The Correct Glass & Timber Screen for the Correct Application (FTN1)
Forza glazed timber frame screens not only provide the correct
level of fire resistance (integrity and insulation) and acoustic
performance for a designated area but also ensure the correct
structural guidelines are adhered to as recommended in Building
Control Regulations and British Standards.
The following notes, extracts, diagrams and tests indicate
how Forza screens comply with the relevant UK standards and
Building control.
British Standard: Barriers in and about Buildings, Code of
Practice. BS 6180 -2011
Definition of a barrier; "element of building or
structure, permanent or temporary, intended to prevent persons from
falling and to retain, stop or guide
persons".
Types of barrier incorporating glass: Full height
barrier: "Where glass forms part or whole of a wall element, the
barrier should be designed in accordance with BS 6180 if any part
of the glass comes below the minimum barrier height" (h. Other
positions 1100mm).
Minimum horizontal imposed loads for parapets, barriers and balustrades
Type of occupancy for part of the building / structure |
Example of specific use |
Horizontal uniformly distributed line load (kN/m) |
Uniformly distributed load applied to the infill (kN/m2) |
A point load applied to part of the infill |
Offices and work areas not included elsewhere, includes storage areas |
(v) Areas not susceptible to overcrowding in office and institutional buildings, also industrial & storage buildings |
0.74 |
1 |
0.5 |
Areas where people might congregate |
(vi) Areas having fixed seating within 530mm of the barrier balustrade or parapet |
1.5 |
1.5 |
1.5 |
Areas with tables or fixed seating |
(vii) Restaurants and bars |
1.5 |
1.5 |
1.5 |
Areas without obstacles for moving people not susceptible to overcrowding |
(viii) Stairs, landings, corridors, ramps |
1.5 |
1.5 |
1.5 |
Areas susceptible to overcrowding |
(x) Footways or pavements less than 3m wide adjacent to sunken areas |
1.5 |
1.5 |
1.5 |
(xi) Theatres, cinemas, discos, bars, auditoria, shopping mall assembly areas, studio, footways / pavements greater thank 3m adjacent to sunken areas |
3 |
1.5 |
1.5 |
|
Retail areas |
(xiii) All retail areas including public areas of banks / building societies or betting shops |
1.5 |
1.5 |
1.5 |
Barriers for the protection of people should be of adequate
strength and stiffness to sustain the applied loads given in the
above table. In addition a barrier that is structurally safe should
not possess sufficient flexibility to alarm building users when
subject to normal service conditions. Therefore, for serviceability
considerations, the limiting condition for deflection appropriate
for a barrier for the protection of people is that the total
horizontal displacement of the barrier at any point from its
unloaded position should not exceed 25mm. Where the infill of a
barrier is subjected to the imposed loads given in the above table,
the displacement of any point of the barrier should not exceed
25mm.
Forza have carried out CAD FEA (Finite Element Analysis) imposed
load simulation tests on a number of standard elevations containing
our preferred range of fire, acoustic and standard glasses fitted
within our timber screens, the results of which (+15% margin
adjusted) indicate the screen performance for the imposed load to
be within the above maximum displacement requirement (Drawing
FZD0509/5).
In addition to reviewing horizontal imposed loads to screens Forza
have also carried out computer simulated structural analysis with
regard to transoms supporting glass (Drawing FZD0488/1). The
results attained indicate the values of deflection of the transom
to be within the guidelines notated in BS EN 1995-1-1
2004.
FREE PATH within a building
The energy level of an impact varies according to the position of
the barrier within a building relative to the unhindered distance a
body can travel in a direction perpendicular to the surface of the
protective barrier otherwise known as the 'Free Path'.
The glass impact classes for toughened glass so that it provides
containment [e.g. it will not break] recommended in BS
6180-2011 for a particular 'Free Path' are:
A] for a free path up to 1500mm [min 6mm thick] minimum class 3 to
BS EN 12600
B] for a free path greater than 1500mm [min 10mm thick] minimum
class 1 to BS EN 12600.
The glass impact classes for laminate glass relating to 'Free Path
'are not recommended within BS 6180 leaving guidance to be sought
from the glass manufacturer. Forza has been recommended by the
supplier of laminate fire glass that the same classes as for
toughened are required.
