SIST-TS CEN/TS 12037:2005
(Main)Wood preservatives - Field test method for determining the relative protective effectiveness of a wood preservative exposed out of ground contact - Horizontal lap-joint method
Wood preservatives - Field test method for determining the relative protective effectiveness of a wood preservative exposed out of ground contact - Horizontal lap-joint method
This Technical Specification describes a method of test for wood preservatives that are intended for use in wood to be exposed to the weather out of contact with the ground without the additional protection of a surface coating.
The method is applicable to the testing of commercial or experimental preservatives applied by techniques appropriate to commercial practice. The method is applicable to chemical products used individually or in combination to prevent the development of decay and/or - optional - the development of disfiguring organisms in wood and, where suitable, in wood-based products.
NOTE The method can also be used to test other treated wood species and naturally durable timbers. It can be adapted for testing the field performance of other wood based systems and treatments designed to enhance durability, for example treated or untreated wood based composites, timber treated with non-biocidal systems, chemically modified or heat treated timber.
Although the test is used to assess decay, it is possible to use the method to additionally assess stain or each separately when relevant.
Holzschutzmittel - Freilandversuche zur Bestimmung der relativen Schutzwirkung eines Holzschutzmittels ohne Erdkontakt - Verfahren mit horizontaler Überplattung (Lap-joint)
Die vorliegende Technische Spezifikation beschreibt ein Verfahren zur Prüfung von Holzschutzmitteln, die für die Behandlung von Holz vorgesehen sind, das ohne Erdkontakt und ohne zusätzlichen Schutz durch eine Oberflächenbeschichtung der Witterung ausgesetzt werden soll.
Das Verfahren ist für die Prüfung kommerzieller oder experimenteller Holzschutzmittel anwendbar, die mit für die kommerzielle Praxis geeigneten Verfahrensweisen auf-/eingebracht werden. Das Verfahren ist auf chemische Erzeugnisse anwendbar, die einzeln oder in Kombination verwendet werden, um die Entwicklung von Fäulnis in Holz und/oder - wahlweise - die Entwicklung von verfärbenden Organismen in Holz und, falls zutreffend, in Holzprodukten, zu verhindern.
ANMERKUNG 1 Das Verfahren darf auch zur Prüfung von anderen behandelten Holzarten und natürlich dauerhaften Nutzhölzern angewendet werden. Es darf zur Prüfung der Gebrauchstauglichkeit im Freiland von anderen Systemen auf der Grundlage von Holz und von Behandlungsverfahren angewendet werden, die dafür ausgelegt sind, die Dauerhaftigkeit zu erhöhen, z. B. bei behandelten oder unbehandelten Holzverbundwerkstoffen, Nutzholz, das mit biozidfreien Systemen behandelt wurde, und chemisch modifiziertem oder wärmebehandeltem Nutzholz.
ANMERKUNG 2 Obwohl die Prüfung für die Bewertung der Fäulnis angewendet wird, kann dieses Verfahren, falls zutreffend, zur zusätzlichen Bewertung der Verfärbung oder zur separaten Bewertung von Fäulnis und Verfärbung eingesetzt werden.
Produits de préservation du bois - Essais de champ pour déterminer l'efficacité protectrice d'un produit de préservation du bois hors de contact avec le sol - Méthode avec un assemblage a joint superposé
La présente Spécification technique européenne décrit une méthode d'essai de produits de préservation du bois destinés au bois exposé aux intempéries hors de contact avec le sol sans application ultérieure d'un revetement de surface.
La méthode est applicable a l'essai des produits de préservation commerciaux ou expérimentaux appliqués par des techniques appropriées utilisées dans la pratique. La méthode s'applique aux produits chimiques utilisés individuellement ou en combinaison pour empecher le développement de pourriture et/ou - en option - d'organismes de discoloration dans le bois et, si adapté, dans les matériaux dérivés du bois.
NOTE 1 La méthode peut aussi etre utilisée pour essayer d'autres essences de bois traités ou bien des bois naturellement durables. Elle peut etre adaptée pour essayer a l'extérieur les performances d'autres systemes a base de bois et des traitements destinés a accroître la durabilité, par exemple des composites a base de bois traités ou non traités, des bois traités avec des systemes non-biocides, des bois modifiés chimiquement ou traités a la chaleur.
