Building structure and associated installation method

Abstract

A building structure (1) for attachment to a pitched roof (100) is provided, comprising: a hollow body (402) with an oblique lower edge (406) for attachment to the pitched roof (100) and an upper edge (514) opposite the lower edge (406); a roof element (602) attachable to the upper edge (516) of the hollow body; and an attachment mechanism (908) on at least one of the hollow body (402) and / or roof element (602). The oblique lower edge (406) of the hollow body (402) is fixable to the pitched roof (100), and the roof element (602) is lowerable onto the upper edge (514) of the hollow body (402) and attachable to the hollow body (402) via the attachment mechanism (908).

Description

[0001] BUILDING STRUCTURE AND ASSOCIATED INSTALLATION METHOD

[0002] Technical Field

[0003] The present invention relates to a building structure and an associated installation method for a building structure.

[0004]

[0005] Installation of building structures, such as dormer windows, chimneys, ventilation louvres, drop-on dovecotes and the like on to roofs, and in particular pitched roofs, requires skilled labour. This installation is usually performed by constructing an underlying timber frame in situ on the roof, and then cladding this frame (such as with metal) on the roof. This is expensive and is a time-consuming job at height. A partially finished installation is vulnerable to metal thieves.

[0006] GB 2551611 discloses a building component to be mounted onto a new building wall or roof or to be retrofitted to an existing wall or roof of a building. The building component is manufactured from Glass Reinforced Plastic (GRP), also known as fibreglass. Fibreglass building components in general suffer from UV discoloration over time and are also not in keeping with areas in which lead roofs are already existing. GB 2551611 provides a thermoplastic material shell for such a GRP building component.

[0007] In addition fibreglass building structures such as those described in GB 2551611 are prefabricated in a single piece and lifted into place using flexible straps extending around the top of the structure. Once the structure is in place these straps are pulled through a gap between the prefabricated building structure and the pitched roof. As a result, this method is limited to a prefabricated structure of a comparatively lightweight construction.

[0008] There is therefore a demand for an improved building structure and associated installation method which is faster to install than the conventional metal-clad building structure and overcomes the deficiencies in the prior art.

[0009] A first aspect of the present invention provides a building structure according to claim 1.

[0010] 17683793 MDN MDNThe separable nature of the hollow body and roof element is beneficial for installation onto a roof with a crane, since it can be lifted without needing straps around the top of the structure. This removes the weight limitation of the prior art. This allows the structure to be made of more durable materials. It also allows the structure to be in a more complete state, for example it may be clad in metal in a factory setting, before being placed on the roof. In turn this significantly reduces the work required for the on-roof installation. A further advantage is that the separable nature of the hollow body and roof element allow for the construction of roof elements with different designs (such as flat roof, apex roof, or curved roof designs) which are all compatible with the same hollow body, thereby allowing for quick installation of visually different building structures.

[0011] The hollow body may be liftable without any modification. However preferably it comprises a lifting point for a crane. This allows it to be more easily lifted with a standard crane hook. Preferably the lifting point is a bar spanning an interior of the hollow body. The bar may be removable, such that the bar is removed once the hollow body is in place so the removable bar does not affect the appearance of the hollow body. Alternatively, the bar may be a joist forming part of the hollow body. Said joist may be at the front and / or upper edge of the hollow body. The bar may be a lifting point in its own right, such as enabling lifting through the connection of straps around the bar, and / or the bar may comprise a loop or hook element, which may be removable, to facilitate lifting.

[0012] The hollow body may further comprise a temporary supporting beam spanning the interior of the hollow body. This temporary supporting beam may ensure the rigidity of the structure during installation and provide a contact point for workers to use when positioning the hollow body on the pitched roof structure.

[0013] The roof element may comprise a plurality of removable loops for attaching lifting straps. This allows it to be more easily lifted. The removable loops may be removable eye bolts which will not affect the appearance of the hollow body in situ.

[0014] The roof element may further comprise a surrounding portion which surrounds at least part of the hollow body. The surrounding portion may comprise a soffit and a fascia. The attachment mechanism may attach the roof element to the hollow body through the surrounding portion. The part of the surrounding portion through which the attachment

[0015] 17683793 MDN MDNmechanism is deployed may then be covered by a covering element such that the attachment mechanism is not visible following installation.

