulation  
Miner al or synthetic fibre wool in rolls which are available in different densities and thicknesses.  
3.1.12 Chord  
Top (rafter) or bottom member of a truss.  
3.1.13 Competent Person  
Person who is qualified, by virtue of his education, training, experience and con textual knowledge, to 
make a determination regarding the performance of a building or part thereof in relation to a functional 
regulation.  
3.1.14 Domestic Dwelling  
Building used for residential purposes, consisting of one or more dwelling units.  
3.1.15 Ene rgy Efficiency  
Measure of the minimisation of the need to use energy for heating and cooling of buildings.  
3.1.16 Expansion Joint  
Discontinuation between elements, such as wall panels, to allow for relative movement between  
adjoining elements and to preven t stresses arising in the elements from such differential movements.  
3.1.17 Exterior Wall  
Wall forming part of the building envelope, and which is normally load -bearing.  
3.1.18 External Wall Cladding  
Weather resistant external skin of a building, fixed to the light steel frame.  
3.1.19 External Wall Cladding  
Weather resistant external skin of a building, fixed to the light steel frame.  
3.1.20 Fibre Cement Board  
Composite material made of cement, sand and cellulose or synthetic fibres (or both).  
3.1.21 Fire R ating   
© KEBS 2022  – All rights reserved  iii 
  Shortest period for which a building element or building component will comply with the  
requirements for stability, integrity and insulation.  
3.1.22 Fire Resistance  
Ability of a composite floor, wall or ceiling assembly to remain stable when exposed to heat  
generated by fire.  
3.1.23 Glass Wool  
Material made from glass, spun into fibre -like structure.  
NOTE Available in different densities (kilogram per cubic metre) for use as insulation.  
3.1.24 Gypsum Board  
Board with a gypsum plaster core with an enve lope of two layers of paper  
NOTE Gypsum board can be specified to be fire resistant or water resistant.  
3.1.25 Light Steel Frame Building  
Buildings in which the load -bearing structure, comprising the wall framing, columns, beams, trusses, panels or 
any com bination of these, consists of assemblies of thin -walled cold -formed steel sections  
3.1.26 Lintel  
Horizontal member in a wall frame spanning over an opening  
3.1.27 Non -load-bearing Walls  
Wall that is not required to carry gravity or wind loads  
3.1.28 Non -load-Bearing Walls  
Wall that is not required to carry gravity or wind loads  
3.1.29 Open Web Joist  
Parallel -chord truss that supports concentrated or distributed loads, such as floor joists, rafters in a roof and 
lintels.  
3.1.30 Purlin  
Member fixed to roof trusses or rafters to support roof  tiles or  sheeting . (roof battens)  
3.1.31 Racking  
In-plane distortion of a framing module such as a wall or a roof, involving movement of the top  
relative to the bottom, in the plane of the module.  
3.1.32 Reflective Insula tion 
Material with a reflective surface such as a reflective foil laminate capable of reducing radiant heat flow 
due to its high reflectivity and low emissivity.   
iv © KEBS 2022  – All rights rese rved 
 3.1.33 R-value  
Measure of resistance to heat flow of a material or composite element, includin g the effects of any air 
spaces or reflective surfaces (or both).  
NOTE The higher the R-value, the better the ability of the material or composite element to resist the flow of heat through it. R  -
values are expressed using the units, m2·K/W.  
3.1.34 Spacin g 
Unless otherwise specified, the centre -to-centre distance between studs, joists, bearers, trusses,  
battens, purlins or other elements  
3.1.35 Span  
Unless otherwise specified, the centre -to-centre distance between the supports of a beam, truss,  
joist, purl in, batten, rafter or roof.  
3.1.36 Stone Wool  
Material made from stone or slag, spun into fibre -like structure.  
NOTE Available in different densities (expressed using the units, kg/m3) for use as insulation.  
3.1.37 Structural Steel  
All steel which forms pa rt of the structure, including the roof construction, wall frame construction,  
floor and ceiling supports.  
3.1.38 Thermal Break  
Air gap or layer of insulating material between two building components to reduce the transfer of  
heat by conduction.  
3.1.39 The rmal Efficiency  
Ability of a composite building component or assembly (floor, wall, ceiling or roof) to resist heat  
transfer.  
3.1.40 Truss  
Latticed frame supporting the roof and ceiling over the full width of the domestic dwelling.  
3.1.41 Uncontrolled Air Flow  
Unintended movement of air into or through a room or a building.  
3.1.42 Weatherproofing  
Measures taken to prevent the ingress of moisture and to minimise uncontrolled air flow.  
3.1.43 Web Member  
Element of a truss or open web joist other than the top and bottom chord.   
© KEBS 2022  – All rights reserved  v 
  3.1.44 Sheathing  
rigid board fastened directly to the wall studs to provide support for exterior cladding material, to lend 
structural support to the light steel frame members or to enhance the insulation of exterior walls  
3.1.45 wall tie  
bracket or wire connecting brick veneer cladding to the steel frame  
 
