GB2468026A

GB2468026A - Insulated building stud

Info

Publication number: GB2468026A
Application number: GB1002608A
Authority: GB
Inventors: Stephen Wise
Original assignee: Knauf Insulation Ltd
Current assignee: Knauf Insulation Ltd
Priority date: 2009-02-20
Filing date: 2010-02-16
Publication date: 2010-08-25
Also published as: GB201002608D0

Abstract

A building stud 40 particularly for construction of walls, has a rigid thermal insulator 41 and a retainer 42 for a mechanical fastener 43. The insulator 41 may be extruded polystyrene foam, the retainer may be sheet material, adhesively secured to the insulation and may form a facing on the surface of the thermal insulator 41. The retainer 42 may be a wood board such as orientated strand board (OSB). The stud preferably has two opposing OSB facing plates. There may be at least one spacer 46, formed integrally with the insulator 41 so as to define a recess 53, preferably comprising an L-shaped corner section, adapted to space and hold a batt of thermal insulation 54 from the wall. Also claimed is the use of the building stud in a thermally insulated wall of a building (fig 3), thermal insulation may be included in the cavity of the wall between adjacent studs. Also described is means to test the force required to remove mechanical fasteners from the stud (fig 5).

Description

Buildinci construction This invention relates to building constructions, particularly constructions of walls comprising two faces separated by batons or studs to define a cavity which is filled with a thermal insulating material, and more particularly to batons or studs suitable for use in such building constructions.

In traditional constructions of, for example, internal walls, timber studs are used to provide structural integrity and to create recesses or cavities between a rear and a front face of a wall which are filled with thermal insulation. One face of the wall is often provided by a sheet material, particularly plaster board, fixed to the studs. The use of timber studs is popular thanks to their suitable characteristics, ready availability and relatively low cost.

According to one of its aspects, the invention provides a building stud as defined by claim 1. Preferred and/or alternative embodiments are defined in the dependent claims.

The thermal insulator of the building studs according to the invention provides low heat transfer through the stud. The stud may have a heat transfer coefficient of greater than or equal to 1.4, 1.5, 1.8, 1.9 or 2.0 Km2/W. The material of the thermal insulator may have a thermal conductivity of less than or equal to 0.040, 0.035, 0.030 or 0.025 W/mK.

Preferably, the thermal insulator comprises a material having greater thermal insulation properties that the retainer.

The good thermal insulating properties of the stud may be used to improve the thermal insulation properties of a structure in which it is incorporated. The relatively poor thermal insulation performance of traditional studs provides a thermal bridge across the insulated space and thus leads to undesirable heat losses. Consequently, it has often been desirable to reduce the number of studs used in building constructions so as to reduce such heat losses. The improved heat insulation characteristics of the studs of the present invention not only reduce such heat losses but may also allow the use of a greater number of studs in a construction, thus improving the physical integrity of the structure, without unduly decreasing the thermal insulation performance.

The thermal insulator is substantially rigid, that is to say it has sufficient rigidity in compression such that the stud is adapted to maintain the structural integrity of a building structure, particularly a wall, in which it is incorporated. Preferably, the thermal insulator has a Young's modulus of at least 2, 3, 4, 5, 8 or 10. It may have a minimum compressive strength of at least 80, 100, 120, or 150 kPa; this may be tested at 10% compression in accordance with BS EN 826: 1996.

Preferably, the thermal insulator provides for low transfer of moisture, particularly water vapour. It may have a water vapour resistance of at least 100, 150, 200, 300 or 400 MN5/gm; this may be tested in accordance with BS 4370-2: 1993. Such levels of transfer of moisture may provide improvements over traditional studs, even when a greater number of studs are used in a construction.

A preferred material for the thermal insulator is extruded polystyrene (XPS). The thermal insulator may have a thickness of at least 10, 20, 30, 40, 50, 55 or 60 mm. It may have a thickness of less than 150, 130 or 100 mm.

The retainer for a mechanical fastener may by provided by a sheet or plate. A sheet of wood board material, for example orientated strand board (OSB), may be particularly suitable. Such a wood board or OSB material may have a thickness of greater than or equal to 5, 8, 10, 12, 14 or 18mm; it may a have thickness of less than or equal to 25, 22 or 18 mm. Such thicknesses may provide suitable pull out resistances for mechanical fasteners. Preferably, the retainer, and particularly a material of the retainer, is adapted to retain a mechanical fastener better than the material of the thermal insulator.

The building stud may comprise a single retainer; alternatively, it may comprise a pair of spaced retainers.

