EN 771-1:2011

SLOVENSKI STANDARD
01-julij-2011
1DGRPHãþD
SIST EN 771-1:2004
SIST EN 771-1:2004/A1:2005
6SHFLILNDFLMD]D]LGDNHGHO2SHþQL]LGDNL
Specification for masonry units - Part 1: Clay masonry units
Festlegungen für Mauersteine - Teil 1: Mauerziegel
Spécification pour éléments de maçonnerie - Partie 1 : Briques de terre cuite
Ta slovenski standard je istoveten z: EN 771-1:2011
ICS:
91.100.25 .HUDPLþQLJUDGEHQLL]GHONL Ceramic building products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 771-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2011
ICS 91.100.25 Supersedes EN 771-1:2003
English Version
Specification for masonry units - Part 1: Clay masonry units
Spécification pour éléments de maçonnerie - Partie 1: Festlegungen für Mauersteine - Teil 1: Mauerziegel
Briques de terre cuite
This European Standard was approved by CEN on 3 March 2011.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 771-1:2011: E
worldwide for CEN national Members.

Contents Page
Foreword .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .6
4 Materials and manufacture .9
5 Requirements for clay masonry units .9
5.1 General .9
5.2 LD units . 10
5.2.1 Dimensions and tolerances (LD units) . 10
5.2.2 Configuration (LD units) . 12
5.2.3 Density (LD units) . 14
5.2.4 Compressive strength (LD units) . 14
5.2.5 Thermal properties (LD units) . 15
5.2.6 Durability (LD units). 15
5.2.7 Water absorption (LD units) . 15
5.2.8 Active soluble salts content (LD units) . 15
5.2.9 Moisture movement (LD units) . 16
5.2.10 Reaction to fire (LD units) . 16
5.2.11 Water vapour permeability (LD units) . 16
5.2.12 Bond strength (LD units) . 16
5.3 HD units . 17
5.3.1 Dimensions and tolerances (HD units) . 17
5.3.2 Configuration (HD units) . 18
5.3.3 Density (HD units) . 19
5.3.4 Compressive strength (HD units) . 20
5.3.5 Thermal properties (HD units) . 21
5.3.6 Durability (HD units) . 21
5.3.7 Water absorption (HD units) . 21
5.3.8 Initial rate of water absorption (HD units) . 21
5.3.9 Active soluble salts content (HD units) . 22
5.3.10 Moisture movement (HD units) . 22
5.3.11 Reaction to fire (HD units) . 22
5.3.12 Water vapour permeability (HD units) . 22
5.3.13 Bond strength (HD units) . 23
6 Description, designation and classification of clay masonry units . 23
6.1 Description and designation . 23
6.1.1 LD units . 23
6.1.2 HD units . 24
6.2 Classification . 24
7 Marking . 25
8 Evaluation of conformity . 25
8.1 General . 25
8.2 Initial type testing . 25
8.3 Factory production control . 26
8.3.1 General . 26
8.3.2 Testing and measuring equipment . 27
8.3.3 Production equipment . 27
8.3.4 Raw materials . 27
8.3.5 Production process . 27
8.3.6 Finished product testing . 27
8.3.7 Statistical techniques . 27
8.3.8 Marking and stock control of products . 27
8.3.9 Traceability . 28
8.3.10 Nonconforming products . 28
Annex A (normative) Sampling for initial type testing and for independent testing of
consignments . 29
A.1 General . 29
A.2 Sampling procedure . 29
A.2.1 General . 29
A.2.2 Random sampling . 29
A.2.3 Representative sampling . 29
A.2.4 Dividing the sample . 30
A.2.5 Number of units required for testing . 30
Annex B (informative) Additional information . 33
B.1 Use of clay masonry units . 33
B.2 Durability . 34
B.3 Freeze/thaw resistance . 34
B.3.1 General . 34
B.3.2 Masonry subjected to severe exposure . 34
B.3.3 Masonry subjected to moderate exposure . 35
B.3.4 Masonry subjected to passive exposure . 35
B.4 Sulfate action on mortars and plasters . 35
B.5 Efflorescence and staining . 36
B.6 General guidance on the appearance of facing clay masonry units . 36
Annex C (informative) Guidelines for test frequencies for designing a FPC system to demonstrate
conformity of finished products with the requirements of the standard and the
declaration of the manufacturer . 37
Annex ZA (informative) Clauses of this European Standard addressing the provisions of the EU
Construction Products Directive . 39
ZA.1 Scope and relevant characteristics . 39
ZA.2 Procedure(s) for attestation of conformity of clay masonry units . 42
ZA.2.1 System(s) of attestation of conformity . 42
ZA.2.2 EC Certificate and Declaration of Conformity . 43
ZA.3 CE marking and labelling. 44
Bibliography . 49

Foreword
This document (EN 771-1:2011) has been prepared by Technical Committee CEN/TC 125 “Masonry”, the
secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2011, and conflicting national standards shall be withdrawn
at the latest by November 2011.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 771-1:2003.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Construction Products Directive
(89/106/EEC).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.