Figure 2 Typical Roof Assemblies  
4 Symbols (and abbreviated terms)  
A  summed area supported by a structural member  
cp  resultant coeffici ent for internal and external wind pressure  
cpe  coefficient for external wind pressure  
cpi  coefficient for internal wind pressure  
cr  terrain roughness factor   
d  distance between points  
G  permanent load (own weight of building)  
H  height  
L  span or length   
vi © KEBS 2022  – All rights rese rved 
 qk  uniformly distributed imposed load  
Qk  concentrated imposed load  
qp  peak wind pressure  
s  spacing of elements  
vb  basic wind speed  
w  wind pressure  
W  wind load  
Wr  wind load on roof  
Ww  wind load on wall  
W(down)   downward -acting wind load  
W(up)   upward -acting wind load  
A  roof slope  
Δ  deflection  
Ρ  air density ”. 
5 Materials  
5.1 General  
Materials that have been proven to meet the requirements of the relevant standards, if used 
appropriately in combination with other materials, and installed to an acceptable quality of 
workmanship, a re listed as being ‘acceptable’ in this section.  
5.2 Steel  
Cold formed steel, used for the structures of light steel frame buildings, shall comply with the 
requirements of an internationally recognised standard and shall have a coating at least equivalent in 
corrosion resistance and robustness to 150 g/m2 aluminium -zinc coating (AZ150) or 200g/m2 
galvanizing (Z200)  and AZ100 .  
Light structural steel members shall be manufactured using the prescribed steel strength grade (for 
example, 300 MPa or 550 MPa mini mum yield strength) in accordance with the design specification  
All steel used shall have sufficient formability to allow the cold forming of profiles without any cracking of 
the steel substrate.  
Steel elements shall comply with the dimensional and straigh tness tolerances given in 5.3 
5.3 Tolerances  
5.3.1 Manufacturing and Assembly Tolerances  
The tolerances for cold -formed sections are determined such that the relevant actual sectional properties 
differ by not more than ± 5 % from the design section propert ies. 
The length of a component shall not deviate from its specified length by more than ± 2 mm.   
© KEBS 2022  – All rights reserved  vii 
  A component that is specified to be straight, shall not deviate about any axis from a straight line drawn 
between the end points by more than L/1000 or 6.0 mm, whichever is less.  
The height of assembled roof trusses may not deviate by more than ± 10 mm from the specified  
dimension.  
Assembled wall panels shall each not deviate from the specified dimension by more than:  
Length: +2, -4 mm;  
Height: ± 2 mm.  
5.4 Fasten ers 
Carbon steel fasteners shall be coated with a zinc or inorganic coating (or both) to provide corrosion 
protection similar, under the prevailing conditions, to the metallic coated steel sheet used for the light steel 
cold-formed sections (for example co ating designation AZ150).  
Fasteners, connectors and fixing methods for the steel structure shall comply with the manufacturer’s 
recommendations, supported by international standards.  
Steel components may be assembled by mechanical fasteners (such as bolts,  rivets or screws). Assembly by 
other means (such as metal stitching and clinching) may also be used where suitable.  
Where dissimilar metals are in contact, attention should be paid to insulation of the metals and the selection of 
suitable fasteners in ord er to inhibit galvanic corrosion.  
5.5 Holding Down Devices  
a) The materials for brackets and washers made from galvanised steel sheet, shall have a minimum  coating 
designation AZ150 or Z200   
6 Basis for Design  
6.1.1 General  
The structure shall resist all t he loads the building will be subjected to, including loads deriving from its own 
mass. However, the lateral support provided to steel elements by the non -structural  
elements of the building, such as the wall or roof cladding or the ceilings, may be taken into account in the 
design of these elements, provided that it can be demonstrated that the non -structural elements have 
adequate strength for lending such support, and that the steel structure will not be subjected to loads its 
elements cannot resist with out such lateral support while the non -structural elements are, for whatever 
reason, not in position.  
A clear path shall be discernable for every force, from where the force acts to the foundations, and all 
members and connections along this path shall hav e adequate strength and stiffness to resist the forces 
generated in them without failure, or deflections that exceed the maximum deflections specified in this 
standard.  
6.1.2 Durability  
The design criteria are based on the assumption that the materials use d and their installation and 
maintenance will ensure that components fulfil their intended structural function for the intended life of 
the structure.  
6.2 Resistances of Structural Elements and Connections   
viii © KEBS 2022  – All rights rese rved 
 6.2.1 Design  Standard  
Cold-formed steel components  shall be designed to meet the require ments of KEBS XXXXX  
except where expressly specified differently in this standard.  
6.2.2 Design Properties  
The yield stress and ultimate strength of the steel shall, except for steel with a minimum yield stress of 
550 MPa, be taken as the listed yield stress and ultimate tensile strength for that grade of steel in the 
applicable standard (see 5.2). The yield stress and ultimate strength of any steel for which the 
mechanical properties cannot be proved by means of a mill  test certificate shall not be taken as higher 
than 200 MPa and 365 MPa, respectively.  
Steel with a minimum yield stress of 550 MPa and of elongation less than 8 % may not be used in base 
metal thicknesses exceeding 0,90 mm. For such steel in base metal th icknesses of not less  than 0,60 
mm, the yield stress and tensile strength shall both be taken as 495 MPa, while for base  metal 
thicknesses less than 0,60 mm the yield stress and tensile strength shall both be taken as 410 MPa.   
The coated thickness of galv anised steel sheet may be referred to as the thickness of the sheet. As the 
coating does not add to the strength of the material, designers shall work with the base metal thickness 
as the thickness, determined as follows:  
Bt = Ct - 0,04 mm  
where  
Bt is the base metal thickness, expressed in millimetres;  
Ct  is the coated metal thickness expressed in millimetres.  
The dimensions of a steel section shall be taken as the specified dimensions, which shall be used  
to derive the section properties.  
Due allowance sh all be made for holes, cutaways and other ways in which the strength of an  
element may be impaired, including holes made during or after erection in the structure to  
accommodate services.  
6.3 Design Actions  
6.3.1 General  
Structural design actions and combi nations of actions, in general, shall be in accordance with  
KS XXXX . The simplified actions described in 6.3.2 to 6.3.4 (inclusive), may be used where  
appropriate.  
Construction loads may become critical on some components of an unfinished building and in s uch 
cases shall be accounted for in the design.  
Where loads other than those specified in 6.3 (such as snow loads, seismic loads, or load  
combination(s) containing such loads) are applicable, they shall be accounted for in the design.  
6.3.2 Imposed Loads f or Domestic Dwellings   
© KEBS 2022  – All rights reserved  ix 
  For the design of domestic dwellings, the following characteristic imposed loads may be used, with the 
uniformly distributed load and the concentrated load not necessarily occurring simultaneously:  
a) For roofs, not accessible except for normal maintenance:  
Uniformly distributed load (qk): 0,5 kPa for contributory areas < 3 m2; 
0,25 kPa for contributory areas >15 m2;  
interpolate in -between;  
Concentrated load (Qk): 1,0 kN applied anywhere.  
b) For general floor areas:  
Uniformly distribut ed load (qk): 1,5 kPa, but if the area  A  supported by a single column, wall, beam or girder 
exceeds 20 m2  
qk = {0,3  + 3,1} 1,5 ≥ 0,75 kPa  
    √A 
 