[0016] The roof element may comprise a double wall structure creating a first void within the roof element for allowing air flow. Air flow is advantageous in metal-clad building structures, and in particular lead-clad building structures, as excessive condensation can result in corrosion of lead-sheet roofs. The first void for allowing airflow will substantially reduce this condensation and thus any corrosion. The surrounding portion, and in particular the soffit or fascia of the surrounding portion, may further comprise a roof element vent for encouraging airflow through the first void.

[0017] The hollow body may further comprise a double wall structure creating a second void around the hollow body. The second void, similarly to the optional first void in the roof element, allows airflow inside the double wall of the hollow body and substantially reduces condensation and thus corrosion therein.

[0018] The building structure preferably has a metal covering. This may be copper, zinc, aluminium, or steel, but is preferably lead.

[0019] The building structure may further comprise a metal roof element covering, wherein the metal roof element covering comprises an installed section, fixed to the roof element, leading to an attachment section folded back over the installed section and deployable, in use, to cover the pitched roof. The attachment section, folded back over the installed section facilitates rapid installation of the building structure, as once installed on the hollow body, the attachment section is simply deployed (such as through unfolding or unrolling) and attached to the existing pitched roof structure.

[0020] The building structure is designed, in particular, for a dormer window, but can be applied to any structure to be installed on a pitched roof such as chimneys, ventilation louvres, drop-on dovecotes and the like.

[0021] A second aspect of the invention also provides a roof structure comprising a building structure according to the first aspect the invention and a pitched roof to which the building structure is attached.

[0022] 17683793 MDN MDNThe pitched roof may further comprise an upstand surrounding an opening, the building structure being received on the upstand. The upstand aids installation and provides a space for a suitable fixing mechanism for attaching the building structure or the hollow body of a building structure to the pitched roof.

[0023] The upstand may be covered in a metal sheet. By cladding the upstand prior to installation, the installation time of a building structure is reduced.

[0024] The roof structure may further comprise a gutter which is recessed relative to the upstand and extends around at least a portion of the oblique lower edge of the building structure. The gutter prevents the build-up of water around the building structure in use and thereby aids the waterproofing of the structure. The gutter may be flush with the roof structure, or may be slightly recessed from the roof structure. In particular, the gutter may be at the same level as the roof joists, and the gutter may be defined by a runner batten situated on the roof joists and the upstand.

[0025] The roof structure may be tiled prior to the installation of the building structure; and in particular, the tiles may be installed on the roof structure so as to partially cover the gutter prior to the installation of the building structure. This has the advantage that the roof structure requires much less time to complete following the lowering of the building structure onto the roof structure.

[0026] If the building structure comprises a double wall structure, an outermost wall can extend down below the upstand towards the gutter. The outermost wall extending down below the upstand protects the interface between the upstand and the building structure from rain. The outermost wall may not extend fully down to the gutter. The resultant gap may be a hollow body cheek vent for encouraging airflow through the double wall structure and thereby reducing condensation and corrosion.

[0027] According to a third aspect of the invention a method is provided according to claim 20.

[0028] Installing a building structure on a pitched roof by lifting the building structure onto an upstand on the pitched roof with an adjacent gutter facilitates the installation of a building structure in reduced time compared to existing methods. In particular, by creating a gutter on the pitched roof prior to installation of the building structure, the need to cut metal

[0029] 17683793 MDN MDNcladding to size following installation (for metal clad building structures) is removed, as the required finishing is performed during prefabrication, or during preparing the roof structure.

[0030] The method may be applied to a one-piece building structure or the separable structure of the first aspect. Where a one-piece building structure is installed, an additional lifting apparatus may be required, as described further herein.

[0031] The method may further comprise a step of covering the upstand and gutter with a metal sheet prior to lifting the building structure onto the roof such that the oblique lower edge rests on a metal sheet covering the upstand. By covering the upstand in advance of installation, the installation time of the building structure may be reduced while maintaining good weatherproofing.

[0032] Further, the method may further comprise a step of tiling the pitched roof to partially cover the gutter prior to lifting the building structure onto the pitched roof. The method allowing for tiling the pitched roof before installation of the building structure can reduce overall installation time on building sites, as the order in which tasks must be completed is now less dictated by the installation of the building structure.