NOTE 2 Bien que l'essai soit destiné a évaluer la pourriture, il est possible d'utiliser la méthode pour évaluer en plus la discoloration, ou alors chacune séparément si pertinent.
Zaščitna sredstva za les - Terenska preskusna metoda za ugotavljanje relativne preventivne učinkovitosti zaščitnega sredstva za les izven stika z zemljo
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 12037:2005
01-julij-2005
1DGRPHãþD
SIST-TS ENV 12037:2004
=DãþLWQDVUHGVWYD]DOHV7HUHQVNDSUHVNXVQDPHWRGD]DXJRWDYOMDQMHUHODWLYQH
SUHYHQWLYQHXþLQNRYLWRVWL]DãþLWQHJDVUHGVWYD]DOHVL]YHQVWLND]]HPOMR
Wood preservatives - Field test method for determining the relative protective
effectiveness of a wood preservative exposed out of ground contact - Horizontal lap-joint
method
Holzschutzmittel - Freilandversuche zur Bestimmung der relativen Schutzwirkung eines
Holzschutzmittels ohne Erdkontakt - Verfahren mit horizontaler Überplattung (Lap-joint)
Produits de préservation du bois - Essais de champ pour déterminer l'efficacité
protectrice d'un produit de préservation du bois hors de contact avec le sol - Méthode
avec un assemblage a joint superposé
Ta slovenski standard je istoveten z: CEN/TS 12037:2003
ICS:
71.100.50 .HPLNDOLMH]D]DãþLWROHVD Wood-protecting chemicals
SIST-TS CEN/TS 12037:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN/TS 12037:2005
TECHNICAL SPECIFICATION
CEN/TS 12037
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
December 2003
ICS 71.100.50 Superscedes ENV 12037:1996
English version
Wood preservatives – Field test method for determining the
relative protective effectiveness of a wood preservative exposed
out of ground contact – Horizontal lap-joint method
Produits de préservation du bois – Essais de champ pour Holzschutzmittel – Freilandversuche zur Bestimmung der
déterminer l’efficacité protectrice d’un produit de relativen Wirksamkeit eines Holzschutzmittels ohne
préservation du bois hors de contact avec le sol – Méthode Erdkontakt – Verfahren mit horizontaler Überlappung (Lap-
avec un assemblage à joint superposé joint)
This Technical Specification (CEN/TS) was approved by CEN on 8 October 2003 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available. It
is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible
conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 12037:2003 E
worldwide for CEN national Members.
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Page
Contents
1 Scope .5
2 Normative reference.5
3 Definitions, symbols and abbreviations.5
4 Principle.6
5 Materials .7
6 Apparatus and equipment .9
7 Sample of preservative .11
8 Test lap-joints .11
9 Untreated control lap-joints.13
10 Exposure test site.13
11 Inspections.13
12 Assessment.13
13 Duration of the test.14
14 Validity of test .14
15 Test report .15
Annex A (informative) Information on an additional test with a reference preservative and
on treatment processes .17
Annex B (informative) Example of a test report.21
Annex C (informative) Determination of the preventive efficacy of a test preservative or
components of a test preservative against staining fungi using horizontal lap-joint
method.27
Annex D (informative) Test field site .29
Bibliography.30
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Foreword
This document (CEN/TS 12037:2003) has been prepared by Technical Committee CEN/TC 38
“Durability of wood and wood-based products”, the secretariat of which is held by AFNOR.
This document supersedes ENV 12037:1996.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Hungary Iceland, Ireland, Italy, Luxembourg,
Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom.
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Introduction
The main objective of the method is to evaluate the relative effectiveness of the preservative, applied
to jointed specimens of Scots pine sapwood by a treatment method relevant to its intended practical
use and as such does not necessarily accelerate decay but reflects probable performance in service.
The method is concerned with the protection against decay after exposure to a wide range of micro-
organisms occurring out of ground contact under natural conditions. It takes into account also physico-
chemical effects of weathering on the performance of the preservative treated wood.
Since the lap-joints are exposed to natural outdoor conditions during the test period, variations in test
conditions from one exposure site to another have to be expected. Differences in climate, especially
rainfall, will inevitably influence the general rate of development of decay fungi. However, by
comparing the results obtained for the test preservative with those obtained for untreated control lap-
joints, the relative protective effectiveness of the preservative under test can be evaluated.