SAFETY GLASS IMPACT CLASS
The performance classification of a glass product tested for
impact in accordance with BS EN 12600 contains its
Class, Type and Class again [breaking in accord with clause 4a]
e.g. a laminate may be 2B2. The class taken from the following
test drop height class:
CLASS 3 conforms to clause 4a/b [test clause 5]
of BS EN12600 at drop ht. 190mm (BS6206-1981 Class C)
CLASS 2 conforms to clause 4a/b [test clause 5]
of BS EN12600 at drop hts. 190/450mm (BS6206-1981 Class B)
CLASS 1 conforms to clause 4a/b [test clause 5]
of BS EN12600 at drop hts.190/450/1200 mm (BS6206-1981 Class A)
Mode of breakage
At the appropriate drop height the mode of breakage shall be
described as follows:
TYPE A [Typical of annealed
glass] numerous cracks appear forming separate fragments
with sharp edges, some of which are large.
TYPE B [Typical of laminate
glass] numerous cracks appear, but fragments hold together
and do not separate.
TYPE C [Typical of toughened
glass] disintegration occurs, leading to a large number of
small particles that are relatively harmless.
Forza range of fire, acoustic and standard glasses have the
following Impact Performance classes as designated by BS EN
12600:
Fire Glass |
Acoustic Glass |
Standard Glass |
|||
Forza Code |
Impact Glass to BS EN12600 |
Forza Code |
Impact Glass to BS EN12600 |
Forza Code |
Impact Glass to BS EN12600 |
GFP7-30/0 |
3B3 |
GS6.8A36 |
1B1 |
SGL6.4 |
2B2 |
GFP12-60/0 |
2B2 |
GS8.8A37 |
1B1 |
SGL6.8 |
1B1 |
GFP13-30/0 |
2B2 |
GS10.8A39 |
1B1 |
SGL8.8 |
1B1 |
GFP16-60/30 |
2B2 |
GS12.8A40 |
1B1 |
SGL10.8 |
1B1 |
GFP20-60/30 |
1B1 |
GS16.8A41 |
1B1 |
SGL12.8 |
1B1 |
GFP25-60/60 |
1B1 |
|
|
SGT6 |
3C3 |
GFS6-60/0 |
1C1 |
|
|
SGT8 |
C |
GFS12-60/0 |
1C1 |
|
|
SGT10 |
1C1 |
|
|
|
|
SGT12 |
1C1 |
British Standard BS 5234-2 1992 Partitions Part 2
Specification for the Performance requirements for strength and
robustness including method of test.
Forza timber framed fire and acoustic screens have undergone a
series of tests at a UKAS approved test centre to demonstrate
compliance with specific performance requirements for strength and
robustness as detailed in BS 5234-2.
Partition grades by categories of duty
Grade |
Category of duty |
Examples |
Light Duty (LD) |
Adjacent space only accessible to persons with high incentive to exercise care. Small chance of accident occurring or of misuse. |
Domestic Accommodation |
Medium Duty (MD) |
Adjacent space moderately used primarily by persons with some incentive to exercise care. Some chance of accident occurring and of misuse. |
Office Accommodation |
Heavy Duty (HD) |
Adjacent space frequently used by the public and others with little incentive to exercise care. Chances of accident occurring and of misuse. |
Public circulation and industrial areas |
Severe Duty (SD) |
Adjacent spaces intensively used by public and others with little incentive to exercise care. Prone to vandalism and abnormally rough use. |
Major circulation and heavy industrial areas |
The scope of the tests covered:
1.6 Criteria for acceptance
1.6.1 Stiffness (Annex A)
When tested in the prescribed manner there shall be no damage or
detachment, loosening or dislodgement of a partitions parts or
fixings. The maximum deflection and residual deformation shall not
exceed the limits for the grade tested given in the following
table.
Grade |
Applied Load (n) |
Maximum Deflection (mm) |
Max Residual Deformation (mm) |
LD |
500 |
25 |
5 |
MD |
500 |
20 |
3 |
HD |
500 |
15 |
2 |
SD |
500 |
10 |
1 |
1.6.3 Resistance to damage by impact from a large soft
body (Annex C)
When tested in the prescribed manner the partition shall be
capable of withstanding the impact energies for the grade being
tested given in the following table without sustaining either
permanent deformation in excess of 2mm.
Grade |
Impact Energy (n m) |
LD |
20 |
MD |
20 |
HD |
40 |
SD |
100 |
1.6.5 Resistance to structural damage by impact from a
large soft body. (Annex E)
When tested in the prescribed manner the partition shall be
capable of withstanding the impact energies for the grade being
tested as given in the following table, without collapsing or
dislocating the partition or any of its fixings.
Grade |
Impact Energy (n m) |
LD |
60 |
MD |
60 |
HD |
120 |
SD |
120 |
1.6.6 Door slamming (Annex F)
When tested in the prescribed manner the partition shall not be
damaged, nor shall door frame fittings and architraves become
detached or loose after the door leaf has been slammed. The number
of slams and the mass of the door leaf for the grade being tested
as given in the following table.