This European Standard also takes into account the general rules for unreinforced and reinforced masonry in
Eurocode 6.
EN 771, Specification for masonry units consists of:
 Part 1: Clay masonry units
 Part 2: Calcium silicate masonry units
 Part 3: Aggregate concrete masonry units (Dense and light weight aggregates)
 Part 4: Autoclaved aerated concrete masonry units
 Part 5: Manufactured stone masonry units
 Part 6: Natural stone masonry units
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

1 Scope
This European Standard specifies the characteristics and performance requirements for masonry units
manufactured from clay for use in masonry construction (e.g. facing and rendered masonry, loadbearing or
non-loadbearing masonry structures, including internal linings and partitions, for building and civil
engineering).
This European Standard is intended to apply to two groups of fired-clay masonry units:
a) LD units (see 3.4 and 5.2) comprising:
1) clay masonry units with a gross dry density of less than or equal to 1 000 kg/m for use in protected
masonry.
b) HD units (see 3.5 and 5.3) comprising:
1) all clay masonry units for use in unprotected masonry;
2) clay masonry units with a gross dry density of greater than 1 000 kg/m for use in protected masonry.
This European Standard includes those clay masonry units of an overall non-rectangular parallelepiped
shape.
It defines the performance related to e.g. dimensional tolerances, strength, density measured according to the
corresponding test methods contained in separate European Standards.
It provides for the evaluation of conformity of the product to this European Standard.
The marking requirement for products covered by this European Standard is included.
This European Standard does not specify standard sizes for clay masonry units, nor does it specify standard
work dimensions, angles and radii of specially shaped clay masonry units. This document does not include
method of measurement, tolerance and range requirements for dimensions, angles and radii characteristics of
specially shaped clay masonry units.
This European Standard does not cover requirements for the following: units for paving, flue liners and storey
height clay masonry units and clay masonry units with an incorporated thermal insulation material bonded to
the faces of the unit susceptible to be exposed to fire. It does, however, include clay masonry units for
external chimney masonry.
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.
