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EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
EN 199512
November 2004
ICS 91.010.30; 13.220.50; 91.080.20
Incorporating corrigenda June 2006 and March 2009
Supersedes ENV 199512:1994
English version
Eurocode 5: Conception et Calcul des structures en bois Part 12: Generates  Calcul des structures au feu  Eurocode 5: Entwurf, Berechnung und Bemessung von Holzbauten  Teil 12: Allgemeine Regeln  Bemessung fur den Brandfall 
This European Standard was approved by CEN on 16 April 2004.
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. Uptodate lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat 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 Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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© 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
Ref. No. EN 199512:2004: E
1Foreword  4  
Background of the Eurocode programme  4  
Status and field of application of Eurocodes  5  
National Standards implementing Eurocodes  5  
Links between Eurocodes and harmonised technical specifications (ENs and ETAs) for products  6  
Additional information specific to EN 199512  6  
National annex for EN 199512  7  
Section 1 General  9  
1.1  Scope  9  
1.1.1  Scope of Eurocode 5  9  
1.1.2  Scope of EN 199512  9  
1.2  Normative references  10  
1.3  Assumptions  10  
1.4  Distinction between principles and application rules  10  
1.5  Terms and definitions  11  
1.6  Symbols  11  
Section 2 Basis of design  14  
2.1  Requirements  14  
2.1.1  Basic requirements  14  
2.1.2  Nominal fire exposure  14  
2.1.3  Parametric fire exposure  14  
2.2  Actions  15  
2.3  Design values of material properties and resistances  15  
2.4  Verification methods  16  
2.4.1  General  16  
2.4.2  Member analysis  17  
2.4.3  Analysis of parts of the structure  18  
2.4.4  Global structural analysis  19  
Section 3 Material properties  20  
3.1  General  20  
3.2  Mechanical properties  20  
3.3  Thermal properties  20  
3.4  Charring depth  20  
3.4.1  General  20  
3.4.2  Surfaces unprotected throughout the time of fire exposure  21  
3.4.3  Surfaces of beams and columns initially protected from fire exposure  23  
3.4.3.1  General  23  
3.4.3.2  Charring rates  26  
3.4.3.3  Start of charring  27  
3.4.3.4  Failure times of fire protective claddings  28  
3.5  Adhesives  29  
Section 4 Design procedures for mechanical resistance  30  
4.1  General  30  
4.2  Simplified rules for determining crosssectional properties  30  
4.2.1  General  30  
4.2.2  Reduced crosssection method  30  
4.2.3  Reduced properties method  31  
4.3  Simplified rules for analysis of structural members and components  32  
4.3.1  General  32  
4.3.2  Beams  32  
4.3.3  Columns  33  
4.3.4  Mechanically jointed members  33  
4.3.5  Bracings  34  
4.4  Advanced calculation methods  34  
Section 5 Design procedures for wall and floor assemblies  35 2  
5.1  General  35  
5.2  Analysis of loadbearing function  35  
5.3  Analysis of separating function  35  
Section 6 Connections  36  
6.1  General  36  
6.2  Connections with side members of wood  36  
6.2.1  Simplified rules  36  
6.2.1.1  Unprotected connections  36  
6.2.1.2  Protected connections  37  
6.2.1.3  Additional rules for connections with internal steel plates  38  
6.2.2  Reduced load method  39  
6.2.2.1  Unprotected connections  39  
6.2.2.2  Protected connections  41  
6.3  Connections with external steel plates  41  
6.3.1  Unprotected connections  41  
6.3.2  Protected connections  41  
6.4  Simplified rules for axially loaded screws  41  
Section 7 Detailing  43  
7.1  Walls and floors  43  
7.1.1  Dimensions and spacings  43  
7.1.2  Detailing of panel connections  43  
7.1.3  Insulation  43  
7.2  Other elements  43  
Annex A (Informative) Parametric fire exposure  45  
A1  General  45  
A2  Charring rates and charring depths  45  
A3  Mechanical resistance of members in edgewise bending  47  
Annex B (informative) Advanced calculation methods  48  
B1  General  48  
B2  Thermal properties  48  
B3  Mechanical properties  50  
Annex C (Informative) Loadbearing floor joists and wall studs in assemblies whose cavities are completely filled with insulation  52  
C1  General  52  
C2  Residual crosssection  52  
C2.1  Charring rates  52  
C2.2  Start of charring  54  
C2.3  Failure times of panels  54  
C3  Reduction of strength and stiffness parameters  56  
Annex D (informative) Charring of members in wall and floor assemblies with void cavities  58  
D1  General  58  
D2  Charring rates  58  
D3  Start of charring  58  
D4  Failure times of panels  58  
Annex E (informative) Analysis of the separating function of wall and floor assemblies  60  
E1  General  60  
E2  Simplified method for the analysis of insulation  60  
E2.1  General  60  
E2.2  Basic insulation values  61  
E2.3  Position coefficients  62  
E2.4  Effect of joints  62  
Annex F (informative) Guidance for users of this Eurocode Part  68 
This European Standard EN 199512 has been prepared by Technical Committee CEN/TC250 “Structural Eurocodes”, 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 May 2005, and conflicting national standards shall be withdrawn at the latest by March 2010.
This European Standard supersedes ENV 199512:1994.
CEN/TC250 is responsible for all Structural Eurocodes.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxemburg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonisation of technical specifications.
Within this action programme, the Commission took the initiative to establish a set of harmonised technical rules for the design of construction works which, in a first stage, would serve as an alternative to the national rules in force in the Member States and, ultimately, would replace them.
For fifteen years, the Commission, with the help of a Steering Committee with Representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980’s.
In 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement^{1} between the Commission and CEN, to transfer the preparation and the publication of the Eurocodes to the CEN through a series of Mandates, in order to provide them with a future status of European Standard (EN). This links de facto the Eurocodes with the provisions of all the Council’s Directives and/or Commission’s Decisions dealing with European standards (e.g. the Council Directive 89/106/EEC on construction products  CPD  and Council Directives 93/37/EEC, 92/50/EEC and 89/440/EEC on public works and services and equivalent EFTA Directives initiated in pursuit of setting up the internal market).
The Structural Eurocode programme comprises the following standards generally consisting of a number of Parts:
EN 1990  Eurocode :  Basis of Structural Design 
EN 1991  Eurocode 1:  Actions on structures 
EN 1992  Eurocode 2:  Design of concrete structures 
EN 1993  Eurocode 3:  Design of steel structures 
EN 1994  Eurocode 4:  Design of composite steel and concrete structures 
EN 1995  Eurocode 5:  Design of timber structures 
EN 1996  Eurocode 6:  Design of masonry structures 
EN 1997  Eurocode 7:  Geotechnical design 
EN 1998  Eurocode 8:  Design of structures for earthquake resistance 
EN 1999  Eurocode 9:  Design of aluminium structures 
^{1}Agreement between the Commission of the European Communities and the European Committee for Standardisation (CEN) concerning the work on EUROCODES for the design of building and civil engineering works (BC/CEN/03/89).
4Eurocode standards recognise the responsibility of regulatory authorities in each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level where these continue to vary from State to State.
The Member States of the EU and EFTA recognise that EUROCODES serve as reference documents for the following purposes:
The Eurocodes, as far as they concern the construction works themselves, have a direct relationship with the Interpretative Documents^{2} referred to in Article 12 of the CPD, although they are of a different nature from harmonised product standards^{3}. Therefore, technical aspects arising from the Eurocodes work need to be adequately considered by CEN Technical Committees and/or EOTA Working Groups working on product standards with a view to achieving full compatibility of these technical specifications with the Eurocodes.
The Eurocode standards provide common structural design rules for everyday use for the design of whole structures and component products of both a traditional and an innovative nature. Unusual forms of construction or design conditions are not specifically covered and additional expert consideration will be required by the designer in such cases.
The National Standards implementing Eurocodes will comprise the full text of the Eurocode (including any annexes), as published by CEN, which may be preceded by a National title page and National Foreword, and may be followed by a National Annex.
The National annex may only contain information on those parameters which are left open in the Eurocode for national choice, known as Nationally Determined Parameters, to be used for the design of buildings and civil engineering works to be constructed in the country concerned, i.e.:
^{2}According to Art. 3.3 of the CPD, the essential requirements (ERs) shall be given concrete form in interpretative documents for the creation of the necessary links between the essential requirements and the mandates for harmonised ENs and ETAGs/ETAs.
^{3}According to Art. 12 of the CPD the interpretative documents shall: give concrete form to the essential requirements by harmonising the terminology and the technical bases and indicating classes or levels for each requirement where necessary; indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods of calculation and of proof, technical rules for project design, etc.; serve as a reference for the establishment of harmonised standards and guidelines for European technical approvals.
