Reference number  
DRS 186-2: 201 8 
© RSB 2018 
   
 RWANDA 
STANDARD  DRS 
186-2 
 
Second  edition  
 
Code of practice for fire safety  
of building — 
Part 2:  
Details of construction  DRS 186-2:201 8 
 
 
ii Error! Reference source not found.  
  DRS 186 -2: 201 8 
iii                 ©RSB 2018 All rights reserved  
 
 In order to match with technological development and to keep continuous progress in industries, 
Standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
 
 
 
 
© RSB 2018 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electro nic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to  
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
Tel. +250 252 586103/582945  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  DRS 186 -2: 201 8 
©RSB 2018 All rights reserved                  iv 
 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................. v 
1 Scope  ................................ ................................ ................................ ................................ ...................... 1 
2 Normative references  ................................ ................................ ................................ ............................ 1 
3 Terms and definitions  ................................ ................................ ................................ ........................... 1 
4 Types of Construction  ................................ ................................ ................................ ........................... 2 
5 Walls  ................................ ................................ ................................ ................................ ........................ 3 
6 Columns and Beams  ................................ ................................ ................................ ............................. 7 
7 Floors and Roofs  ................................ ................................ ................................ ................................ ...7 
8 Air-Conditioning  ................................ ................................ ................................ ................................ .. 15 
9 Smoke and fire venting  ................................ ................................ ................................ ......................  17 
10 Service ducts  ................................ ................................ ................................ ................................ ....... 17 
11 Basements  ................................ ................................ ................................ ................................ ...........  17 
12 Chimneys  ................................ ................................ ................................ ................................ .............  18 
13 Staircases and lifts  ................................ ................................ ................................ .............................  19 
13.1  Staircases  ................................ ................................ ................................ ................................ ............  19 
13.2  Lifts  ................................ ................................ ................................ ................................ ......................  19 
14 Refuge area  ................................ ................................ ................................ ................................ .........  20 
15 Refuge Chutes  ................................ ................................ ................................ ................................ ..... 20 
16 Drainage  ................................ ................................ ................................ ................................ ...............  20 
17 Electrical Services  ................................ ................................ ................................ ..............................  20 
18 Finishes  ................................ ................................ ................................ ................................ ...............  21 
 DRS 186 -2: 201 8 
v                 ©RSB 2018 All rights reserved  
 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on  the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 186-2 was prepared by Technical Committee RSB/TC 28, Fire Safety  
In the preparation of this standard, reference was made to the following standard s: 
IS 1642; Fire Safety of Buildings (General): Details of constructio n-Code of practice  
The assistance delivered from the above source is hereby acknowledged with thanks.  
This second edition cancels and replaces the first edition (RS  186-2: 2013) of which has been technically 
revised . 
DRS 186 consists of the following parts , under the general title Code of practice  for fire safety of building  
Part 1: General Principles of Fire Grading and Classification  
Part 2: Details of Construction  
Part 3: Fire Safety in public buildings  
Part 4: Selection , installation and mainten ance of automatic fire detection and alarm system  
Part 5: Exit requirements and personal hazard  DRS 186 -2: 201 8 
©RSB 2018 All rights reserved                  vi 
 
  
Committee membership  
The following organizations were represented on the Technical Committee on Fire Safety (R SB/TC 28) in the  
preparation of this standard.  
City of Kigali  
College of Science and Technology  
CABLELINE  
Energy Utility Corporation Limited  
ELECTRICOM  
ISCO  
Institute of Engineers Rwanda  
Ministry of Disaster Management and Refugees  
Ministry of Infrastructure  
Rwanda Housing Authority (RHA)  
Rwanda Motor  Ltd 
Rwanda National Police  
REAL  
Société Rwandaise d’Assurance (SONARWA)  
SONATUBES  
Rwanda Standards Board (RSB) - Secretariat  DRS 186 -2: 201 8 
vii                 ©RSB 2018 All rights reserved  
 
 DRS 186 -2: 201 8 
1                 ©RSB 2018 All rights reserved  
 
 Code of practice for fire safety of building  — Part 2: Details of 
construction  
1 Scope  
This standard lays down the essential requ irements of fire safety of buildings with respect to details of 
construction.  
2 Normative references  
The following referenced documents are indispensable for the application 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.  
RS 186 -5, Code of Practice for Fire Safety of Building ― Part 5: Exit requirements and personal hazards  
3 Terms and definitions  
For the purposes of this standard, the follow ing terms and definitions apply . 
3.1  
Fire Resistance  
Ability of an element of building constru ction, component for structure to fulfil, for a stated period of time, 
the required stability, fire integrity and/or thermal insulation and/or other expected duty in a standard fire 
resistance test  
3.2  
Fire Separation  
The distance in metres measured from  any other building on the site, or from other site or from the 
opposite side of street or other public space to the building for the purpose of preventing the spread of 
fire. 
3.3  
Fire Resisting Wall  
The wall that provides complete separation of one build ing from another or part of a building from 
another part of the same building to prevent any communicator of fire or any access or heat transmission 
to wall itself which may cause or assist in the combustion of materials of the side opposite to that portio n 
which may be on fire.  
3.4 
Venting fire  
The process of inducting heat and smoke to leave a building a s quickly as possible by such pa rts that 
lateral spread of fire and heat is checked, fire fighting operations are facilitated and minimum fire 
damage is c aused.   
©RSB 2018 All rights reserved                  2 
 
 4 Types of Construction  
4.1 The design of any building and the type of materials used in its construction are important factors 
in making the building resistant to a complete burn -out and in preventing the rapid spread of fire, smoke 
or fumes, which m ay otherwise contribute to the loss of lives and property.  
4.2 The types of construction according to fire resistance are classified into four categories   as defined 
in RS 186 -1. The fire resistance ratings for various types of construction for structural and non -structural 
members should be as given in Table 1.   
Table 1  — Fire Resistance Ratings of Structural Elements (in Hours)  
 