EN 772-1, Methods of test for masonry units — Part 1: Determination of compressive strength
EN 772-3, Methods of test for masonry units — Part 3: Determination of net volume and percentage of voids
of clay masonry units by hydrostatic weighing
EN 772-5, Methods of test for masonry units — Part 5: Determination of the active soluble salts content of clay
masonry units
EN 772-7, Methods of test for masonry units — Part 7: Determination of water absorption of clay masonry
damp proof course units by boiling in water
EN 772-9, Methods of test for masonry units — Part 9: Determination of volume and percentage of voids and
net volume of clay and calcium silicate masonry units by sand filling
EN 772-11, Methods of test for masonry units — Part 11: Determination of water absorption of aggregate
concrete, autoclaved aerated concrete, manufactured stone and natural stone masonry units due to capillary
action and the initial rate of water absorption of clay masonry units
EN 772-13, Methods of test for masonry units — Part 13: Determination of net and gross dry density of
masonry units (except for natural stone)
EN 772-16, Methods of test for masonry units — Part 16: Determination of dimensions
EN 772-19, Methods of test for masonry units — Part 19: Determination of moisture expansion of large
horizontally perforated clay masonry units
EN 772-20, Methods of test for masonry units — Part 20: Determination of flatness of faces of aggregate
concrete, manufactured stone and natural stone masonry units
EN 772-21, Methods of test for masonry units — Part 21: Determination of water absorption of clay and
calcium silicate masonry units by cold water absorption
EN 1052-3, Methods of test for masonry — Part 3: Determination of initial shear strength
EN 1745, Masonry and masonry products — Methods for determining thermal properties
EN 13501-1, Fire classification of construction products and building elements — Part 1: Classification using
data from reaction to fire tests
EN ISO 12572, Hygrothermal performance of building materials and products — Determination of water
vapour transmission properties (ISO 12572:2001)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Annex B to this European Standard is informative and gives descriptions of such matters as applications,
exposure and durability.
3.1
masonry unit
preformed component intended for use in masonry construction
3.2
clay masonry unit
masonry unit made from clay or other argillaceous materials with or without sand, fuel or other additives fired
at a sufficiently high temperature to achieve a ceramic bond
3.3
protected masonry
masonry which is protected against water penetration
NOTE It can either be masonry in external walls which is protected, (e.g. by a layer of suitable render or by cladding),
or it can be the inner leaf of a cavity wall or it can be an internal wall. It may or may not be loadbearing.
3.4
LD unit
clay masonry unit with a low gross dry density for use in protected masonry
3.5
HD unit
clay masonry unit for unprotected masonry as well as clay masonry unit with a high gross dry density for use
in protected masonry
3.6
co-ordinating size
size of the co-ordinating space allocated to a masonry unit including allowances for joints and tolerances
3.7
work size
size of a masonry unit specified for its manufacture, to which the actual size conforms within permissible
deviations
3.8
actual size
size of a masonry unit as measured
3.9
regular-shaped masonry unit
masonry unit with an overall rectangular parallelepiped shape
3.10
specially shaped masonry unit
masonry unit which is not a rectangular parallelepiped
3.11
accessory unit
masonry unit which is shaped to provide a particular function, e.g. to complete the geometry of the masonry
3.12
interlocking features
shaped matched projections and indentations on masonry units
EXAMPLE Tongue and groove systems.
3.13
vertical perforation
formed void that passes completely through a masonry unit perpendicular to the bed face
3.14
horizontal perforation
formed void that passes completely through a masonry unit parallel to the bed face
3.15
cell
formed void that does not pass through a masonry unit
3.16
frog
depression formed in one or both bed faces of a unit
3.17
recess
depression or indentation in one or more surfaces of a masonry unit
EXAMPLE Mortar pocket, rendering keyway, grip hole.
3.18
grip hole
hole in a masonry unit to enable it to be more readily grasped and lifted by hands or machine
3.19
shell
peripheral material between a perforation and the surface of a masonry unit
3.20
web
solid material between the perforations in a masonry unit
3.21
declared value
value that a manufacturer is confident in achieving, bearing in mind the precision of test and the variability of
the manufacturing process
3.22
mean compressive strength of masonry units
arithmetic mean of the compressive strengths of masonry units
3.23
normalized compressive strength
compressive strength of masonry units converted to the air dry compressive strength of an equivalent 100 mm
wide × 100 mm high masonry unit
NOTE See the procedure given in EN 772-1.