The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.
There is a need for consistency between the harmonised technical specifications for construction products and the technical rules for works^{4}. Furthermore, all the information accompanying the CE Marking of the construction products which refer to Eurocodes shall clearly mention which Nationally Determined Parameters have been taken into account.
EN 199512 describes the principles, requirements and rules for the structural design of buildings exposed to fire, including the following aspects.
EN 199512 is intended for clients (e.g. for the formulation of their specific requirements), designers, contractors and relevant authorities.
The general objectives of fire protection are to limit risks with respect to the individual, society, neighbouring property, and where required, directly exposed property, in the case of fire.
Construction Products Directive 89/106/EEC gives the following essential requirement for the limitation of fire risks:
“The construction works must be designed and built in such a way, that in the event of an outbreak of fire
According to the Interpretative Document “Safety in Case of Fire^{5}” the essential requirement may be observed by following the various fire safety strategies prevailing in the Member States like conventional fire scenarios (nominal fires) or natural fire scenarios (parametric fires), including passive and/or active fire protection measures.
The fire parts of Structural Eurocodes deal with specific aspects of passive fire protection in terms of designing structures and parts thereof for adequate loadbearing resistance and for limiting fire spread as appropriate.
Required functions and levels of performance can be specified either in terms of nominal (standard) fire resistance rating, generally given in National fire regulations, or by referring to the fire safety engineering for assessing passive and active measures. Supplementary requirements concerning, for example
^{4}see Art.3.3 and Art. 12 of the CPD, as well as clauses 4.2, 4.3.1, 4.3.2 and 5.2 of ID 1.
^{5}see clauses 2.2, 3.2(4) and 4.2.3.3
6Numerical values for partial factors and other reliability elements are given as recommended values that provide an acceptable level of reliability. They have been selected assuming that an appropriate level of workmanship and of quality management applies.
A full analytical procedure for structural fire design would take into account the behaviour of the structural system at elevated temperatures, the potential heat exposure and the beneficial effects of active fire protection systems, together with the uncertainties associated with these three features and the importance of the structure (consequences of failure).
At the present time it is possible to undertake a procedure for determining adequate performance which incorporates some, if not all, of these parameters, and to demonstrate that the structure, or its components, will give adequate performance in a real building fire. However, where the procedure is based on a nominal (standard) fire the classification system, which calls for specific periods of fire resistance, takes into account (though not explicitly), the features and uncertainties described above.
Options for the application of Part 12 of EN 1995 are illustrated in figure 1. The prescriptive and performancebased approaches are identified. The prescriptive approach uses nominal fires to generate thermal actions. The performancebased approach, using fire safety engineering, refers to thermal actions based on physical and chemical parameters.
For design according to this part, EN 199112 is required for the determination of thermal and mechanical actions acting on the structure.
It is expected that design aids based on the calculation models given in EN 199512, will be prepared by interested external organisations.
The main text of EN 199512 includes most of the principal concepts and rules necessary for direct application of structural fire design to timber structures.
In an annex F (informative), guidance is given to help the user select the relevant procedures for the design of timber structures.
This standard gives alternative procedures, values and recommendations with notes indicating where national choices may have to be made. Therefore the National Standard implementing EN 199512 should have a National annex containing all Nationally Determined Parameters to be used for the design of buildings and civil engineering works to be constructed in the relevant country.
National choice is allowed in EN 199512 through clauses:
2.1.3(2) Maximum temperature rise for separating function in parametric fire exposure;
2.3(1)P Partial factor for material properties;
2.3(2)P Partial factor for material properties;
2.4.2(3) Reduction factor for combination of actions;
4.2.1(1) Method for determining crosssectional properties.
Figure 1 – Alternative design procedures
8European Standards:
EN 300  Oriented strand boards (OSB) – Definition, classification and specifications 
EN 301  Adhesives, phenolic and aminoplastic for loadbearing timber structures; classification and performance requirements 
EN 309  Wood particleboards – Definition and classification 
EN 3131  Plywood – Classification and terminology. Part 1: Classification 
EN 3142  Plywood – Bonding quality. Part 2: Requirements 
EN 316  Wood fibreboards Definition, classification and symbols 
EN 520  Gypsum plasterboards – Definitions, requirements and test methods 
EN 912  Timber fasteners – Specifications for connectors for timber 
EN 13631  Fire resistance tests – Part 1: General requirements 
EN 13651  Fire resistance tests for loadbearing elements – Part 1: Walls 
EN 13652  Fire resistance tests for loadbearing elements – Part 2: Floors and roofs 
EN 1990:2002  Eurocode: Basis of structural design 
EN 199111:2002  Eurocode 1 Actions on structures 
Part 11: General actions – Densities, selfweight and imposed loads for buildings  
EN 199112:2002  Eurocode 1: Actions on structures – Part 12: General actions – Actions on structures exposed to fire 
EN 199312  Eurocode 3: Design of steel structures – Part 12: General – Structural fire design 
EN 199511  Eurocode 5: Design of timber structures – Part 11: General – Common rules and rules for buildings 
EN 123691  Woodbased panels – Characteristic values for structural design – Part 1: OSB, particleboards and fibreboards 
EN 13162  Thermal insulation products for buildings – factorymade mineral wool (MW) products – Specifications M/103 
ENV 133817  Test methods for determining the contribution to the fire resistance of structural members – Part 7: Applied protection to timber members 
EN 13986  Woodbased panels for use in construction – Characteristics, evaluation of conformity and marking 
EN 140811  Timber structures – Strength graded structural timber with rectangular cross section – Part 1, General requirements 
EN 14080  Timber structures – Glued laminated timber – Requirements 
EN 14374  Timber structures – Structural laminated veneer lumber – Requirements 
Borderline between the charlayer and the residual crosssection.
Crosssection of member in a structural fire design based on the reduced crosssection method. It is obtained from the residual crosssection by removing the parts of the crosssection with assumed zero strength and stiffness.
Duration of protection of member against direct fire exposure; (e.g. when the fire protective cladding or other protection falls off the timber member, or when a structural member initially protecting the member fails due to collapse, or when the protection from another structural member is no longer effective due to excessive deformation).
Any material or combination of materials applied to a structural member or element for the purpose of increasing its fire resistance.
Ultimate limit state design for ambient temperatures according to EN 199511.
Members for which measures are taken to reduce the temperature rise in the member and to prevent or reduce charring due to fire.
Crosssection of the original member reduced by the charring depth.
For the purpose of EN 199512, the following symbols apply:
Latin upper case letters
A_{r}  Area of the residual crosssection 
A_{t}  Total area of floors, walls and ceilings that enclose the fire compartment 
A_{v}  Total area of vertical openings of fire compartment 
E_{d}  Design effect of actions 
E_{d,fi}  Design modulus of elasticity in fire; design effect of actions for the fire situation 
F_{Ed,fi}  Design effect of actions on a connection for the fire situation 
F_{R,0.2}  20 % fractile of a resistance 
F_{Rk}  Characteristic mechanical resistance of a connection at normal temperature without the effect of load duration and moisture (k_{mod} = 1) 
G_{d,fi}  Design shear modulus in fire 
G_{k}  Characteristic value of permanent action 
K_{fi}  Slip modulus in the fire situation 
K_{u}  Slip modulus for the ultimate limit state at normal temperature 
L  Height of storey 
O  Opening factor 
Q_{k,1}  Characteristic value of leading variable action 11 
S_{05}  5 % fractile of a stiffness property (modulus of elasticity or shear modulus)at normal temperature 
S_{20}  20 % fractile of a stiffness property (modulus of elasticity or shear modulus)at normal temperature 
S_{d.fi}  Design stiffness property (modulus of elasticity or shear modulus) in the fire situation 
W_{ef}  Section modulus of effective crosssection 
W_{r}  Section modulus of residual crosssection 
Latin lower case letters
a_{0}  Parameter 
a_{1}  Parameter 
a_{2}  Distance 
a_{3}  Distance 
a_{fi}  Extra thickness of member for improved mechanical resistance of connections 
b  Width; thermal absorptivity for the total enclosure 
b_{0}  Parameter 
b_{1}  Parameter 
c  Specific heat 
d  Diameter of fastener 
d_{0}  Depth of layer with assumed zero strength and stiffness 
d_{char,0}  Charring depth for onedimensional charring 
d_{char,n}  Notional charring depth 
d_{ef}  Effective charring depth 
