This shows you how bricks meet BS standards and shows you the sizes and the differrent types of bricks available

1. BRICK
CLASSIFICATION

2. European StandardsEuropean Standards
Currently bricks are manufactured and tested to
British Standard 3921:1985. By the end of 2004
BS EN 771, the new European Standard will be
introduced. It will run alongside BS 3921 until the
end of 2005 when BS 3921 will be withdrawn.
This training module is based upon BS3921 and will
be updated to take into account the new European
Standard when necessary.

3. What is a brick?
A brick is defined in BS3921:1985 as a masonry
unit with overall dimensions not exceeding
338mm in length, 225mm in width and 113mm in
height.
BS 3921 : 1985 Definitions

4. Stretcher
Bed
Header
FACES
Note Bricks are guaranteed to be
faced on 1 stretcher and 1 header

5. Manufacturing Methods
Stock brick Brick originally made in the South-East
of England, so called from the timber
‘stock’ fixed to the bench and used to
form the frog.
Wire Cut Formed by extruding a column of clay
through a die, the column is then cut to
brick size by taught wires.
Soft Mud Process Process of forming bricks using clay with
a water content too high to allow the
bricks to be handled without deformation
immediately after shaping
Hand Made Brick Brick formed by throwing by hand a clod
of clay into a mould

6. Varieties of Clay bricks
Common
Useful but plain
Engineering
Strong & dense
Facing
Beautiful

7. Varieties of Clay Bricks
Common unit Masonry unit suitable for general construction
work
Engineering brick Fired-clay brick having a dense and strong
semi-vitreous body, conforming to defined
limits for water absorption and compressive
strength
Facing brick Masonry unit specially made or selected to
give an attractive appearance

8. Types of Clay bricks
Solid Perforated Frogged

9. Types of Clay Bricks BS3921:1985
Solid brick A brick without any perforations or frogs I.e.
100% solid clay un

10. Frogged brick
Masonry unit in which any frogs do exceed
20% of the gross volume of the brick

11. Perforated brick
Masonry unit in which any perforations do exceed 25%
of the gross volume of the brick

12. BS 3921 : 1985 Clay Bricks
Introduction
Scope
Definitions
Sizes
Dimensional deviations
Durability – soluble salt content amended 1995
Efflorescence – omitted 1995
Compressive strength
Water absorption
Sampling for testing
Marking

13. BS 3921 : 1985 Sizes
Work size
Coordinating size
215mm
65mm
102.5mm
Note – Bricks are guaranteed faced on 1 stretcher and 1 header
Scanned image here

14. Why 215 X 102.5 X 65
1 stretcher
2 Headers + 1 joint
3 Bricks on edge + 2 joints
215
102.5 102.5
65 65 65

15. BS 3921 : 1985 Appendix A
Take 24 bricks as described in clause 9. Remove any blisters, small projections
or loose particles of clay adhering to each brick. Place the bricks in contact with
each other in a straight line upon a level surface, using the appropriate
arrangement for each work size in figure 1.
Measure the overall dimension (length, width or height) to the nearest
millimetre, using inextensible measure long enough to measure the whole row
at one time, e.g. a steel tape.
Record each result.
Alternatively, divide the sample in half and form two rows of 12 bricks.
Measure each row separately and record the sum of two rows.
Using a gauge box or similar means, check that the size of any brick in the
sample does not exceed the coordinating size given in table 1.
Scanned image

16. BS 3921 : 1985 Dimensional Deviations
The overall measurements of 24 bricks sampled in accordance
with clause 9 and measured as described in appendix A shall not
fall outside the limits given in table 2. In addition, the size of any
individual brick in the sample shall not exceed the coordinating
size given in table 1.
Scanned table here

17. Durability
Will the brick stand up to the conditions prevailing in the wall?
Will it be durable? Is it frost resistant?
These are typical designers/specifiers questions.
Durability is a function of the brick but also the type of situation it will be used in.
For example a brick durable in London may fail on the west coast of Scotland
When water freezes it expands by about 9%. In so doing it exerts tremendous
force.
Frost resistant bricks are able to withstand freezing and thawing cycles whilst
saturated either :-
a) Because clay is so composed that it has spaces to absorb the forces,
e.g. H1 soft mud or
b) The brick is so dense that little water is able to get into the brick and it is
strong enough to withstand the forces, Sedgley or Kingsbury

