Passive Firewalls Design and Construction

DAVID JOBPRINCIPAL BUILDING SURVEYORCERTCON PTY LTD – BUNDABERG

BUILDING CERTFIERSFire Safety Adviser QFRS Lic. No: 0525

Bachelor Building Surveying Graduate Certificate in Performance Based Building & Fire Codes

Graduate Diploma in Building Fire Safety & Risk Engineering

OVERVIEWReferenced document is Building Code

of Australia (BCA 2009); What is the difference between

proprietary and passive fire systems?What design information in is required

on plans in relation to passive fire products?

What is a tested passive fire system and how do you know?

How is this information required to be referenced?

10/04/23 BDAQ 2009 Spring PD Road Show

PROPRIETARY FIRE SYSTEMIs concrete block or brick veneer

construction a proprietary building element or a passive fire building element?

A proprietary building element is a material or form of construction that can be used as a fire wall system provided it has been constructed in accordance with an acceptable code or guideline as specified in the legislation, in this instance Part 1.2 of the BCA.


PROPRIETARY FIRE SYSTEMBoth concrete block and brick veneer

when constructed in accordance with AS3600 and AS3700 respectively are assumed to meet the Deemed-to-Satisfy provisions of the BCA for the required FRL.

The proprietary systems are defined in the prescriptive requirements of specification is referenced in part 1.2.3 of volume 2 of the BCA.


PROPRIETARY FIRE SYSTEMSection 5 of AS3600 provides the

design criteria for fire resistance levels for concrete structures and in particular section 5.7 for walls.

As with the concrete structures Section 6 of AS3700 sets out the design of masonry to resist the effects of fire and provides the methods for determining fire resistance levels for masonry.


PROPRIETARY FIRE SYSTEMMost proprietary product suppliers have

documentation for fire resistance levels for their building elements when used as fire separating wall as discussed previously.

This information must be included in detail on the plans so as to avoid any ambiguity between the design and the construction stages.

Some example of proprietary products are technical manuals from manufactures: Hebel – Adbir masonry – Austral bricks etc.


PROPRIETARY FIRE SYSTEMThese technical manuals will provide the following

information as per the Adbir masonry manual:


PROPRIETARY FIRE AND SOUND SYSTEMThese proprietary manuals can include

additional information in relation to sound insulation for the wall systems as per the Adbir masonry manual .

2.2 Design of walls for sound insulationThese wall systems are usually used in internal applications

in commercial, industrial, institutional, domestic and high-rise domestic construction, or in the renovation of older buildings. Wall systems generally incorporate single leaf concrete masonry, CSR Bradford® Insulation products and CSR Gyprock®.

Systems which require CSR product are based on the CSR ‘The Red Book TM’ Section ‘D’ Masonry Wall Systems.

The Rw and Rw + Ctr values shown in the wall systems are only applicable when using Hanson Masonry products and CSR products.


PROPRIETARY FIRE AND SOUND SYSTEMThis proprietary system has been tested in

conjunction with the CSR products to achieve both the fire and sound requirements for construction.

This manual also provided an indication where that particular sound transmission and impact requirements from the BCA are required.

Again the relevant point is that the system used must be the system specified and tested!


PROPRIETARY FIRE AND SOUND SYSTEM


PROPRIETARY FIRE AND SOUND SYSTEM


This particular system uses resilient battens with a cavity in the block to achieve the required sound levels and the discontinuous construction

PROPRIETARY FIRE AND SOUND SYSTEMThis system if used as part of the design for

our units would be documented as:Bounding construction FRL as per Adbir

masonry manual Table B (non-basalt) 20.01 details, and

Sound transmission system Rw + Ctr and discontinuous construction as per Adbir masonry manual Table J system A11.


PROPRIETARY FIRE AND SOUND SYSTEMIt is important as designers to clarify and

document the type of system used in the design to achieve the required fire and sound levels. This will be further clarified in the case study to follow.