[0033] Brief Description of the Drawings

[0034] The present specification makes reference, by way of example only, to the accompanying Figures in which:

[0035] Figure 1 is a top-down view of part of a roof structure with a pitched roof having an upstand for receiving a building structure;

[0036] Figure 2 is a side view of a part of the roof structure of Figure 1 ;

[0037] Figure 3 is a cross-section of the upstand and part of pitched roof;

[0038] Figure 4 is a schematic of the installation of a dormer window on an upstand;;

[0039] Figure 5 is a perspective view of a hollow body with a lifting bar;

[0040] Figure 6 is a perspective view of a roof element of a dormer window with a plurality of removable loops and attached lifting straps;

[0041] Figure 7 is a cross-sectional view of the roof structure of Figure 2 with a dormer window installed;

[0042] Figure 8 is a further cross-sectional view of an installed dormer window with a vented soffit; and

[0043] Figure 9 is a perspective view of a roof element with a metal roof element covering.

[0044] 17683793 MDN MDNDetailed Description

[0045] The drawings show a dormer window and its installation on a pitched roof. Although the detailed description makes reference to a dormer window, the description is equally applicable to similar building structures for installation on a pitched roof, such as chimneys, dovecotes, ventilation louvres and the like.

[0046] The building structure in the Figures is a building structure 1 formed of at least two separable parts (a hollow body 402 and a roof element 602).

[0047] A pitched roof 100, forming part of a roof structure 10, prior to installation of a building structure 1 is shown in Figure 1. The arrow 114 denotes the direction of the roof pitch; in other words, the arrow 114 is pointing towards the top of the pitched roof 100. An upstand 102 is installed on part of the pitched roof 100 around opening 104. The upstand comprises a bottom edge 108 and two side edges 110. In the embodiment of Figure 1, the bottom edge 108 is particularly a dormer apron upstand. The upstand protrudes above the level of the roof joists 304 as shown in Figures 2 and 3.

[0048] In the embodiments of Figures 1 and 2, the upstand further comprises a top surface 105, wherein the top surface 105 is formed by oblique end faces 202 of the two side edges 110. In alternative embodiments, the top surface 105 may be formed by a separate structural piece, such as a piece of timber which spans across the upstand 102, in a manner analogous to the bottom edge 108 shown in Figure 1.

[0049] A gutter 106 which is recessed relative to the upstand 102 extends along the exterior of the side edges 110, between the side edges 110 and runner battens 112. In the embodiment of Figure 3, the gutter 106 is situated between joists 304 which form part of the pitched roof 100, such that the gutter 106 is aligned with the top of the joists 304. The gutter 106 is supported by gutter substrate supporting timbers 308 which are attached to the joists 304. The runner batten 112 extends above the gutter 106. The runner batten 112 may extend above the gutter 106 by at least 25 mm. The height of the runner batter 112 above the gutter 106 may depend on the pitched roof 100 covering. The elevation of the upstand 102 above the gutter 106 may be between 150 - 400 mm, and more preferably between 250 -300 mm. The upstand 102 may be timber and more particularly constructed from 2 x4 structural timber.

[0050] 17683793 MDN MDNThe gutter 106 may have a width between the exterior of the side edge 110 and the runner batten 112 in the range 150 - 300 mm, and more preferably from 200 - 250 mm. In particular, the gutter 106 may have a width of 230 mm. The dimensions of the opening 104 are determined by the dimensions of the building structure 1 to be installed; for a dormer window, the width of the opening may be between 1 m and 3 m; for a chimney, the width of the opening may be between 30 cm and 100 cm.

[0051] Figure 3 shows a cross-section of a side edge 110 of the upstand 102, in which the gutter 106 is at the level of the pitched roof 100, but below the level of the runner batten 112.

[0052] The gutter 106 and the side edge 110 shown in Figure 3 have been clad in a metal cladding 302. The metal cladding 302 extends up and over the runner batten 112 on the exterior side of the gutter 106.

[0053] The upstand 102 and / or the whole pitched roof 100 may be clad in metal, such as lead, zinc, copper, aluminium, or stainless steel. Tiles 702 may be installed above the metal cladding 302 on the pitched roof 100 prior to the installation of the building structure 1. The tiles 702 may be installed to partially cover the gutter 106.