d_{g}  Gap depth 
f_{20}  20 % fractile strength at normal temperature 
f_{d.fi}  Design strength in fire 
f_{k}  Characteristic strength 
f_{v,k}  Characteristic shear strength 
h_{eq}  Weighted average of heights of all vertical openings in the fire compartment 
h_{ins}  Insulation thickness 
h_{ρ}  Fire protective panel thickness 
k  Parameter 
k_{ρ}  Density coefficient 
k_{0}  Coefficient 
k_{2}  Insulation coefficient 
k_{3}  Postprotection coefficient 
k_{fi}  Coefficient 
k_{flux}  Heat flux coefficient for fasteners 
K_{h}  Panel thickness coefficient 
k_{j}  Joint coefficient 
k_{mod}  Modification factor for duration of load and moisture content 
k_{mod,E,fi}  Modification factor for modulus of elasticity in the fire situation 
k_{mod,fi}  Modification factor for fire 
k_{mod,fm,fi}  Modification factor for bending strength in the fire situation 
k_{n}  Notional crosssection coefficient 
k_{pos}  Position coefficient 
k_{Θ}  Temperaturedependent reduction factor for local strength or stiffness property 
l_{a}  Penetration length of fastener into unburnt timber 
l_{a,min}  Minimum anchorage length of fastener 
l_{f}  Length of fastener 
l_{ρ}  Span of the panel 
p  Perimeter of the fire exposed residual crosssection 
q_{t,d}  Design fire load density related to the total area of floors, walls and ceilings which enclose the fire compartment 
t  Time of fire exposure 
t_{0}  Time period with a constant charring rate 12 
t_{1}  Thickness of the side member 
t_{ch}  Time of start of charring of protected members (delay of start of charring due to protection) 
t_{dfi}  Time of the fire resistance of the unprotected connection 
t_{f}  Failure time of protection 
t_{ins}  Time of temperature increase on the unexposed side of the construction 
t_{ins,0,j}  Basic insulation value of layer “i” 
t_{p,min}  Minimum thickness of panel 
t_{R}  Time of fire resistance with respect to the loadbearing function 
t_{req}  Required time of fire resistance 
y  Coordinate 
z  Coordinate 
Greek upper case letters
Γ  Factor accounting for the thermal properties of the boundaries of the compartment 
Θ  Temperature 
Greek lower case letters
β_{0}  Design charring rate for onedimensional charring under standard fire exposure 
β_{n}  Design notional charring rate under standard fire exposure 
β_{par}  Design charring rate during heating phase of parametric fire curve 
η  Conversion factor for the reduction of the loadbearing capacity in fire 
η_{f}  Conversion factor for slip modulus 
γ_{GA}  Partial factor for permanent actions in accidental design situations 
γ_{M}  Partial factor for a material property, also accounting for model uncertainties and dimensional variations 
γ_{M,fi}  Partial factor for timber in fire 
γ_{Q,1}  Partial factor for leading variable action 
λ  Thermal conductivity 
ρ  Density 
ρ_{k}  Characteristic density 
ω  Moisture content 
ψ_{1.1}  Combination factor for frequent value of a variable action 
ψ_{2.1}  Combination factor for quasipermanent value of a variable action 
ψ_{fi}  Combination factor for frequent values of variable actions in the fire situation 
NOTE 1: See EN 199112:2002 for definitions.
NOTE 2: There is no risk of fire spread due to thermal radiation when an unexposed surface temperature is below 300°C.
NOTE: The recommended values for maximum temperature rise during the decay phase are ΔΘ_{1} = 200 K and ΔΘ_{2} = 240 K. Information on National choice may be found in the National annex.
where:
f_{d,fl}  is the design strength in fire; 
S_{d,fi}  is the design stiffness property (modulus of elasticity E_{d,fi} or shear modulus G_{d,fi}) in fire; 
f_{20}  is the 20 % fractile of a strength property at normal temperature; 
S_{20}  is the 20 % fractile of a stiffness property (modulus of elasticity or shear modulus) at normal temperature; 
k_{mod,fi}  is the modification factor for fire; 
γ_{M,fi}  is the partial safety factor for timber in fire. 
NOTE 1: The modification factor for fire takes into account the reduction in strength and stiffness properties at elevated temperatures. The modification factor for fire replaces the modification factor for normal temperature design k_{mod} given in EN 199511. Values of k_{mod,fi} are given in the relevant clauses.
NOTE 2: The recommended partial safety factor for material properties in fire is γ_{M,fi} = 1,0. Information on National choice may be found in the National annex..
where:
R_{d,t,fi}  is the design value of a mechanical resistance in the fire situation at time t; 
R_{20}  is the 20 % fractile value of a mechanical resistance at normal temperature without the effect of load duration and moisture (k_{mod} = 1); 15 
η  is a conversion factor; 
γ_{M,fi}  is the partial safety factor for timber in fire. 
Note 1: See (1) above Note 2.
Note 2: Design resistances are applied for connections, see 6.2.2 and 6.4. For connections a conversion factor η is given in 6.2.2.1.
f_{20} = k_{fi} f_{k} (2.4)
S_{20} = k_{fl} S_{05} (2.5)
where:
f_{20}  is the 20 % fractile of a strength property at normal temperature; 
S_{20}  is the 20 % fractile of a stiffness property (modulus of elasticity or shear modulus) at normal temperature; 
S_{05}  is the 5 % fractile of a stiffness property (modulus of elasticity or shear modulus) at normal temperature 
k_{fi}  is given in table 2.1. 
k_{ft}  
Solid timber  1,25 
Gluedlaminated timber  1,15 
Woodbased panels  1,15 
LVL  1,1 
Connections with fasteners in shear with side members of wood and woodbased panels 
1,15 
Connections with fasteners in shear with side members of steel 
1,05 
Connections with axially loaded fasteners  1,05 
R_{20} = k_{fi} R_{k} (2.6)
where:
k_{fi}  is given in table 2.1. 
R_{k}  is the characteristic mechanical resistance of a connection at normal temperature without the effect of load duration and moisture (k_{mod} = 1). 
E_{d,fi} ≤ R_{d,t,fi} (2.7)
where
E_{d,fi}  is the design effect of actions for the fire situation, determined in accordance with EN 199112:2002, including effects of thermal expansions and deformations; 
R_{d,t,fi}  is the corresponding design resistance in the fire situation. 
NOTE: For verifying standard fire resistance requirements, a member analysis is sufficient.
E_{d,fi} = η_{fi} E_{d} (2.8)
where:
E_{d}  is the design effect of actions for normal temperature design for the fundamental combination of actions, see EN 1990:2002; 
η_{fi}  is the reduction factor for the design load in the fire situation. 
or, for load combinations (6.10a) and (6.10b) in EN 1990:2002, as the smallest value given by the following two expressions
where:
Q_{k,1}  is the characteristic value of the leading variable action; 
G_{k}  is the characteristic value of the permanent action; 
γ_{G}  is the partial factor for permanent actions; 
γ_{Q,1}  the partial factor for variable action 1; 17 
ψ_{fi}  is the combination factor for frequent values of variable actions in the fire situation, given either by ψ_{1,1} or ψ_{2,1} see EN 199111; 
ξ  is a reduction factor for unfavourable permanent actions G. 
NOTE 1: An example of the variation of the reduction factor η_{fi} versus the load ratio Q_{k,1}/G_{k} for different values of the combination factor ψ_{fi} according to expression (2.9) is shown in figure 2.1 with the following assumptions: γ_{GA} = 1,0, γ_{G} = 1,35 and γ_{Q} = 1,5. Partial factors are specified in the relevant National annexes of EN 1990:2002. Expressions (2.9a) and (2.9b) give slightly higher values.
Figure 2.1 – Examples of reduction factor η_{fi} versus load ratio Q_{k,1}/G_{k} according to expression (2.9)
NOTE 2: As a simplification, the recommended value is η_{fi} = 0,6, except for imposed loads according to category E given in EN 199121:2002 (areas susceptible to accumulation of goods, including access areas) where the recommended value is η_{fi} = 0,7. Information on National choice may be found in the National annex.
NOTE 3: The National choice of load combinations between expression (2.9) and expressions (2.9a) and (2.9b) is made in EN 199112:2002.
NOTE 1: A simplified method for the reduction of the strength and stiffness parameters of timber frame members in wall and floor assemblies completely filled with insulation is given in annex C (informative).
NOTE 2: A simplified method for the reduction of the strength of timber members exposed to parametric fires is given in annex A (informative).
NOTE: Values of temperaturedependent mechanical properties are given in annex B (informative).
NOTE: For thermal analysis, design values of thermal conductivity and heat capacity of timber are given in annex B (informative).
NOTE: This assumption is valid for most softwoods and hardwoods.
NOTE: For parametric fire exposure, see annex A (informative).
d_{char,0} = β_{0} t (3.1)
where:
d_{char,0}  is the design charring depth for onedimensional charring; 
β_{0}  is the onedimensional design charring rate under standard fire exposure; 
t  is the time of fire exposure. 
Figure 3.1 — Onedimensional charring of wide cross section (fire exposure on one side)
d_{char,n} = β_{n}, t (3.2)
where:
d_{char,n}  is the notional design charring depth, which incorporates the effect of corner roundings; 
β_{n}  is the notional design charring rate, the magnitude of which includes for the effect of corner roundings and fissures. 
When the smallest width of the cross section is smaller than b_{min}, notional design charring rates should be applied.
NOTE: For timber members in wall and floor assemblies where the cavities are completely filled with insulation, values for notional design charring rates β_{n} are given in annex C (informative).
Figure 3.2 — Charring depth d_{char,0} for onedimensional charring and notional charring depth d_{char,n}
β_{0,ρ,t} = β_{0} k_{ρ} k_{h} (3.4)
with
where:
ρ_{k}  is the characteristic density, in kg/m^{3}; 
h_{p}  is the panel thickness, in millimetres. 
NOTE: For woodbased panels characteristic densities are given in EN 12369.
β_{0} mm/min 
β_{n} mm/min 

