BS 1722-7-2006 - Fences
BS 1722-7-2006 - Fences
BS 1722-7-2006 - Fences
BRITISH STANDARD
Fences
Part 7: Specification for wooden post
and rail fences
ICS 91.090
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
BSI 2006
Publication history
First published November 1951
Second edition April 1963
Third edition July 1972
Fourth edition October 1986
Fifth edition March 1999
Sixth (present) edition November 2006
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
Contents
Foreword ii
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Dimensions, designation and general characteristics 2
5 Timber components for sawn post and rail fences 4
6 Timber components for fences with cleft hardwood rails and
sawn, round or cleft posts 5
7 Other components 9
8 Installation 9
9 Statement of Conformity 11
Annexes
Annex A (normative) Timber components 13
Annex B (informative) Suggested sampling method for use when
measuring the limiting characteristics of timber 21
Annex C (informative) Specifying a wooden post and rail fence 22
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Bibliography 24
List of figures
Figure 1 General characteristics of sawn post and rail fences 3
Figure 2 Position and dimensions of side-by-side mortices for
cleft rails 7
Figure 3 Position and dimensions of single mortices for cleft rails 8
Figure 4 Measurement of girth of cleft posts and rails 8
Figure 5 Measurement of girth of cleft posts 9
Figure A.1 Knot projection 15
Figure A.2 Measurement of wane 16
Figure A.3 Measurement of slope of grain 16
Figure A.4 Measurement of checks and end shakes 18
Figure A.5 Measurement of straightness 19
List of tables
Table 1 Designation, dimensions and general characteristics of sawn
post and rail fences 2
Table 2 Designation, dimensions and general characteristics of
morticed sawn or cleft post and cleft rail fences 2
Table 3 Determination of moisture content of timber to be treated for
use in fencing 4
Table 4 Minimum dimensions of side-by-side mortices for cleft rails 7
Table 5 Minimum dimensions of single mortices for cleft rails 8
Table A.1 Characteristics and defects of sawn softwoods and
hardwoods 14
Table B.1 Single sampling plan 21
Summary of pages
This document comprises a front cover, an inside front cover,
pages i to iii, a blank page, pages 1 to 24, an inside back cover and a
back cover.
BSI 2006 i
BS 1722-7:2006
Foreword
Publishing information
This part of BS 1722 was published by BSI and came into effect on
30 November 2006. It was prepared by Technical Committee B/201,
Fences and Gates. A list of organizations represented on this
committee can be obtained on request to its secretary.
Supersession
This part of BS 1722 supersedes BS 1722-7:1999, which is withdrawn.
Part 9: Specification for mild steel (low carbon steel) fences
with round or square verticals and flat horizontals
Part 10: Specification for anti-intruder fences in chain link
and welded mesh
Part 11: Specification for prefabricated wood panel fences
Part 12: Specification for steel palisade fences
Part 13: Specification for chain link fences for tennis court
surrounds 1)
Part 14: Specification for open mesh steel panel fences
Part 16: Specification for organic powder coatings to be used
as a plastics finish to components and mesh
Part 17: Electric security fences. Design, installation and
maintenance Specification
Part 18: Specification for steel mesh site perimeter
temporary fencing systems 2)
1) Obsolescent.
2) Part 18 is in development and will be published as a Draft for Development
(DD).
ii BSI 2006
BS 1722-7:2006
card) or equivalent and all other operatives should hold the basic fence
operative card (green card) or equivalent.
At the time of publication of this British Standard the registration cards
are validated by the Joint Fencing Industry Skills Scheme (FISS) and
Construction Scheme Skills Certification Scheme (CSCS). FISS/CSCS
maintains a national register of fence installers and operatives. There
might be other schemes available.
Presentational conventions
The provisions of this standard are presented in roman (i.e. upright)
type. Its requirements are expressed in sentences in which the principal
auxiliary verb is shall.
Commentary, explanation and general informative material is
presented in smaller italic type, and does not constitute a
normative element.
Requirements in this standard are drafted in accordance with The BSI
guide to standardization Section 2: Rules for the structure,
drafting and presentation of British Standards, subclause 11.3.1,
which states, Requirements should be expressed using wording such
as: When tested as described in Annex A, the product shall .... This
means that only those products that are capable of passing the specified
test will be deemed to conform to this standard.
1 Scope
This part of BS 1722 specifies requirements for wooden post and rail
fences, using both sawn and cleft components. It includes requirements
for the installation of the fencing at the specified location.
