इंटरनेट मानक

Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,
in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.

“जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न' 5 तरफ”

Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru
“The Right to Information, The Right to Live” “Step Out From the Old to the New”

IS 6408-2 (1992): Recommendations for modular co-ordination

in building industry: Tolerances, Part 2: Principles and
applications [CED 51: Planning, Housing and pre-fabricated
construction]

“!ान $ एक न' भारत का +नम-ण”

Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह”

है”
ह
Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
 ( Reaffirmed 2005 )

Indian Standard
RECOMMENDATIONSFORMODULAR
CO-ORDINATION INBUILDING INDUSTRY:
TOLERANCES
PART 2 PRINCIPLES AND APPLICATIONS

f First Revision )

UDC 621~753.1 : 721.013 ( 389.63)

@ BIS 1992

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002

January 1992 Price Group 7

Planning, Byelaws and Dimensional Co-ordination Sectional Committee, CED 10

FOREWORD

This Indian Standard ( First Revision ) was adopted by the Bureau of Indian Standards, after the draft
finalized by the Planning, Byelaws and Dimensional Co-ordination Sectional Committee had been approved
by the Civil Engineering Division Council.

One of the aims of modular co-ordination is to provide compatibility and inter-changeability of compo-
nents. In earlier days a practicai system of tolerances was derived as clearance fit, prescribing minus
tolerances on each component without any allowance to the space in which it is to be placed In the past,
the building industry never faced the problem of tolerances, except in the field of mechanical and
structural engineering. It is a common practice, to instal readymade doors/windowsets while brickwork
is in progress. Any inaccuracies in size, shape or position of doors/windowsets is adjusted by the brickwork
and inaccuracies in the brick itself adjusted in mortar joints. The extensive use of prefabricated elements
and componeots in building construction have provoked the concept of tolerance in recent years. The
concept of tolerance is indeed a tool to be used for dimensional control of the component which can fit
without any problem ~for size, squareness, bow, plumbness, position and appearance.

The value of tolerances is subject to fabrication and assembly of materials, design of moulds and manu-
facturing~process. Moreover it can be employed to delimit the dimensional variations for factory produced
or site-cast, precast and precast prestressed concrete products. This can be used by designers, architects,
engineers, general contractors, manufacturers, erectors, quality control agencies and related or interfacing
trades.

This standard is intended to be a working reference for the dimensional control of prefabricated compo-
nents and precast concrete products.

This standard was originally published as IS 6408 : 1971 ‘Recommendations for modular co-ordination
application of tolerance in building industry’. In the usage of this standard, a need was felt to cover the
terminology in a comprehensive manner in addition to effecting the other technical changes deemed
necessary on the basis of the experience gained over the years, As a result, the standard has been published
in the following two parts:

Part 1 Glossary of terms, and

Part 2 Principles and applications.

This part has been made comprehensive by incorporating the advancement made in the field of joint
design systems and process of manufacture for precast concrete products and other allied components
employed in building construction. Further, general concept concerning tolerances for building and building
components and illustrative examples supported by figures have been included. The derivation of manufac-
ture sizes for modular space, calculation of joint clearance, distribution of tolerances, specification of
tolerances and indication of tolerances on drawings have also been elaborated to make this standard
comprehensive.
In the preparation of this standard considerable assistance has been rendered by the National Buildings
Organization, New Delhi.

In the preparation of this standard due weightage has been given to international co-ordination among
the standards and practices prevailing in different countries in addition to relating it to the practices in the
field in this country. This has been met by deriving assistance from the following documents:
a) Industrialized building and modular design. Henrik Nissen Cement and Concrete Association,
London 1972.
b) The principles of modular co-ordination in building ( revised ). CTB W24. The International
Modular Group 1982.
c) Modular co-ordination of low cost housing. United Nations Publications 1970.

( Continued on third cover )

 Indian Standard
RECOMMEN-DATIONSFORMODULAR
CO-ORDINATION INBUILDING INDUSTRY:
TOLERANCES
PART 2 PRlNClPlES AND APPLICATIONS

( First Revision )

1 SCOPE IS No.
1.1 This standard ( Part 2 ) covers the basic 4993 : 1983
principles to be adopted for the inaccuracies
which occur in setting out of the building on the
sites, erecting or manufacturing of building 6408 Recommendations for modular
components. ( Part 1 ) : 1991 co-ordination ’ building
industry : ~Toleraces, Part 1
1;2 This deals with theory and application of Glossary of terms
dimensional deviations which shall be limited by
3 ALMS
these tolerances in construction industry.
3.1 Every process of construction entails some
1.3 Tolerances are intended to be applied whether degree of inaccuracy due to dimensional variation
or not a system of dimensional co-ordination is material and methods employed for production.
used in design process. These will become apparent only when compo-
nents will not fit into their allocated modular
2 REFERENCES spaces or when spaces between two components
become so large or small that components fail to
The following Indian standards are necessary meet joint requirements. It becomes necessary to
adjuncts to this standard: assess the likely variation that may occur in joint
clearances in order to select suitable joint techni-
IS JVO. Title
ques or building components so designed to
1077 : 1986 Specification for common accommodate the extremes of variations ( see
burnt clay building bricks Fig. 1 ). Such a process helps to derive the work
(fourth revision ) size of building components.