a) Softwood and beech Gluded laminated timber with a characteristic density of ≥ 290 kg/m^{3} 
0,65  0,7 
Solid timber with a characteristic density of ≥ 290 kg/m^{3} 
0,65  0,8 
b) Hardwood Solid or glued laminated hardwood with a characteristic density of 290 kg/m_{3} 
0,65  0,7 
Solid or glued laminated hardwood with a characteristic density ≥ 450 kg/m^{3} 
0,50  0,55 
c) LVL with a characteristic density of ≥ 480 kg/m^{3} 
0,65  0,7 
d) Panels Wood panelling 
0,9^{a}  – 
Plywood  1,0^{a}  – 
Woodbased panels other than plywood  0,9^{a}  – 
^{a}The values apply to a characteristic density of 450 kg/m^{3} and a panel thickness of 20 mm; see 3.4.2(9) for other thicknesses and densities. 
NOTE 1: Other fire protection available includes intumescent coatings and impregnation. Test methods are given in ENV 133817
NOTE 2: The protection provided by other structural members may be terminated due to
NOTE 3: The different stages of protection, the times of transition between stages and corresponding charring rates are illustrated in figures 3.4 to 3.6.
NOTE 4: Rules for assemblies with void cavities are given in annex D (informative).
NOTE: Test methods are given in ENV 133817.
Figure 3.3 — Examples of fire protective claddings to: a) beams, b) columns,
24Figure 3.4 — Variation of charring depth with time when t_{ch} = t_{f} and the charring depth at time t_{a} is at least 25 mm
Figure 3.5 — Variation of charring depth with time when t_{ch} = t_{f} and the charring depth at time t_{a} is less than 25 mm
25Figure 3.6 — Variation of charring depth with time when t_{ch} < t_{f}
k_{2} = 1–0,018 h_{p} (3.7)
where h_{p} is the thickness of the layer, in millimetres.
Where the cladding consists of several layers of gypsum plasterboard type F, h_{p} should be taken as the thickness of the inner layer.
Thickness h_{ins} mm  k_{2} 
20  1 
≥ 45  0,6 
or for t_{ch} < t_{f} (see figure 3.6)
where β_{n} is the notional design charring rate, in mm/min. Expressions (3.8) and (3.9) also apply to onedimensional charring when β_{n} is replaced by β_{0}.
For the calculation of t_{f} see 3.4.3.4.
NOTE: Expression (3.8b) implies that a charlayer of 25 mm gives sufficient protection to reduce the charring rate to the values of table 3.1.
where:
h_{p} is the thickness of the panel, in case of several layers the total thickness of layers;
t_{ch} is the time of start of charring;
t_{ch} = 2,8 h_{p} – 14 (3.11)
where:
h_{p} is the thickness of the panel, in mm.
At locations adjacent to joints with unfilled gaps with a width of more than 2 mm, the time of start of charring t_{ch} should be calculated as
t_{ch} = 2,8 h_{p} – 23 (3.12)
where:
h_{p} is the thickness of the panel, in mm;
NOTE: Gypsum plasterboard type E, D, R and I according to EN 520 have equal or better thermal and mechanical properties than type A and H.
where:
t_{ch}  is the time of start of charring in minutes; 
h_{ins}  is the thickness of the insulation material in millimetres; 
ρ_{ins}  is the density of the insulating material in kg/m^{3}. 
t_{f} = t_{ch} (3.14)
where t_{ch} is calculated according to expression (3.10).
t_{f} = t_{ch} (3.15)
where t_{ch} is calculated according to expression 3.4.3.3(3).
NOTE: In general, failure due to mechanical degradation is dependent on temperature and size of the panels and their orientation. Normally, vertical position is more favourable than horizontal.
l_{f,req} = h_{p} + d_{char,0} + l_{a} (3.16)
where:
h_{p}  is the panel thickness; 
d_{char,0}  is the charring depth in the timber member; 
l_{a}  is the minimum penetration length of the fastener into uncharred timber. 
Increased charring near corners should be taken into account, see 3.4.2(4).
NOTE: For some adhesives, the softening temperature is considerably below the charring temperature of the wood.
NOTE: The recommended procedure is the reduced crosssection method given in 4.2.2. Information on the National choice may be found in the National annex.
d_{ef} = d_{char,n} + k_{o} d_{o} (4.1)
with:
d_{0} = 7 mm
d_{char,n}  is determined according to expression (3.2) or the rules given in 3.4.3. 
k_{0}  is given in (2) and (3). 
NOTE: It is assumed that material close to the char line in the layer of thickness k_{0} d_{0} has zero strength and stiffness, while the strength and stiffness properties of the remaining crosssection are assumed to be unchanged.
Figure 4.1 — Definition of residual crosssection and effective crosssection
k_{0}  
t < 20 minutes  t/20 
t ≥ 20 minutes  1,0 
Figure 4.2 — Variation of k_{0}: a) for unprotected members and protected members where t_{ch} ≤ 20 minutes, b) for protected members where t_{ch} > 20 minutes
where:
p  is the perimeter of the fire exposed residual crosssection, in metres; 
A_{r}  is the area of the residual crosssection, in m^{2}. 
Figure 4.3 — Illustration of expressions (4.2)(4.4)
Figure 4.4 — Continuous column
K_{fi} = K_{u} η_{t} (4.5)
where:
K_{fi}  is the slip modulus in the fire situation, in N/mm; 
K_{u}  is the slip modulus at normal temperature for the ultimate limit state according to EN 199511 2.2.2(2), in N/mm; 
η_{f}  is a conversion factor according to table 4.2. 
Nails and screws  0,2 
Bolts; dowels: split ring, shear plate and toothedplate connectors 
0,67 
NOTE: Guidance is given in annex B (informative).
NOTE 1: For wall and floor assemblies with cavities completely filled with insulation a design method is given in annex C (informative).
NOTE 2: For wall and floor assemblies with void cavities, design rules are given in annex D (informative).
NOTE: A design method is given in annex E (informative).
Time of fire resistance t_{d,fi} min 
Provisions^{a}  

