Field of Invention

This invention relates to a smoke vent for buildings.

Background of Invention

Most current building codes require that commercial buildings such as factories, warehouses and similar buildings be provided with smoke vents to prevent the accumulation of smoke in the building in the event of fire. Some of the vents currently in use have blades, louvres or the like to close the vent o _p ening and which are held in the closed position by fusible links which will fuse when a fire occurs to o _p en the ven _t s. Such vents require continual maintenance to ensure that they will operate when required. Also having moving _p arts the _y are costly to manufacture. Electrically driven exhaust fans are not satisfactory in that during a fire the sup _p ly of electricity is inevitably interrupted.

The object of the present invention is to provide a smoke vent construction which does not require fusible links, has no moving parts and which is substantially cheaper in construction than those currently in use.

Description of Invention

It has been found that if an opening or gap is provided in

SUBSTITUTE SHEET

the roof cladding and a secondary roof spaced above the opening or gap to cover the same, a very effective smoke vent can be provided if at least part of the secondary roof is clad with material which will burn without substantial disintegration into debris or molten particles when subjected to high temperatures. The destruction of at least part of the secondary roof provides a greatly increased space through which smoke can discharge from the interior of the building.

Thus the present invention resides in a smoke vent for a roof covered with cladding having an opening or gap formed therein comprising upwardly projecting walls or supporting structure positioned around the periphery of the opening, a secondary roof supported on the upper end of said walls or supporting structure to cover said opening, and one or more outlets located below said secondary roof connecting the opening to atmosphere, characterised in that at least portion of the secondary roof is clad with material which will burn when subjected to high temperatures without substantial disintegration into debris or molten particles.

By avoiding the formation of debris or molten particles the possibility of starting secondary fires is substantially reduced. Suitable materials include fibre glass and acrylic or polycarbonate based plastic sheeting such as that marketed under the trade mark "Alsynite" .

For practical purposes it is essential that the ingress of rain, snow and the like into the building through the opening

« SUBSTITUTE SHEET !

-'

should be prevented. This can be accomplished by extending the secondary roof so that it projects over the main roof adjacent the opening.

More _p articularly, the invention resides in a smoke vent for buildings having a roof formed of cladding sup ^p orted on _p urlins, said vent comprising one of more supporting members _p ositioned around the periphery of a gap or opening in the cladding and projecting upwardly therefrom to define a substantially vertical passage leading from the opening, a plurality of secondary purlins or the like supported on the up _p er end of the su _p porting members, sheeting fixe ^d t ^o the secondary purlins to cover the opening and to overlap the roof ad _j acent the opening to define a substantially horizontal passage communicating with the vertical passage, the ends and/or the bottom of the horizontal passage being open to atmos _p here, said sheeting being formed of a material which burns when subjected to high temperatures without substantial disintegration into debris or molten ^p articles.

In order that the smoke can discharge ^q uickl ^y i is preferable, if not essential, that any building fitted with smoke vents of any description be provided with air vents adjacent the floor of the building to assist in clearing the smoke. One suitable air vent for walls comprising wall cladding sheets fixed to horizontal purlins which are in turn fixed to vertical columns may be formed by locating the lowermost _p urlin and the lower end of the wall cladding above the level of the floor of the building and the ground

SUBSTITUTE SHEET f

4 external to the building. Preferably a channel is fixed to the columns adjacent the floor level and a bird screen fixed between the lowermost purlin and the channel.

Brief Description of Drawings

The invention will be better understood by reference to the following description of the embodiments shown in the accompanying drawings wherein:

Fig. 1 is a fragmentary sectional ^' view of a roof with one form of smoke vent incorporated therein;

Fig. 2 is a fragmentary sectional view of a roof with a second form of smoke vent incorporated therein;

Fig. 3 is a fragmentary sectional view of the lower portion of a wall of a building with an air vent incorporated therein.

Detailed Description of Embodiments

As shown in Fig. 1 of the drawings the roof is o conventional construction consisting of Z-sha _P ed purlins 1 fixed to trusses ₍ not shown) and covered with sheets o cladding 12 preferably of steel. To form the smoke vent on of the sheets of cladding is omitted to form a gap or openin 13. The gap will generally extend from one side of the roo to a position close to the ridge of a gable type roof Flashing members 14 are fixed to the cladding on each side o the gap. Each flashing member comprises a horizontal portio

i SUBSTITUTE SKcrr ^;

which lies in contact with the cladding and a vertical portion 14a the upper edge of which is provided with an outwardly projecting flange 14b. Vertical baffles ⁽ not shown) are provided at each end of the gap to define the end walls of a vertical passage. A series of secondary purlins or supporting/spacing members 15 are fixed to the upper portion of the flashing members, preferably in substantial alignment with the roof purlins. The secondary purlins are long enough to bridge the gap and project over the roof cladding on each side of the gap. Sheets of cladding preferably of acrylic or polycarbonate based plastic sheeting such as that marketed under the trade mark "Alsynite" are fixed to the secondary purlins and the edges covered by flashing 17. The spacing between the lower edge A of the flashing 17 and the upper edge B of the flashing is equal to or greater than the minimum height of the secondary purlins 16. If desired an insect or bird screen 18 may be fitted across the gap at the top of the flashing members 14. The dimensions of the flashing 17 and the overhanging portions of the secondary purlins 15 are calculated to meet the requirements of the Building Code and with sufficient overlap such that rain will not normally be blown into the vent and reach the gap 13.

In the embodiment shown in Fig. 3 of the drawings the construction is substantially identical with that of the embodiment shown in Fig. 1 with the exception that the height of the vertical portion of the flashing members 314a is greater than the portion 14a in Fig. 1 and the flashing members 317 at each end of the secondary cladding extend

SUBSTITUTE SHEET

——— —* , l

downwardly a sufficient distance to close the ends of the substantially horizontal passage defined by the purlins 315. The space between the purlins 315, the upper edge of the flashing members 314 and the lower edge of the flashing 317 is fitted with an insect or bird screen 318. It will be evident that the vent has a vertical passage leading from the ga ^p 313 to a horizontal passage which has openings at the bottom so that any smoke discharged through the vent will follow the paths indicated by the broken lines C and D. The height of the vent above the roof cladding and the discharge openings at the bottom of the secondary purlins is such as to meet Building Code requirements.

In both embodiments it will be seen that in the event that the secondary cladding will, when subjected to a high enough temperature, burn without the formation of substantial debris or molten particles capable of starting secondary fires thus creating a much greater size of opening through which smoke can escape.

In order to create a strong' flow through the vent it is preferable, if not essential, to provide one or more air vents at the bottom or lower portion of the walls of the building. One suitable form of air vent may be formed by fixing the lowermost horizontal purlin 23 to the vertical column 20 above the ground and the floor 21. A channel member 22 is fixed to the inside of the columns 20 at floor level. The lower ends of the wall cladding sheets 24 are terminated above ground level. Preferably, a bird screen 25

SUBSTITUTE SHEET

of wire mesh or other suitable perforated material is fixed between the purlin 23 and the channel 22.

SUBSTITUTE SHEET