FIG. 1 DIMENSIONAL
VARIATION
1
3.2 The pre-requisite to achieve aim of precast,‘ 4.5 The modular co-ordination shall provide
prestressed or prefabricated building components. co-ordinating length, width and thickness of
that are connected on site without shaping, can components. By this, it means it shall provide
only be achieved if components are produced with flexible dimensional compatibility between the
a suitable degree of accuracy. position of different material sub-systems compris-
ing the components and positioning and
3.3 The components must fit into their modular dimensions of these functional sub-systems.
zones without an accumulation of error while
installing them in position ( see Fig. 2 ). 4.6 The modular sizes shall provide the basis only
for determining the manufacturing sizes of
3.4 With the use of the fabricated building com-
components as explained in Fig. 3.
ponents which are neither intended to nor capa-
ble of being shaped on site, it is necessary to 4.7 Deduction from the modular sizes shall
obtain certain degree of accuracy in both manu- require to be made to accommodate any allowance
facturing and placing/assembly. for joint and for the dimensional deviations that
occur in production and erection.
3.5 While preparing dimensional specification and
quality requirements of fabricated building com-
ponents the~controlling dimensions, basic dimen- 4.8 The System of Tolerances to Modular
sions and tolerances shall be specified by the Components
supplier to encourage the use of their products in
the construction industry. 4.8.1 In this system the space -between modular
planes or gridlines is a whole multiple of the
4 FIELD OF APPLICATION
basic module. This is also the modular size of the
component, which is used for architectural design
in general arrangement of plans, elevations and
4.1 Derivation of Dimensions for Modular
sections. For detailed drawings of joints and for
Coxnponent
specifying the size to be manufactured, it is neces-
In component building design the application of sary to consider the aspects given in 4.8.1.1
the special reference system and the selection of and 4.8.1.2.
preferred sizes for component and space dimen-
sions is only the first step towards ensuring that 4.8.1.1 First the width of the joint between
components as supplied can be assembled with components shall be deducted (Zg) and next an
ease of fit. allowance for inaccuracy in erection ( position
tolerance ). These two together comprise the
4.2 The reference system enables designers to minimum deduction from the modular size to
relate the position and size of components by give the maximum size for the component. Then
means of modular planes. Such co-ordinating an allowance is made for inaccuracy in manufac-
planes form the boundaries of modular compo- ture ( the manufacturing tolerance ) and the
nent spaces and include allowances for inaccuracy minimum size for the manufacture component is
and the size clearances. reached. Care shall be taken that the tolerances
are not so coarse that the maximum deduction
4.3 In modular design practice, therefore, these create too large a space for available techniques
spaces shall be defined by co-ordinating dimen- in jointing.
sions which are modular.
4.8.1.2 This being a proven system for derivation
4.4 It is important to stress the essential theoreti- of work size to a modular component, further
cal nature of such dimensions in the context of guidance shall be required on tolerance values to
building component manufacture. be prescribed for gap, position and production.

SPACE

COMPONENT

FIG. 2 MODULAR COMPONENTS

2
 Sib6408 ( Part 2 ) : 1992

MODULAR PLANES

MODULAR SPACE

MODULAR SIZE

h MINIMUM GAPS

Ic-

-P POSITION TOLERANCE

-2g*P MINIMUM DEDUCTION

MINIMUM SIZE

-T MANUFACTURING
TOLERANCE

MINIMUM SIZE

2g*P*f MAXIMUM DEDUCTION

-4

FIG. 3 SYSTEM OF TOLERANCESFOR MODULAR COMPONENTS

4.9 Reliable information on the quantification of of tolerances so that manufacturers, designers and
building tolerances is hard to find. As some builders may improve the dimensional control in
indication of the order of magnitude is to be manufactured products at design, production and
taken into consideration, values for various assembly stages.
tolerance classes are given in Annex A, which are
based on the experiencep gained in the field by 6.2 Small variations in dimensions are unavoid-
undertaking study and.Bnalysis of actual measure- able in construction ‘industry which can be
ments. tolerated within certain limits, if the linkage is
to be made as designed. The limits of the permis-
5 TERMINOLOGY sible deviations determine the tolerance, that is,
For the purpose of this standard, the definitions permitted deviations for the building components
and total building unit.
given in IS 6408 ( Part 1 ) : 1990 and IS 4993 :
1983 shall apply.
6.3 The manufacturing, setting-out and erection
6 GENERAL CONCEPT tolerances together shall comprise the construction
tolerance. These shall be determined with respect
6.1 The concept of tolerances applicable to build- to construction method adopted for satisfactory
ing and building components is relatively new performance. Sometimes these are also recognized
and less known in our country. Therefore, it is as product, erection and interfacing tolerances in
proper to lay down uniform:rules.for application industrialized building construction methods.