Nails  15  d ≥ 2,8 mm 
Screws  15  d ≥ 3,5 mm 
Bolts  15  t_{1} ≥ 45 mm 
Dowels  20  t_{1} ≥ 45 mm 
Connectors according to EN 912  15  t_{1} ≥ 45 mm 
^{a} d is the diameter of the fastener and U is the thickness of the side member 
where:
a_{fi} = β_{n} k_{flux} (t_{req}t_{d,fi}) (6.1)
β_{n}  is the charring rate according to table 3.1; 
k_{fux}  is a coefficient taking into account increased heat flux through the fastener; 
t_{req}  is the required standard fire resistance period; 
t_{d,fi}  is the fire resistance period of the unprotected connection given in table 6.1. 
Figure 6.1 — Extra thickness and extra end and edge distances of connections
t_{ch} ≥ t_{req} − 0,5 t_{d,fi} (6.2)
where:
t_{ch}  is the time until start of charring according to 3.4.3.3; 
t_{req}  is the required standard fire resistance period; 
t_{d,fi}  is the fire resistance of the unprotected connection given in table 6.1. 
t_{ch} ≥ t_{req} − 1.2 t_{d,fi} (6.3)
Figure 6.2 — Examples of additional protection from gluedin plugs or from woodbased panels or gypsum plasterboard (the protection of edges of side and middle members is not shown)
Figure 6.3 — Example of protection to a bolt head
b_{st}  
Unprotected edges in general  R 30  ≥ 200 mm 
R 60  ≥ 280 mm  
Unprotected edges on one or two sides  R 30  ≥ 120 mm 
R 60  ≥ 280 mm 
Figure 6.4 — Protection of edges of steel plates (fasteners not shown): a) unprotected, b) protected by gaps, c) protected by gluedin strips, d) protected by panels
where d is the diameter of bolt or dowel, in mm.
F_{v,Rk,fi} = η F_{v,Rk} (6.5)
with
η = e^{−ktd,fi} (6.6)
where:
F_{v,Rk}  is the characteristic lateral loadcarrying capacity of the connection with fasteners in shear at normal temperature, see EN 199511 section 8; 39 
η  is a conversion factor; 
k  is a parameter given in table 6.3; 
t_{d,fi}  is the design fire resistance of the unprotected connection, in minutes. 
NOTE: The design loadbearing capacity is calculated corresponding to 2.3 (2)P.
where:
k  is a parameter given in table 6.3; 
η_{fi}  is the reduction factor for the design load in the fire situation, see 2.4.2 (2); 
η_{o}  is the degree of utilisation at normal temperature; 
k_{mod}  is the modification factor from EN 199511, subclause 3.1.3; 
γ_{M}  is the partial factor for the connection, see EN 199511, subclause 2.4.1; 
k_{fi}  is a value according to 2.3 (4); 
γ_{M,fi}  is the partial safety factor for timber in fire, see 2.3(1). 
Connection with  k  Maximum period of validity for parameter k in an unprotected connection min 