Concentrated load (Qk): 1,5 kN.  
c) Balconies and roofs used for floor type activities 1,0 m or more above gr ound:  
Uniformly distributed load (qk): 4,0 kPa;  
Concentrated load (Qk): 3,0 kN  
d) Lateral horizontal loads applied to balustrades on balconies:  
Uniformly distributed load: 0,5 kN/m applied at the top of the balustrade;  
Concentrated load: 1,0 kN applied at the top of the balustrade.  
6.3.3 Wind Loads  
6.3.3.1 General  
The wind loads used in the design of buildings meeting the geometric limitations of figure 1 may be calculated 
in accordance with 6.3.3.2 and 6.3.3.3.  
6.3.3.2 Peak Wind Speed Pressure  
The peak win d speed pressure qp expressed in kilopascals shall be determined using equation (1).  
qp =      1       .p (1,4 c r vb0) 2 
2000  
 
6.3.3.3 Wind Pressure on Surfaces  
6.3.3.3.1 General  
Wind load on structures and structural elements shall be determined taking in to account the  
simultaneous action of external and internal wind pressures.   
x © KEBS 2022  – All rights rese rved 
 The net pressure on a wall, roof or other element is the difference between the pressures on the  
opposite surfaces taking due account of their signs. Pressure directed towards the surface is taken  
as positive, and suction, directed away from the surface, is taken as negative.  
6.3.3.3.2 Internal Wind Pressure  
For a building without a wall with a dominant opening, the internal pressure coefficient cpi shall be taken 
as +0,2 or -0,3, w hichever causes the more severe loading in combination with the  
appropriate external wind pressure.  
For a building with a dominant opening in the windward wall, the internal pressure coefficient cpi shall 
be taken as +0,75. If this dominant opening can be assumed to be closed during storm  
conditions, the internal pressure coefficient cpi may be taken as +0,6.  
A wall shall be regarded as containing a dominant opening if the area of its openings is at least  
twice the sum of the area of openings and leakages i n the remaining exterior walls of the building.  
The wind pressure, w (expressed in kilopascals), on walls and ceilings in the building shall be  
determined using equation (2) and the appropriate internal pressure coefficient cpi, as defined above.  
w  = qp.c pi 
6.3.3.3.3 External Wind pressure on Walls  
The external pressure coefficients cpe for buildings and parts of buildings depend on the size of the 
loaded area A, which is the tributary area of the structure that produces the wind action effect in the 
struc tural component to be calculated. The external pressure coefficients are given for loaded areas of 
1 m2 and 10 m2 in the tables for the appropriate building configurations as cpe.1 , for local coefficients, 
and cpe,10, for overall coefficients, respectivel y. 
Values for cpe.1 , are intended for the design of small elements and fixings with an area per element of 
1 m2 or less, such as cladding or roofing elements. Values for cpe,10 may be used for the design of the 
overall load bearing structure of buildings.  
The external wind pressure w (measured in kilopascal) on the vertical walls of the building shall be 
determined using equation (3) and the appropriate external pressure coefficients  
we  =  qp.cpe  
 6.3.3.3.4 Resultant Wind Pressure  
The resultant wind press ure w on walls or roofs is the sum of the internal and external wind  
pressures, and shall be calculated using equation (4) and the appropriate internal and external  
pressure coefficients  
 W = qp (Cpe + Cpi)  
6.3.3.3.5 Wind Pressure on Roof Overhangs  
The pre ssure on the underside of the roof overhang is equal to the pressure for the zone of the   
© KEBS 2022  – All rights reserved  xi 
  vertical wall directly connected to the overhang; the pressure at the top side of the roof overhang is equal to 
the pressure of the zone, defined for the roof.  
6.3.3.3 .6 External Wind Pressure on Mono -pitch Roofs  
The roof, including protruding parts, shall be divided into zones  
6.3.3.3.7 External Wind Pressure on Duo -pitched Roofs  
The roof, including protruding parts, shall be divided into zones  
6.3.3.3.8 Local Wind Pre ssure at Corners of Roofs  
The local external pressure coefficient for the square extending for 2 m in both directions horizontally from the 
corners of a roof shall be taken as -2,9. This pressure coefficient shall be used in conjunction with the 
pressure o n the underside of the roof for the design of purlins, battens and sheeting and their fixings in this 
area.  
6.3.4 Actions During Construction  
Critical loads and combinations of loads during construction may be different from those for the  
complete structur e. These include:  
a) Imposed load arising from the stacking of construction materials.  
b) Imposed load arising from people working on the incomplete frame.  
c) The wind load during construction may be based on a design wind speed with a mean return  
period o f 10 years. The wind load effects on the incomplete structure may be different from that  
on the complete structure, for example, supported walls may become free standing walls during  
construction, or roof sheeting in the internal zone of a roof could becom e edge sheeting, and  
therefore need temporary bracing.  
d) Unbalanced loads arising during construction.  
e) Loads on roofs during construction:  
uniformly distributed load (qk): 0,50 kPa for contributory areas <3,0 m2, or 0,25kPa for contributory areas ˃ 15 
m2, with linear interpolation in -between.  
6.4 Design Criteria  
6.4.1 Strength and Stability  
The building as a whole, and its parts, shall be des igned to prevent overturning, uplift, sliding or  
excessive settlement, as well as failure of either the steel elements or the non -structural materials  
by collapse, tearing, unacceptable cracking or local deformations.  
The design load for the ultimate limit  state shall be that combination of (factored) loads which  
produce the most adverse effect on the building.   
xii © KEBS 2022  – All rights rese rved 
 6.4.2 Serviceability  
The design criteria for serviceability shall be taken from, but not limited to, the criteria given in  
sections 6.6 to 6 .8 (incl usive).  
6.5 Methods of Assessment of Resistances  
6.5.1 General  
The assessment of the resistance to loads of a structural element or structural assembly shall be  
carried out by one of the following methods:  
a) calculation;  
b) testing; or  
c) combination of c alculation and testing.  
6.6 Roof members  
6.6.1 General  
All roof roof members including purlins or roof battens, roof trusses or rafters, ceiling brandering and 
bracing shall be designed to act together as a structural unit to transfer all the loads imposed  on the 
roof, including forces resulting from the fact that the roof provides lateral support to the walls under the 
action of wind load to appropriate supports.  
6.6.2 Roof Battens and Purlins  
6.6.2.1 Design for strength  
The combinations used for the deter mination of the design load effects for strength are:  
 1,2 Gk + 1,6 Qk  
 1,2 Gk + 1,6 qk  
 0,9 Gk + 1,3 Wk(up)  
 1,2 Gk + 1,3 Wk(down)  
6.6.2.2 Design for Serviceability  
For satisfactory performance under each issue of concern, the calculated value of the serv iceability 
parameter under the nominated load(s), shall be kept within the limiting value of the response.  
6.6.3 Roof trusses or Rafters  
6.6.3.1 Design for Strength  
The combinations used for the determination of the design load effects for strength are:  
1,2 Gk + 1,6 Qk  
 1,2 Gk + 1,6 qk  
 0,9 Gk + 1,3 Wk(up)   
© KEBS 2022  – All rights reserved  xiii 
   1,2 Gk + 1,3 Wk(down)  
6.6.3.2 Design for Serviceability  
For satisfactory performance under each issue of concern, the calculated value of each parameter  
in the table below shall be kept within the limiti ng value of the response, under the action of the appropriate 
load.  
 