3
IS6408 ( Part 3) : las?

7 TYPE OF DIMENSIONAL DEVIATIONS (a) choice of jointing technique and selection of

7.0 Dimensional deviations are of two types: work size for the components, (b) design of joint
to ensure movement which may occur at a
a) induced deviations, and particular place, and (c) large size wall elements
b) Inherent deviations. made of materials having low thermal expansion
7.1 Induced deviations are divided in three coefficients and low moisture movement exposed
groups: namely, (a) manufacturing deviations, to weather.
(b) setting out deviations, and (c) location devia- 7.3 The dimensional tolerance, orientation tole-
tions. rance and shape tolerance together shall comprise
7.1.1 Induced deviations shall arise’ as a result of the manufacturing tolerance.
manufacturing and building processes. 7.4 The positional and orientation tolerances for
7.1.2 While selecting the size of components and arranging components together shall comprise the
their joints to suit a standard modular component, setting out tolerance.
the inherent deviations are summed arithmetically
7.5 The position and orientation tolerances for
and combined with the statistically summed indu-
erection together shall comprise the erection
ced deviations to provide a sensible indication of
tolerance.
the total allowance for all relevant specified
permitted deviations. 8 DEVIATIONS AND TOLERANCES
7.1.3 These geometrical deviations are caused by 8.1 Deviations arise in all work processes, produc-
human error, inaccuracy of tools and limitations tion and assembly. No dimensional specification
in precise measurements, can be fulfilled with 100 percent accuracy.
7.2 Inherent deviations falls in two groups:
8.2 In order to ensure linkage and correct func-
namely, (a) Irreversible, and (b) reversible. tioning, these deviations shall be limited. This
7.2.1 These shall arise as a result of inherent shall be done by selecting limits for permissible
property of materials used in manufacture of deviations.
components and elements.
8.3 In construction industry the tolerances shall
7.2.2 The irreversible deviations are caused by be specific-d with f deviations from the specified
initial shrinkage, settlement and creep. dimension which shall be called basic dimension.
7.2.3 The reversible deviations are caused by the The basic dimensionshall be within the controlling
change in temperature or humidity or by deflec- dimensions ( see Fig. 4 ).
tion due to live/wind loading. 8.4 The tolerance shall then be defined as the
7.2.4 It shall be necessary, when dealing with total difference between maximum and minimum
tolerances, to specify reference conditions, such as, permissible dimensions ( see Fig. 5 ).

0 0
CON1 ROLLING
DIMENSION 12 M

6 6 6
All dimensions in millimetres.
FLG. 4 CONTROLLING DIMENSION AND BASIC DIMENSION

OBSERVED DIMENSION
J
BASIC DiMENSlO N DEVIATION
m
j ‘-

_MlNIMUM PERMISSIBLE DIMENSION TOLERANCE T

MAXIMUM PERMISSIBLE DtMENSlON

I

FIG. 5 OBSERVEDDIMBNSION AND DEVIATION

4
8.5 The tolerance specification shall denote the 9.5 Measurement of the deviation ‘a’ of an arbi-
symmetrical tolerance system. trary point~P is achieved in practice from a check
plane ( line ) 3 at known distance ‘6’ from the
Example:
basic plane ( or line ) 2 ( see Fig. 6 ).
The length shall be specified by the basic
dimensions 2990 mm. It shall be permissible 9.6 Flatness Deviations
for this length to vary between the limits: 9.6.1 Flatness deviations shall be determined by
2985 mm ( minimum permissible dimensions ), the principles as shown in Fig. 7. Deviation is the
and distance from any point on the surface to a
surface representing a median plane for all four
2995 mm (maximum permissible dimensions). corner points.
The tolerance shall be 2995 - 2985 9 10 mm. 9.6.2 In practice the measurement shall be made
The basic dimensions with tolerances shall be from a plane exterior to the component and
expressed as 2990 f 5 mm. parallel to two main directions of the component.
8.6 In other branches of industry following diffe- 9.6.3. Deviation shall be measured at various
rent methods of specifying tolerances are used on points over the entire surface area.
drawings:
+ 15 + 10 +7 + 0 - 5 9.7 Skewness
2980 2985 2988 2945 3000
+ 05 + 0 -3 - 10 - 15 9.7.1 Skewness is a special case of flatness devia-
tion affecting a rectangular surface with well
and these five dimensional specifications shall defined corners ( see Fig. 8 ).
correspond to same dimensions and same limits
for the deviations. 9.8 Angular Deviations
8.7 The length obtained by actual measurement 9.8.1 Correspondingly, angular deviations shall
of component shall be called as ‘observed dimen- be expressed in three ways as deviation in length.
sions’ and the difference between the length and
the controlling dimension shah denote the ‘devia- 9.8.1.1 The difference between the observed angle
tion’ ( see Fig. 6 ). The deviation shall be and the basic angle is expressed by means of the
reckoned with signs ( f ). length 1 and d as given below ( see Fig. 9 and

OBSERVED SURFACE

=&g$g

FIG. 6 DIWIATIONFROMBASICPLANE( expressed by ‘a’ )