Nails and screws  0,08  20 
Bolts woodtowood with d ≥ 12 mm  0,065  30 
Bolts steeltowood with d ≥ 12 mm  0,085  30 
Dowels woodtowood^{a} with of ≥ 12 mm  0,04  40 
Dowels steeltowood^{a} with d ≥ 12 mm  0,085  30 
Connectors in accordance with EN 912  0,065  30 
^{a} The values for dowels are dependent on the presence of one bolt for every four dowels 
a_{fi} = β (t_{req} − t_{d,fi}) (6.8)
where:
β_{n}  is the notional charring rate according to table 3.1; 
t_{req}  is the required standard fire resistance; 40 
t_{d,fi}  is the fire resistance of the unprotected connection loaded by the design effect of actions in the fire situation, see 2.4.1. 
a_{2} ≥ a_{1} + 40 (6.9)
a_{3} ≥ a_{1} + 20 (6.10)
where a_{1}, a_{2} and a_{3} are the distances, in millimetres.
where:
41a_{1}  is the side cover in mm, see figure 6.5; 
t_{d,fi}  is the required fire resistance period, in minutes. 
Figure 6.5 — Crosssection and definition of distances
where:
t_{p,min}  is the minimum thickness of panel in millimetres; 
t_{p}  is the span of the panel (spacing between timber frame members or battens) in millimetres. 
Figure 7.1 — Timber members protected by gypsum plasterboard — Examples of penetration length of fastener into unburnt timber: a) Timber frame assembly with insulation in cavity, b) Wide timber member in general
Figure 7.2 — Examples of fixing of fire protective panels to beams or columns
(Informative)
NOTE: A method for the determination of parametric timetemperature curves is given in EN 199112:2002, annex A.
with
where:
O  is the opening factor, in m^{0.5}; 
β_{n}  is the notional design charring rate, in mm/min; 
A_{v}  is the total area of openings in vertical boundaries of the compartment (windows etc.), 
A_{t}  is the total area of floors, walls and ceiling that enclose the fire compartment, in m^{2}; 
A_{i}  is the area of vertical opening “i”, in m^{2}; 
h_{eq}  is the weighted average of heights of all vertical openings (windows etc.), in metres; 
h_{i}  is the height of vertical opening “i”, in metres; 
Γ  is a factor accounting for the thermal properties of the boundaries of the compartment; 
b  is the absorptivity for the total enclosure, see EN 199112:2002, annex A; 
λ  is the thermal conductivity of the boundary of compartment, in Wm^{−1}K^{−1}; 
p  is the density of the boundary of the compartment, in kg/m^{3}; 
c  is the special heat of the boundary of the compartment, in Jkg^{−1}K^{−1}. 
Figure A1 — Relationship between charring rate and time
with
where:
t_{o}  is the time period with a constant charring rate, in minutes; 
q_{t,d}  is the design fire load density related to the total area of floors, walls and ceilings which enclose the fire compartment in MJ/m^{2}, see EN 199112:2002. 
The rules given in (1) and (2) should only be used for:
where:
b  is the width of the crosssection; 
h  is the depth of the crosssection. 
where:
d_{char,n}  is the notional charring depth; 
b  is the width of the member. 
For 3t_{0} ≤ t ≤ 5t_{0} the modification factor for fire may be determined by linear interpolation.
NOTE: Where the reduced properties method given in 4.2.3 is invalidated by the National annex, for t ≤ 3t_{o} the modification factor for fire can be derived from the reduced crosssection method as
where:
W_{ef}  is the section modulus of the effective crosssection determined according to 4.2.2; 
W_{r}  is the section modulus of the residual crosssection. 
(Informative)
NOTE: Where thermal models do not take into account phenomena such as increased heat transfer due to mass transport, e.g. due to the vaporisation of moisture, or increased heat transfer due to cracking which causes heat transfer by convection and/or radiation, the thermal properties are often modified in order to give results that can be verified by tests.
NOTE: The mechanical properties of timber given in annex B include the effects of thermal creep and transient states of moisture.
For standard fire exposure, values of thermal conductivity, specific heat and the ratio of density to dry density of softwood may be taken as given in figures B1 to B3 and tables B1 and B2.
NOTE 1: The thermal conductivity values of the char layer are apparent values rather than measured values of charcoal, in order to take into account increased heat transfer due to shrinkage cracks above about 500°C and the consumption of the char layer at about 1000°C. Cracks in the charcoal increase heat transfer due to radiation and convection. Commonly available computer models do not take into account these effects.
NOTE 2: Depending on the model used for calculation, modification of thermal properties given may be
48necessary.
Figure B1 – Temperaturethermal conductivity relationship for wood and the char layer
Temperature °C 
Thermal conductivity Wm^{−1}K^{−1} 

