GB2400868A

GB2400868A - Trapezially ridged roofing sheet supporting insulation

Info

Publication number: GB2400868A
Application number: GB0408525A
Authority: GB
Inventors: David Lowe
Original assignee: SPEEDDECK BUILDING SYSTEMS Ltd
Current assignee: SPEEDDECK BUILDING SYSTEMS Ltd
Priority date: 2003-04-26
Filing date: 2004-04-16
Publication date: 2004-10-27
Also published as: GB0408525D0

Abstract

A roof structure comprises a structural deck 12 preferably formed from sheet metal having a plurality of laterally spaced primary ridges 22, 22' of trapezial cross-section, and an inter-ridge region (26, fig 2) adapted to receive insulation 16. The connecting region may comprise secondary ridges 24, 24' and can be used as a gutter by inserting a waterproof lining. Primary 22 and secondary ridges 24 may be hollow with insulation retained within the underside of the primary ridge 22. The connecting region (26) may be provided with a window (50, figs 6,7). A roof may be assembled by over-locking primary ridges of adjacent structural decks 12 (fig 5). The ridges may be fixed together through holes 42 and sealed. A thermal break 40 may be provided between the top of the primary ridges 22, 22' and a roof covering 14. In use, the deck 12 replaces purlins simplifying roof construction, and is also easily stackable when stored.

Description

Title: Improved Roof Structure

Field of the Invention

This invention relates to a roof structure comprising a structural deck and a method of assembling such a roof structure into a roof.

Background to the Invention

Certain roof structures are made using structural decks roll formed from sheet steel or aluminium. These roof structures are particularly of use in large metal framed buildings where purlins run between beams, subdividing the length of each beam. The structural decks then span the main frame, running across and supported by the main structural frame.

To accommodate the need for insulation in such roof structures, cassette trays are often used to replace the purling. The cassette trays are capable of receiving insulation material, which is part retained by an integral flange. However the flange has the disadvantage of preventing the trays from interlocking when stacked. This means that the trays require a large volume of transport space.

It is an aim of the present invention to overcome some of the disadvantages of the prior art roofing systems.

Summary of the Invention

In accordance with the present invention, there is provided a roof structure comprising a structural deck formed from sheet material with a plurality of laterally spaced primary ridges of trapezoidal cross-section, with a connecting region between successive primary ridges being adapted to receive insulation. This allows the insulation to be retained within the structural deck, simplifying roof construction.

Typically the sheet material is metal such as steel or aluminium, with the ridges preferably formed into the material by a roll forming process. Preferably the primary ridges are of a height H which equals or exceeds a depth of insulation which is required. Typically H will be around 200mm, but can be varied dependent on the insulation requirements relating to a given roof design in which the roof structure is to be used. Thus for an insulation depth of 290mm, the height H can be increased accordingly.

The connecting region may further comprise a plurality of secondary ridges, thereby to improve rigidity of the sheet material. The secondary ridges are typically also of trapezoidal cross-section, but have a height h much less than the height H of the primary ridges. Thus typically the secondary ridges will have a height h of 25mm.

The connecting region may be used as an integral gutter, typically by inserting a waterproof lining in the connecting region. The integral gutter is usually placed at the lowermost edge of a roof, any roof covering placed over the structural deck being truncated just before the gutter, so as to allow the gutter to collect rain water.

Preferably apertures are punched at regularly spaced intervals along the sides of the primary ridges. This ensures that on assembly of a roof from a plurality of roof structures, a first primary ridge near an edge of a first roof structure can be overlain with a second primary ridge near an edge of a second roof structure, the apertures allowing the respective primary ridges to be secured together so as to improve the overall strength of a roof made from such a roof structure.

Further apertures may be punched between the secondary ridges in the connecting region.

This ensures that the sheet material is preformed with the holes necessary to secure the sheet material to form a roof, and avoids fitters needing to make a decision on where to place apertures.

Desirably the structural deck has a cross-sectional profile which enables close stacking of a plurality of structural decks. This saves on space required to transport the structural decks.

S The primary and secondary ridges are typically hollow, and if desired insulation may be retained underneath and within the primary ridges by a securing means such as a cover plate. This improves the insulation properties of the completed roof structure, and is particularly useful where acoustic insulation is required for buildings such as sports halls.

In accordance with a further feature of the invention, a thermal break is secured to a flat uppermost edge of the primary ridge. The thermal break may be in the form of a metal bracket or an insulating block and ensures that a roof covering placed over the sheet material is substantially thermally isolated from the sheet material, and also provides a load path between the external metal weatherproof covering and the structural deck.

Primary overlapping ridges may include factory applied side lap sealant.