9 BASIC SHAPE, OBSERVED SHAPE AND

DEVIATION IN SHAPE
9.1 In practice, it is seldom possible to manage
with one dimension tolerances. Limits have to be
set for the deviation in shape occurring in all
three dimensions of building components.
9.2 In case of one dimension tolerance, the pres-
cribed shape shall denote the basic shape. The
difference between the observed and the basic FIG. 7 FLATNESS
DEVIATION
shape shall be called the ‘deviation in shape’.
9.3 Deviation in length, angle, straightness or
planeness shall be expressed by means of ‘devia-
tion in length’.
9.4 The deviations from a plane or a straightness
at one of edges of a member shall be expressed
by means of distance from points, lines or planes
eon an observed surface ( or curve ) 1, to the basic
plane or a line 2 ( see %ig. 6 ). FIG. 8 SKEWNESS

5
IS 6408 ( Part q )JV‘rSS2

Fig. 10 ): 9.9 Setting Out Deviatioti ’

a) Observed angle is more than basic angle : 1 9.9.1 The setting out deviation shall be determin-
b) Observed angle is less than basic angle ed by the principle as shown in Fig. 11.

( 4 - 11> 9.10 Erection Deviation

c) Observed diagonal is less than basic dia- 9.10.1 The erection deviation shall be determined
gonal ( A - dl ) by the principle as shown in Fig, 12.

10 BOX PRINCIPLE
10.1 Box is the imaginary and arbitrary shape
which encloses three dimensional space between
two forms of surface symmetrical to each other
and are so placed that the distance of each one of
them is one quarter of a tolerance away from the
basic surface inside and outside directions.
10.2 Shape tolerances which are intended to
limit the deviations in a component length, angle,
straightness and planeness easily become confus-
r,AS,C ANG.LE
ing and difficult to apply in practices. The tole-
9A rances on the shape of a component are, therefore,
collectively used in box principle.
IO.3 Figure 13 shows an arbitrary basic shape lying
between an inner and outer figure, the surfaces of
which are located symmetrically about the surface
of the basic figure. One surface shall be located
T/4 inside the surface of the basic figure, and the
other T/4 outside it.

‘Afi BASIC ANGLE

96
FIG. 9 DEVIATIONIN ANGLE
ANGLE
10.4 This principle has limitation of adoption in
both shape and size. It delimits the control of
three length tolerances. However, it does not
establish the inside control of figure.

11 COMBINATION OF TOLERANCES
11.1 When a number of components are linked,
[ expressed by length I and ( I2 - Z1) ] their partial dimensions and joints shall often
amount to series of dimensions having a total
dimension. The tolerances on partial dimensions
and total dimensions shall be interdependent.
11.2 Additive P&ciple
11.2.1 The most elementary way of establishing
this relationship shall be by means of adding the
values of partial tolerances. Thus, assuming the
1 LOBSERVED
BASIC ANGLE
ANGLE series of partial tolerances as II, 2-s ,......... Tn the
maximum deviation on total sum dimensions ‘A,’
shall be calculated from the following equation:
FIG. 10 DEVIATION IN SHAPE
[ expressed by ( da - 411 A 6 = zt J/2 x 1 Tl + Tr + .-....... Trl 1

ACTUAL ! REFERENCE
POSITION I

i
----- a----
-5-----
REFERENCE
POSITION

11 A POSITIONAL 11 B ORIENTATION
FI’G~ 11 SETTING Our DEVIATIONFOR A LINE

6
 IS 6408 ( Part 2 ) I 1992

:-,---y-3+
L+____-A
1

1
a

- qzfEq+
12A POSITIONAL 12 6 ORIENTATION

FIG. 12 ERECTION DEVIATIONS FOR A.COMPONBNT

FIG. 13 Box PRINCIPLE ( DEVIATION OF FORM )

11.2.2 Assuming total tolerance T, is equal to 12 CO-ORDINATE TOLERANCES

2As, it will always hold good. If it is required to
Application of the additive principle can lead to
select a part tolerance on the basis of a given sum
unrealistic values for small part tolerances or
( total ) tolerance Z-s, the sum may be worked
large sum tolerances. The principle can, therefore,
out from the following relationship:
be ~modified by introducing further tolerances
T’r + T9 +.- . . . . . . . 7.” > Te which act differently on one and the same dimen-
sion, the so-called collaterally regulating toleran-
11.2.3 This relationship between partial tolerances ces or co-ordinate tolerances. These details are
and total tolerances is called the additive principle. explained in 13 to 17.
This principle is also known as arithmetical
summation principle. 13 CHOICE OF TOLERANCE SlZE
11.3 Summation of Tolerances
13.1 The size of tolerance shall be chosen on the
11.3.1 It is a theoretical presumption that each basis of the production method, jointing system,
component shall be erected within its allocated aesthetics and economy.
modular space with high degree of workmanship
13.2 The relationship of four dimension, namely,
in joints. But in practice, it is seldom achieved.
(a) controlling dimension, (b) basic dimension,
11.3.1.1 The inaccuracy which occurs in size, (c) joint dimension, and (d) tolerances shall
squareness, bow, plumbness and position of each depend on the connections between the
component and minimum joint width, if summed components.
arithmetically, shall result into large space for
joints (see Fig. 14). For example, if minimum 5 mm 13.3 The tolerances on the basic dimensions
is applied to five aspects of tolerances for two of a component are absorbed and equalized in
components shall result into ( 5 ~5 ) + 5 + joints between additive elements. For example of
(5x5)= 55 mm space forjoint. This will be too tolerance equalization Fig. 15 may be referred
large sum tolerance for a component. to