 
6.6.4 Ceiling Brandering  
6.6.4.1 Design for strength  
The load combinations used for the determination of the design load effects for strength are:  
 0,9 G k + 1,3 W k(up)  
 1,2 G k + 1,3 W k(down)  
6.6.4.2 Design for Serviceability  
For satisfactory performance under each issue of concern, the calculated value of the parameter  
under the nominated load shall be kept within the limiting value of the response, as shown in the  
table below.   
xiv © KEBS 2022  – All rights rese rved 
  
6.6.5 Roof Connections and Roof Bracing  
Connections in the roof structure shall be designed in accordance with 6 .6.6. Roof bracing shall be 
designed in accordance with 6 .6.7 
6.7. Connections  
6.7.1 General  
Connection elements include co nnection components (frame anchors, brackets, straps, plates,  
parts of members to be connected) and connectors (welds, bolts, screws, rivets, clinches, nails,  
structural adhesives).  
6.7.2 Design Criteria  
a) Connection elements shall be capable of resisting  design load effects arising in the connection as the 
result of the design load effects in the connecting members and their supports.  
b) Deformations at the connection shall be within the acceptable limits.  
c) Appropriate allowance shall be made  for any ec centrici ty at the connection.  
d) Appropriate allowance shall be made for any local effects at the connections (for example, stress 
concentration and local buckling).  
e) The uplift forces due to wind load shall be assessed and adequate tie -down shall be pro vided to 
resist these forces.  
6.8 Bracing  
6.8.1 General  
Temporary bracing may be required during construction.  
6.8.2 Roof Bracing  
6.8.2.1 General  
All roof members including roof battens or purlins, roof trusses or rafters, brandering and bracing shall be 
designed to act together as a structural unit to transfer all the loads imposed on the roof to appropriate 
supports. For lateral restraints, it is generally assumed that the roof battens or purlins will provide the lateral 
support for the top chords of the trusses and the ceiling brandering will provide the lateral support for the 
bottom chords of the trusses.  
6.8.2.2 Truss Bracing  
 