3.24
damp proof course unit
clay masonry unit which, when laid in two courses with broken bond in a strong cementitious mortar, will resist
rising damp in masonry
3.25
high precision clay masonry unit
clay masonry unit with small dimensional tolerance especially in unit height
3.26
vertically perforated or hollow clay masonry unit
clay masonry unit with one or more formed voids that pass completely through a masonry unit perpendicular
to the bed face
3.27
horizontally perforated or hollow clay masonry unit
clay masonry unit with one or more formed voids that pass completely through a masonry unit parallel to the
bed face
3.28
clay masonry unit for concrete or mortar infill
clay masonry unit with special perforation suitable for concrete or mortar infill
3.29
clay masonry unit for masonry panels
clay masonry unit suitable for production of reinforced masonry or masonry storey height panels with vertical
channels for mortar or concrete infill
3.30
clay masonry subject to severe exposure
masonry or elements of masonry which, under end use conditions, are subjected to saturation with water
(driving rain, ground water) combined with frequent freeze/thaw-cycling, due to climatic conditions and
absence of protective features
3.31
clay masonry subject to moderate exposure
masonry or elements of masonry which, under end use conditions, are exposed to moisture and freeze/thaw-
cycling, excluding constructions subjected to severe exposure
3.32
clay masonry subject to passive exposure
masonry or elements of masonry which, under end use conditions, are not intended to be exposed to moisture
and freezing conditions
3.33
Category I masonry units
units with a declared compressive strength with a probability of failure to reach it not exceeding 5 %
NOTE This may be determined via the mean or characteristic value.
3.34
Category II masonry units
units not intended to comply with the level of confidence of Category I units
3.35
combined thickness of webs and shells
sum of the thicknesses of the shells and webs from one face or header of a masonry unit to the opposite face
or header respectively along whichever path, via the formed voids, gives the smallest value, expressed as a
percentage of the unit width or length respectively
3.36
product group
products from one manufacturer having common values for one or more characteristics
3.37
consignment
shipment from the supplier
4 Materials and manufacture
See 3.2, 8.3.4 and 8.3.5.
5 Requirements for clay masonry units
5.1 General
The requirements and properties specified in this standard shall be defined in terms of the test methods and
other procedures referred to in this European Standard.
NOTE It should be noted that the test methods are not usually applicable to specially shaped and accessory units as
defined in 3.10 and 3.11.
The conformity criteria given in the following subclauses relate to initial type testing (see 8.2) and, when
relevant, to consignment testing (see Annex A). For the compressive strength of Category I units use a 50 %
fractile (p = 0,50) for mean values and a confidence level of 95 %.
For production evaluation, the manufacturer shall define the conformity criteria in the factory production
control documentation (see 8.3).
The manufacturer shall declare whether the unit fulfils the requirements for LD units (see Figure 2) or HD units
(see Figure 3).
5.2 LD units
5.2.1 Dimensions and tolerances (LD units)
5.2.1.1 Dimensions (LD units)
The dimensions of a clay masonry unit shall be declared by the manufacturer in mm for length, width, and
height, in that order (see Figure 1). They shall be given in terms of work size.
NOTE In addition the co-ordinating size may be given.

Key
1 Length 3 Height 5 Face
2 Width 4 Bed 6 Header
NOTE This relates to the normal use of the masonry unit in the wall.
Figure 1 — Dimensions and surfaces
The measurement procedure shall be in accordance with EN 772-16.
5.2.1.2 Dimensional tolerances (LD units)
5.2.1.2.1 Tolerances (LD units)
The manufacturer shall also declare which of the tolerance categories for mean values in 5.2.1.2.2 the clay
masonry units fulfil.
When relevant to the uses for which the unit is placed on the market, the manufacturer shall also declare
which of the range categories in 5.2.1.2.3 a given consignment of the clay masonry units fulfils.
NOTE This additional declaration may be made for example in relation to:
− achievement of the required accuracy (planarity, bonds and thin layer joints) of the masonry;
− use of detailed project drawings to achieve these requirements.