7
Referring to the sizes shown in the Fig. the or,
distance between C and D lines:
Tf = i-i s 2 Trn
With large component and small joint:

13.3.1 It can be seen that the given relationship

between two dimensions shall result in uneven
With small component and large joint: joints which perhaps may not absorb the tolerance
on joint. It can also be seen that the positional
tolerance tends towards zero value due to high
value of tolerance on component. This shall call
From above two equations:
for high degree of site workmanship which may
F max -Fmin- lrn8x- lrnin+ 2 Trn not be practical.

‘_-
1

1; L
I I
I I
I I
I
I I
I I
I I
I I

I \

I I
I
I
\

_^ .I

1LA SIZE 146 SQUARENESS

E
I’ I’
I 1
I I ;:
I \ I ’I
I
I
b
I
I
I’
’
I
I

I I
I ’
I I
I I
‘: ::
b’
l&C BOW
4 - I c

i
I
I
I
I
I I
I I
I I
I
I
I

l&D POSITI 1LE PLUM8

FIG. 14 ASPECTS OF TOLBRANCB

8
 IS 6408 ( Part 2 ) : 1992

CONTROLLING mm4sloN

32x -+$$OS,T,ON
Lmi .
1’ ’ TOLERANCE Tm

i i
! LIZ i
c, I,
L/2
-I
t JOINT G h JOINT fc JOINT %
MODULAR ZONE MO OULAR ZONE

L- Controlling dimension Tm - Position tolerance

1 - Basic dimension component Tl - Tolerance on component
F- Basic dimension joint Tf - Tolerance on joint
FIG. 15 RELATIONSHIP BETWEBN CONTROLLING DIMENSIONS, COMPONENTS DIMBNSIONS,
JOINT DIMENSIONS AND TOLBRANCBS

14 TOLERANCE OF FLOOR 15 TOLERANCE ON BRICK SIZE

COMPONENTS
15.1 Modular Size
14.1 In linkage of the floor components the joint
is assumed to be self-forming, which can be possi- 15.1.1 As shown in Fig. 16 modular standard
ble by grouting the joint from top without form brickwork result in horizontal controlling dimen-
work and without mortar running right through. sions that are divisible by 1 M ( = 100 mm ). In
order that the controlling dimension may be
Examjle: observed during construction, bricks must be
The floor components comply with their con- produced having suitable degree of accuracy.
trolling dimension 1 200 mm.
15.1.2 The stretcher course with full bricks and
This means the floor components shall not be corresponding vertical joint, the marginal dimen-
wider than 1 200 mm. sion of work shall be determined as under:
The basic dimension for the width is expressed
The controlling dimension = 200 mm
as 1198f2mm.
!Maximum permissible joint = 16mm
This limits the following dimensions for the
Minimum permissible joint = 8mm
eomponent:
Minimum permissible dimension 1 196 mm 15.1.2.1 On the basis of above assumptions:
Maximum permissible dimension 1~200 mm
Upper marginal dimensions for the brick
Basic dimension 1 198 mm
Tolerance 4mm = 200 - 8 = 192 mm

9
IS 6498 ( Part 2 ) : 1992

Lower marginal dimension for the brick NOTE - As per IS 1077 : 1986, tolerance on 20 brick
lengths is & 80 mm which gives an ‘average’ tolerance
= 200 - 16 = 184 mm of f 4 mm per brick length and hence a ‘ma? tolerance
( 192 + 184 ) off 6 mm per brick can be permitted, provided that
The basic dimension of brick tolerance on any 20 bricks shall not exceed f 80 mm.
2
= 188 mm and
Tolerance = 192 - 184 p: 8 mm or f 4 mm. 15.1.3.1 It can be seen from above that joint
15.1.2.2 In order to achieve controlling dimension dimensions calculated are unrealistic and very
of 200 mm, each brick must have limits for joint often too large for achieving controlling dimensions
dimension with length of 188 -f 4 mm or f 2.1 of 200 mm, even if it is calculated average of 20
percent. bricks.
15.1.3 In case, 200 mm controlling dimension is
to be observed with nominal dimension of brick The deviations are equalized over larger length
190 mm and tolerance of f 6 mm ( in accordance of brickwork, while adhering to the essential
;hi;h IS lq77 : 19F6 ) (. see Note ) it results in dimensions for openings for doors and windows, it
margmal dlmenslons with variations shall not be attained. Therefore, tolerances stipu-
f 3.1 percent. lations should be based on statistical basis.
Maximum brick length = 190 + 6 - 196 mm
Minimum brick length = 190 - 6 = 184 mm. 15.1.3.2 In order to achieve desired controlling
This corresponds to joint of 4 mm minimum and dimensions, dimensions of each brick should have
16 mm maximum. limits as specified in 15.1.2~1 and 15.2.2.1.

i
O,,,l,,,,s
J i

IiWl 190
N 0 MINAL
I
i
10

inr
il_ 188 _I$_
‘BASIC DIMENSION.