© KEBS 2022  – All rights reserved  xv 
  6.8.2.2.1 Top Chord Bracing  
The requirement for a top chord bracing system is to transfer the forces generated in the top chord restraints 
(usually by battens or purlins) back to the supporting structures. The loads to be considered are those 
required to restrain the top chord against buckling.  
Diagonal bracing shall be installed at an angle of between 30° and 60° to the truss top chord or  
rafter, and it shall not sag more than 1/500 of the distance between supports. Where tension  
devices are used to remove excessive sag, care shall be taken not to over -tension the braces.  
6.8.2.2.2 Bottom Chord Bracing  
Bottom chord bracing is requi red to restrain bottom chords against lateral buckling under wind uplift. It shall be 
fixed to each truss and to the wall in the same manner as for top chord bracing.  
The loads to be considered are those required to restrain the bottom chord against buckli ng, which may be 
taken as equal to 0,02 times the maximum compressive force in the bottom chord, as well as wind load on 
walls supported at the bottom chord level.  
A planar ceiling consisting of panels screwed to brandering, which is in turn screwed to the  bottom chords of 
the trusses, may be regarded as providing adequate bracing to these chords.  
6.8.2.2.3 Web Bracing  
Where the truss design requires bracing of the web members, acceptable bracing, properly  
supported and connected, shall be provided.  
6.9 Tes ting 
6.9.1 General  
Tests of steel and steel elements or assemblies shall be carried  out as specified in Ks xxxxx . The design 
resistance of an element, connection or assembly may alternatively be determined by testing. Only full size 
prototypes of an elemen t, connection or assembly shall be used in tests.  
6.9.2 Coefficient of Variation  
The coefficient of variation of structural characteristics ( ksc), refers to the variability of the total population of 
the production units. This includes the total populatio n variation due to fabrication (ksc)and material ( km). It 
can be approximated as follows:  
ksc = √(kf2 + km2) 
6.9.3 Establishment of Design Values for a Specific Product Using Prototype Testing  
6.9.3.1 General  
When the design resistance Rd, for a specific product is established by prototype testing of that  
product the following conditions shall be satisfied:  
a) the minimum number of tests shall be 3;  
b) the design value Rd shall satisfy:  
Rd  ≤ (Rmin . lkt)   
xvi © KEBS 2022  – All rights rese rved 
 NOTE: The condition of the product under test shoul d be the same as the condition of the product in 
use. 
6.9.3.2 Interpolation of Values Obtained by Prototype Testing  
When prototype testing is conducted for a range of a specific parameter (for example span), to  
establish design values for a speci fic produc t in accordance with 6 .9.3.1, it is permissible to  
interpolate the obtained results for that parameter provided that there is no change in structural  
behaviour (for example no change in collapse mode) within the interpolating range.  
No extrapolation of tes t values is permitted.  
6.10 Construction of the steel frame  
6.10.1 Introduction  
Buildings can be highly vulnerable during construction. An incomplete building is still required to be safe 
for the people on site. The actions that need to be taken depend on the method of  construction.  
6.10.2 Factors to be considered during construction  
The following factors shall be considered:  
a) The partially complete structure may be subjected to a variety of loadings  
b) Regulatory safety requirements for workers in accord ance with the relevant national legislation (see 
foreword).  
c) Provision of scaffolding and barriers, particularly those that rely on the building frame for support.  
d) Temporary bracing and tie -down during the installation of permanent bracing and tie -down. 
Particular care should be taken to provide adequate temporary bracing for the lower storey of  
multi -storey construction where racking loads are significantly higher than those in single storey  
buildings.  
6.11 Tolerances  
6.11.1  Installation tolerances  
6.11.1.1  Attachment to supporting structure  
For load -bearing walls (including shear panels), gaps between the bottom plate and the concrete  
slab greater than 3 mm shall be packed with load -bearing shims under each stud.  