Accurate information must be shown on the documentation to avoid ambiguity and incorrect construction practice.

Additionally the documentation should clarify that if the proposed system, as designed is varied, the designer and the certifier must be consulted prior to affecting any changes.


HISTORY AND TESTING


HISTORY & TESTINGFirst Australian Standard No. A.30

Based on BS 476 - 1932• First Published in 1935 and last

published 1969• It incorporated the following:

Combustibility Test of MaterialsFlammability Test of MaterialsEarly Fire Hazard Test of MaterialsFire-Resistance Test of Structures


HISTORY & TESTINGHeating curve was not a standard

curve but tabulated and graphed for first hour and 2-6 hours to achieve the following temperatures:

538°C at 5 min 704°C at 10 min 843°C at 30 min 927°C at 1 hr 1010°C at 2 hr 1021°C at 4 hr 1204°C at 6 hr


HISTORY & TESTINGThis test evolved into AS1530.4 and

was first published 1975 and last published in 1979Based on A.S. No. A.30 but published

with ‘metric units’Combustibility, Flammability and Early

Fire Hazard separated into AS 1530.1, AS 1530.2 and AS 1530.3 respectively.


HISTORY & TESTINGAS1530.4 was first published on 10 May 1985Based on the essential principles of ISO 834AS1530.4 1985 included separate sections for:

Doorsets, Shutter Assemblies and Damper Assemblies Elements Penetrated by Services Floors, Roofs, Floor/Ceiling Systems and Roof/Ceiling

Systems Beams, Girders and Trusses Walls and Partitions Columns Air Ducts Glazing


HISTORY & TESTINGAS1530.4 1990 was first published 19 January

1990,introducing the concept of Fire-resistance levels

(FRL) in which the performance of the element with regard to Structural Adequacy, Integrity and Insulation are reported separately.


HISTORY & TESTINGThe tests used a standard time temperature curve


HISTORY & TESTINGTypical test of passive products with furnace behind


HISTORY & TESTINGDiagrammatic example of a typical fire test for passive

fire systems. This example shows an FRL of 60/60/60. This means that during a fire test, the system did not fail for 60 minutes for each of the criteria.


HISTORY & TESTINGThe same type of furnace test is undertaken for

the Resistance to the Incipient Spread of Fire (RISF). Resistance to the Incipient Spread of Fire is the ability of a ceiling to limit the temperature rise in the ceiling cavity, stopping flashover.


HISTORY & TESTINGThe testing processes and procedures for

passive fire systems are specific and stringent.

Therefore the use of these systems for the construction of fire separating walls to replicate the tested specimen is also specific and stringent.

Not only from a building designers documentation but also the construction practices used on site.


HISTORY & TESTINGInvariably there may be some deviations from

the tested specimen, as part of the construction process.

It would seem impossible for on site construction techniques to replicate laboratory testing but construction must replicates the prototype.

In the case study we will look at some of these deviations and the consequences that developed as a result of a fire!


PASSIVE FIRE PRODUCTSThere are many manufactures of passive fire

products and these manufactures incorporate numerous products in addition to wall linings.

As can be seen from a previous slide they also include:

Ceiling lining;Fire collars;Fire pillows;Fire doors;Fire shutters;Fire sealant etc.


PASSIVE FIRE PRODUCTSHaving considered the significance of

specifying the correct systems, What are we looking for in our design and how are we to document the products?

Firstly as with the previous presentation a decision has to be made in relation to the BCA DtS requirements for our separating walls.


PASSIVE FIRE PRODUCTSOur units will require a 60/60/60 wall.Some part of the wall will require an Rw +

Ctr ≥ 50 whilst other parts of the wall require an Rw + Ctr ≥ 50 with discontinuous construction.

Will these differing construction requirements (some in the same wall plane) effect the construction of the wall/s, thickness etc?