BASIC DIMENSION AND

MARGINAL DIMENSlOl;i$j
~~ Al1 dimensions in millimetres.
FIG. 16 MODULAR BRICK TOLERANCES
10
.15.2 Non-aroduiar Coirventional Size 15.2.2.2 In order to achieve controlling “dimen-
15.2.1 As shown in Fig. 17, the non-modular sion of 240 mm, the each brick must have limits
conventional brickwork result in horizontal con- for joint dimension with length of 228 f 4 mm or
trolling dimensiom that are divisible by 60 mm f 1.8 percent.
( 4 brick ). In order that the controlling dimen-
15.2.3 In case, 240 mm controlling dimension is
sion may be observed during construction, bricks
to be observed with nominal dimension of brick
must be produced having a suitable degree of
,, ’ 230 mm and tolerance of f 3 percent and f 8
accuracy.
percent, for class A and-class B types of bricks; it
15.2.2 The stretcher,. course with full bricks and results in the marginal dimensions.
corresponding vertical joints, the marginal dimen-
sions of brick shall be determined as under: Class A
The controlling dimension = 240 mm Maximum brick length = 230 + 3 %
Maximum permissible joint p 16 mm = 237 mm
Minimum permissible joint = 8mm Minimum brick length = 230 - 3 o/o .
= 223 mm
-15.2.2.1 On the basis of above assumptions:
This corresponds to a joint of 3 mm minimum
Upper marginal dimension for the brick
and 17 mm maximum.
= 240 - 8 = 232 mm
Lower marginal dimension for the brick Class B
=240- 16- 224mm Max’imum brick length = 230 + 8 y0
The basic dimension of brick = 248 mm
232 + 224 Minimum brick length = 230 - 8 O/O
L: 2 = 228 mm, and = 212 mm
Tolerance = 232 - 224 = 8 mm or f 4 mm. This corresponds to a joint of 28 mm.

;L--yQ
NOMINAL DIMENSION

BASIC DIMENSION AND

‘MARGINAL DIMENSIONS
CLASS A -, 3’10
CLASS B r 8O/o

All dimensions in millimetres.

FIG. 17 STANDARP BRICK TOLERANCES
‘11
IS 6408 ( Part 2 ) : 1992

15.2.3.1 It can be seen from above that the joint components, but nevertheless, the procedure for-
dimensions calculated are unrealistic and large for calculation shall abreast t,hem to deliberate with
strict adherence to the controlling dimensions of manufacturers who can render advise on manu-
240 mm. Therefore, tolerance specification shall facturing tolerances for a product-positional
have to be prepared on a statistical basis. tolerances which are based on information gained
16 TOLERANCE ON COMPONENT, from site -assembly experiences.
DOORSET/ WINDOWSET WIDTH
16.2 The process ~of calculating maximum and
16.1 Building designers are not usually accom- minimum size acceptable on site for a modular
plished to determine the tolerances for building component is illustrated in Fig. 18.

(
MODULAR SPACE
Lx3M:lZM
assume 12 M width

1200 ) MODULAR SIZE

MINIMUM GA?
-m -9 g = 3+nm

1 POSITI ONAL TDLERANCe

p=3mm

MANUFACTURING
-t TOLERANCE
t=3 mm

MINIMUM GEDUCTION
- c
2g+p -9mm

MAXIMUM SIZE
1200-g = 1191mm

MINIMUM SIZE
1191-3 =1166 mm

MAXIMUM GAP
gz3+3+l;5z7*5mm

MINIMUM GAP
g= 5 (1200~-1191- 3)

g=3 mm

MANUFACTURING
DIMENSIONS TO
BE SPECIFIED
1189.5: l-5mm * AS 1169 ,- l-5 mm

All dimensions in millimetres.