Structural Element  Type of Construction  
Type 
1 Type 
2 Type 
3 Type 
4 
     
 
Exterior 
walls  Fire separation  
less than 3.7m  Bearing  4 2 2 1 
Non-bearing  2 ½ 1 1 
Fire separation of 3.7 m or More 
but  
less than 9 m  Bearing  4 2 2 1 
Non-bearing  ½ 1 1 1 
Fire separation of 9 m or more  Bearing  4 2 2 1 
Non-bearing  1 1 1 1 
Fire walls  4 2 2 2 
Fire separation assemblies (like File check doors)  4 2 2 2 
Fire enclosures of exit ways, exit - 
Way hallways, and stairways  2 2 2 2 
Shaft other than exit way elevator  
Hoist ways  2 2 2 2 
Exit way access corridors  1 1 1 1 
Vertical separation of tenant spaces  1 1 1 1 
Dwelling unit separ ation  1 1 1 1 
Non-load bearing partitions  At least half an hour  
Interior hearing walls, bearing  Supporting more than one floor  
Partition, columns, girders, 
trusses (other than roof trusses)  4 2 2 2 
Supporting one  
and framing floor only  3 1½ 1 1 
Suppo rting a roof only  3 1½ 1 1 
Structural members support walls  3 1½ 1   1 DRS 186 -2: 201 8 
3                 ©RSB 2018 All rights reserved  
 
 Floor construction including walls  3 1½ 1   1 
Roof construction  5 m or less in height to lowest 
member  2 1½ 1 1 
More than 5m but  
less than 6.7 m in height to 
lowest member  1 1 1 1 
6.7 m or more in height to lowest 
member   0 0 0 0 
Note: Fire Resistance Ratings of Type 5 wooden frame shall be based on fire rated coating or cover 
extends the fire resistance rating of structural members at least 1 hour  
4.3 For buildings above 15 m i n height non -combustible materials should be used for construction and 
the internal walls of staircases should be of brick work or reinforced concrete or any other mate rial of 
construction with mini mum of 2 h  rating. The walls for the chimney shall be of T ype 1 or Type 2 
construction depending upon whether the gas temperature is above 200 °C or less.  
4.4 When tes t is done according to relevant approved national or international standard, the  fire 
resistance of an element of structure or combination of eleme nts is determined from one of the follo wing 
three methods:  
a) Information as established by research data;  
b) Direct application of the results of fire resistance t est on an element of structures;  and  
c) On the basis for calculating the fire resi stance of a struct ural element ; except for columns  or walls . 
5 Walls  
5.1 The fire ratings of some types of constructi ons for walls are given in Tables 2 to 7. The 
specifications of materials should be so selected as to give these ratings:   
©RSB 2018 All rights reserved                  4 
 
  
Table 2 — Masonry walls: Solid (required for resisting fire from one side at a time; see 5.1) 
Nature of Construction and Materials.  Minimum Thickness (mm), Excluding any Finish, for a  
fire Resistance (Hours) of :  
        Load Bearing           Non-Load Bearing  
1           1½          2          3            4       1           1½         2           3           4  
Reinforced  a cement concrete  120       140        160       200       240  
(25)b      (25)b      (25)b    (25)b      (25)b  
 
Unreinforced cement concrete  150        175      -            -             -  
Non-fines concrete with:  
a) 13 mm cement/sand or 
gypsum/sand.  
b) 13 mm lightweight aggregate 
gypsum Plaster    
150        150       50         150       150  
 
150       150       150        150       150  
Bricks of clay:  
a) Without fin ish. 
b) With 13mm  lightweight 
aggregate  Gypsum plaster   
90       100        100       170      170  
90        90           90        100      100   
75        90         100         170      170 
75        90          90          90         100  
Bricks of sa nd lime:  
a) Without finish  
b)  With 13 mm lightweight 
aggregate Gypsum plaster   
90       100         100       190     190  
90         90         90          100     100   
75        90         100         170       170 
75        90          90           90        100 
Blocks of concrete:  
a) Without finish  
b) With 13 mm lightweight 
aggregate Gypsum plaster  
c) With 13 mm cement/sand or 
gypsum/ Sand.   
90        100       100         —       — 
 
90        90         90         100      100  
75         90         100         140       150 
75         75         75            90        100 
 
75          90……… 90        100       140 
Blocks of lightweight concrete:  
a) Without finish  
b) With 13 mm light weight 
aggregate Gypsum plaster  
a) c) With 13 mm cement/sand or 
gypsum/ Sand   
90        100        100       140       150  
90          90          90        100       100  
 
  
75          75          75         125        140  
50          63          75          75         75 
 
75         75           75          90         100  
Blocks of aerated conc rete: 
a) Without finish  
b) With 13 mm lightweight 
aggregate Gypsum plaster   
90           100      100       140        180  
90           90       100…….100        150   
50          63          63         75         100  
a Walls containing at least 1 percent of ver tical reinforcement  
b Minimum thickness of actual cover to reinforcement  DRS 186 -2: 201 8 
5                 ©RSB 2018 All rights reserved  
 
  
Table 3 — Masonry w alls: Hollows (r equired for resisting fire  from one side at a time ) 
Nature of Construction  
and Materials  Minimum Thickness , Excluding any Finish, for a Fire  
Resistance (Hours) of:  
Load Bearing  Non-Load Bearing  
1  1½ 2 3 4 1½  1  1½  2  3  4  
Bricks of clay:  
a) a)Without finish  
 
b) b)With 13 mm lightweight 
aggregate Gypsum plaster   
170  
170  
170  
200  
200  
75  
100  
100  
170  
170  
200 
100 100 170 170 170 75 75 90 100 100 170 
Block s of concrete:  
a) a)Without finish  
 
b) With 13 mm cement/sand or 
gypsum/ sand.  
 
c) c) With 13 mm lightweight 
aggregate gypsum plaster   
  
  
  
  
  
90   
125  
125  
140  
140  
150 
      
90   
125  
125  
140  
140  
140 
190  200 200 ━ ━ 75  90 90 100 125 125 
Blocks of lightweight concrete:  
a) Without finish  
b) With 13 mm cement/sand or 
gypsum/ Sand  
c) With 13 mm lightweight 
aggregate Gypsum plaster   
100 
  