20  0,12 
200  0,15 
350  0,07 
500  0,09 
800  0,35 
1200  1,50 
Figure B2 – Temperaturespecific heat relationship for wood and charcoal
49Figure B3 – Temperaturedensity ratio relationship for softwood with an initial moisture content of 12 %
Temperature °C 
Specific heat capacity kJ kg^{−1} K^{−1} 
Ratio of density to dry density^{a} 

20  1,53  1 + ω 
99  1,77  1 + ω 
99  13,60  1 + ω 
120  13,50  1,00 
120  2,12  1,00 
200  2,00  1,00 
250  1,62  0,93 
300  0,71  0,76 
350  0,85  0,52 
400  1,00  0,38 
600  1,40  0,28 
800  1,65  0,26 
1200  1,65  0 
^{a} ω the moisture content 
NOTE: The relationships include the effects of transient creep of timber.
50Figure B4 – Reduction factor for strength parallel to grain of softwood
Figure B5 – Effect of temperature on modulus of elasticity parallel to grain of softwood
(Informative)
Figure C1 — Notional residual crosssection of timber frame member protected by cavity insulation
β_{n} = k_{s} k_{2} k_{n} β_{0} for t_{ch} ≤ t ≤ t_{f} (C.1)
β_{n} = k_{s} k_{3} k_{n} β_{0} for t ≥ t_{f} (C.2)
where:
52k_{n} = 1,5  
β_{n}  is the notional design charring rate; 
k_{s}  is the crosssection factor, see (3); 
k_{2}  is the insulation factor, see (4); 
k_{3}  is the postprotection factor, see (5); 
k_{n}  is a factor to convert the irregular residual crosssection into a notional rectangular crosssection; 
β_{0}  is the onedimensional design charring rate, see 3.4.2 table 3.1; 
t  is the time of fire exposure; 
t_{ch}  is the time of start of charring of the timber frame member, see C2.2; 
t_{f}  is the failure time of the cladding, see C2.3. 
b mm 
k_{s} 
38  1,4 
45  1,3 
60  1,1 
k_{2} = 1,05 − 0,0073 h_{p} (C.3)
k_{2} = 0,86 − 0,0037 h_{p} (C.4)
where h_{p} is the total thickness of all panel layers in millimetres.
Figure C2 — Joint configurations in gypsum plasterboard panels with one and two layers
k_{3} = 0,036 t_{f} + 1 (C.5)
where t_{f} is the failure time of the lining, in minutes.
t_{ch} = t_{f} (C.6)
where the failure time t_{f} is calculated according to C2.3(1).
where:
t_{f}  is the failure time, in minutes; 
h_{p}  is the panel thickness, in millimetres; 
β_{o}  is the design charring rate for onedimensional charring under standard fire exposure, in mm/min. 
t_{f} = 2,8 h_{p} − 14 (C.8)
NOTE: More information on test methods is given in EN 13631, EN 13651 and EN 13652.
with
k_{1} = 1,0 for panels not jointed over the timber member (C.10)
k_{j} = 1,15 for joint configurations 1 and 3 (C.11)
54where:
t_{ch}  is the time of start of charring; 
l_{f}  is the length of the fastener; 
l_{a,min}  is the minimum penetration length of the fastener into unburnt wood; 
h_{p}  is the total thickness of the panels; 
k_{s}  is the crosssection factor, see C2.1(3); 
k_{2}  is the insulation factor, see C2.1(4); 
k_{n}  is a factor to convert the irregular residual crosssection into a notional rectangular crosssection, see C2.1(2); 
β_{0}  is the design charring rate for onedimensional charring under standard fire exposure, see 3.4.2 table 3.1. 
The minimum penetration length l_{amin} into unburnt wood should be taken as 10 mm.
Figure C3 — Illustration of use of steel channels for fixing panels in the ceiling
where:
t_{sf}  is the failure time of the steel channels; 
t_{s}  is the thickness of the steel channels; 
k_{3}  is the postprotection factor; 
the other symbols are given in (5).
where:
a_{0}, a_{1}  are values given in table C2 and C3; 
d_{char,n}  is the notional charring depth according to expression (3.2) with β_{n} according to expression (C.1) and (C.2); 
h  is the depth of the joist or the stud. 
Case  h mm 
a_{0}  a_{1}  