FIG. 18 DERIVATIONOP MANUFACTURESIZES

12
 IS6408( Part 2,) :1992-

16.2.1 As a first step, select modular size of the 17.2.1 If site concrete joint width of 60 mm ( .iX<
-component, and define the maximum gap, posi- 60 ) minimum is required and floor component
tional and manufacturing tolerances. should have support of minimum 35 mm corres-
ponding to the width of joist and maximum
16.2.2 When the above have been settled, add 75 mm from centre line, which are also on
up g + p + g and deduct it from modular size, modular line.
which is the maximum size.
17.2.2 The displacement between floor and joist/
16.2.3 Manufacturing tolerance deduced from wall arises as a result of inaccuracies in:
maximum size shall be a minimum size.
a) thickness of joist/wall component
16.2.4 Check the maximum gap = g + fi + t/2
and also minimum gap = l/2 ( modular size - = T1 = thickness
maximum - positional tolerance ), or difference b) erection of floor component
between maximum size and minimum size. = 7-s = placement
16.2.5 Lastly specify manfacturing dimension c) length of floor component
as + l/2 minimum gap after adding l/2 minimum s Is = length
gap to minimum size.
d) assembly of floor component
17 MODIFICATION OF THE ADDITIVE = I , = placement
PRINCIPLE BY ADJUSTMENT
17.2.3 The tolerance are selected taking into
17.1 When building elements are assembled by consideration the normal practice followed in
means of joints which may vary within definite production and assembly. To determine 7-1
limits, one may within these limits adjust the ( assuming Tl = 6 mm, TB e= 10 mm, and TS =
position of the element during assembly taking 10 mm and taking the minimum~displacement ‘F’
into consideration the actual measurement of the from the location determined from the basic
element. For a given joint tolerance, therefore, it dimensions to minimum support ), the calculation
is possible to set a large tolerance on the element shall be as follows:
than what is permitted by the additive principle.
Such a modification implies, however, that it is F _++++ ++ +=lOmm
not possible to combine all measurements which
satisfy the indicated tolerance required.
that is, 10 mm
17.2 Taking an example of a prefabricated or
partially prefabricated building having precast
therefore, Tr = 2 mm
concrete planks for floor component and the load
bearing precast beam/joist ( connection as shown This is quite an unrealistic tolerance to be applied.
in Fig. 19 ), the maximum permissible displace- In such cases adjustment may be done on site to
ment of floor in relation to joint is f 10 mm. obtain the required joint width.
n
Tz PLACING OF LOADBEARING
COMPONENT

T, THICKNESS OF -LOADBEARING
COMPONENT

All dimensions in millimetres.

FIG. 19 LOAD-BEARING FLOOR-BEAM/WALLCONNECTIONIN
PARTLY PRB-CASTJOISTSAND PRB-CASTRC PLANKS

13
IS 6408 -( Part 2 ) t 1992

18 APPLICATION 0F CO-ORD~NATE 19 THE SQUARE ROOT RULE

TOLERANCES
19.1 In practice, tolerance of the types T,, Tr,.
18.1 Co-ordinate tolerance are based on the Ts and Td are also calculated with this orincioles:..
assumption that erection on a number of parallel
prefabricated wall components shall be adjusted
on site. Thus Ts is introduced with a value of
10 mm, for determining the displacement of the
support ( see Fig. 20 ). This shall be calculated
_P.
that is
F =E- 2+ = 10

that is 2.5 + 2.5 + -$ I 10

therefore, T4 = 10 mm
that is
18.1.1 It can be noticed from above two princi-
ples that the effect TI and T, is replaced by the g + q + _!A!& + [%-J ‘]I’* = l@
effect of Tb, which offers more realistic value for C
adoption in erection work. Therefore, T4 - 16;3 mm

PV GATEWAY

(? n

BASIC ROOM DIMENSION e

TOLERANCES
T1 = Thickness of wall component
Tn = Placing of wall component
T3 = Length of floor component
T4 = Placing of floor component
Ts = Room dimension
Iv = Dimension of wall component
Id = Dimension of floor component

FIG. 20 CO-ORDINATETOLERANCES

1.4
 .-IS 6408 ( Pslit y+2
) 2‘1992

$9.2 .The. calculation is based on ‘following 21 SHRINKAGE,AND,CREEP

assumptions:
21.1 The dimensions in various building products
a) All the deviations in thickness, length and are subjected to constant alteration due to change
assembly have normal distribution, in temperature and moisture content, shrinkage
b) There are no systematic errors, and other deformation under conditions of use.
This shall be clearly specified in order to avoid
c) It has some probability of error, and
possible rejection.
d) All deviations shall be independent.
21.2 The contributions from measuring instru-
19.3 It is seldom possible to have fulfilment of ments and methods adopted to determine the
above assumptions in practice. Thus, error on Tr ~deviation shall remain negligible if authorised
will be equal to Tr, Ts, and Ts. quality control department is involved for carrying
out the tests on rendom samples.
29 CONTROL OF MEASUREMENT 22 APPROVAL
22.1 If the control measurements show deviations
29.1 In order to avoid ambiguity for control with numerical values which are less than or
measurement, it shall be necessary to satisfy the equal to half the tolerance, the dimension shall
tolerance measurement precisely. be adopted, otherwise it shall be rejected.

29.2 It shall include the information on numbers 22.2 Agreement on production and supply shall
of measurements, methods of production and contain clear understandings on consequences
manufacturer’s constraints also. arising from possible rejection.

