GB2155968A - Condensation drainage - Google Patents

Abstract

A building having a metal frame (1) is insulated externally of the frame by batts or slabs of essentially vapour-impermeable insulation material (3), which is provided with ventilation channels (6) which slope downwardly from the inner surface to the outer surface of the material. Thus water vapour is able to flow from the frame to an outer cavity (4) but water is prevented from running from the cavity to the frame. <IMAGE>

Description

SPECIFICATION Improvements in or relating to metalframed buildings This invention relates to metal-framed buildings and more especially to steel-framed domestic buildings.

The problem of keeping structural steelframes warm and of avoiding condensation on such frames is set out in U.K. patent specification 2,11 9,828A published in November 1 983. This specification also offers one solution to these problems, using moisture-permeable external insulation.

However where the external steel-frame insulation is in the form of batts or slabs of essentiaily moisture impermeable foamed plastics material e.g. faced closed-cell polyurethane foams, the solution proposed in the above specification is not applicable.

We have now devised a solution to the problems referred to above for the case where the external insulation material is substantially impermeable to water vapour.

This invention consists in a wall for a metalframed building in which substantially watervapour-impermeable insulation material is applied to the exterior of the metal frame and this material is separated by a cavity from an outer cladding wall, characterised in that the impermeable insulation material is provided with ventilation channels of controlled width, these channels sloping downwardly from the interior to the exterior surfaces of the insulation material.

Preferably the ventilation channels run substantially horizontally across the layer of insulation material.

Preferably the width of the channels is between 1 and 5mm.

Preferably the external insulation material is in the form of slabs or batts of closed-cell foamed plastics material and the vertical joints between the slabs or batts are butted together and sealed.

Preferably the downward slope of the channels from interior to exterior surfaces of the insulation is at an angle of at least 5" to the horizontal, more preferably at least 10 to the horizontal.

The invention will be further described with reference to the accompanying single figure of diagrammatic drawing which represents a section through a wall according to the invention as cut by a vertical plane at right angles to the wall.

As can be seen the steel frame 1 is sandwiched between an inner layer of plasterboard 2-2 and an outer layer of slab foamed insulation material 3, the latter being separated, by a cavity 4 from an outer cladding wall of brick or block material 5. According to the invention the insulating slab material is provided with ventilation channels 6 which run substantially horizontally along the slabs but are angled, in section, so that there is a downward slop from the inner to the outer surfaces of the slab. This angle is sufficient to prevent the flow of liquid moisture from the cavity to the steel frame but acts as a ventilation channel for water vapour flowing outwardly from the frame to the cavity. In this way the steel frame is kept warm by heat flowing from the house interior but water vapour is allowed to flow outwardly from frame to cavity.

1. A wall for a metal-framed building in which a substantially water-vapour-impermeable insulation material is applied to the exterior of the metal frame and this material is separated by a cavity from an outer cladding wall, characterised in that the insulation material is provided with ventilation channels of controlled width which slope downwardly from the interior surface to the exterior surface of the insulation material.

2. A wall as claimed in claim 1 in which the ventilation channels run in substantially horizontal lines across the layer of insulation material.

3. A wall as claimed in claim 1 in which the width of the ventilation channels is between 1 and 5 millimetres.

4. A wall according to claims 1-3 in which the insulation material is in the form of slabs or batts of closed-cell plastics material and vertical joints between such slabs or batts are sealed.

5. A wall according to claims 1 to 3 in which the downward slope of the channels is at least 5" to the horizontal.

6. A wall according to claims 1 or 5 in which the downward slope is at least 10 to the horizontal.

7. A wall for a metal-framed building substantially as hereinbefore described, with reference to the accompanying drawing.

8. A method of building a wall for a metal-framed building substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to metalframed buildings This invention relates to metal-framed buildings and more especially to steel-framed domestic buildings. The problem of keeping structural steelframes warm and of avoiding condensation on such frames is set out in U.K. patent specification 2,11 9,828A published in November 1 983. This specification also offers one solution to these problems, using moisture-permeable external insulation. However where the external steel-frame insulation is in the form of batts or slabs of essentiaily moisture impermeable foamed plastics material e.g. faced closed-cell polyurethane foams, the solution proposed in the above specification is not applicable. We have now devised a solution to the problems referred to above for the case where the external insulation material is substantially impermeable to water vapour. This invention consists in a wall for a metalframed building in which substantially watervapour-impermeable insulation material is applied to the exterior of the metal frame and this material is separated by a cavity from an outer cladding wall, characterised in that the impermeable insulation material is provided with ventilation channels of controlled width, these channels sloping downwardly from the interior to the exterior surfaces of the insulation material. Preferably the ventilation channels run substantially horizontally across the layer of insulation material. Preferably the width of the channels is between 1 and 5mm. Preferably the external insulation material is in the form of slabs or batts of closed-cell foamed plastics material and the vertical joints between the slabs or batts are butted together and sealed. Preferably the downward slope of the channels from interior to exterior surfaces of the insulation is at an angle of at least 5" to the horizontal, more preferably at least 10 to the horizontal. The invention will be further described with reference to the accompanying single figure of diagrammatic drawing which represents a section through a wall according to the invention as cut by a vertical plane at right angles to the wall. As can be seen the steel frame 1 is sandwiched between an inner layer of plasterboard 2-2 and an outer layer of slab foamed insulation material 3, the latter being separated, by a cavity 4 from an outer cladding wall of brick or block material 5. According to the invention the insulating slab material is provided with ventilation channels 6 which run substantially horizontally along the slabs but are angled, in section, so that there is a downward slop from the inner to the outer surfaces of the slab. This angle is sufficient to prevent the flow of liquid moisture from the cavity to the steel frame but acts as a ventilation channel for water vapour flowing outwardly from the frame to the cavity. In this way the steel frame is kept warm by heat flowing from the house interior but water vapour is allowed to flow outwardly from frame to cavity. CLAIMS

1. A wall for a metal-framed building in which a substantially water-vapour-impermeable insulation material is applied to the exterior of the metal frame and this material is separated by a cavity from an outer cladding wall, characterised in that the insulation material is provided with ventilation channels of controlled width which slope downwardly from the interior surface to the exterior surface of the insulation material.

2. A wall as claimed in claim 1 in which the ventilation channels run in substantially horizontal lines across the layer of insulation material.

3. A wall as claimed in claim 1 in which the width of the ventilation channels is between 1 and 5 millimetres.

4. A wall according to claims 1-3 in which the insulation material is in the form of slabs or batts of closed-cell plastics material and vertical joints between such slabs or batts are sealed.

5. A wall according to claims 1 to 3 in which the downward slope of the channels is at least 5" to the horizontal.

6. A wall according to claims 1 or 5 in which the downward slope is at least 10 to the horizontal.

7. A wall for a metal-framed building substantially as hereinbefore described, with reference to the accompanying drawing.

8. A method of building a wall for a metal-framed building substantially as hereinbefore described.