Grade |
Test Door Leaf Mass Kg |
No. of Slams |
LD |
35+/-0.5 |
20 |
MD |
35+/-0.5 |
20 |
HD |
60+/-0.5 |
100 |
SD |
60+/-0.5 |
100 |
1.6.7 Crowd Pressure (Annex G)
When tested in the prescribed manner there shall be no collapse or
damage that would render the partition dangerous, due to any of its
parts becoming dislodged or shattered, in a manner that could cause
injury. The Sustained load applied, for 2 minutes, to the
timber beam shall be 0.75kN/m, 1.5kN/m or 3.0kN/m.
Forza Timber Framed Screens tested in accordance with
BS5234-2 (Methods - Annex A/C/E/F) achieved
performance levels summarised as grade requirement Severe Duty and
is documented in certificate reference FTS.12/01 (Drawing
FZD0514/2).
British Standard BS 6262-4.2005 Glazing for buildings -
Part 4. Code of practice for safety related to human
impact.
Part 4 of this standard gives safety recommendations for the
vertical [true vertical within a tolerance of 15 degrees] use of
glass in critical locations [in and around doors particularly in
side panels which might be mistaken for doors and walls /partitions
at low levels] most likely to be subject to accidental human
impact. The recommendations are intended to reduce impact related
injuries and in particular the risk of cutting and piercing
injuries.
Critical locations are further described as follows with the
respective class [BS EN12600] of glass recommended:
Doors
For glazing wholly or partly within 1500mm from floor or ground
level
Minor dimension of pane greater than
900mm - Class 2
Minor dimension of pane equal or less than 900mm
- Class 3
Door Side panels
For glazing wholly or partly within 300mm from the edge of a door
and wholly or partly within 1500mm from floor or ground level
Minor dimension of pane greater than
900mm - Class
2
Minor dimension of pane equal or less than
900mm - Class 3
Low Level Glazed Area
For glazing wholly or partly within 800mm from floor or ground
level not covered in 1 or 2
Irrespective of pane
dimension
- Minimum Class 3
The second and third characters of glass classification in BS EN
12600 are not utilised in the classification of glass in BS
6262.
In all three instances above if the smaller dimension of the pane
is 250mm or less and its area is 0.5m2 or less then glass not
classified within BS EN 12600 may be used provide its nominal
thickness is not less than 6mm. This note specifically relates to
Forza Fire Glass G90/1 and G120/1 used in vision panels in Forza
FD90 and FD120 doors.
Approved Document K (requirement K4: Protection against impact
with glazing) details the above as complying with the requirement
from Part K of schedule 1 to the Building Regulations 2010 (Drawing
FZD0518/3).
Glass classifications noted in Approved Document K4 (Section 5.4)
referring to BS 6206 are superseded by BS EN 12600.
FIRE PROPERTIES OF GLASS EXCLUDING FIRE RESISTANCE as noted in BS 6262-3:2005
GLASS TYPE |
NON COMBUSTIBILITY |
FIRE PROPAGATION INDEX TESTED IN
ACCORDANCE WITH |
SURFACE SPREAD OF FLAME TESTED |
||
IN ACCORDANCE |
|||||
WITH BS 476-7: 1987 |
|||||
ANNEALED |
Non-combustible |
I < 12 and i(1) < 6 |
CLASS 1 |
||
WIRED |
Non-combustible |
I < 12 and i(1) < 6 |
CLASS 1 |
||
TOUGHENED |
Non-combustible |
I < 12 and i(1) < 6 |
CLASS 1 |
||
LAMINATE |
|
|
|
I < 12 and i(1) < 6 |
CLASS 1 |
-FIRE |
Non-combustible |
I < 12 and i(1) < 6 |
CLASS 1 |
||
-ACOUSTIC |
Interlayer combustible |
I < 12 and i(1) < 6 |
CLASS 1 |
Structural Performance Guides | |
Single Glaze - Transom - Load 246kg - FZD0488/1 |
|
Single Glaze - Elevation H - Imposed Load - FZD0509/5 |
|
Strength and Robustness Certificate FTS.12/01 |
|
Test Contruction Drawing - FZD0514/2 |
|
Strength and Robustness Certificate FTS.12/02 |
|
Test Contruction Drawing - FZD0525/1 |
|
BS 6180:2011 Glass Impact Class Recommendations for 'Free Path' Criteria - FZD0513/5 |
|
Glazing in Critical Locations - FZD0518/3 |
|