18. BS 3921 : 1985 Durability
5.1 Frost resistance :-
The bricks shall be classified into one of the following categories:
Frost resistant (F). Bricks durable in all building situations including those
where they are in a saturated condition and subjected to repeated freezing and
thawing.
Moderately frost resistant (M). Bricks durable except when in a saturated
condition and subjected to repeated freezing and thawing.
Not frost resistant (O). Bricks liable to be damaged by freezing and thawing if
not protected as recommended in BS5628 : part 3 during construction and
afterwards, e.g. by an impermeable cladding. Such units may be suitable for
internal use.
5.2 Soluble Salt Content :-
The bricks shall be classified into one of the following categories:
Low (L). A limited percentage by mass of soluble salts.
Normal (N). No limit on soluble salt content.

19. BS 3921 : 1985 Durability
Scanned table here

20. Strength
Nowadays the brickwork leaf is generally only carrying its own
self weight.
However, there may be the need for the bricks to have sufficient
strength to carry the loads imposed by the roof, floors, or even
retained earth. Will the brick have sufficient strength.
Scanned images here

21. Water Absorption
Some designers believe that the amount of water a brick can
absorb indicates how frost resistant it will be.
THIS BELIEF IS WRONG
A low absorption is not always an indicator or frost resistance
whilst a high one doesn’t always mean a poor frost resistance.
Structural engineers can use lower absorption’s to reduce safety
factors in their designs. This is the most relevant use of water
absorption figures. (The lower the absorption, the higher the
brick/mortar bond.)
To obtain the figures we quote, e.g. 7%, 23%, etc bricks are first
boiled for 5 hours to try and fill the accessible pores (spaces). The
weights before and after boiling are compared and the difference
expressed as a percentage.

22. BS 3921 : 1985 Engineering Bricks
2 classes of engineering bricks are defined :-
Compressive
Strength
N/sq mm
Water
Absorption
% by mass
Class A 70 4.5
Class B 50 7.0
Compressive strength value is
a minimum water absorption
is a maximum
Compressive strength, water absorption alone designate engineering
bricks. We make no claims about their appearance. Users choosing to
build them into facing brickwork do so at their own responsibility.
Engineering bricks are traditionally used in manholes, sewerage works,
foundations, etc where the strength and low absorption are desirable.

23. Test Certificates
The properties we claim for our bricks are listed on the data sheets.
These are usually “safe” figures which we know our bricks will
comfortably exceed / better.
However, some customers will not accept Baggeridge’s word and they
ask for independent information to confirm our claims.
To provide this independent information confirmation for the customer
and as part of ongoing quality control, we send bricks to testing
laboratories not commercially connected with Baggeridge.
Their test results come back to us in the form of TEST CERTIFICATES.
Test Certificates are used to show that our CLAIMS (on data sheets) are
met or bettered in practice.
Designers should actually design based on the information on the data
sheets.

24. Mortars
Mortar makes up 17% of the surface area of facing brickwork.
We recommend cement, lime and sand mortars mixes in line with
British Standards designations (i) (ii) or (iii)
In general, the weakest mix possible should be selected except in
more secerley exposed areas, such as below d.p.c’s, cappings
and cills etc. where a stronger mix is advised.
All mortar joints should be fully filled with a thouroughly mixed
mortar to avoid “bleaching”.
Bucket handle or weather struck joints recommend to assist
weathering of brickwork.
Recessed joints may be used after cafeful consideration

25. Movement
Brickwork movement is a combination of both :
a) Long term moisture expansion of the bricks – between 20 and
60 years.
b) Reversible thermal movement caused by temperature
changes.
As a rule of thumb BS.5628 : Part 3, 2001 advises an expansion
of 1mm per metre run of brickwork – both horizontally and
vertically.
Movement joints should be typically spaced at 12 metre centres –
BS.5628 allows spacing up to 15 metres. Maximum.
Joints should be filled with a compressible filler and sealed with a
sealant both durable and tolerant

26. Good Brickwork Practice
Bricks should be handled and sorted in such a way as to minimize
any damage.
Bricks should be off-loaded onto a level hardstanding
To ensure bricks are well blended, bricks should be taken from a
minimum of three packs at one time.
Correct proportioning of mortar constituents is necessary for both
mortar strength and to avoid colour variations.
All new and incomplete brickwork should be protected by
waterproof sheeting.