For non -load bearing walls, gaps great er than 3 mm shall be packed with load -bearing shims or grouted at 
jamb studs and points where the bottom plate is fastened to the slab. Where the gap under the bottom plate 
exceeds 10 mm the space between the bottom plate and the slab shall be filled with  grout after installation of 
the shims.  
For the attachment of floor joists, bearers, trusses and rafters to walls, where the gap exceeds  
3 mm, the gap shall be packed with load -bearing shims.   
© KEBS 2022  – All rights reserved  xvii 
  6.11.1.2 Walls  
Walls shall be positioned within 5 mm from their specified position.  
Walls and studs shall not deviate from the vertical by more than h/600 or 3 mm, whichever is greater (where h 
is the height of the wall frame).  
Walls, specified as straight, shall not deviate from a straight line by more than 5 mm over a 
3 m length. Where wall panels join to form a continuous wall, the critical face or faces of the panel may not 
deviate by more than ± 2 mm at the joint.  
The flatness of an individual wall that is to be lined shall be such that when a 1,8 m long straight  
edge is placed parallel to the wall face, the maximum deviation from the straight edge does not  
exceed 3 mm over 90 % of the area, and does not exceed 4 mm over the remaining area.  
6.11.1.2  Trusses, Rafters, Ceiling Joists and Floor Members  
Trusses, rafters , ceiling joists and floor members shall be positioned within 20 mm from their specified 
position.  
Trusses, rafters, ceiling joists and floor members shall be installed so that they will not deviate from a straight 
line by more than L/500 where L is the le ngth of the member  
The difference in the level of points on adjacent members that are intended to be on the same level shall not 
exceed 1/150 of the spacing of the members or 6 mm, whichever is less.  
Out of plumb at any point along the length of the truss from top to bottom, shall not exceed h/100 unless the 
trusses are specifically designed to be installed out of plumb  
The flatness of the floor surface shall be within ± 10 mm over the entire room, but not exceeding  
± 5 mm over any 3 m length, unless specif ically designed with a slope. Abutting floors between  
rooms shall be aligned, unless specifically designed otherwise.  
When members such as joists, rafter trusses and structural wall studs (above or below a wall plate) are 
designed to be vertically aligned,  the centre lines of the members shall not be more than 20 mm apart.  
6.12 Durability and Corrosion  
6.12.1  Steel Structure  
Steel covered by wall or roof cladding, or surrounded by sub -floor walling, and not within 500 m of the sea, as 
well as steel that is not covered by cladding or surrounded by sub -floor walling, and not within 10 km of the 
sea or within a heavy industrial area, shall be continuous hot -dip galvanized sheeting with minimum coating 
class Z200, or a coating with corrosion resistance at least equivalent to 100 g/m2 galvanising, per side. An 
appropriate higher level of corrosion protection is required for steel structures located closer to the sea or 
within heavy industrially polluted areas.  
Wherever galvanised steel has been welded or cut by fl ame, the affected areas shall be painted  
with a zinc -rich paint having at least 85 % of zinc in the dry film.  
6.12.2 Fasteners  
6.12.2.1  The minimum specification for corrosion protection of fasteners is supplied in the table below:   
xviii © KEBS 2022  – All rights rese rved 
  
6.12.2.2  Test for compliance with coating class requirements: Screws shall be driven into a  
galvanized sheet of at least 15 mm thickness, then removed and mounted on an inert material for  
testing. The significant surface (i.e. head and un -driven shank ) shall be evaluated. Salt fog tests  
shall be made in accordance with K S xxxx , with an additional 240 hours of UV exposure before this for 
fasteners with organic coatings. The UV requirements shall be in accordance with ISO 11997 -2, as follows:  
a) Lamps an d wavelength: UVB 313/280 nm  
b) Cycle: 4 h UV/60 °C, 4 h condensation/50 °C  
For C1 after exposure for 72 h, C2 after 240 h, and C3 after 1 000 h, no more than 5 % of the  
significant exposed surface shall show red rust and there shall be no blistering of th e coating.  
6.12.2.3  Fasteners of the coating types in table below comply with the test requirements for the  
respective coating classes.  
 