5.2.1.2.2 Tolerances of the mean value (LD units)
When clay masonry units are sampled from a consignment in accordance with Annex A and tested in
accordance with EN 772-16, the difference for all dimensions between the declared value and the mean value
derived from measurements of the test sample shall not be greater than the declared one of the following
categories, where the value shall be rounded to the whole mm:
Category Maximum range
T1:
± 0,40 (work size dimension) mm or 3 mm whichever is the greater
T1+:
± 0,40 (work size dimension) mm or 3 mm for length and width whichever is the greater and
± 0,05 (work size dimension) mm or 1 mm for the height whichever is the great
T2:
± 0,25 (work size dimension) mm or 2 mm whichever is the greater
T2+: ± 0,25 (work size dimension) mm or 2 mm for length and width whichever is the greater and
± 0,05 (work size dimension) mm or 1 mm for the height whichever is the greater
or Tm: a deviation in mm declared by the manufacturer (may be wider or closer than the other
categories).
5.2.1.2.3 Range (LD units)
When declared and regular-shaped clay masonry units are sampled from a consignment in accordance with
Annex A and tested in accordance with EN 772-16, the maximum range for any given dimension (i.e. the
difference between the largest and smallest determined dimensions on individual units) to be found within the
test sample shall be within the declared one of the five categories indicated below, where the value shall be
rounded to whole mm:
Category Maximum range
R1:
0,6 (work size dimension) mm
R1+:
0,6 (work size dimension) mm for length and width and 1,0 mm for the height
R2:
0,3 (work size dimension) mm
R2+:
0,3 (work size dimension) mm for length and width and 1,0 mm for the height
or Rm: a range in mm declared by the manufacturer (may be wider or closer than the other categories).

5.2.1.2.4 Flatness of bed faces (LD units)
When clay masonry units are intended to be used with thin layer mortar, the manufacturer shall declare the
maximum deviation from flatness of the bed faces.
When regular-shaped clay masonry units are sampled from a consignment in accordance with Annex A and
tested in accordance with EN 772-20, the deviation from flatness of the bed faces shall not exceed the
declared value.
5.2.1.2.5 Plane parallelism of bed faces (LD units)
When clay masonry units are intended to be used with thin layer mortar, the manufacturer shall declare the
maximum deviation from plane parallelism of the bed faces.
When regular-shaped clay masonry units are sampled from a consignment in accordance with Annex A and
tested in accordance with EN 772-16, the deviation from plane parallelism of the bed faces shall not exceed
the declared value.
5.2.2 Configuration (LD units)
5.2.2.1 General (LD units)
a) Vertically perforated unit b) Vertically perforated unit c) Vertically perforated unit
with mortar pocket with grip holes

d) Vertically perforated unit e) Horizontally perforated unit f) Horizontally perforated unit
with tongue and groove system (for partition walls) with rendering keyways

g) Horizontally perforated unit h) Unit for concrete or i) Unit for masonry panels
with mortar pocket mortar infill
Figure 2 — Examples of LD units
When relevant to the uses, for which clay masonry (LD) units are placed on the market, the configuration shall
be declared. The declaration may be made by reference to one or another of the groups defined in
EN 1996-1-1 or EN 1996-1-2 and/or it may include one or more items such as those in the following list, as
relevant:
 shape and features, including the direction of perforations (by means of a drawing or illustration, when
relevant);
 volume of all formed voids as a percentage of the length × width × height of the unit;
 volume of the largest of any formed voids as a percentage of the length × width × height of the unit;
 volume of grip holes as a percentage of the length × width × height of the unit;
 thickness of webs;
 thickness of shells;
 combined thickness of webs and shells from face to face;
 combined thickness of webs and shells from header to header;
 area of voids on a bed face as a percentage of the length × width of the unit.
NOTE The header of clay masonry units may have interlocking features, e.g. mortar pockets, tongue and groove
systems. The face of clay masonry units may have a surface-profile (rendering keyways).
Each declared value shall be stated as either an upper limit or a lower limit or as a range of values. When clay
masonry units are sampled from a consignment in accordance with Annex A and tested in accordance with
EN 772-16, EN 772-9 and EN 772-3, as specified below, the mean value derived from measurements of the
test sample shall be within the range or limit declared.