The retainer(s) may be provided at a face of the stud; this provides convenient proximity for receiving a mechanical fastener used, for example, to secure a plate or sheet material forming part of a wall structure to the stud. Alternatively, the retainer(s) may be arranged within the body of the building stud. The mechanical fastener may be a nail, a screw or a staple.

The withdrawal force required to pull out a mechanical fastener from the stud, as defined herein, may be: Type of Withdrawal force Withdrawal force Withdrawal force mechanical at least preferably at least more preferably fastener at least Screw 360 N 450 N 800 N Nail 160 N 200 N 360 N Staple 80 N 100 N 160 N The retainer and the thermal insulator may be secured together by an adhesive.

This may facilitate assembly and retention as an integral stud. The adhesive may be a fast curing two part polyurethane adhesive; one part may comprise an iso-cyanate and the other part may comprise a hardener.

The stud may thus be comprised of: * A thermal insulator which provides one or a combination of: low thermal transfer across the stud; sufficient rigidity for desired applications; low moisture transfer; poor retention of mechanical fasteners; and * A retainer which provides a combination of good retention for mechanical fasteners with lower heat insulating performance that the thermal insulator.

The low moisture transfer of the stud may be particularly useful in applications where a moisture control barrier is provided in the building construction. For example, plasterboard sheets provided with a facing of a vapour or moisture control material, for example a plastics or metal film, may provide one face of an insulated wall construction. Use of studs according to the present invention in such constructions may enhance the moisture or vapour control characteristics of the overall construction. This may be particularly useful where abutting edges of, for example, plasterboard sheets are arranged to overlay a stud.

An additional vapour or moisture control may be incorporated into the studs of the present invention. This may comprise a sheet material; this may be arranged at a surface of the retainer.

The studs of the present invention may be used in a construction to lie behind all abutting surfaces of plasterboard or other sheets used to form one face of a wall construction. This may provide moisture or vapour control at all such abutting joints whilst the thermal performance of the studs prevents significant degradation of the overall thermal performance of the structure.

Studs according to the invention may be used for internal or external walls; they may be used when constructing a new wall or fitted to an existing wall, particularly an existing external wall, to provide a recess for insulation material.

One aspect of the invention provides for such constructions and/or methods of construction.

The studs may be secured to an existing wall by a mechanical fastener; this may be driven through the retainer and the thermal insulator of the stud and secured at the existing wall.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.

Brief descriDtion of drawings Fig 1 is a perspective view of a building stud; Fig 2 is a perspective view of an alternative building stud; Fig 3 is a schematic side view of a wall constructed using building studs; Fig 4 is a plan view of a construction using a further alternative stud; Fig 5 is a side view of apparatus for use in testing withdrawal force.

The building stud 10 of Fig 1 comprises a substantially rigid thermal insulator 11 and a retainer 12 for a mechanical fastener secured together by a polyurethane adhesive (not shown). In this embodiment, the thermal insulator 11 is provided as a core of the stud and the retainer 12 is provided as a facing plate. The thermal insulator 11 consists of extruded polystyrene (XPS) having a thickness tl of 60mm. The retainer 12 consists of a sheet of orientated strand board (OSB) having a thickness t2 of 15mm.

In the embodiment of Fig 2, retainers 22 are provided on opposite faces of a thermal insulator core 21. This facilitates attachment by mechanical fasteners to each of these faces of the building stud. In this embodiment, the retainers 22 are again provided by sheets or plates of orientated strand board (OSB). Such a stud may be particularly suitable for use for a spandrel panel.

Fig 3 shows the use of building studs 10 in accordance with the invention in an internal wall 30 of a building. The wall 30 comprises a rear face 31 and a front face 32 with intervening studs 10 so as to define a series of cavities 33 between the front and rear faces. In this embodiment, the front face 32 is provided by sheets of plaster board 34 (some of which have been removed from the illustration for clarity) which are attached to the studs 10 using mechanical fasteners 35, for example nails or screws. Each panels 34 to be fixed to a stud lies against the orientated strand board retainer that is provided as a facing of the stud. The mechanical fasteners 35 cooperate with the retainer(s) 12 of the studs 10 to secure the plasterboard 34 to the studs 10 by passing into and/or through the retainer 12.

Fig 4 illustrates a further embodiment of a building stud 40 arranged in the cavity of a wall between a rear face 51 and a front face 52. This form of building stud 40 is particularly suitable where it is desired to provide a separation or void 53 between the rear wall 51 and thermal insulating material 54, for example mineral wool insulation, provided in the cavity of the wall. Such a construction is particularly suitable when the rear face 51 is provided by fair faced masonry.