NOTE The procedures described in this Technical Specification are intended to be carried out by suitably
trained and/or supervised specialists. Appropriate safety precautions should be observed throughout the use of
the Technical Specification.
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1 Scope
This Technical Specification describes a method of test for wood preservatives that are intended for
use in wood to be exposed to the weather out of contact with the ground without the additional
protection of a surface coating.
The method is applicable to the testing of commercial or experimental preservatives applied by
techniques appropriate to commercial practice. The method is applicable to chemical products used
individually or in combination to prevent the development of decay and/or – optional – the
development of disfiguring organisms in wood and, where suitable, in wood-based products.
NOTE 1 The method may also be used to test other treated wood species and naturally durable timbers. It
may be adapted for testing the field performance of other wood based systems and treatments designed to
enhance durability, for example treated or untreated wood based composites, timber treated with non-biocidal
systems, chemically modified or heat treated timber.
NOTE 2 Although the test is used to assess decay, it is possible to use the method to additionally assess stain
or each separately when relevant.
2 Normative reference
This Technical Specification incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this Technical Specification only when incorporated in it by amendment
or revision. For undated references the latest edition of the publication referred to applies (including
amendments).
EN 212, Wood preservatives — Guide to sampling and preparation for analysis of wood preservatives
and treated timber.
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of this Technical Specification, the following definitions, symbols and abbreviations
apply :
3.1.1
active ingredient(s)
individual chemical compound or compounds included in the wood preservative product to give it
specific activity against the particular biological agencies of deterioration
3.1.2
additional process
any process or application of a product, as defined by the supplier, designed to improve the
effectiveness of the preservative
3.1.3
penetrating treatment process
process which includes features or procedures intended to overcome the natural resistance of wood to
penetration by a wood preservative product in its ready for use form
NOTE Such processes include for example currently practised technologies of diffusion treatments, double-
vacuum and vacuum-pressure methods.
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3.1.4
superficial application process
process which does not include particular features or procedures intended to overcome the natural
resistance of wood to penetration by a wood preservative product in its ready for use form
NOTE Such processes include for example brush and spray techniques and short-term immersion (dipping)
processes in which wood normally has only a few minutes contact time with the preservative.
3.1.5
representative sample
sample having its physical or chemical characteristics identical with the volumetric average
characteristics of the total volume being sampled (see EN 212)
3.1.6
supplier
sponsor of the test
3.1.7
target retention
retention recommended by the supplier
3.1.8
application rate
amount of preservative product per square metre to be applied in superficial processes recommended
by the supplier
3.2 Symbols and abbreviations
3.2.1
nUD
V
nominal median rating for the upper side of the lap-joints for sets of replicates at the assessment of the
extent of decay
3.2.2
nLD
V
nominal median rating for the lower side of the lap-joints for sets of replicates at the assessment of the
extent of decay
3.2.3
nJD
V
nominal median rating for surfaces within the joint areas of the lap-joints for sets of replicates at the
assessment of the extent of decay
NOTE For symbols for the optional assessment of attack by staining fungi see Annex C.
4 Principle
Jointed specimens (lap-joints) consisting of two overlapping parts (joint members) held together
mechanically are placed horizontally, out of contact with the ground and exposed to the weather. The
lap-joints are dismantled and examined at intervals. The extent of microbiological attack on the
external surfaces and within the joint areas is rated according to a specified rating system. Data for
lap-joints treated with the test product are compared with those generated from untreated specimens
to assess relative effectiveness.
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5 Materials
5.1 Test specimens
5.1.1 Wood species
The reference species is Scots pine (Pinus sylvestris Linnaeus)
NOTE Additional tests may be carried out using other species.
5.1.2 Quality of wood
The wood shall be free from visible cracks, stain, decay, insect damage and other defects. Some
knots are permitted. The wood shall not have been water-stored, floated, chemically treated or
steamed. The wood shall originate from trees preferably felled in winter.
NOTE Wood that has been kiln dried at temperatures below 60 °C may be used.
The Scots pine shall be exclusively sapwood containing little resin and having between 2,5 and 8
annual rings per 10 mm. The proportion of latewood in the annual rings shall not exceed 30 % of the
whole. Use wood without reaction wood or juvenile wood.