PASSIVE FIRE PRODUCTSWhat passive products are available to use?Boral, Lafarge and CSR are just a few

manufactures with literature available .It should be emphasised that most tested

systems have maximum wall height limitation in relation to their products.

The base construction material for the construction of the passive fire separating wall may be either steel or timber.


PASSIVE FIRE WALL DESIGNFor the purposes of this presentation, our

designer has selected timber as the base material and also CSR systems 670 and 671 from the CSR red book.


PASSIVE FIRE WALL DESIGN


PASSIVE FIRE WALL DESIGNCSR 670 is proposed to be used between the

garage and the adjoining unit and CVSR 671 between the bathroom/laundry and the living kitchen of the adjoining unit.

You will note that the systems do not offer a stud size only a top and bottom plate size.

The stud sizes are a design requirement for the building designer and are linked to the proposed wall height as noted previously.


PASSIVE FIRE WALL DESIGNTable C2 contains the stud sizes for the

particular wall type and wall height.


PASSIVE FIRE WALL DESIGNNote the stud thickness from table C2 for the

stagged stud wall!

Can we use a 120 plate when the studs are required to be 120 and still have staggered and discontinuous construction?


PASSIVE FIRE WALL DESIGNAll of this information must be considered and

documented with the design criteria.Without this information how will the

contractor undertaking the construction of the fire walls, construct them in accordance with the tested prototype?

If a problem or a situation arises who is responsible for rectification?

As you will see in the case study, a situation did arise and it is still to be determined who or whom is to be held responsible!


PASSIVE FIRE WALL DESIGNA further point to consider when selecting and

designing a fire separating wall that has a load bearing capacity is the axial effect on the wall in a fire situation.

The CSR manual states the following design considerations:

Load bearing Walls;Walls designed as load bearing, with studs at 600mm maximum centres

and lined with GYPROCK FYRCHEK, meet the requirements of BCA Specification C1.8 Clause 3.4 – Walls generally.

The building designer must ensure load bearing walls have been designed:• To resist all applied loads.• To be in accordance with AS1720.1 or AS1684.• Assuming no contribution to axial strength is required of the wall

linings


PASSIVE FIRE WALL DESIGNFor bracing capacities in accordance with

brochure NºGYP545 To meet the stated Fire Resistance Level (FRL), the axial load capacity of some wall systems is reduced. This is a result of loss of stud section from charring during a fire test. The systems are noted with an Axial Capacity Reduction (ACR) Group number. In these systems, the designer must increase the applied loads to compensate for the axial capacity reduction percentage, as shown in Table C3.


PASSIVE FIRE WALL DESIGNThe axial capacity reduction are noted in the tables

and refers the designer to Table C3 of the manual.


PASSIVE FIRE WALL DESIGNThe CSR manual clarifies this table by stating :The FRL associated with a system noted in

Table 3 applies when the timber studs are designed for reduced axial capacity.

This reduction in stud capacity may be achieved by increasing the design vertical load by the appropriate percentage of the reduction.

What does this mean!


PASSIVE FIRE WALL DESIGNTypically it refers to a reduction in the axial

load capacity of the timber studs in a fire situation, specifically where timber studs are subjected to charring as a result of the fire.

The charring rates of timber is a property of timber and once the timber reaches the prescribed level of char the performance of the wall is compromised and a capacity reduction applied as noted in table C3.


SUMMARYIt must be stressed that the design

documentation includes;A passive fire system that meets the DtS

provisions of the BCA.The passive fire system that is proposed has

been tested to achieve the DtS provisions of the BCA.

The separating wall system has been designed and tested to achieve the sound weighting levels and discontinuous requirements for the particular location within the building.


SUMMARYSections and elevations as applicable to

alleviate any uncertainty in the proposed construction of the wall system by contractors.

Notations that if the proposed system is to deviate from the design criteria as documented, the relevant persons must be informed prior to undertaking any such changes.


Passive Firewalls Design and Construction

Documents

Transcript of Passive Firewalls Design and Construction