Fire door

Abstract

A fire door formed around a door moulding 2, with at least one section including a layer of wood material located either side of a layer of fire-retardant cloth 18, which may be polyurethane cloth imp

Description

Field of Invention This invention relates to a fire door. More especially, the invention relates to a fire door constructed of a number of layers, one of which being fire retardant. Background to the invention Fire doors are critical to prevent spread of fire through a building. The most common type of fire door is an FD30, a fire door that will last 30 minutes in a fire. FD60 (60 minutes) fire doors are commonly used in commercial settings. FD30 fire doors are typically 44 / 45mm thick, as opposed to the standard door thickness of 35 to 40mm. FD60 fire doors are normally 54mm thick. Most fire doors have a solid core construction which can include particleboard, flaxboard, magboard and solid timber. The assembly of a fire door can vary greatly, some have a timber framing around the core with a laminated veneer; others have a lipping (5 to 20mm thick) around the core with a veneer on top; and in some cases a plywood, veneer or MDF facing is glued on to the core without framing or lippings. There is no preferred construction method, as long as the desired fire rating is achieved. A fire door must be fitted with approved intumescent strips which play a crucial part in achieving the fire door rating. When subjected to heat, the intumescent strips expand and seal the gap between the door edge and the frame. Intumescent seals can be fitted within the door frame or grooved into the door edge. The Applicant manufacturers and distributes fire retardant paint to coat the door. Intumescent strips and / or fire retardant paint are not able to achieve the required fire rating when applied to 35mm doors because the thinness of the door is such that its structural integrity is quickly compromise, in the event a fire, causing the door to buckle. Door frames and thresholds are pre-constructed and it is not generally possible to increase the size to fit a wider door and as such the only option is to use a non-fire door when the door frame and threshold is sized to fit a 35mm door, the most common sized internal door in houses. The present invention seeks to provide a 35mm fire door that meets appropriate fire regulations. In particular, fire tests have found that the fire door of the present invention can achieve FD60 fire rating. Statements of the Invention According a first aspect of the invention there is provided, a fire door constructed from a plurality of material layers formed around a door moulding, at least one section of the layers including a layer of wood material located either side of a layer of fire-retardant cloth. Preferably, the fire-retardant cloth is a polyurethane cloth impregnated or coated with intumescent material. Preferably, at least one section of the layers comprises a first layer of plywood core, a fire-retardant cloth adhered to one side of the plywood core, and a second layer of plywood adhered to the other side of the fire-retardant cloth. Preferably, the total thickness of the door is around 35mm. Preferably, the moulding has a rebate to receive intumescent strips. Preferably, the fire door is constructed of: a central door moulding, one side of which has secured a plurality of material layers including: a plywood core layer; a fire-retardant cloth layer; and a plywood face layer; and the opposing side of door moulding having secured thereto a plurality of material layers including: a hardboard layer; and a plywood face layer. Preferably, the plywood core layer has a thickness of around 12mm; the fire retardant cloth has a thickness of around 1mm; each plywood face layer has a thickness of around 9mm; and the hardboard has a thickness of around 3mm. Preferably, each plywood face layer includes one or more apertures to receive plywood infill panels. Preferably, the plywood infill panels have a thickness of around 3mm. Brief Description of the Drawings The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which: - Figure 1 is an exploded view of a fire door constructed in accordance with the invention; and Figure 2 us a cross-section of the fire door. Detailed Description of the Invention The component layers of a fire door of the invention are shown in figure 1. In total, the thickness of the door is around 35mm, so as to categorised as 35mm door in the market. The layers are constructed around a hardwood moulding 2 to head and stiles. The moulding 2 is rebated 4 to receive intumescent strips 6 (best shown in figure 2). Different material layers extend from each side of the moulding 2. For the ease of reference, each side of the door, either side of the moulding will be described in turn. A layer of 3mm hardboard 8 is adhered or otherwise secured to one side of the moulding 2. A 9mm plywood panel 10A is adhered or otherwise secured to the face of the hardboard layer 8 on the side distal to the moulding 2. The plywood panel 10A forms the front face of the door when constructed. The panel 10A includes four apertures 12A cut to accept respective 3mm plywood infill panels 14A. A 12mm plywood core 16 is adhered or otherwise secured to the other side of the moulding 2 distal to the hardboard layer 8. A 1mm thick polyurethane cloth 18 impregnated or coated with an intumescent layer of around 0.55mm thickness is then adhered or otherwise secured to the plywood core 16 on the side distal to the moulding 2. A 9mm plywood panel 10B is adhered or otherwise secured to the cloth layer 18 on the side distal to the plywood core 16. The plywood panel 10B forms the rear face of the door when constructed. The panel 10B includes four apertures 12B cut to accept respective 3mm plywood infill panels 14B. As can be seen in figure 2, the plywood core 16, cloth 18 and plywood face panel 10B are secured together by 18mm CSK screws 20. It is appreciated that “front” and “rear” are interchangeable when describing the door side. Fire tests conducted by the Applicant have found that constructing a door with an internal fire-retardant layer (in the present case, the intumescent cloth 18), allows for thinner doors to meet desired fire ratings. In this case, a 35mm door achieve FD60 fire rating. Achieving a fire rating for such doors enables all standard internal doors to be fire resistant.

Claims

1. A fire door constructed from a plurality of material layers formed around a door moulding, at least one section of the layers including a layer of wood material located either side of a layer of fire-retardant cloth.

2. A fire door according to claim 1, wherein the fire-retardant cloth is a polyurethane cloth impregnated or coated with intumescent material.

3. A fire door according to claim 1 or claim 2, wherein at least one section of the layers comprises a first layer of plywood core, a fire-retardant cloth adhered to one side of the plywood core, and a second layer of plywood adhered to the other side of the fire-retardant cloth.

4. A fire door according to any of claims 1 to 3, wherein the total thickness of the door is around 35mm.

5. A fire door according to any one of claims 1 to 4, wherein the moulding has a rebate to receive intumescent strips.

6. A fire door according to any preceding claim, wherein the door is constructed of:a central door moulding, one side of which has secured a plurality of material layers including:a plywood core layer;a fire-retardant cloth layer; anda plywood face layer;and the opposing side of door moulding having secured thereto a plurality of material layers including:a hardboard layer; and a plywood face layer.

7. A fire door according claim 6, wherein:the plywood core layer has a thickness of around 12mm;the fire retardant cloth has a thickness of around 1mm;each plywood face layer has a thickness of around 9mm; andthe hardboard has a thickness of around 3mm.

8. A fire door according to claim 6 or 7, wherein each plywood face layer includes one or more apertures to receive plywood infill panels.

9. A fire door according to claim 7, wherein the plywood infill panels have a thickness of around 3mm.

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