5.2.2.2 Thickness of shells and webs (LD units)
If relevant for vertically or horizontally perforated loadbearing clay masonry units, the manufacturer shall
declare the thickness of shells and webs, and if relevant for clay masonry units for concrete or mortar infill the
minimum thickness of shells in the facing and of shells in the header and of webs shall be declared by the
manufacturer.
NOTE For clay masonry units intended to establish storey height channels to be filled with concrete or mortar
experience shows that a minimum thickness of shells in the facing of 20 mm and a minimum thickness of shells in the
header and of webs of 14 mm are sufficient.
5.2.2.3 Grip hole (LD units)
If relevant for vertically perforated loadbearing clay masonry units, the manufacturer shall declare the area of
grip holes.
5.2.2.4 Channel for concrete/mortar infill (LD units)
The perforation shall be arranged in such a way, that a vertically continuous channel is established if clay
masonry units are set in bonds. The channel for concrete/mortar infill shall be arranged axial in direction of the
unit's width. The channel for concrete/mortar infill shall have a minimum area of 1 500 mm and a minimum
dimension of 30 mm.
5.2.2.5 Percentage of voids (LD units)
The determination of the percentage of voids shall be obtained in accordance with EN 772-3.
For the determination of the percentage of voids for vertically perforated clay masonry units, the grip holes
shall be considered, but not the mortar pockets and the rendering keyways.
For the determination of the percentage of voids for clay masonry units intended to establish storey height
channels to be filled with concrete or mortar infill, the channels for concrete/mortar infill shall be considered,
but not the rendering keyways (recesses).
5.2.3 Density (LD units)
5.2.3.1 Gross dry density (LD units)
The gross dry density shall be declared by the manufacturer and shall be equal to or less than 1 000 kg/m .
NOTE 1 The manufacturer may also inform in what way the declared gross dry density fits into a national classification
system.
The manufacturer shall also declare which of the deviation categories in 5.2.3.3 applies.
NOTE 2 This declaration may be made for evaluation of:
− loading;
− airborne sound insulation;
− resistance to fire;
− thermal insulation.
In addition, the manufacturer may declare the minimum and maximum individual values of gross dry density.
5.2.3.2 Net dry density (LD units)
When relevant to the uses for which the unit is placed on the market, the net dry density shall be declared by
the manufacturer.
NOTE The manufacturer may also inform in what way the declared net dry density fits into a national classification
system.
The manufacturer shall also declare which of the deviation categories in 5.2.3.3 applies.
In addition, the manufacturer may declare the minimum and maximum individual values of net dry density.
5.2.3.3 Tolerances (LD units)
When clay masonry units are sampled from a consignment in accordance with Annex A and tested in
accordance with EN 772-13, the mean gross and net dry density derived from measurements of the test
sample shall not differ from the manufacturer's declared dry density by more than one of the following
categories:
 D1: 10 %
 D2: 5 %
or
 Dm: a deviation in % declared as a whole number by the manufacturer (may be wider or closer than the
other categories).
5.2.4 Compressive strength (LD units)
When relevant to the uses for which the unit is placed on the market and in all cases for masonry units
intended to be used in elements subject to structural requirements, the mean compressive strength shall be
declared by the manufacturer. The manufacturer shall also declare the normalized compressive strength when
relevant.
NOTE 1 The manufacturer may also inform in what way the declared compressive strength fits into a national
classification system.
NOTE 2 EN 772-1 gives instructions on how to convert the unit compressive strength into the normalized compressive
strength.
In addition, the manufacturer shall declare whether the clay masonry unit is Category I or Category II.
When the clay masonry units are sampled from a consignment in accordance with Annex A and tested in
accordance with EN 772-1, then:
 mean compressive strength of the specified number of clay masonry units from a consignment shall be
not less than the declared compressive strength;
 individual strengths of specimens measured within the test sample shall be not less than 80 % of the
declared value.
The declaration shall relate to and indicate the orientation(s) of the clay masonry units as tested, the methods
of bedding the units and whether any voids present are intended to be fully filled with mortar.