100  
100  
—  
—  
75  
75 
 
63  
905 
75 
 
63  
90 
75 
 
75  
100 
100 
 
75  
140 
140 
 
90  
150 
140 
 
100 
 
Table 4 — Framed c onstruction, load bearing (required for resist ing fire from one side at a time ) 
 Nature of Construction and Materials/  
Faced on Each Side with Timber Studs at Centres not exceeding 
600 mm  Minimum Thickness (mm) of 
Protection  for a Fir e Resistance 
of 1 h  
Plasterboard layers with joints staggered, joints in outer layer  taped and 
filled ━Total thickness for each face  25 
Lightweight aggregate gypsum plaster One layer of 12.7 mm 
plasterboard with a finish of  13 
Metal lath and plaster, thickness of plaster  Lightweight 
aggregate gypsum 
plaster :  22 
Sanded gypsum 
plaster (metal 
lathing gra de) 13  
©RSB 2018 All rights reserved                  6 
 
  
Table 5 — Framed Construction, Non -Load Bearing (Required to Resist Fire from One Side at a 
Time)  
 
Nature of Construction and Materials/Steel or 
Timber Frame at Centres not Exceeding 600 mm, 
Facing on Both Sides of   
 Stud  
Construction  Minimum Th ickness (mm) of  
Protection for a Fire  
Resistance of  
½ h         1h 1½ h         2h 
Dry lining with materials fixed direct  to studs (without plaster finish):  
One layer of plasterboard with taped and filled joints  Timber or steel  12.7    
Two layers of  plasterboard with Joints staggered, 
joints in outer Thickness for each face Layer taped 
and filed —Total  thickness for each face  Timber or steel  19 25   
One layer of wood wool slabs  Timber  25    
One layer of chipboard or of plywood  Timber or steel  18    
Lining with materials fixed direct to  studs, with plaster finish  
Plasterboard of thickness :     
1) Finish With no less than 5 mm gypsum 
plaster  Timber or steel  
 9.5    
2) With not less than 13 m gypsum plaster 
finish   12.7   
Wet finish  
Metal lath and plaster, thickness of Plaster:      
1) plaster Sanded gypsum plaster  Timber or steel  13    
2) Lightweight aggregate gypsum  Timber   13 19 25 
steel   13   
Table 6 — Framed external walls load bearing (required for resisting  fire from one side at a time)  
Nature of Construction and Materials  Minimum Thickness ( mm) of Protection for a 
Fire Resistance of 1 h  
Timber studs at centres not exceeding 600 mm With internal 
linings of plasterboard la yers with joints in outer layer  taped 
and filled, total thickness  31 
 
5.2 The separating walls should be carried through the roof to a height of at least 60 cm above except 
in the case of reinforced brick/concrete slab roof where it should be bonded flash with a top level of the 
slab. At the time of designing openings, particu lar attention should be paid to all such factors as will limit 
fire spread through these openings. Every opening in the wall should be protected by fire resisting doors 
having the fir e rating of not less than 1 h . Similar protection should also be done in other openings like 
rope races , motor alley ways, staircases, etc. of rating not less than 2 h . However, for Types 1, Type 2,  
Type 3 construction, a doorway or opening in a separating wall of any floor should be limited to 56m2 in 
area with a maximum heigh t of 2.75 m and maximum width of 2 m.  DRS 186 -2: 201 8 
7                 ©RSB 2018 All rights reserved  
 
 5.3 When building(s) and /or compartment(s) are separated by separating wall(s) and there is a 
verandah on one or more sides of such building(s) and/or compartment(s), it is necessary that the 
separating wall should be  built out across the verandah and be carried through the roof of the same; 
otherwise the building(s) and/or compartment(s) should be regarded as having internal communication 
and, therefore, subject to danger of spread of fire.  
5.4 When opening in walls a re provided to allow cable, etc, the space around cables and the wall 
should be protected in accordance with approved standard. However, such space in case of openings 
provided to allow plumbing/gas/steam pipes and similar services should be scaled with fi lter material of 
fire rating not less than that of the walls in which these are situated.  
5.5 Where openings are permitted, they should not exceed three -fourths of the area of the wall in case 
of an external wall.  
5.6 A separating wall should be supported in a vertical line by a similar separating wall through all 
storeys below. The separating wall should be carried and bonded to the floor of appropriate fire -resisting 
construction.  
5.7 When a separating wall runs parallel to the axis of the north light ope ning or gabled roof, the 
screen wall should be carried through, and 60 cm above the top of the north light opening except in 
cases where the screen wall becomes of such a height that horizontal distance between the north light 
opening and the roof of the a djoining building and/or compartment or between two sloping faces of the 
two consecutive roofs at the level of the top of the screen wall, is at least 6 m.  If, however, the separating 
wall is at right angles to the axis of the north light opening or the ga bled roof, the ‘saw tooth’ gaps should 
be bricked up and screen wall extended above the ridge of the north light or the gabled roof.  
5.8 All separating walls should be built out to extend 15 cm beyond the eaves of the roof so as to 
effectively cut off the roofs of the parts so separated. The eaves should be cut away on each side of this 
extension of the separating wall. If there is an opening on both sides of the separating within 3 m of the  
wall, those on one side should  be bricked up to full thickness of wall, or an alternative should be provided 
with fire resisting doors of fi re rating not less than of 2 h for walls of 4 h  rating and 1 hour for other rating.  
5.9 Common wooden roof members (trusses, joists and purlins) should not pass through the 
separatin g walls but they may be embedded there -in provided they do not extend more than 22.5 cm into 
wall and are separated from the similar roof member in the adjoining building by at least 11 cm or solid 
wall material.  
5.10 Partition is used for separating  secto rs or rooms of a building  but is not expected to have a fire 
resistance equal to any of the values. In fact, in practice it should not be considered otherwise than 
structure of light dimension and strength consistent with the purpose for which it is used. The minimum 
fire rating of the partition is given in Table 1.  
6 Columns and Beams  
The fire ratings of some types of con struction are given in Table 8, Table 9, Table 12 and Table 13. The 
specifications or materials should  be so selected as to give  ratings  there-in. 
7 Floors and Roofs  
7.1 The fire ratings of some types of construction is given in Tables 10, 11, 14, 15, and 16; This 
specifications of materials should be so selected so as to give these ratings.   
©RSB 2018 All rights reserved                  8 
 
 Table 7 .A — Framed  external walls non -load bearing r equired to resist fire only from inside the 
building  
S/No.  Nature of Construction and 
Materials  Minimum Thickness (mm) of Protection For a 
Modified Fire Residence of  
 