ANNEX A
( Clause 4.9 )

SERIES OF EXAMPLES OF THE PRECtSION CLASSES

Precision class PC 4 : Steel sections; Installations ( such as gas,

water and heating pipes).
Timber moulding and
profiles of fine grained Precision class PC 7 : Forged and fabricated
ashlar. frames and railings;
Wrought components
Precision class PC 5 : Steel windows, door, fra-
( such as floors, wall
mes, trim; wood trim
coverings, steps );
windows and door sec-
tions; components in fine Planed boards, -planks
grained ashlar; wall, ceil- battens;
ing, and floor surfaces. Coarse flooring, Medium-
Precision class PC 6 : Prepared and fitted com- grained concrete compo-
ponents ( such as frame- nents;
work, staircases, railings, Ashlar facing;
floors, panels, cladding, Plaster surfaces;
gutters, rainpipes );
Faces of joints.
Metal castings;
Precision class PC 8 : Unwrought components,
Wood windows and doors; carpentary ( such as
Built in furniture; framework joints, refters,
Parquet flooring; unplanted boards, planks,
battens );
Fine flooring, fine concrete
Components having finish-
components;
ed surfces of state degree
Components of medium of accuracy ( such as con-
grained ashlar; crete facework compo-
Fine ceramics (e.g. paving nents cast in metal
tiles, ceramic tile clad- forms );
dings); Surface of heavy concrete
Floor coverings; decks;

15
156408(Part2):1992

Facing brickwork, Fair- Table 1 Exact Values of Tolerance Grades

face walling, Clay block-.
( Cluuse 4.9 )
work, masonry.
Precision class PC 9 : Components to be plaste- Tolerance grades for basic size ranges ( millimetres )
red or clad ( such as
components cast in
wooden forms, heavy Class Up 100 250 1000 2500 Over
decks and stairs in the 16"o 2 GO 220 IOGO 10 000,
rough concrete );
(1) (2) (3) (4) (5) (6) (7)
Components to be plaster-
ed or clad ( such as walls, PC 1 0.25 0’4 0’6 O’% 1’0 1’2
piers, decks stairs ); PC 2 0’4 0’6 1’0 1.2 1.6 2’0
Rough brickwork and
PC 3 0’6 1-O 1’6 2’0 2’5 3.2
blockwork.
PC 4 1.0 1’6 2’5 3’2 4’0 5’0
Precision class PC 10 : Components not requiring
great accuracy ( such as PC 5 1’6 2’3 4’0 5.0 6.0 8.0
foundations );
PC 6 2’5 4 6 8 10 12
Walls, Room dimensions;
PC 7 4 6 10 12 16 28
Components not requiring
great accuracy ( such as PC 8 6 10 16 20 25 32
foundations, retaining
PC 9 IO 16 25 32 40 50
walls ) unless an even
coarser degree
_~ of accu- PC 10 16 25 40 50 60 80
racy is sufficient.

16
( Continuedfrom second cover )

d) Dimensional co-ordination for building. DC12. HMSO Publication 1972.

e) PC1 committee report on Tolerances for precast and prestressed concrete, PC1 Journal, Vol 30,
No. 1, Jan/Feb. 1985.
f) IS0 4464-1980 Tolerances in buildin_:: - relationship between the different types of deviations and
tolerances used for specification. International Organization for Standardization.
g) DS/R 1050-1982 Application of dimensional tolerances in building. Dansk Standardiseringsraad.
h) DlN 18201-1984 Tolerances in buildings: terminology, principles, application and testing. Deust-
sehes Institute for Normong.
j) DIN 18201-1958 Dimensional tolerances in buildings: terminology, fundamental tolerances,
application and testing. Deustsehes Institute for Normong.

For the purpose of deciding whether a particular requirernent of the standard is complied with, the final
value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance
with IS 2 : 1960 ‘Rules for rounding off numerical values ( revised )‘. The number of significant places
retained in the rounded off value should be the same as that of the specified value in this standard.

Standard Mark
The use of the Standard Mark is governed by the provisions of the Bureau of Indian
Standards Act, 1986 and the Rules and Regulations~made thereunder.
The Standard Mark on
products covered by an Indian Standard conveys the assurance that they have been
produced to comply with the requirements of that standard under a well defined system of
inspection, tosting and quality control which is devised and supervised by BIS and operated
by the producer. Standard marked products are also continuously checked by BIS for con-
formity to that standard as a further safeguard. Details of conditions under which a licence
for the use oft he Standard Mark may be granted to manufacturers or producers may be
obtained from the Bureau of Indian Standards.
Bweao of Indian Standards

BlS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote
harmonious development of the activities of standardization, marking and quality certification of goods
and attending to connected matters in the country.

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BIS has the copyright of all its publications. No part of these publications may be lieproduced in any
form without the prior permission in writing of BIS. This does not preclude the free use, in the course of
implementing the standard, of necessary details, such as symbols and sizes, type or grade designations,
Enquiries relating to copyright be addressed to the Director ( Publications ), BIS.

Revision of Indian Standards

Indian Standards are reviewed periodically and revised, when necessary and amendments, if any, are
issued from time to time. Users of Indian Standards should ascertain that they are in possession of the
latest amendments or edition. Comments on this Indian Standard may be sent to BIS giving the
following reference:

Dot : No. CED 10 ( 4295 )

Amendments Issued Since Publication

Amend No. Date of Issue Ted Affected

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