2 Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this part of this British
Standard. For dated references, subsequent amendments to, or
revisions of, any of these publications do not apply. For undated
references, the latest edition of the publication referred to applies.
BS EN ISO 1461, Hot dip galvanized coatings on fabricated iron
and steel articles Specifications and test methods
BS 957-2, Specification for feeler gauges Part 2: Metric units
BS 1202-1, Specification for nails Part 1: Steel nails
BS 4978, Specification for visual strength grading of softwood
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
concrete
EN 206-1 Part 2: Specification for constituent materials and
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top to
bottom B)
Morticed Nailed m m m mm
MPR 11/3 SPR 11/3 1.1 1.80 1.60 3 325, 275
MPR 11/4 SPR 11/4 1.1 1.80 1.60 4 225, 200, 175
MPR 13/4 SPR 13/4 1.3 2.10 1.80 4 250, 250, 225
A)
B)
Only used in morticed fences.
See 8.1.3.1 for the relative position of the top rail.
Table 2 Designation, dimensions and general characteristics of morticed
sawn or cleft post and cleft rail fences
Fence type designation Height from ground to Length of main Number of Spacing between
top of top rail posts rails rails at posts,
from top to
bottom A)
2 BSI 2006
BS 1722-7:2006
1 2
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a) Morticed fence
Key
1 Main post 3 Rails
2 Prick post
1 2
b) Nailed fence
Key
1 Main post
2 Joints normally staggered 3 Rails
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BS 1722-7:2006
When determining the suitability of a charge of timber for preservation,
moisture readings shall be made on no fewer than (n/2) separate
components, where n is the total number of components in the charge.
The components to be measured shall be taken from random positions
in the charge. The number of heartwood and sapwood faces sampled
shall reflect the relative proportions of these types of wood in the charge
as a whole.
If a moisture meter is not used, the oven-dry method of determining
moisture content as described in BS EN 212 shall be used.
To achieve the recommended moisture content of 28% (m/m) timber
shall be either air dried or kiln dried. For either process, fencing timber
shall be debarked and stacked so that air can circulate freely. Kiln
drying shall be used if natural drying is unlikely, for example in winter
conditions.
4 BSI 2006
BS 1722-7:2006
5.3 Posts
5.4 Rails
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BSI 2006 5
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(see Figure 4).
The section at the rail ends shall be sufficient to produce a tenon that
adequately fills the mortice.
6 BSI 2006
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Minimum dimensions shall be as specified in Table 4.
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BS 1722-7:2006
F W F
H
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
F
Minimum dimensions (see Figure 3)
mm
W C H T
Sawn post 38 38 110 150 38
Cleft post 50 38 110 150 50
A B
8 BSI 2006
BS 1722-7:2006
7 Other components
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7.1 Fittings
Nails shall be round, plain-head nails conforming to BS 1202-1 and
hot-dip galvanized in accordance with BS EN ISO 1461.
7.2
Concrete surrounding bases of posts
Concrete for surrounding the bases of posts and struts shall be at least
one part cement to 10 parts 20 mm all-in ballast to BS EN 12620:2002
mixed with the minimum requisite quantity of clean water, or grade
C8/10 or ST2 concrete to BS 8500 parts 1 and 2. The concrete shall be
placed in position before commencement of the initial set.
8 Installation
8.1 Fences with sawn rails
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8.1.2 Posts
8.1.2.1 Main posts
8.1.2.1.1 Spacing
Main posts shall be provided at intervals, measured centre-to-centre of
the posts, of not more than 2.85 m for morticed fences and not more
than 1.8 m for nailed fences.
8.1.2.1.2 Setting
Main posts shall be set vertically in the ground to a depth of 0.6 m for
fences 1.1 m high, and to a depth of 0.7 m for fences 1.3 m high. Holes
for main posts set in concrete shall be not less than 0.3 m 0.3 m in
plan, or, if round, as produced by an auger, not less than 0.3 m in
diameter. Alternatively posts may be driven. The holes for posts set only
in rammed backfill shall be as small as is practicable to allow for refilling
with backfill and ramming. All holes shall have vertical sides.
NOTE 1 It is realized that the ground at the top of a hole is damaged
during digging. This is acceptable provided that the damage is limited to
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the top of the hole and does not extend downward such that the hole itself
is tapered out towards the top.
Concrete surrounding the base of main posts shall fill at least half the
depth of the hole. The remainder of the hole shall be filled with backfill.
