GB2466854A

GB2466854A - Lintel with improved thermal efficiency

Info

Publication number: GB2466854A
Application number: GB0904153A
Authority: GB
Inventors: Stanley Pritchard Daykin; Jordan Andrew Daykin
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-01-08
Filing date: 2009-03-11
Publication date: 2010-07-14
Also published as: GB0904153D0; GB0900221D0

Abstract

A lintel including an external wall support section comprising a horizontal 39 and vertical 38 plate at right angles and an internal wall support section comprising a horizontal 42 and a vertical 41 plate at right angles, where the two sections are joined by a sloping plate 40 and the horizontal plate of the internal wall support section is higher than the horizontal plate of the external wall support section, creating a recess. The core of the lintel may be provided with thermal insulation material 46 such as expanded polystyrene, rigid urethane foam etc. There may also be a horizontal thermal insulation material 44 and a lignocellulosic material 45, such as wood or timber, attached beneath the internal wall support section extending under the sloping panel leaving an air gap 47 between the insulating material and the sloping wall. Preferably there is a horizontal strengthening plate 43 between the external and internal wall support section and a thermally insulated metal mounting support base connected to provide support for the internal wall support section resulting in it being built up to the same level as the external wall support section.

Description

IMPROVED OPEN BACK CAVITY WALL STEEL LIIS%ITELS

INCORPORATING THERMAL INSULATION AND

LIGNOCELLULOSIC MATERIAL INSERTS

BACKGROTITh]J Lintels are used in the construction of buildings and are positioned above the windows and door apertures to support masonry, floors and roofs.

Steel lintels are well known in the building construction industry, but the design, construction and installation has shown that over time, water condensation can migrate due to capillary action into the building and causes mould growth in and around doors and windows. Mastic sealants are recommended and when applied correctly have been successful in preventing moisture entering the buildings, however, monitoring of the sealant beading has to be regularly inspected for separation and should be re-sealed if necessary.

There is a continuing requirement to improve the thermal efficiency of the lintels to reduce cold bridging or thermal bridging, previous attempts such as bonding wood wool and cement has been used, but the current demand is for a higher efficiency of thermal insulation. The core of existing lintels are filled with thermal insulation but this does not satisfy the all the problems of cold bridging.

In an attempt to reduce cold bridging a horizontal base plate is provided to span the cavity between the horizontal plates that support the internal and external masonry walls, the horizontal cavity plate is provided with holes or slots punched into the cavity plate and along the leading edge castellation or tabs are welded to the horizontal external wall support plate, this is referred to as Negligible Cold Bridging Effect'. What the manufacturers have failed to realise is that the lintel metalwork spanning the cavity is not insulated and is exposed to the cold air within the building cavity and is subject to the formation of condensation and the effect of the cold steel lintel absorbing more heat from within the heated building.

There is also a need to provide an improved method of securing attachments and accessories such as pelmets, curtain and blind rail brackets and fixings to the internal vertical and horizontal surfaces of the steel lintels.

Double glazed windows are fitted with trickle ventilators, the ventilators are mounted on the top beam of the window frame and have to be removed prior to the fixing of plasterboard or plastering. To prevent cold bridging, thermal insulation is recommended to be installed underneath the bottom flange of the lintel prior to the fixing of the plasterboard, with this extra thickness of insulation material the trickle ventilators has to be re-positioned on the window frame, usually down one side, which creates extra installation site work.

Stepped lintels are available but are not designed and manufactured to prevent the ingress of water condensation into the building, they are provided and used for bracing the windows in severe windy areas.

Examples of conventional open back lintels are shown as follows; Figure us a conventional lintel manufactured as a one piece folded metal section 3.

Figure 2 is a further example of a conventional lintel, manufactured similarly as Figure 1 but with a perforated plate connecting the two horizontal flanges.

Figure 3 is a cross-sectional view of the lintel 3 showing the formed metalwork 5 having holes 6 in the bottom flange. The core of the lintel is provided with thermal insulation material 7.

