TIMBER – EXPOSED WOOD MEMBERS – BEAMS AND COLUMNS
Specifiers, Architects and Engineers, and fire officials recognize that some large wood beams and columns perform well in actual fires. There are a number of Industry Councils whom have published design procedures to calculate the fire resistance of Exposed Wood Members. Generally to quickly estimate the fire endurance time of a wood member when exposed to standard fire test condition, one should take into account the size of the wood beam or column and the percent of maximum allowable design load applied. The procedure estimates the cross-sectional dimensions of the uncharred portion of a beam or column and the effects of elevated temperatures on the load-carrying capability of the residual section. This procedure has been incorporated in the provisions of the International Building Code.
Although the above is appropriate, it is also true that special attention should be paid though to beams and columns in buildings which have been previously used as ‘Woolstores’. It is common knowledge that timber will readily absorb lanolin which sometime is used as a protective /impregnating coating and consequently timber floors, structural beams and columns would, by soaking up the lanolin from the thousands of wool bales that had passed through the ‘Woolstores’ over the decades, become very flammable.
LAF’s Vermitex® FLOOR CEILING SYSTEM fire test included steel and timber beams. Both elements were protected, the steel beam with LAF’s proprietary Vermibloc® precast panel whilst the timber beam was lined with Ripple Iron and then sprayed with 25 mm of LAF’s Vermitex® material. Both systems offer a simple and cost effective solution, and are outlined in CSIRO FCO-0670 in order to upgrading floors but also steel and structural members from 60 minutes to 180 minutes. The two (2) hour FRL ROOF CEILING SYSTEM also complies with the criteria of ‘Resistance to the incipient spread of Fire’ (RISF), and is light and thin.
In order to circumvent structural members penetrating through walls, LAF have researched systems for upgrading and providing fire protection to structural steel elements which might penetrate fire walls in order to also satisfy the insulation criteria. LAF’s innovation revolves around metal as well timber sections measuring softwood, hardwood and a softwood joist member made to penetrate a 230 mm masonry wall. The test allows for the FIRE UPGRADE of the elements of construction without impeding the integrity and insulation of a wall by coating the joist in Quikmesh® and then trowelling/spraying-on LAF’s fire protective Vermitex® AF. This arrangement around the penetration maintains the integrity and insulation criteria of the wall/ceiling during a fire emergency.
LAF VALUE ENGINEERING
The Vermitex® system is a very simple and cost effective arrangement. It can be used extensively to provide TIMBER FLOOR FIRE PROTECTION by coating purlins, I-beams and/or circular members penetrating through ‘party walls’ when they form part of a timber floor assembly by spraying the penetrating member 25 mm thick for a distance of 300 mm.
SI-20 – FIRE RESISTANCE TEST ON A TRADITIONAL SOFTWOOD-FRAMED TERRA-COTTATILED ROOF PROTECTEDWITH A CEILING OF CARRUGATED STEEL SHEETING FIXEDTO THE UNDERSIDE OF THE CEILING JOISTS AND SPRAYED WITH VERMITEX
SI-81 – FIRE RESISTANCE TEST ON A SYSTEM OF HARDWOOD FLOOR OR STEEL BEAM
FCO-0670 – LIKELY FIRE RESISTANCE OF FLOOR/CEILING SYSTEMS