NOTE 2 The concrete should be placed after insertion of the post and
should be well rammed as the filling proceeds. The backfill should be well
rammed before the commencement of the initial set of the concrete.
rammed backfill.
NOTE 3
If main posts are set directly in the ground they shall be surrounded by
8.1.3 Rails
8.1.3.1 General
The top rail shall be fixed so that its top edge is 100 mm 5 mm from
the top of the main post. The spacing of subsequent rails shall be as
given in Table 1. The centreline of the rail shall not at any point deviate
by more than 25 mm from a straight line within the length between any
two consecutive main posts of a nailed fence, or between any
consecutive main post and prick post of a morticed fence.
10 BSI 2006
BS 1722-7:2006
8.2.1 Level
The fence shall follow lines and levels specified by the purchaser. The
top of the fence shall follow approximately the profile of the ground, to
levels previously indicated by the purchaser.
The presence of any electricity, gas, water or other underground
services shall be established prior to commencement of excavation,
drilling or erection in the working area.
NOTE Unless specified (see Annex C), the installation of the fence does
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
8.2.2 Posts
Posts shall be installed in accordance with 8.1.2.1.2, except that posts
for fences 1.05 m high shall be set vertically in the ground to a depth
of 0.6 m, and fences 1.25 m high, to a depth of 0.7 m.
8.2.3 Rails
Cleft rails shall be tenoned into the posts and shall fit properly into the
mortices. When side-by-side mortices are used, the tenons shall pass
through the posts. When single mortices are used, the rails shall be
scarfed over and under, or side by side. The length of the scarf shall be
not less than 200 mm. The top mortices shall be set 150 mm down from
the top of the post to the top of the mortice. The spacing of subsequent
rails shall be as given in Table 2. The rails shall be fixed so that the bark
is on the underside.
9 Statement of Conformity
9.1 Fence manufacturer
On delivery, the manufacturer/supplier of the fence shall provide the
installer with a certificate, conforming to 9.3, confirming that the fence
and/or gates are manufactured in accordance with the clients
instructions.
NOTE This certificate can be in the form of an invoice, provided this
conforms to 9.3.
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9.3 Certificate
In addition to the requirements of 9.1 and 9.2, the certificate shall also
include the following information:
a) the supplier's name and address;
b) the contract or order number;
c) the date of delivery or installation, as appropriate;
d) the purchasers name and address.
9.4 Statement
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trading statements supplied with quotations.
12 BSI 2006
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considered a valid reason for subsequent rejection after the initial
inspection within 14 days of delivery, either to the preservation treatment
works or to the site.
BSI 2006 13
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15 mm on any
corner.
At least two At least two adjacent corners shall
adjacent corners be free of wane
shall be free
of wane
Slope of grain Not more than 1 in 6 to the longitudinal axis of the piece
Rate of growth
Checks B)
End shakes B)
Unlimited
The depth of each check shall not exceed one half of the thickness of the
piece
Not longer than 150 mm
Resin pockets Unlimited Not longer than the width of the piece
Bark pockets Unlimited Not longer than the width of the piece and not wider
than 5 mm
Rot Not permitted
Active insect attack Not permitted
Lyctus damage Not permitted
Pin holes Not more than 20 Not more than 10 in any 0.6 m length
in any 0.3 m
length
Blackheart Unlimited C)
Blue stain Unlimited C)
Straightness B) Bow Not more than 10 mm per 1 m length
Spring Not more than 10 mm per 1 m length
Twist Not more than 2 mm per 25 mm width
Cup Not more than 1 mm per 25 mm width
Boxed heart Unlimited
A) Within a parcel, no fewer than 90% of the pieces shall have a K.A.R. of or less. A K.A.R. not exceeding 3/5 is
permitted in up to 10% of the pieces in the parcel.
B) Defects affected by changing climatic conditions (see Note 2 to A.2.1).
C) Not considered a defect.
14 BSI 2006
BS 1722-7:2006
1
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2
3
a) View showing in three dimensions a group of knots and their projection on a cross-sectional plane
k
k
w
2
Key
1 Width
2 Pith
3 Plane of projection
4 Face
5 Edge
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2
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Key
1 Face 2 Wane
Figure A.3 Measurement of slope of grain
B
C A
A.2.2.3 Wane
(See Figure A.2.)
Place a straightedge against a face or edge of the piece and measure the
wane.
16 BSI 2006
BS 1722-7:2006
A.2.2.5 Checks
(See Figure A.4a.)