   ½ h        1h   1½h          2h   3h   4h 
Steel frame with an external cladding of   
Non-combustible sheets (excluding sheet steel),  
With a steel supporting framework and internal  
lining of:   
 
1 Metal lath and plaster thickness  of 
plaster:  
 a) Sanded gypsum plaster 
(metal lathing grade)  13 13     
b) Lightweight: aggregate 
gypsum plaster  10 13 15 15 15 19 
2 Two layer of plasterboard with joints 
staggered Joints in outer layer taped 
and filed -Total Thickness   
21  
32     
3 Plasterboard of thickness:        
 a) With not less than 5 mm 
gypsum plaster finish  12.7      
b) With not less than 13 mm 
gypsum plaster finish  9.5      
c) With not less than 10 mm 
lightweight aggregate 
gypsum plaster.  9.5      
4 One layer of wood/wool slabs without 
finish   50     
5 One layer of compressed straw 
building slabs:        
 a) Without finish  50      
b) With not less than 5 mm 
gypsum plaster finish   50     
6 Aerated concrete blocks  50 50 63 63 75 100 
7  Bricks of clay:        
 a) Without finish  75 75 90 90 100 100 
b)  With not less than 13 mum 
lightweight Aggregate 
gypsum plaster    75 75 90 90 
 
 
 
 DRS 186 -2: 201 8 
9                 ©RSB 2018 All rights reserved  
 
 Table 7 .B — Framed ext ernal walls non -load bearing required to resist fire only from inside the 
building;  
SNo.  Nature of construction and materials  
 Maximum thickness (mm) of 
protection to provide sufficient 
insulation to achieve a modified 
fire resistance of up to 4 h.  
Steel  frame with an external cladding of sheet steel fully lapped, steel bolted 
and fixed to steel sheeting rails, with timber or steel supporting framework and 
internal lining of:   
1 Metal lath and plaster thickness of plaster:   
a) Sanded gypsum plaster (metal  lathing Grade)  13 
 
b) Lightweight aggregate gypsum plaster  10 
2 One layer of plasterboard with joints taped  and filled.  12.7 
3 Plasterboard of thickness, with not less  than 5 mm gypsum plaster 
finish  9.5 
4 One layer of wood/wool slabs  25 
5 One layer of  compressed straw building slabs  50 
6 One layer of chipboard (fibreboard  ) or of plywood   18 
7 Aerated concrete blocks  50 
8 Bricks of clay  75 
9 Any internal decorative lining with a cavity fill  independently 
supported and retained in position of minera l fibre insulating material 
(excluding glass) or a density of 48 kg/m3 50 
 
Table 7 .C Framed Walls Non -Load Bearing Required to Resist Fire Only from Inside the Building  
SN° Nature of construction and materials  
Timber frame with external cladding of weat her 
Baoding or external plywood, 9.5 mm with an  
Internal lining of:  Minimum thickness 
(mm) of protection for 
a fire resistance of 1½ 
h 
1 Plasterboard not less than 9.5 mm thick, finished With:   
c) Gypsum plaster   
d) Lightweight aggregate gypsum plaster  13 
10 
2 Plasterboard not less than 12.7 mm thick, finished  With:   
a) Gypsum plaster  10 
b) Lightweight aggregate gypsum plaster  10 
 
  
©RSB 2018 All rights reserved                  10 
 
  
Table 8  — Reinforced concrete columns  (see 6.1) 
S/N 
Nature of Construction and 
Materials  Minimum  Dimension (m), Excluding a ny Finish, for a Fire 
Resistance of  
 ½ h 1 h 1½ 2h 3h 4h 
1 Full exposed  Width  150 200 250 300 400 450 
cover  20 25 30 35 35 35 
2 50 percent exposed  width  125 160 200 200 300 350 
cover  20 25 25 25 30 35 
3 One face exposed  Thickness  100 120 140 160 200 240 
cover  20 25 25 25 25 25 
 
Table 9  — Concrete Beams (se e 6.1) 
S/N 
Nature of Construction and 
Materials  Minimum Dimensions (mm),, Excluding any Finish, For a 
Fire Resistance of  
 ½ h 1 h 1½ 2h 3h 4h 
1 Reinforced concrete (simply 
supported)  Width 80 120 150 200 240 280 
cover  20 30 40 60 70 80 
2 Reinforced concrete 
(continuous)  width  80 80 120 150 200 240 
cover  20 20 35 50 60 70 
3 Pre-stressed concrete (simply 
supported)  width  100 120 150 200 240 280 
cover  25 40 55 70 80 90 
4 Pre-stressed concrete 
(continuous)  width  80 100 120 150 200 240 
cover  20 30 40 55 70 80 
 
Table 10 — Concrete floors  (see 7.1)  
S/N 
Nature of Construction and 
Materials  Minimum Dimensions (mm), Excluding any Finish  
for a Fire Resistance of  
 ½ h 1 h 1½ 2h 3h 4h 
1 Reinforced concrete (simply 
supported)  Thickness  75 95 110 125 150 170 
cover  15 20 25 35 45 55 
2 Reinforced concrete 
(continuous)  Thickness  75 95 110 125 150 170 
cover  15 20 20 25 35 45 DRS 186 -2: 201 8 
11                 ©RSB 2018 All rights reserved  
 
  
Table 11  — Concrete  floors:  Ribbed open soffit (see 7.1) 
S/N 
Nature of Construction and 
Materials  Minimum Dimension (mm), Excluding any finish, for a fire 
resistance of 
 ½ h 1 h 1½ 2h 3h 4h 
1 Reinforced concrete (simply 
supported)    Thickness  70 90 105 115 135 150 
Width  75 90 110 125 150 175 
cover  15 25 35 45 55 65 
2 Reinforced concrete 
(continuous)  Thickness  70 90 105 115 135 150 
Width  75 80 90 110 125 150 
cover  15 20 - 35 45 55 
 
Table 12  — Encased steel columns, 203 mm x 203 mm  
(Protection applied on four sides; see 6.1)  
 