5.1.3 Provision of test specimens
The longitudinal faces shall be parallel to the direction of the grain. The annual rings shall have a
contact angle of not greater than 10 ° to the broad faces of the test specimens. Make transverse cuts,
neatly to give sharp edges and a fine-sawn finish to the end-grain surfaces.
All the wood used in the test shall have been handled and dried in the same way.
NOTE 1 If additional wood species are used, these should be mentioned in the test report together with their
density and the number of annual rings per 10 mm of the timber used for the test specimens.
Wood from at least three trees shall be used and evenly distributed among the different groups of lap-
joints.
Condition in a conditioning chamber (see 6.2) the timber stock to (12 ± 2) % (m/m) moisture content.
Prepare lengths of timber with (38 ± 1) mm · (85 ± 1) mm cross section by sawing (see 6.1) and
planning (see Figure 1). From the lap-joints subsequently machined from a single length of timber, not
more than one shall be included in each set of replicates (see 5.1.5).
NOTE 2 A moisture meter of the two-pronged electrical conductivity type is suitable for assessing moisture
content.
Each lap-joint shall be prepared from a single piece of wood as two members (180 ± 1) mm long and
separated by no more than 100 mm, to allow for removal of knots and associated grain aberration, to
ensure a tight fit during the test (see Figure 1). Within the overlapping part and the adjacent 50 mm
there shall be no knots and in the rest of each member there are no more than 3 sound knots, the
diameter of which shall not exceed 10 mm.
Machine the joint in a way that after assembly of the two members the pith faces are on the same side
of the assembled joint (see Figure 1).
Store the joint members in the conditioning chamber (6.2) until required for treating.
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Dimensions in millimetres
Key
1 Cable strap
Figure 1 — Lap-joint
NOTE The lap-joint members are held together by two cable straps (6.7). The lap-joint is shown without the
weatherproof end seal.
5.1.4 Dimensions and density of test specimens
The dimensions of each lap-joint at (12 – 2) % (m/m) moisture content shall be (300 – 2) mm ·
(85 – 1) mm · (38 – 1) mm with an overlapping close fitting part at mid-length of (60 – 1) mm (see
Figure 1).
3
The wood shall have a density, at 12% (m/m) moisture content, in the range between 400 kg/m and
3
550 kg/m corresponding to a mass of each joint member ranging of about 190 g to 260 g.
In a batch of specimens to be treated, the density of an individual is permitted to differ from the mean
value of the batch by – 10 %. This tolerance is increased to – 20 % for the untreated specimens. The
mean density of the treated specimens used for the test shall be recorded in the test report.
5.1.5 Number of lap-joints
Prepare at least 10 lap-joints for each combination of test parameters [wood species (see 5.1.1), test
preservative (see clause 7), retention level or application rate (see 8.3), and untreated control (see
clause 10)].
NOTE It is normally necessary to treat a higher number of lap-joints so that the required number can be
selected after treatment (see 8.2) and the inclusion of "abnormal" joints avoided. Optionally extra lap-joints may
be prepared for chemical analyses during exposure.
5.1.6 Labelling of lap-joints
Individual members of each lap-joint shall be assigned unique identification numbers in such a way
that these numbers are retained through all preparation operations. After preservative treatment an
identification label or tag of long-Iasting material shall be affixed to the lower side of each lap-joint
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away from the joint area. The labels shall be of a material which is inert to the wood and the chemicals
it contains after treatment and conditioning.
5.2 End-seal compounds
5.2.1 Preservative resistant end-seal : a material resistant to the penetration of the test preservative
solutions.
NOTE Polyvinyl acetate (PVAc) glues have been found to be suitable for many organic solvent formulations.
For water-borne formulations the weatherproof end-seal (5.2.2) may be used.
5.2.2 Weatherproof end-seal : a material which prevents water entry as well as microbial infection
and remains effective during long term exposure to the weather.
NOTE Two coats of an epoxy-resin/pitch compound have been found to be suitable.
6 Apparatus and equipment
6.1 Wood working equipment, including a saw capable of producing a fine sawn finish.
6.2 Conditioning chamber, well ventilated and controlled at (20 ± 2) °C and (65 ± 5) % relative
humidity.
6.3 Equipment, suitable for carrying out the treatment specified by the supplier.
6.4 Balance, capable of weighing to the nearest 0,1 g.
6.5 Safety equipment and protective clothing, appropriate for the test product, to ensure the
safety of the operator.