Measure the maximum depth to which a 0.2 mm feeler gauge
conforming to BS 957-2 can be inserted without using excessive force.
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A.2.2.7 Straightness
Measure bow, spring, twist and cup as shown in Figure A.5, taking the
actual length or width (as relevant) of the piece as the reference.
BSI 2006 17
BS 1722-7:2006
c
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a) depth of check
c is the depth of check
NOTE Both checks are the same length.
d/2
18 BSI 2006
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x
2
a) Bow b) spring
y 3 4
L L
z
c) twist d) cup
L is the actual length of the piece
BS 1722-72006
BSI 2006
19
BS 1722-7:2006
A.2.3.2 Procedure
A.2.3.2.1 Select a section in the piece that intersects the knot or group
of knots.
A.2.3.2.2 In calculating the knot area ratio of the whole piece, consider
all the knots and knot holes with diameters greater than 5 mm which are
intersected by the chosen section.
A.2.3.2.3 Make full scale drawings of the chosen section. Mark points
on the appropriate side of the rectangle representing any knot on that
surface. The points marked shall represent the widest projection of the
knot on that face or edge.
A.2.3.2.4 Measure the total area of knots as described in either a) or b),
according to whether or not the pith occurs within the cross-section.
For the purpose of estimating the position of the pith, within or outside
the cross-section, examine the nearest end of the piece and assume that
all annual rings are concentric with the pith.
a) If the pith is within the cross-section (see Figure A.1), join the
points representing the limits of the knots on the drawing by
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the assumption that each knot is approximately a cone with its
apex at the pith. Measure the area thus enclosed, corresponding to
the estimated position of the knots, for the whole cross-section.
In both cases a) and b), express the total area of knots within the
cross-sectional area of the piece as a proportion of the cross-sectional
area of the piece, to determine the knot area ratio. (See A.2.2.1.)
20 BSI 2006
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Annex B (informative)
when measuring the limiting
characteristics of timber
B.1 Purpose
This sampling plan is for use in determining initially if a parcel of timber
pieces conforms to Table A.1. It does not preclude the subsequent
rejection of individual pieces for non-conformity with Table A.1, except
for defects due to changing climatic conditions (see Table A.1).
B.2 Procedure
Sample in accordance with Table B.1. Take the pieces comprising the
sample at random. Inspect by defective pieces, not by defects (i.e. a
piece containing one or more defects is to be counted as a defective
piece).
Reject a parcel if the number of defective pieces is equal to, or exceeds,
the rejection number.
BSI 2006 21
BS 1722-7:2006
b) site preparation:
1) site clearance;
2) cutting or filling of ground level;
c) any specific requirements for non-standard post lengths due to
ground conditions (see Foreword);
d) number and position of any gates or stiles.
NOTE 1 The requirements given in this standard for the length of posts
(see Table 1 and Table 2) and for foundation sizes relate to normal
ground conditions. This standard does not cover situations where the
ground is particularly firm or soft, when it may be necessary to modify the
specified lengths or foundation sizes. The method used to set posts in the
ground is also determined by the local ground conditions.
NOTE 2 Morticed post and rail fences cannot be installed on a tight
radius. This problem is most marked with scarfed rails.
22 BSI 2006
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For cleft rails, the spacing of posts will be approximately 150 mm to
250 mm less than the length of the rails, according to the method used
to fix the rails. Rails are traditionally cut at 3.05 m or 2.91 m lengths.
BSI 2006 23
BS 1722-7:2006
Bibliography
Standards publications
BS 7359:1991, Nomenclature of commercial timbers including
sources of supply
BS EN 335-1:1992, Use classes of wood and wood-based products
against biological attack Part 1: Classification of use classes
BS EN 350-1:1994, Durability of wood and wood-based products
Natural durability of solid wood Part 1: Guide to the principles of
testing and classification of natural durability of wood
BS EN 460:1994, Durability of wood and wood-based products
Natural durability of solid wood Guide to the durability
requirements for wood to be used in use classes
Other publications
[1] GREAT BRITAIN. Statutory Instrument 2003 No. 3274: The
Environmental Protection (Controls on Dangerous Substances)
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
[4] GREAT BRITAIN. Statutory Instrument 2003 No. 1511: The
Creosote (Prohibition on Use and Marketing) (No. 2) Regulations
2003. London: The Stationery Office.
[5] Wood Protection Association. Use of creosote and
creosote-treated timber.3)
24 BSI 2006
Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, BSI
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