© KEBS 2022  – All rights reserved  xix 
   
6.12.2.4  Fasteners not inside the building envelope and not washed by rain (for example und er 
overhangs) in marine and industrial environments, require additional protection against corrosion, such  as 
organic coatings.  
6.12.2.5  Fasteners or the packaging (or both) should be acceptably marked to show compliance.  
6.12.2.6  Manufacturers of rivets s hould provide evidence that rivets, once installed, have durability required by 
the design, i.e. life expectancy equivalent to that of the materials being connected and compatibility with those 
materials.  
6.13 Support of Wall Cupboards and Fittings  
Nogging s or other structural elements of sufficient strength shall be provided as required to support fittings 
such as kitchen cupboards or sanitary fittings and taps.  
6.14 Earthing  
The steel frame shall be properly electrically earthed to comply with KENBSXX ___ ___. 
7 Special  Wall,  Roofs and Suspended Floors  
6.1 Scope  
The requirements of this section cover the cladding, insulation, waterproofing and other materials 
attached to or installed between the elements of the steel frame. Windows, doors and other installa tions 
for ventilation such as, natural lighting are excluded. All buildings shall be designed to meet the 
requirements of the relevant national legislation for such buildings, and any additional applicable 
requirements.  
6.2 General Requirements  
6.2.1 Damp and Weatherproofing  
 
xx © KEBS 2022  – All rights rese rved 
 Roofs, floors and external walls shall prevent the ingress of moisture from outside the building  
envelope that can affect the health or comfort of occupants.  
7.2.2 Durability  
The building shall, with appropriate maintenance, be able to survive for its design life.  
7.2.3 Energy Efficiency  
7.2.3.1 General  
The building shall facilitate, through its thermal performance, the efficient use of energy for artificial 
heating or cooling, while providing an acceptable indoor environment for its occ upants or the processes 
conducted in the building.  
A number of factors impact on the thermal efficiency of a building, such as roof colour, orientation of the 
building, area and type of glazing, shading for windows, sealing against uncontrolled air flow an d 
insulation of walls, ceilings and floors. Only the limitation of uncontrolled air flow and insulation are 
addressed in this standard.  
7.2.3.2 External walls  
In order to meet the requirement of 7.2.3.1, the external walls of a domestic dwelling shall meet  the 
thermal insulation requirements in the table below. Where a garage is attached to a domestic dwelling, 
either the outer wall of the garage, or the wall separating the garage from the domestic dwelling, shall 
meet the requirements in the table below.  
 
 
© KEBS 2022  – All rights reserved  xxi 
   
 
7.2.3.3 Roofs and Ceilings  
The combination of roof and ceiling insulation of a domestic dwelling shall meet the thermal  
insulation requirements in the table below.  
 
xxii © KEBS 2022  – All rights rese rved 
  
 
7.2.3.4 Floors  
7.2.3.4.1  With the exception of climate zone 5, a concrete slab -on-ground shall have insulation  
installed around the vertical edge of its perimeter which shall  
a) have an R -value of not le ss than 1,0  
b) be water resistant in order to retain its thermal insulation properties,  
c) be continuous from the adjacent finished ground level  
1) to a depth of not less than 300 mm, and  
2) for the full depth of the vertical edge of the concrete slab -on-ground,  
d) with an in -slab heating system, shall be insulated underneath the slab with insulation having a  
R-value of not less than 1,0.  
7.2.3.4.2  With the exception of climate zone 5, a suspended floor that is part of a building’s  
 
© KEBS 2022  – All rights reserved  xxiii 
  envelope shall have insul ation installed  
a) for climate zones 1 and 2, with a partially or completely unenclosed exterior perimeter, which  
shall achieve a R -value of 1,5.  
b) for climate zones 3, 4 and 6, with a partially or completely unenclosed exterior perimeter, which shall 
achieve a R -value of 1,0.  
c) with an in -slab heating system, around the vertical edge of its perimeter and underneath the slab, having a 
R -value of not less than 1,0.  
d) The insulation shall be water resistant in order to retain its thermal insulation prop erties.  
7.2.4 Acoustic insulation  
The acoustic insulation in a building shall ensure that its occupants can use it for its normal  
purposes without being unduly disturbed by noise coming from adjacent rooms or from outside, or being 
concerned that they may cause disturbance to people not in the same room.  
The requirements for acoustic insulation for the walls of a domestic dwelling are contained in  
the table below.  
 