6.6 Labels and fixing pins, both long-lasting, inert (see 5.2.6) and corrosion resistant with similar
fixing pins.
6.7 Fixing material : cable straps, inert and weather resistant to be used for fixing the two
members of each joint together.
NOTE A suitable material of the straps is clear or white polyamide with a dimension of ca 360 mm 5 mm.·
These straps can easily be removed at the inspections and replaced by new straps when joints are returned to
the exposure racks.
Alternatively custom designed stainless steel metal clips may be used. A suitable clip design is shown
in Figure 2.
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Figure 2 — Suitable clip fabricated out of stainless steel to hold lap-joint in place
NOTE Two clips are needed per test assembly.
6.8 Exposure rack, (see Figure 3) made of preservative treated wood, aluminium profiles or any
other similar durable material and located at least 1 m above ground level and at least 0,5 m above
any low vegetation (see Figure 3). The test specimens shall be separated from the rack by spacing
pieces, cross-section, minimum 5 mm · 5 mm, maximum 10 mm · 10 mm, made of a long-lasting
weather resistant material, that will not react with timber or treated lap-joints (see Figure 4).
Key
1Test samples
Figure 3 — Example of an exposure rack (6.8)
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Figure 4 — Example of a suitable arrangement of lap-joints on a rack (6.8)
NOTE The samples shall be separated from each other by a minimum of 5 mm. Test samples shall also be
separated from the rack with a spacer manufactured from an inert, durable material with a cross section of a
minimum 5mm · 5mm to a maximum 10mm · 10mm.
7 Sample of preservative
The sample of preservative shall be representative of the product to be tested.
Samples shall be stored and handled in accordance with any written requirements from the supplier
including the product safety data sheet.
NOTE For the sampling of preservatives from bulk supplies, the procedures given in EN 212 should be used.
8 Test lap-joints
8.1 Initial end sealing
For each joint member, seal the end grain surface remote from the joint area twice with a preservative
resistant end seal (5.3.1) ; allow to dry.
8.2 Treating process
The preservative treatment is carried out after machining and initial end sealing but prior to
assembling.
Apply the test preservative to the end-sealed test joint members using the process specified by the
supplier.
NOTE 1 A range of model treatments is given in Annex A.
NOTE 2 When using a penetrating treatment for development products it is preferable to test at more than one
retention of the active ingredients, ideally three, ranged about that thought to be appropriate for out of ground
contact use. The concentration or target retention (X) may be achieved by varying the concentration of active
ingredient(s) in the formulation. Alternatively, the parameters of the treatment process can be altered. A suitable
range of retention could be 0,5 X, 1 X and 2 X. A narrower range can be used if the effectiveness of the product is
sufficiently well known, for example, a geometrical series with a factor of
treatment process it is preferable to test at more than one application rate of the active ingredients, ideally three,
ranged about that thought to be appropriate for out of ground contact use.
For all treatments except brushing, determine and record the volume of each of the lap-joint members
and its mass to the nearest 0,1 g immediately before treatment. After treatment allow to drain for
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several minutes or wipe off excess solution from the surface with a cloth. Then reweigh each member
immediately and record the mass after treatment.
For brush treatment, calculate the amount of preservative in grams to be applied on each surface of
the lap-joint member to correspond to the uptake in grams or millilitres per square metre
recommended by the supplier.
NOTE 3 This can be done by putting the members on the balance one by one and brush them while lying
there, surface after surface with enough time in between for the preservative to be soaked up.
Apply double the calculated amount of preservative to the end grain surfaces of the joint area.
8.3 Retention of preservative
Calculate the uptake of preservative solution for each member and express the retention in kilograms
of preservative product as supplied for the test per cubic metre of wood for penetrating and/or vacuum
treatment processes and in grams per square metre (solid products or concentrates) or millilitres per
square metre (ready to use products) of wood surface for superficial application processes.
NOTE 1 For processes resulting in unknown penetration, retention should be expressed in both ways.
NOTE 2 Although long term immersion is considered as a penetrating process (see EN 599-1), normally the
penetration and the uptake of preservative solutions are relatively low. Therefore an expression of retention in
grams per square metre (solid products or concentrates) or millilitres per square metre (ready to use products) is
preferable.