The structural deck may be provided with at least one translucent medium within the connecting region so as to provide a window. Typically the translucent medium will be provided by cutting a square aperture within the connecting region and placing a translucent plastics material, such as glass reinforced plastics, over this region in mating engagement with the connecting region. Where such windows are provided, typically a load spreader is used to reinforce the reduced area of connecting region adjoining the aperture. This ensures structural continuity across the entire connecting region.

The end of the sheet may be cut at an angle so as to replicate the angle needed in a hipped- roof construction.

In accordance with another aspect of the invention, there is provided a method of assembling a roof, comprising taking a plurality of roof structures in accordance with a first aspect of the invention, and interlocking adjacent structural decks by overlaying a first primary ridge of a first structural deck over a second primary ridge of a second structural deck. The overlapping primary ridges may be secured together by fixing means such as screws.

The method may further comprise cutting the roof structure at a predesigned angle ready for assembly into a roof, such as a tripped roof.

The invention will now be described by way of example, and with reference to the accompanying drawings in which: Figure 1 shows a schematic of a building using a roof structure in accordance with the present invention; Figure 2 shows an edge profile of a structural deck forming part of the roof structure; Figure 3 shows a cutaway perspective view of a portion of the roof structure; Figure 4 shows a detailed section along line IV-IV of Figure 3; Figure 5 shows an edge profile of interconnecting structural decks; Figure 6 shows a perspective view of a structural deck incorporating a roof light; Figure 7 shows a plan view of a roof with a plurality of structural decks, each structural deck incorporating a roof light.

Description

In Figure 1, a schematic of a steel frame building incorporating beams 10, 10', 10" is shown. A roof is formed from structural decks 12 in accordance with the present invention and a roof covering 14. The structural decks 12 run between the beams 10, 10', 10" and have a cross-sectional profile which has sufficient strength and rigidity such that the decks act as their own purling. Once the decks 12 are placed across the beams, insulation 16 is rolled part way along the length of each deck 12 before being covered with the roof covering 14.

When assembling the roof, it is important to ensure that the insulation 16 is protected from the elements as soon as possible. Therefore usually insulation is rolled along a number of adjoining decks for approximately the same distance, and then covered with the roof covering before the insulation is rolled out further.

By truncating the roof covering 14 just before the lowest part of the roof, it is possible to incorporate an integral gutter 20 within part of the structural deck. Typically this part of the structural deck will be provided with a gutter lining. The integral gutter avoids the need for a separate gutter, and the fixing steps associated with such a gutter.

The roof may be in the form of a tripped construction and where this is the case, the structural decks can be cut either on site or at the manufacturing plant to ensure they have the correct slant at either end for the tripped profile. Thus where an architect knows the profile of the tripped roof to be built, the manufacturer can simply be advised of the relevant angles and rake cutting performed on the structural decks to ensure they are the correct length and slant for direct assembly. This avoids cutting on-site and reduced tolerances generally associated with such cutting.

A side profile of a single sheet of structural deck 12 is shown in Figure 2. The deck 12 has two hollow primary ridges 22, 22' which are roll formed into galvanised sheet steel or aluminium so that the ridges extend the entire length of the deck. Two secondary ridges 24, 24' are provided in the connecting region 26 between each primary ridge, the purpose of the secondary ridges 24, 24' being to strengthen the connecting region 26 and improve its rigidity. The connecting region between the two primary ridges is typically 445mm in width, with the two secondary ridges regularly spaced throughout this region, each secondary ridge being typically of a height of approximately 20mm with a 5mm radii slant.

The structural stability of the deck is such that the deck is usable on its own without purling, acting as its own support between beams. This provides improved efficiency for roof assembly and reduces material costs.

Typically each sheet of structural deck has a width of around 900mm and can range in length up to 30m. The primary ridges 22, 22' have a height H of around 200mm, with a base 28 width of approximately 200mm, and a top 30 width of approximately 50-60mm.

The height of the primary ridges 22, 22' can be altered dependent on the depth of insulation required, with corresponding alterations in the width of the base 28 and top 30 as appropriate. In this way, the deck profile can be modified to accommodate greater depths of insulation.

The primary ridges in profile can be seen to incorporate a number of web stiffeners 32 to improve the rigidity of the ridge 22, 22'. If required, microribs 33 can be provided to all faces to further stiffen the metal, see Figure 4. The configuration of the profile is such that sheets of structural deck can be stacked one on top of the other without any substantial gap. This reduces transport costs as many close stacked sheets can be carried on one vehicle, without space being wasted.

Figure 3 shows a detailed perspective view of part of the roof and illustrates the individual layers within the roof, namely the structural deck 12, insulation 16 retained by the connecting region 26, and the roof covering 14. Insulation is rolled along the connecting region 26 and retained by the upstanding trapezoidal ridges 22, 22'. The structural deck thus incorporates an integral region adapted to receive insulation. The insulation 16 does not need to be cut to fit the connecting region 26. Typically it will be pushed down into and rolled along the connecting region 26 so that it fills the space formed by the region, and spills over onto the upper face 30 of the trapezoidal primary ridges 22, 22'. When all the insulation is in place, a substantially contiguous insulation surface is provided over the top of the structural deck.