1  Bending strength with exposed side in tension  95  0,60  0,46  
145  0,68  0,49  
195  0,73  0,51  
220  0,76  0,51  
2  Bending strength with exposed side in compression  95  0,46  0,37  
145  0,55  0,40  
195  0,65  0,48  
220  0,67  0,47  
3  Compressive strength  95  0,46  0,37  
145  0,55  0,40  
195  0,65  0,48  
220  0,67  0,47  
^{a} For intermediate values of h, linear interpolation may be applied 
Case  h mm 
a_{0}  a_{1}  

1  Compressive strength  
145  0,39  1,62 
where:
b_{0}, b_{1}  are values given in tables C4 and C5; 
d_{char,n}  is the notional charring depth according to expression (3.2) with β_{n} according to expression (C.1) and (C.2); 
h  is the depth of the joist. 
Case  h mm 
b_{0}  b_{1}  

1  Buckling perpendicular to wall plane  
95  0,50  0,79  
145  0,60  0,84  
195  0,68  0,77  
2  Buckling in plane of wall  
95  0,54  0,49  
145  0,66  0,55  
195  0,73  0,63  
^{a} For intermediate values of h, linear interpolation may be applied. NOTE: In the illustration to case 2 the studs are braced by noggins. 
Case  h mm 
b_{0}  b_{1}  

1  Buckling perpendicular to wall plane  145  0,37  1,87  
2  Buckling in plane of wall  145  0,44  2,18  
^{a} For intermediate values of h, linear interpolation may be applied. NOTE: In the illustration to case 2 the studs are braced by noggins. 
(Informative)
t_{ch} = t_{f} (D.1
where t_{f} is determined according to D4(1).
t_{ch} = t_{f} (D.2)
where the failure time t_{f} is determined according to D4(2). For definition of narrow and wide sides of timber member, see figure D1.
Figure D1 — Definition of narrow and wide sides of timber member
where:
t_{f}  is the failure time, in minutes; 
h_{p}  is the panel thickness, in millimetres; 
β_{0}  is the onedimensional charring rate, in mm/min. 
t_{f} = 2,8 h_{p} − 11 (D.4)
t_{f} = 2,8 h_{p} − 12 (D.5)
where h_{p} is the thickness of the cladding, in mm. For claddings consisting of two layers, the thickness h_{p} should be taken as the thickness of the outer layer and 50 % of the thickness of the inner layer, provided that the spacing of fasteners in the inner layer is not greater than the spacing of fasteners in the outer layer.
(Informative)
NOTE: A test method is given in ENV 133817.
t_{ins} ≥ t_{req} (E.1)
where:
t_{ins}  is the time taken for the temperature increases on the unexposed side given in 2.1.2(3) to occur; 
t_{req}  is the required fire resistance period for the separating function of the assembly. 
where:
t_{ins,0,i}  is the basic insulation value of layer “i” in minutes, see E2.2; 
k_{pos}  is a position coefficient, see E2.3; 
k_{j}  is a joint coefficient, see E2.4. 
The relevant number of layers should be determined from table E1 and figure E1.
NOTE: A joint does not have an effect on the separating performance if it is backed with a batten or a structural element, which will prevent the travel of hot gases into the structure.
Temperature rise on unexposed side K 
Heat transfer path according to figure E1  

General construction  140  a 
Joints  180  b 
Services  180  c,d 
Figure E1 — Illustration of heat transfer paths through a separating construction
t_{ins,0} = 0,95 h_{p} (E.3)
t_{ins,0} = 1,1 h_{p} (E.4)
t_{ins,0} = 0,5 h_{p} (E.5)
t_{ins,0} = 1,4 h_{p} (E.6)
where:
t_{ins,0}  is the basic insulation value, in minutes; 
h_{p}  is the panel thickness, in millimetres. 
t_{ins,0,i} = 0,2 h_{ins} k_{dens} (E.7)
t_{ins,0,i} = 0,1 h_{ins} k_{dens} (E.8)
where:
h_{ins}  is the insulation thickness in millimetres; 
k_{dens}  is given in table E2. 
k_{pos} = 0,07 h_{p} − 0,17 (E.10)
where h_{p} is the thickness of the panel on the exposed side.
Where the exposed panel is made of materials other than gypsum plasterboard type F, the position coefficient, k_{pos}, for a void cavity and an insulation layer should be taken as 1,0. Where the exposed panel is made of gypsum plasterboard type F, the position coefficient should be taken as:
NOTE: For wood panelling the effect of joints is included in the basic insulation values t_{ins,0} given by expression (E.5).
Cavity material  Density kg/m^{3}  k_{dens} ^{a} 

Glass fibre  15  0,9 
20  1,0  
26  1,2  
Rock fibre  26  1,0 
50  1,1  
^{a} For intermediate densities, linear interpolation may be applied 
Panel on the exposed side  Thickness mm 
Position coefficient for panels backed by  

rock or glass fibre insulation  void  
Plywood with characteristic density ≥ 450 kg/m^{3}  9 to 25  Expression (E.9)  0,8 
Particleboard, fibreboard with characteristic density ≥ 600 kg/m^{3}  9 to 25  
Wood panelling with characteristic density ≥ 400 kg/m^{3}  15 to 19  
Gypsum plasterboard type A, H, F  9 to 15 
Panel on the exposed side  Thickness of panel on exposed side mm 
Position coefficient for panels preceded by  

Glass fibre  Rock fibre of thickness^{a}  Void  
45 to 95  145  195  
Plywood with density ≥ 450 kg/m^{3}  9 to 25  Expression (E.10)  1,5  3,9  4,9  0,6 
Particleboard and fibreboard with density ≥ 600 kg/m^{3}  9 to 25  Expression (E.10)  0,6  
Wood panelling with density ≥ 400 kg/m^{3}  15 19 
0,45 0,67 
0,6  
Gypsum plasterboard type A, H, F  9 to 15  Expression (E.10)  0,7  
^{a} For intermediate values, linear interpolation may be applied. 
Construction: Layer number and material 
Layer number  

1  2  3  4  5  
1, 2, 4, 5 3 
Woodbased panel Void 
0,7  0,9  1,0  0,5  0,7 
1, 2, 4, 5 3 
Gypsum plasterboard type A or H Void 
1,0  0,8  1,0  0,8  0,7 
1, 5 2, 4 3 
Gypsum plasterboard type A or H Woodbased panel Void 
1,0  0,8  1,0  0,8  0,7 
1, 5 2, 4 3 
Woodbased panel Gypsum plasterboard type A or H Void 
1,0  0,6  1,0  0,8  0,7 
1, 2, 4, 5 3 
Woodbased panel Rock fibre batts 
0,7  0,6  1,0  1,0  1,5 
1, 2, 4, 5 3 
Gypsum plasterboard type A or H Rock fibre batts 
1,0  0,6  1,0  0,9  1,5 
1, 5 2, 4 3 
Gypsum plasterboard type A or H Woodbased panel Rock fibre batts 
1,0  0,8  1,0  1,0  1,2 
1, 5 2, 4 3 
Woodbased panel Gypsum plasterboard type A or H Rock fibre batts 
1,0  0,6  1,0  1,0  1,5 
Figure E2 — Definition of layer numbers
65Joint type  k_{j}  

a  0,2  
b  0,3  
c  0,4  
d  0,4  
e  0,6 
Joint type  Type  k_{j}  

Filled joints  Unfilled joints  
a  A, H, F  1,0  0,2  
b  A, H,F  1,0  0,15 
(informative)
Figure F1 — Flow chart outlining the design procedure to check the loadbearing function of structural members
68Figure F2 — Flow chart for the design procedure of connections
69