The stud 40 comprises an XPS thermal insulator 41 and a retainer 42 provided at its front face. The retainer, in this embodiment a sheet or plate of orientated strand board, receives a mechanical fastener 43, for example a screw or nail, used to attach the front face 52 of the wall (which may be provided by a sheet of plasterboard) to the stud 40.

The rear of the stud comprises a spacer 44 which projects laterally beyond a side surface 45 of a body of the stud and which is adapted to space a batt 54 of insulating material from the rear wall 51. In this embodiment, the stud comprises a second spacer 46 projecting laterally opposite the first spacer so that the stud 41 is of substantially T shaped cross section, the stem of the T adapted to be positioned between the faces 51, 52 of the wall and the cross bar of the T providing projections adapted to act as spacers between and insulation material 54 and the rear wall 51.

Fig 5 illustrates apparatus used to measure the withdrawal force required to pull a mechanical fastener out of a stud and comprises: * A coupling ring 61 * A clamping device 62 adapted to the type of fastener (the figure shows a clamping device for screws) * A support plate 63, the dimensions being: height Hi 3mm, height H2 10mm, diameter Dl 20mm, diameter D2 40mm * The stud 64 (partially shown) being tested.

In testing the withdrawal force of studs of the invention, the following conditions are used:

Type of mechanical specification

fastener Screw black phosphated self drilling and self tapping screws with countersunk Phillips heads for fixing plasterboard to timber framing, diameter 4mm, for example screws available from Knauf Drywall UK (article no 933 04 500) Nail Electro-zinc plated nails with annular ring shank

for fixing plasterboard to timber backgrounds,

shank diameter 2.65 mm, for example available from Knauf Drywall UK (article no 932 77 500) Staple staple specifically designed for fixing plasterboard to timber framing The fastener is driven perpendicular in to the retainer of the stud to a depth of 20mm (or to fully penetrate the retainer if the retainer is less than 20 mm thick) and a progressive force is applied at a rate of 450 N per minute to determine the total withdrawal force.

The test is repeated 20 times with the average value being taken.

Claims

Claims 1 A building stud comprising a substantially rigid thermal insulator and a retainer for a mechanical fastener.
2 A building stud in accordance with any preceding claim, in which the thermal insulator comprises a foam insulation material.
3 A building stud in accordance with claim 2, in which the thermal insulator comprises a polystyrene insulation material.
4 A building stud in accordance with claim 2, in which the thermal insulator comprises an extruded polystyrene insulation material.
A building stud in accordance with any preceding claim, in which the thermal insulator has a thickness within the range 40 to 100 mm.
6 A building stud in accordance with any preceding claim, in which the retainer comprises a sheet material.
7 A building stud in accordance with any preceding claim, in which the retainer is provided as a facing on a surface of the thermal insulator.
8 A building stud in accordance with any preceding claim, in which the retainer comprises a wood board.
9 A building stud in accordance with claim 8, in which the retainer comprises orientated strand board.
A building stud in accordance with any preceding claim, in which the retainer has a thickness wfthn the range 5 to 30 mm.
11 A building stud in accordance with any preceding claim, in which the thermal insulator and the retainer are secured together by an adhesive.
12 A building stud in accordance with any preceding claim, in which the building stud comprises at least one spacer, integral with the thermal insulator which defines a recess adapted to receive a panel or batt of thermal insulation and space the batt of thermal insulation from a wall.
13 A building stud in accordance with claim 12, in which the recess adapted to receive a panel or batt of thermal insulation comprises a substantially L shaped corner section.
14 A building stud comprising a pair of orientated strand board (OSB) facing plates each having a thickness of 5-30mm and each being adapted to retain a mechanical fastener, the orientated strand board OSB facing plates being separated by a substantially rigid, XPS thermal insulator having a thickness of 40-100mm.
Use of a building stud in accordance with any preceding claim in a thermally insulated wall of a building.
16 A thermally insulated wall of a building having a cavity defined between a front face and a rear face, the wall comprising a plurality of building studs in accordance with any one of claims 1 to 14 arranged within the cavity, at least one of the faces of the wall being secured to the building studs by a mechanical fastener secured to the retainer of the building studs.
17 A thermally insulated wall of a building in accordance with claim 16, in which panels of thermal insulation material are arranged between adjacent building studs within the cavity of the wall.