Figure 4 is a cross-sectional view of the lintel 4 showing the formed metalwork 8 with holes 9 and a base plate 10 with holes 11. The core of the lintel is provided with thermal insulation material 12.

Figure 5 is a cross-sectional view showing a conventional lintel 3 in relationship to the internal wall 13 and the external wall 14, the window frame 15 is positioned below the lintel 3 and the vertical plasterboard 16 is attached to the internal wall with adhesive dabs 17. The horizontal plasterboard 18 is attached to the lintel internal wall support flange 19 on dabs 20. External sealant 21 is shown attached to the window frame 15 and the lintel 3.

STATEMENT OF INVENTION

The scope of the invention is defined by the listed claims To overcome the problem of water condensation entering the building the invention proposes that the lintel is constructed to provide an ascending step or recess in the base of the lintel's horizontal internal supporting wall flange and at each end of the lintel a formed mounting plate is provided to support the lintel on the internal masonry at the same level/height as the external masonry.

To improve the thermal efficiency of the lintel and to reduce cold bridging the present invention proposes to place extra thermal insulation on the internal facing surface of the horizontal flange of the steel lintel.

To improve the method of securing attachments and accessories to horizontal internal flange of the steel lintels such as blind rails brackets and fixings the present invention proposes to provide and attach lignocellulosic material inserts preferably but not exclusively, lengths of laminated timber to enable the securing of attachments.

A further objective of the invention is to provide thermal insulation between the metalwork bottom flange of the steel lintel and the lignocellulosic material insert thus overcoming the need to re-position the window trickle ventilators and the door trickle ventilators.

DETAILED DESCRIPTION

Lintel constructions according to the invention are diagrammatically illustrated by way of example and without limitation, with reference to Figures 6 to 11 of the accompanying drawings, in which: Figure 6 shows a perspective view of an open back lintel; Figure 7 shows a perspective view of an alternative open back lintel with a horizontal cavity plate.

Figure 8 shows a vertical transverse cross-sectional view of the lintel of Figure 6.

Figure 9 shows a vertical transverse cross-sectional view of the lintel of Figure 7.

Figure 10 is an isometric view of one end of the lintel as shown on Figure 7 supported on masonry.

Figure 11 is an isometric view of one end of the lintel as shown on Figure 6 supported on masonry.

Referring to Figures 6 and 8 is a lintel 25 formed from galvanized mild steel and plastic coated or stainless steel, the angled plate 27 and vertical plate 29 connects with a horizontal plate 28 to support the outer leaf of the wall above an aperture and the vertical angled plate 30 connects with a horizontal plate 31 which supports an inner leaf of the cavity wall.

The angled support plate 27 connects the vertical angled plates 30, when the lintel is in position in a cavity wall, the angled support plate 27 extends over the cavity.

The difference in height of the external wall horizontal plate 28 and the internal wall horizontal plate 31 allows for the fixing of thermal insulation material 32 such as expanded polystyrene or rigid urethane foam (these materials are not exclusive or exhaustive) and lignocellulosic material insert 34 these materials are secured into position by fasteners 35 screwed into standoff pillars 36. Alternative securing systems can be used. The core of the lintel 33 is filled with thermal insulation material such as expanded polystyrene or rigid urethane foam (these materials are not exclusive or exhaustive).

An air gap 37 is formed between the angle plate 29 and the lignocellulosic material insert 34. This gap or air space continues for the length of the lintel and is not bridged at any point along its entire length.

The gap 37 serves to prevent the migration of water condensate from the outside atmosphere to the internal walls of the building causing mould growth and discolouration of the building's decorations.

At each end of the recessed lintel plate 31, a thermally insulated metal mounting support base 37 is connected to provide end support to the lintel on the internal wall horizontal flange 3 lwhich is built up to the same level/height as the external wall horizontal flange 28.