The acoustic insulation for floors between habitable rooms in dom estic dwellings shall meet the  
requirements in the table below.  
 
xxiv © KEBS 2022  – All rights rese rved 
  
6.2.5 Fire Resistance  
The required fire resistances of the elements of a domestic dwelling are given in the table below.  
 
6.2.6 Air Inf iltration  
The uncontrolled movement of air through the shell of the building shall be minimized, to enhance the 
acoustic and thermal performance and energy efficiency of the building. Openings in walls such as for 
doors and windows, and abutments against c eilings and floors shall be sealed by caulking, and the use 
of sealants, skirtings, architraves and cornices.  
6.2.7 Robustness  
The fabric of the building shall be robust enough to survive deliberate or accidental impact of a  
magnitude that could reasonably  be expected, caused by human agents, animals or the weather,  
with no or minimal damage.  
6.3 Roofs and Ceilings  
NOTE: The R -value of roofing insulation is obtained by adding the R -values of different insulation media together.  
6.3.1 General Requirements  
In an aggressive industrial or marine (within 10 km from the sea) environment, exposed parts of  
trusses and purlins under the eaves shall be coated with an acceptable paint coating to enhance  
 
© KEBS 2022  – All rights reserved  xxv 
  the corrosion resistance of the galvanized sheet.  
6.3.2 Deemed -to-satisfy Thermal Insulation Requirements  
The table in 6.2.3.3 shows the minimum insulation requirements for roof -and-ceiling system for the various 
climate zones.  
In regions 3 and 5 the required R -value of the thermal insulation may be reduced by 0,5 if t he roof surface is 
light in colour, i.e. ranging from dull grey (weathered galvanised sheet) to cream and white.  
6.3.3 Added Insulation  
Required added insulation may be installed under the cladding or above the ceiling lining, (or both). See table 
A in 6.2 .3.2 for R -values of different insulation materials.  
If reflective foil is used, an air gap of at least 25 mm shall be maintained between the heat source  
and the foil.  
The R -values of reflective foil used in different roof or ceiling applications are prov ided in table B of 6.2.3.3.  
6.3.4 Typical Construction Details  
6.3.4.1 General  
The typical construction details in 6.3.4.1 to 6.3.4.4 (inclusive), are deemed to satisfy the requirements given 
in 6.2, however, proof of compl iance should be supplied by the m aterial  
manufacturers. Other methods and materials may be used, subject to proof of compliance with the 
requirements of 6.2.  
6.3.4.2 Ceiling Linings  
The R -value of roof and ceiling materials attached to the underside of rafters is as follows:  
Metal claddin g = 0,35 m2·K/W;  
Cement/clay tiles = 0,37 m2·K/W.  
The fire rating is 30 min.  
The ceiling lining attached to the underside of rafters is shown in the figure below,  
Ceiling lining attached to underside of rafters  
The ceiling lining attached to the underside  of battens or purlins is shown in the figure below.  
Ceiling lining attached to underside of battens or purlins  
6.3.4.3 Pitched Roof and Horizontal Ceilings  
6.3.4.3.1 Ventilated Roof Spaces  
The R -value of roofing materials for ventilated roof spaces (see figure below) is as follows:  
Cement/clay tiles = 0,22 m2.K/W;  
Steel roof cladding = 0,20 m2.K/W;   
xxvi © KEBS 2022  – All rights rese rved 
 The fire rating is 30 min.  
 Pitched roof and horizontal ceiling — Ventilated roof space  
NOTE: For added insulation options see the table below.  
 6.3.4.3.2 Unve ntilated Roof Spaces  
The R -value of roofing materials for unventilated roof spaces (see figure below) is as follows:  
Metal cladding = 0,38 m2·K/W;  
Clay/concrete tiles (with underlay) = 0,40 m2. K/W.  
The fire rating is 30 min.  
 Pitched roof and horizontal c eiling – Unventilated roof space  
     
8 Marking  
Tags, paint, ink marks or other suitable means shall be used to identify members of unassembled 
components or parts. Erection marks that damage the material or finished surfaces exposed to view 
shall not be used. Each structural member shall be legibly marked with the following information:  
a. The manufacturer’s name or trademark or both  
b. The Batch identification  
c. Thickness in mm  
d. Coating designation  
e. Manufacturer’s Standardization Mark (SM) permit number  
 
  
© KEBS 2022  – All rights reserved  xxvii 
  ANNEXURE 1  
(normative)  
 
Roof Construction  
A.1 Typical roof construction  
The guide in table A.1 can be used for load calculations for typical roof construction.  
 
Typical ly, asphalt shingles should be fixed / stuck on top of water proofing applied to OSB or similar boards 
which are laid on top of the LGS roof battens.  
Roof battens are spaced suitably for the boards (generally, 600mm c/cs for boards measuring 1.2m x 2.4 m) 
 
 
 
 