S/N Nature of Con struction and Materials  Minimum Thickness (mm) of 
Protection  For a Modified Fire 
Residence of  
 1 h       1½h         2h        3h         4h       
Hollow protection (without an air cavity over the flanges) :       
1 aMetal lathing with towelled  light wei ght  aggregate gypsum 
plaster   13 
 15 20 32  
2 Plasterboard with 1*6 mm wire binding at 100 mm pitch, 
finished with Lightweight aggregate gypsum plaster not less 
than the thickness Specified:  10 13 15 15 15 
 a) 9.5 mm plasterboard  10 15    
 b) 19 mm plasterb oard 10 13 20   
3 Solid bricks of clay, composition sand  lime, reinforced in 
every  Horizontal joint, unplastered  50 
 50 
 50 
 75 
 100 
 
5 aerated concrete blocks  60 60 60   
6 Solid blocks of lightweight concrete hollow protections (with an 
air cavity ov er the flanges)  50 50 50 60 75 
Solid protection       
1 Concrete, not leaner than 1:2: 4 mix (unplastered):       
 a) Concrete not assumed to be load bearing, reinforced)   
25  
25  
25  
40  
60 
 b) Concrete assumed to be load bearing  50 50 50 75 75 
2 bLightweigh t concrete § not learner than 1 : 2 : 4 (mix) 
(unplastered)  concrete not assumed to be load bearing, 
reinforced  25 25 25 40 60  
©RSB 2018 All rights reserved                  12 
 
 a So fixed, or designed, as to allow full penetration for mechanical bond.  
b Reinforcement shall consist of steel binding wire n ot less than 2*3 mm in thickness or a steel mesh weighing not less than 
0*5 kg/m2. In concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction  
 
Table 13 — Encased Steel Beams, 406 mm x 176 mm   
(Protection applied on three sides; see 6.1)  
S/N Nature of Construction and Materials  Minimum Thickness (mm) of Protection for a 
fire resistance of  
  ½ h        1 h           1½         2 h         3 h        4 h 
Hollow protection (without an air cavity beneath the 
lower flang e).  
 1 * Metal lathing with trowelled lightweight aggregate  
Gypsum plaster (metal lathing grade)Plasterboard 
with  
1*6 mm wire binding at 100 mm pitch, finished with 
lightweight aggregate gypsum  plaster not less than 
the thickness specified:   13 13 15 20 25  
 9*5 mm plasterboard  10 10 15    
 19 mm plasterboard  10 10 13 20   
Solid protection        
1 Concrete, not leaner than 1:2 : 4 mix (unplastered):   
  
  
  
  
  
 
 a) Concrete not assumed to be load bearing, 
reinforced  25 25 25 25 50 75 
 b) Concrete assum ed to be load bearing  50 50 50 50 75 75 
2 Lightweight concrete 4not learner than 1 : 2 : 4 (mix) 
Unplastered  25 25 25 25 40 60 
1 So fixed, or designed, as to allow full penetration for mechanical bond.  
2 Where wire binding cannot be used, expert advice s hould be south regarding alternative methods of support to enable the lower 
edges of the plasterboard to be fixed together and to the lower flange, and for the top edge of the plasterboard to be held i n 
position.  
3 Reinforcement shall consist of steel bind ing wire not less than 2.3 mm in thickness or a steel mesh weighing not less than 0.5 
kg/m2. In concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction.  
4 Concrete not assumed to be load bearing, reinforced 
 
Table 1 4 — Timber floors ━ tongued and grooved boarding, or sheets of tongued and grooved 
plywood or wood chipboard, of not less than 21 mm finished thickness  
S/N Nature of Construction and Materials  
 Minimum Thickness (mm) 
of Protection for a Fire 
Resistance of : 
½ h         1 h        2 h  
37 mm (minimum) timber joists with a ceiling of:   
1 Timber lathing and plaster, plaster of thickness  15   
2 Metal lathing and plaster, thickness of plaster:     
Sanded gypsum plaster (metal lathing grade)  15   DRS 186 -2: 201 8 
13                 ©RSB 2018 All rights reserved  
 
 Lightweight aggregate gypsum plaster  13 13 25 
3 One layer of plasterboard with taped and filled 
joints  12.7   
4 Two layers of plasterboard with joints staggered, 
joints in outer layer taped and filled total thickness   
19  
31  
5 One layer of plasterboard not less th an 9 .5 mm 
thick, finished with:     
Gypsum plaster  5   
Sanded gypsum plaster  13   
Lightweight aggregate gypsum plaster  13   
6 One layer of plasterboard not less than 12*7 mm 
thick, finished with:     
Gypsum plaster  5   
Lightweight aggregate gyps um plaster  10   
7 One layer of asbestos insulating board with any 
transverse joints  backed by fillets of asbestos 
insulating board not less than 9 mm thick, or by 
timber  9 12  
 
Table 15 — Timber floors ━ Tongued and grooved boarding, or sheets of tongued and grooved 
plyw ood or wood chipboard, of not less than 15 mm finished thickness  (see 7.1)  
 
S/N Nature of construction and materials  Minimum Thickness 
(mm) of Protection for 
fire resistance of  
1½ 1 h 2 h 
37 mm (minimum) timber joists with a ceiling of :     
1 Timber lathing and plaster, plaster of thickness  15   
2 Metal lathing and plaster, thickness of plaster for     
Sanded gypsum plaster (metal lathing grade)  15   
Lightweight aggregate gypsum p laster  13 13 25 
3 One layer of plasterboard with joints taped and filled and 
backed by timber  12.7   
4 Two layers of plasterboard with joints staggered, joints in 
outer layer taped and filled total thickness  22 31  
5 One layer of plasterboard not less t han 9*5mm thick, finish 
with:     
6 Gypsum plaster  5   
Sanded gypsum plaster  15 
    
©RSB 2018 All rights reserved                  14 
 
 Lightweight aggregate gypsum plaster  13   
7 One layer of plasterboard not less than 9*5 mm thick,  
Finish with:   
   