Typically a thermal break 40 is provided between the structural deck 12 and the roof covering 14 or sheeting. The thermal break can either be in the form of an inverted U- shaped metal bar 40, or an insulating block. The structural deck 12 includes punched holes 42 spaced regularly along the middle of the primary ridge 22, 22' at approximately 450mm centre. By pre-punching these holes, the fitters know precisely where to secure successive sheets to one another. Within the connecting region 26, holes 44 are punched at the end of the profile between the secondary ridges, again to avoid fitters needing to decide where to place the holes when securing the deck to the beams 10.

If desired, acoustic insulation can be placed within the hollow of the primary ridges, for example by using a cover plate 46 to secure the insulation in place. Typically, the cover plate will have upturned edges, angled inwards to fit within the hollow ridge. The cover plates 46 may be secured by use of conventional fixings through the pre-punched holes 42 along the length of the primary ridges, or by any other appropriate means.

When securing successive structural decks 12, 12' to the beam, adjacent structural decks are overlapped so that adjoining primary ridges overlap in their entirety, as seen in Figure 5. This increases the strength of the structural deck. If desired, side stitching can be performed along the length of the overlapping primary ridges by securing the ridges to each other using screw fasteners through the apertures 42. This further increases the IS strength of the composite deck structure as all the decks will then act together as one member. In addition, sealant may be placed between two decks as they are overlapped.

In view of a recent move towards use of natural lighting within such structures, the structural deck 12 may incorporate roof lights SO as shown in Figure 6. Typically a square aperture 52 is cut from within the connecting region 26, and a transparent or translucent structure SO secured over and to this aperture. It is important that the seal between the transparent material, typically glass reinforced plastics material, and the ridges within the connecting region is watertight. To prevent the aperture 52 weakening the structural deck unduly, reinforcing angles 54 are provided at the join of the primary ridge 22 with the connecting region 26. These act to spread the load and ensure structural continuity throughout the deck. Typically two reinforcing angles will be used, one for each primary ridge. As shown in Figure 7, usually a plurality of structural decks 12, 12', 12" will be provided with these roof lights SO, 50', 50", so as to ensure the maximum natural light possible within a building.

Claims

Claims 1. A roof structure comprising a structural deck formed from sheet

material with a plurality of laterally spaced primary ridges of trapezoidal cross-section, with a connecting region between successive primary ridges being adapted to receive insulation.
2. A roof structure according to claim 1, wherein the ridges are formed into the material by a roll forming process.
3. A roof structure according to any of the preceding claims, wherein the primary ridges are of a height H which equals or exceeds a depth of insulation which is required.
4. A roof structure according to any of the preceding claims, wherein the connecting region comprises a plurality of secondary ridges, thereby to improve rigidity of the sheet material.
5. A roof structure according to any of the preceding claims, wherein the connecting region is used as an integral gutter.
6. A roof structure according to any of the preceding claims, wherein apertures are punched at regularly spaced intervals along the sides of the primary ridges.
7. A roof structure according to any of the preceding claims, wherein further apertures are punched between the secondary ridges in the connecting region.
8. A roof structure according to any of the preceding claims, wherein the structural deck has a cross-sectional profile which enables close stacking of a plurality of structural decks.
9. A roof structure according to any of the preceding claims, wherein the primary and secondary ridges are hollow, and insulation is retained underneath and within the primary ridges by a securing means.
10. A roof structure according to any of the preceding claims, wherein a thermal break is secured to a flat uppermost edge of the primary ridge.
11. A roof structure according to any of the preceding claims, wherein primary ridges include factory applied side lap sealant.
12. A roof structure according to any of the preceding claims, wherein the structural deck is provided with at least one translucent medium within the connecting region so as to provide a window.
13. A roof structure according to any of the preceding claims, wherein the end of the sheet material is cut at an angle so as to replicate the angle needed in a tripped-roof construction.
14. A method of assembling a roof, comprising taking a plurality of roof structures in accordance with any of the preceding claims, and interlocking adjacent structural decks by overlaying a first primary ridge of a first structural deck over a second primary ridge of a second structural deck.
15. A method of assembling a roof according to claim 14, wherein the overlapping primary ridges are secured together by fixing means.
16. A method of assembling a roof according to either claim 14 or claim 15, the method further comprises cutting the roof structure at a predesigned angle ready for assembly into a roof.
17. A roof structure and a method of assembling a roof substantially as herein particularly described with reference to and as illustrated in the accompanying drawings.