Referring to Figures 7 and 9 a lintel 26 formed from galvanized mild steel and plastic coated or stainless steel, the angled plate 38 connects with the external wall horizontal support flange 39 and the angled plate 40 extends over the cavity and connects with the vertical plate 41. An internal wall horizontal support flange 42 is connected to the vertical plate 41.

A support plate 40 connects the angled plates 38 and 41. When the lintel is in position in a cavity wall, the support plate 40 extends over the cavity.

A bracing plate 43 connects the angled plate 38 to the angled plate 41.

The difference in height of the external wall horizontal support plate 39 and the higher internal wall horizontal support plate 42 allows for the fixing of thermal insulation material 44 such as expanded polystyrene or rigid urethane foam (these materials are not exclusive or exhaustive) and lignocellulosic material insert 45, these materials are secured into position by fasteners 35 screwed into standoff pillars 36. Alternative securing systems can be used. The core of the lintel 26 is filled with thermal insulation material 46.

An air gap 47 is formed between the angled plate 38 and the lignocellulosic material insert 45. This gap or air space continues for the full length of the lintel and is not bridged at any point along its entire length. The gap 47 serves to prevent the migration of water condensate from the outside atmosphere to the inside walls of the building causing mould growth and discolouration of the building's decoration.

At each end of the recessed lintel plate 42, a thermally insulated metal mounting support base 48 is provided to support to the lintel 26 on the internal wall. The internal masonry wall is built up to same level/height as the external wall.

Figure 10 shows the thermal insulation 44 and the lignocellulosic material insert 45 extending to the end of the lintel and encasing the bracing plate 43. The air gap 47 is also shown.

Figure 11 shows the insulation 33 and the lignocellulosic material insert 34 extending to the end of the lintel and supporting the thermal insulation 33. The air gap 37 is also shown.

Claims

CLAIMS1. A lintel for use in bridging/spanning an aperture in a cavity wall, the lintel is an elongated open ended metal structure formed with plates inclined at right angles arranged to support an external wall and an internal wall, wherein a horizontal external wall support is connected to a slopping plate which is inclined and spans the cavity, and a further right angle section is connected to the slopping plate at the apex, and at the base of the right angle section a horizontal internal wall support plate protrudes to support the internal wall, the height of the horizontal internal wall support plate is terminated at a level above the horizontal external wall support plate, wherein the difference in levels between the internal and external support plates creates a recess.
2. A lintel according to claim 1 in which the core of the lintel is provided with thermal insulation material such as expanded polystyrene or rigid urethane foam or other insulating materials.
3. A lintel according to claim 1, which has a elongate horizontal recess, in which thermal insulation such as polystyrene or rigid urethane or other insulating material is placed beneath the metalwork facing the internal room and secured in position together with a lignocellulosic material insert with fasteners and that the thermal insulation and lignocellulosic material extends the entire length of the lintel.
4. A lintel according to claim 1, which is provided with an air gap formed between the horizontal external wall support plate, the vertical right angled plate and the thermal insulation and the lignocellulosic material insert.
5. A lintel according to claim 1 for use in bridging an aperture in a cavity wall substantially as herein described and provided with a metal strengthening plate connected to the vertical plates and as illustrated in Figures 7 and 9.
6. A lintel according to claim 1 and claim 5 in which the core of the lintel is provided with thermal insulation material such as expanded polystyrene or rigid urethane foam or other insulating materials.
7. A lintel according to claim 1, claim 2 and claim 4 which has elongate horizontal recess in which thermal insulation such as polystyrene or rigid urethane or other insulating material is placed beneath the metalwork facing the internal room and secured in position together with a 1 ignocellulosic material insert with fasteners.
8. A lintel according to claims 1, which is provided with an air gap formed between the horizontal external wall support plate, the vertical right angled plate, the thermal insulation and the lignocellulosic material insert.
9. A lintel according to claims 1, which is provided with a thermally insulated metal mounting support base is connected to provide end support to the lintel on the inner leaf wall which is built up to the same level or height as the outer leaf wall.