Gypsum plaster  5   
Lightweight aggregate gypsum  plaster  10   
 
Table 16 — Timber floors ━ Any structurally suitable flooring of timber or particle  boards (see 
7.1) 
S/N Nature of Construction and Materials  Minimum thickness 
(mm) of protection 
for a fire resistance 
of: 
½ h 1 h 
37 mm  (minimum) timber joists with a ceiling of :    
 1 Timber lathing and plaster, plaster of thickness.  15  
 2 Metal lathing and plaster, thickness of plaster for:  
   
 a) Sanded gypsum plaster (metal lathing grade)  15  
 b) Lightweight aggregate gypsum plaster  13 19 
3 One layer of plasterboard with joints taped and fi lled and 
backed by timber  2*7  
4 Two layers of plasterboard with joints staggered, joints in 
outer layer taped  
and filled total thickness  25  
5 Two layers of plasterboard, each not less than 9*5 mm thick, 
joints between Boards staggered and outer layer f inished 
with gypsum plaster  5  
6 One layer of plasterboard not less than 9.5 mm thick, 
finished with:    
 a) Sanded gypsum plaster  13  
 b) Lightweight aggregate gypsum plaster  15 
7 One layer of plasterboard not less than 12*7 mm thick, 
finished with:    
 a) Sanded gypsum plaster  15  
 b) Lightweight aggregate gypsum plaster  13 
7.2 In case of a building of more than 15 m in height, all floors should be compartmented with area not 
exceeding 750 m2 by a separation  wall with 2 h  fire rating. F or floors h aving provisi on of sprinklers, t he 
area may be increased by 50 %. In long buildings, the fire separation walls should be at distance not 
exceeding 40 m. For dep artmental stores, shopping centr es and similar occupancies,  the area may be 
reduced to 500 m2. Where this is not possible provision of the sprinklers should be kept with appropriate 
spacing.  DRS 186 -2: 201 8 
15                 ©RSB 2018 All rights reserved  
 
 7.3 A surface covering of non -combustible and non -toxic material should be laid directly on the 
incombustible floor. Wood flooring may be laid directly on such surface cov ering or directly on such floor 
provided that in either case there is no intervening space and that any wood fillets for affixing such 
flooring is bedded not more than 2.5 cm  thickness  in the non -combustible floor.  
7.4 In the case of building used for storage  purposes, the floor surface should conform to the above, in 
addition, it should be at least 15 cm above the ground level or the level of the door sills whichever is 
higher, and should slant towards the doors. An opening through a floor should comply with the following:  
a) at the time of designing openings particular attention should be paid to all such factors which will limit 
fire spread through these openings.  
b) when opening in floors are provide d to allow cable, etc, the space around cable and the floor shou ld 
be protected according to the provision of relevant national or international standard; However s uch 
space in case of openings provided to allow plumbing/gas/steam pipes and similar services should 
be sealed with filler material of fire rating not le ss than 1 h . 
c) openings for steam, gas and/or water pipes and electrical conduits, whether of iron or earthenware, 
should have a radial clearance, to allow for any heat expansion, not greater than 3 mm.  
d) the enclosure for staircases and hoists should be construc ted entirely of brick, concrete or of 
reinforced concrete or similar materia l of construction having 2 h  rating. Every opening from the 
enclosure on to a roof used as floor or to any other part of the building should be fitted with a fire 
resistant doo r of rating not less than 1 h . 
e) if any staircase or hoist extends to the top storey of a  building the roof of which is not a roof used as 
a floor, the enclosing walls should be carried t hrough and at least 45 cm above  the roof of the 
building and a skylight or window glazed should be provided above the roof of the building. 
Alternatively, if the roof of the building is used as a floor; it should comply with (d), and this should 
also apply for any furnace or motor chamber communicating with the sta ircase or hoist  enclosure.  
7.5 Linings or false ceilings should not be permissible in buildings and in situations  where permitted, 
such additions should not detract in any way from minimum fire rating of half an hour.  In some cases, 
requiring provision of skylights, moni tor lights or north lights in the roofs and where these are necessary, 
the glazings should be of glass in metal frames for fire rating of half an hour minimum.   
7.6 Composite roofs may be used over as addition to the roofs of buildings as a weather proofin g, but 
should not be considered as a roof in itself that is, without the support of a non -combustible construction 
beneath, unless it is of n ot less than half an hour fire resistance.  
8 Air-Conditioning  
8.1 Air-conditioning systems should be so installed and  maintained as to minimize the danger of 
spread of fire, smoke or fumes thereby from one floor or fire area to another, or from outside into any 
occupied building or structure.  
8.2 Air-conditioning systems circulating air to more than one floor area should  be provided with 
dampers designed to close automatically in case of fire and thereby prevent spread of fire or smoke. 
Such a system should also be provided with automatic controls to stop fans in case of in which case 
these should be designed to remain in  operation.   
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 8.3 Air–conditioning systems serving large places of assembly (over 1 000 persons), large depart -
mental stores or hotels with over 100 rooms in a single block should be provided with effective means for 
preventing circulation of smoke through t he system in the case of fire in air filters or from other sources 
drawn into the system even though there is insufficient heat to actuate heat sensitive devices controlling 
fans or dampers. Such means should consist of approved effective smoke detectors . 
8.4 Air-conditioning should conform to the following:  
a) escape routes like staircases, common corridors, lift lobbies, etc, should no t be used as return air 
passage;  
b) the ducting should be constructed of metal in ac cordance with relevant national standard;  
c) wherever the ducts pass through fire walls or floors, the opening around the ducts should be sealed 
with fire resisting materials of same rating as of walls/floo rs; 
d) as far as possible, metallic ducts should be used even for the return air instead o f space ab ove the 
false ceiling;  
e) the material used for insulating the duct system (inside or outside) should be of flam e resistant and 
non-conductor of heat ; 
f) area more than 750 m2 on individual floor should be segregated by a fire wall and automatic fire 
dampers for  isolation should be provided;  and 
g) in case of more than one floor, automatic fire dampers arrangement should be providing by ducting 
on each  floor for isolation purposes . Where plenums  used for return air passage, ceiling and its 
fixtures and air filters o f the air handling units should be flame resistant [(see 8.4 (e)]. Inspection 
panels should be provided in the main trucking. No combustible material should be fixed nearer than 
15 cm to any duct unless such ducting is properly enclosed and protected with flame resistant 
material.  
h) The fire dampers should be located in and return air ducts passages at the following points 
automatically operate and simultaneously switch off air handling fans:  
1) at the fire separation wall,  
2) where ducts/passages enter the centr al vertical shaft,  
3) where the ducts pass through floor, and  
4) at the inlet of supply air duct and the  return air duct of each compartment on every floor.  
8.5 In case of buildings more than 24 m in height in non -ventilated lobbics corridors, smoke extraction 
shaft should be provided. The automatic fire damper should be so arranged so as to close by gravity in a 
direction of movement and to remain tightly closed upon operation.  DRS 186 -2: 201 8 
17                 ©RSB 2018 All rights reserved  
 