NOTE 3 The requirements for compressive strength given in this clause are not necessarily applicable to specially
shaped and accessory masonry units.
5.2.5 Thermal properties (LD units)
When relevant to the uses for which the units are placed on the market and in all cases for masonry units
intended to be used in elements subject to thermal insulation requirements, the manufacturer shall provide the
mean λ -value and the determination model as prescribed in EN 1745 or alternatively give gross dry
10,dry,unit
density or net dry density and configuration.
Additionally another fractile may be provided. In such cases both the additional fractile and the corresponding
λ -value shall be given.
10,dry,unit
When the clay masonry units are sampled in accordance with Annex A and tested in accordance with EN
1745 following the model provided, then the obtained λ-value of the specified number of clay masonry units
shall be not greater than the provided λ-value.
When relevant to the use for which the units are placed on the market, the value of specific heat capacity
given in EN 1745 may be provided.
5.2.6 Durability (LD units)
NOTE When the intended use of the product provides a complete protection against water penetration (e.g. thick
layer of suitable render, cladding, inner leaf of a cavity wall, internal walls), no reference to freeze/thaw resistance is
required (F0).
When the intended use of the product only provides limited protection (e.g. thin layer of render), in countries
where there is a requirement for freeze/thaw resistance, it shall be evaluated and declared according to the
provisions valid in the intended place of use of the units.
5.2.7 Water absorption (LD units)
NOTE Because of the intended use of LD masonry units there are no requirements taking into account the water
absorption.
5.2.8 Active soluble salts content (LD units)
When the intended use of the product only provides limited protection (e.g. thin layer of render) the content of
active water soluble salts shall be declared by the manufacturer on the basis of the categories given in
Table 1. When clay masonry units are sampled from the consignment in accordance with Annex A and tested
in accordance with EN 772-5, the content of water soluble salts shall not be greater than the declared active
soluble salts content.
Table 1 — Active soluble salts content categories
Total % by mass not greater than
Category
+ + 2+
Na + K Mg
S0 No requirement No requirement
S1 0,17 0,08
S2 0,06 0,03
NOTE 1 When the intended use of the product provides complete protection against water penetration (e.g. thick layer
of suitable render, cladding, inner leaf of a cavity wall, internal walls) no requirement for active soluble salts content (S0).
NOTE 2 See B.4 for further information.
5.2.9 Moisture movement (LD units)
In countries where there is a requirement for moisture movement, it shall be declared in accordance with
EN 772-19 for clay masonry units with horizontal perforation, which have one dimension equal or greater than
400 mm and a shell thickness less than 12 mm and which are intended to be rendered respectively by
reference to the provisions valid in the intended place of use of the units.
5.2.10 Reaction to fire (LD units)
For units intended to be used in elements subject to fire requirements the manufacturer shall declare the
reaction to fire classification of the masonry unit.
For masonry units containing ≤ 1,0 % by mass or volume (whichever is the most onerous) of homogeneously
distributed organic materials the declaration may be fire Class A1 without the need to test.
Masonry units containing > 1,0 % by mass or volume (whichever is the most onerous) of homogeneously
distributed organic materials shall be classified in accordance with EN 13501-1 and the appropriate fire
classification declared.
NOTE Attention is drawn to the Commission Decision 96/603/EC, amended by Commission Decision 2000/605/EC,
in which non-combustible masonry units containing not more than 1,0 % by mass or volume (whichever is the more
onerous) of homogeneously distributed organic materials are classified as reaction to fire Class A1 without testing.
5.2.11 Water vapour permeability (LD units)
For units intended to be used in external elements, the manufacturer shall provide information on the water
vapour permeability through the water vapour diffusion coefficient tabulated values given in EN 1745 or
determined in accordance with EN ISO 12572.
5.2.12 Bond strength (LD units)
5.2.12.1 General (LD units)
For clay masonry units intended to be used in elements subjected to structural require
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