Reject lap-joints where any member has a retention deviating by more than 15 % from the median and
substitute an appropriate alternative (see 5.1.5) which falls within this range. For superficial application
processes, report any deviation from the application rate calculated before treatment.
8.4 Post-treatment handling of the test lap-joints
8.4.1 Conditioning
The recommendations of the supplier shall be followed.
If no recommendations are given by the supplier, dry the treated lap-joint members in a well-ventilated
covered area protected from rain and frost. Ensure free ventilation by storing the members horizontally
on supporting rods of a material that does not react with the preservative, for example, glass for
organic solvent based preservatives.
8.4.2 Final end sealing (prior to exposure)
For each joint member, seal the end grain surface remote from the joint area with the weatherproof
end seal (5.3.2) and carry it over 2 mm to 3 mm onto the lateral surfaces to provide a complete seal. If
necessary remove the initial sealing.
8.4.3 Labelling
Fix permanent labels (6.6) to both of the members well away from the joint area.
8.4.4 Assembling lap-joints
Prior to exposure, fix together the two joint members of each lap-joint using two cable straps or two
stainless steel metal clips (6.7) (see Figure 1).
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9 Untreated control lap-joints
A series of at least 10 untreated control lap-joints of Pinus sylvestris sapwood shall be installed at the
exposure site at the start of every experiment or group of experiments. The control lap-joints shall be
prepared, sealed, stored and handled in the same way as treated lap-joints before installation.
10 Exposure test site
10.1 Selection of test site
Select a test site producing use class 3 conditions conducive to decay.
10.2 Installation of the lap-joints at the test site
The total number of lap-joints used in the test shall be placed randomly on the exposure rack (6.8) with
the pith face downwards. The lap-joints shall be separated from each-other by a minimum of 5 mm
and shall be fixed in such a way that movement during exposure as a result of changes in moisture
content is not restricted (see Figure 4).
11 Inspections
The lap-joints shall be inspected at one year intervals.
First a visual inspection shall be carried out by examining the condition of all external surfaces. Next,
each lap-joint shall be taken apart and the condition of joint areas inspected. Using a blunt pointed
instrument gentle probing is then carried out on all surfaces to reveal softened areas. Both the
condition of the surfaces and of the joint areas are recorded using the rating scale given in 12.2.
Each lap-joint shall then be re-assembled and returned to the exposure racks from which it was
removed.
NOTE 1 For more detailed information about the course of degradation it may be preferable to inspect the lap-
joints at shorter intervals than one year, for instance every six months.
NOTE 2 If the lap-joint method is also used for testing the preventive efficacy of preservatives against wood
staining fungi, inspections should be made at least every six months. In this case the rating scale given in Annex
C should be used.
12 Assessment
The grading system shown in Table 1 shall be used to assess the extent of decay of the lap-joints.
Observations shall be made separately on the upper side and the lower side of the lap-joints and on
the surfaces within the joint area exposed by dismantling the joint. Three ratings, UD (upper side :
decay), LD (lower side : decay) JD (joint area : decay), shall be recorded for each lap-joint. The lap-
joints shall be assessed in moist condition. If the surfaces are dry at the date of assessment, they shall
be moistened by gentle spraying with tap water.
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Table 1 — Grading system for decay
Rating Description Definition
0 Sound No evidence of decay.
1 Slight attack Visible signs of decay, but no significant softening or weakening of the wood.
2
2 Moderate attack
Areas of decay (softened, weakened wood); typically not more than 3 cm and to a
depth of 2 to 3 mm.
2 + Moderate attack + Approaching 3, severe attack
3 Severe attack Marked softening and weakening of the wood typical of fungal decay; distinctly
2
more than 3 cm affected and to a depth of 3 or 5 mm or 5 to 10 mm over a few
2
cm .
3 + Severe attack + Approaching 4, failure
4 Failure Very severe and extensive rot, joint member(s) often capable of being easily
broken.
NOTE 1 Discoloration obviously due to the attack of wood destroying Basidiomycetes and / or soft rot fungi shall be
recorded and mentioned in the test report. If recommended by the sponsor of the test discoloration due to staining
fungi should be rated according to Annex C, Table C.1.
NOTE 2 Due to physico-chemical lignin degradation defibration of the wood cells may occur at the upper surface of
the lap-joints. Together w
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