 9 Smoke and  fire v enting  
9.1 Provision has to be made for venting allows escape of hot  gases and smoke release by accidental 
burning of combustible material stored or are being processed inside a building, and will give ample time 
for all the inmates to escape before the roof collapses either in part or  wholly in the event of fire.  
Provisi ons in this regard are essential for industrial buildings; details of which are  covered in a separate 
standard. The form of vent should be a ventilator -cum-exhaust which in addition to the requisite grading 
of fire rating is easily openable . 
9.2 Smoke vent ing facilities, where required for safe use of exits in windowless buildings, underground 
structures, large area factories, departmental store, domestic dwelling, theatres, cinemas, lecture halls, 
and  where required  should be automatic in action.  
9.3 Natu ral draft smoke venting should utilize roof vents or vents in walls at or near the ceiling level; 
such vents should be normally open, or if closed, should be designed for automatic opening in case of 
fire, by release of heat smoke sensitive elements, break age of glass, or melting of plastic under the 
influence of heat; or by other approved methods . 
9.4 Where smoke venting facilities are installed for purposes of exit safety, these should be adequate 
to prevent dangerous accumulation of smoke during the peri od of time necessary to eva cuate the area 
served, using available exit facilities with a margin of safety to allow for unforeseen contingencies.  
9.5 The discharge apertures of all natural draft smoke vents should be so arranged as to be readily 
susceptible  to opening by fire service personnel.  
9.6 Power operated smoke exhausting systems may be substituted for natural draft vents  
9.7 In case of buildings more than 15 m in height the staircase should be ventilated to the atmosphere 
at each landing and a vent  at the top, the vent openings should be 0.5 m in the external wall and top.  
If the staircase cannot be ventilated because of location or other reasons, the provision should be made 
for pressurization (50 Pa) to be separated automatically with the fire al arm. The roof of the shaft in the 
latter case should be I m above the surrounding roofs. Glazing or glass bricks should not be used in the 
staircase.  
10 Service ducts 
10.1 Service ducts should be enclosed by walls and doors (if any) of 2 hours fire ra ting; if  ducts are 
larger than 1  m3 the floor should seal than, but provide suitable openings for the pipes to pass through, 
with the gaps sealed.  
10.2 A vent opening at the top of the service shaft should be provided between one -fourth and one -half 
of the area of  the shaft.  
11 Basements  
11.1 Each basement should be separately ventilated. Vents with cross -sectional area not less than 2. 5 
% of the floor area , spread evenly round the perimeter of the basement , should be provided in the form 
of grills or breakable stall board lights or pavement lights or by way of shafts .   
©RSB 2018 All rights reserved                  18 
 
 Alternatively, a system of air inlets should be provided at basement floor level and smoke outlets at 
basement ceiling level.  
Inlets and extractors may be terminated at ground level with stall board or  pavement lights as before, but 
ducts to convey fresh air to the basement floor level have to be laid.  
Stall board and pavement lights should be in positions easily accessible to the fire  brigade and clearly 
marked “SMO KE OUTLET”, or “AIR INLET” with an i ndication of area served at or near the opening.  
11.2 The staircase of basements should be of enclosed type having fire resistance of not less than 2 
hours and should be situated at the periphery of the basement to be entered at ground level only from 
the open air and in such positions that smoke from any fire in the basement should not obstruct and exit 
serving the ground and upper storeys of the building and should communicate with basement through a 
lobby provided with fire resisting self -closing doors o f 1 hour fire resistance. If  the travel distance 
exceeds 18. 50 m, additional star  cases should be provided at proper places.  
11.3 In multi -level basements, intake ducts may serve all basement levels, but each basement and 
basement compartment should have s eparate smoke outlet duct or ducts.  
Mechanical extractors for smoke venting from low basement levels should also be provided, with 
provision of automatic and manual operation of system actuation of heat/smoke detectors or sprinklers.  
Mechanical extractor s shall have an inter -locking arrangement, such  that extractors continue to operate 
and supply fans stop automatically with the actuation of fire detectors.  
Mechanical extractors shall have an alternative source of supply. Ventilating ducts should be inte grated 
with the structure and made out of brick masonry or RCC as far as possible and when this duct crosses 
the transformer area or electrical switch board, fire dampers should be provided.  
Basement:/sub -basement should not be used for storage, cooking p urposes, garage and shop unless 
provision is made for sprinkler system. If cut  out, openings in the basements should be protected by 
automatic spray in the event of a fire.  
12 Chimneys  
Over and above the provisions given in 4.2, the following provisions shoul d be followed:  
a) a clearance of at least 4 cm between the outer surface of the chimney and any adjacent combustible 
material forming part of a wa ll lining enclosing the chimney;  
b) the fire resistance of any structure surrounding a flew or flew pipe should be n ot less than that for 
external walls. In the case of flew pipe there should be an air space between it and the surrounding 
structure of sufficient width to permit access to the  pipe for inspection and repair;  
c) when a flue pipe passes though any other room o r an enclosed roof space it should be protected by 
structure having a fire resista nce equal to the external walls;  
d) the chimney excluding the pot should be carried to a minimum height of 1 m above the highest poin t 
of its junction with the roof;  DRS 186 -2: 201 8 
19                 ©RSB 2018 All rights reserved  
 
 e) the outlet of a flue from domestic appliance having a roof covering sh ould be at least 2. 5 m in a  
horizontal plain from the roof of any structure bu ilt upon the roof or at least 0. 6 m higher than any 
ridge within 2. 5 m; 
f) if the roof covering is not  fire resistant, n o flue outlet should be lower than the ridge for the highest 
point of the roof or less th an 1 m above any ridge within 2. 5 m; and  
g) where a metal chimney passes through a roof covering which is not fire resistant, it shall be guarded 
by a suitable iron or me tal thimble extending not less than 22.5 cm above and below roof 
construction and of a size to provide not less than 15 cm clearance on all sides of chimneys.  
13 Staircases a nd lifts 
13.1 Staircases  
The details with regard to the provisions of stairc ases have been  given in RS 186 -5.  
13.2 Lifts   
13.2.1  The general requirements for the provision of lifts should be as follows:  
a) walls of lifts and enclosures shou ld have a fire rating of 2 h ; lift shaft should have a vent at the top of 
area not less than 0.2 m2; 
b) lift motor r oom should be located preferably on top of the shaft and separated from the  shaft by the 
floor of the room;  
c) landing doors in lifts and enclosures should have a fire re sistance of not less than 1h;  
d) the number of lifts in one lift tank should not exceed 4. I ndividual shafts in a bank  (of two rows)  
should b e separated by a wall of 2 h fire rating;  
e) lift care door should have a fire resistanc e rating of not less than 1 h;  
f) collapsible gates should not be used for lifts and  if used  should have doors with fi re resi stance of at 
least 1 h;  
g) in opening other than the lift job by door in the lobby enclosure wall should also have the mini mum 
fire resistance of one hour;  
h) exit from the lift lobby, if located in the core of the building should be to a self -closing stop door of 
minimum 1  h fire rating;  
i) lifts should not norma lly communicate to the basement;  
j) suitable arrangements, such as providing slope in the floor of lift lobby should be made to prevent 
water used during fire fighting  on any landi ng from entering the lift sha ft; and   
©RSB 2018 All rights reserved                  20 
 
 k) the sign should be posted and maintained at every floor at or near the lift indicting that in case of fire 
occupants, should use the stairs unless instructed otherwise. The sign should also contain a plan for 
each floor showing the location of stai rcase.  
13.2.2  Where applicable, fire lifts should be provided with a minimum capacity for 8 passengers wit h 
floor area of not less than 1. 4 m2 and fully automated with emergency switch on the ground level. In 
general, building over 15 m in height should be  provided with fire lifts. Each fire lift should be equipped 
with suitable inter -communication equipment communicating with the control room on th e ground floor of 
the building. The number and location of fire lifts in a building should be decided after ta king into 
consideration various factors like building, population, floor, areas, section of building, etc. The words 
‘fire lift’ should be conspicuously displayed in illuminous paint on the lift landing door at each floor level.  
14 Refug e area 
In case of buil dings more than 24 m  in height, refu ge area of 15 m2 or an area equal to 0. 25 m2 per 
person to accommodate the occupants of two consecutive floors, whichever is higher, should be 
provided as under. Refu ge area should be provided on the periphery of the flo or and open to air at least 
on one side protected with suitable railings:  
a) For floors above 24 m and up to 39 m ━ one refuse area on the floor immediately above 24 m.  
b) For floor above 39 m one refuse area on the floor immediately above 39 m and soon after every 15 
m. 
15 Refus e chutes  
Refus e chutes should have an enclosure wall of non -combustible material with fire res istance of not less 
than 2 h . They shall not be located within the staircase enclosure or service shafts, or air -conditioning 
shafts. Inspection panel and doors should be tight fittin g with 1 h  fire resistance; the chutes should be as 
far away as possible fo rm exits.  
16 Drainage  
16.1 It is essential to make provision for drainage of any such water on all floors to prevent or minimize 
water damage of the contents.  
16.2 The drain pipe should be provided on the external wall for drainage of water from all floors. O n 
large area floors several such pipes may be necessary which should be spaced 30 m apart. The pipe 
should conform to relevant Rwanda  Standards.   
17 Electrical Services  
The electrical services should conform to the following:  
a) The electric distribution cables/ wiring should be laid in a separate duct. The duct should be sealed at 
every alternative floor with non -combustible materials having the same fire resistance as that of the 
duct. Low and medium voltage wiring running in shaft and above false ceiling should  run in separate 
conduits.  DRS 186 -2: 201 8 
21                 ©RSB 2018 All rights reserved  
 
 b) Water mains, telephones lines, inter -comeliness, gas pipes or any other service line should not be 
laid in the duct for electric cables.  
c) The inspection panel doors and any other opening in the shaft should be provided with fire d oors 
having fire re sistance of not less than 1 h . 
d) Medium and low v oltage wiring running in shafts  and within false ceiling should run in metal conduit. ; 
the false ceiling including all fixtures used for its suspension should be of non -combustible material.  
e) An independent and well -ventilated service room of a 2h minimum fire  resistance should be provided 
on the ground floor with direct access from outside or from the corridor for the purpose of 
termination of electric supply .. 
f) Transformer bays H.T. and L.T. supply rooms, air -conditioning plant systems and boiler rooms shall 
be in separate fire resisting rooms and shall conform to RS 186 -2 and Rwanda Building Control 
regulations  
18 Finishes  
18.1 The use of flammable surface finishes on walls (including external f açade of the building) and 
ceilings affects the safety of the occupants of a building. Such finishes tend to spread the fire and even 
through the structural elements may be adequately fire resistant, serious danger to life may result. It is, 
therefore, ess ential to have adequate precautions to minimize spread of flame of wall, facade of building 
and ceiling surfaces.  Any materials used for various surfaces and décor should be such that the flame 
spread rating should not be more than the recommended values a nd in addition should not generate 
toxic smoke/fumes.  
18.2 Susceptibility to fire of various types of wall surfaces is determined in terms of flame spread  
18.3 Based on the rate of spread of flame, four classes are determined as follows:  
Class 1: Surfaces  of very low flame spread  
Class 2: Surfaces of low flame spread  
Class 3: Surfaces of medium flame spread  
Class 4; Surfaces of rapid flame spread   
18.3 In case of buildings more than 15 m in height, the inte rior finish material should not  have rating 
exceed ing Class 1.  
18.4 The situation under which materials falling into various classes should be used in building 
construction is given below:  
a) Class 1  may be used in any situation  
b) Class 2  may be used in any situation  except on walls  facade of the building , and ceilings of 
staircases , walls and partitions , and corridors ;  
©RSB 2018 All rights reserved                  22 
 
 c) Class 3  should be used only in living rooms, and bedrooms (but not in r ooms on the roof) and only 
as a lining to solid n ot on staircases or façade of the building.  
NOTE  Panelling  (lining) should  be permitted in a limited area. It should not be permitted in a vestibule.  
18.5 When frames, walls, partitions or floors are lined with combustible materials the surfaces on both 
sides of the material should conform to the appropriate class.  
 RS 186 -2: 2013  
ICS 13.220.40  
 
 
©RBS 2013 All rights reserved