[0054] The first aspect of the present invention provides a building structure 1 which is separable, comprising a hollow body 402 and a roof element 602, for installation on a pitched roof 100, such as that described above. The hollow body 402 has an interior which forms part of the inside of a finished building in use; in the examples shown in the Figures, the hollow body 402 is part of a dormer window.

[0055] The roof element 602 is configured to attach to the hollow body so as to create a closed or generally closed structure (notwithstanding any window or ventilation openings). In the example shown in Figure 6, the roof element is a flat roof for the hollow body of Figure 5, which together form a dormer window. Other combinations of hollow bodies 402 and roof elements 602 are possible, such as a hollow body 402 being a chimney stack and a roof element 602 being the complementary chimney flaunching and chimney pots. Other building structures which may be possible include ventilation louvres, dovecotes and the like.

[0056] 17683793 MDN MDNA hollow body 402 of a building structure 1 being lowered onto an upstand 102 is shown in Figure 4. The hollow body 402 has metal cladding 302. The metal cladding 302 extends beyond a front edge 404 of the hollow body 402 to partially cover the upstand 102. There is preferably a gap between the metal cladding 302 of the building structure 1 and the upstand 102; this is preferably between 2 and 25 mm, and more preferably around 10 mm. The oblique lower edge 406 of the hollow body 402 is not covered in metal. The bottom edge 108 of the upstand 102 is covered in a clipped metal apron 408. The lower oblique edge 406 of the hollow body 402 is designed to be contiguous with the upstand 102 and rests on the upstand 102 once installed.

[0057] The hollow body 402 may be lowered onto an upstand 102 with a crane.

[0058] The hollow body 402 has a lifting point 502 which comprises a removable bar 504 spanning an interior 506 of the hollow body 402. The removable bar 504 comprises eyelets 508 for attaching straps 510 connected to a crane for installation; however alternative embodiments in which straps are tied around the removable bar 504 directly are also possible. The removable bar 504 may be reusable between different building structures 1.

[0059] In particular, the removable bar 504 is a solid bar with eye points at each end, wherein the eye points are bolted to the hollow body 402. The removable bar 504 is then removed after installation by removing the bolts which secure the removable bar 504. The bolts for securing the removable bar 504 may be installed at a marked balance position on the hollow body 402, wherein the marked balance position is calculated prior to lifting the hollow body 402 for insertion such that the hollow body 402 remains at the correct orientation during lifting.

[0060] The hollow body 402 shown in Figure 5 also has a temporary supporting beam 512 spanning the interior 506 of the hollow body 402 for ensuring the rigidity of the structure during installation, and providing a contact point for workers positioning the hollow body 402 on the pitched roof 100. The temporary supporting beam 512 may be made of timber, and more particularly may be a 4 x 2 structural timber piece. Both the removable bar 504 and the temporary supporting beam 512 are removed following installation of the hollow body 402.

[0061] 17683793 MDN MDNThe temporary supporting beam 512 may be parallel to the removable bar 504, or alternatively, may be a cross-brace. The removable bar 504 is preferably closer to the upper edge 514 of the hollow body 402 than the oblique lower edge 406 and is further preferably perpendicular to the upper edge 514. The position of the removable bar 504 may be chosen to maintain the building structure 1 in the correct orientation for it to be lowered onto an upstand 102 in the pitched roof 100; this may mean that the position of the removable bar 504 is different depending on the metal coating the hollow body 402.

[0062] As an alternative to the embodiment shown in Figure 5, the temporary supporting beam 512 may be replaced with or supplemented by an additional lifting point 502. The additional lifting point 502 may be configured such that the attachment points of straps 510 to the hollow body 402 form a triangle, which may aid stability in the lowering operation. In particular, this may be a configuration in which the temporary supporting beam 512 is replaced with an additional lifting point 502, and an additional removable bar 504.

[0063] The hollow body 402 may be fixed to the upstand 102 through at least one fixing mechanism 704, such as nails 705 or screws. At least one of the hollow body 402 and / or pitched roof 100 to which the hollow body 402 is to be attached may comprise a fixing mechanism 704 for attaching the hollow body 402 to the pitched roof 100. Preferably, the pitched roof 100 comprises an upstand 102 for receiving the hollow body 402 and at least one of the hollow body 402 and / or upstand 102 to which the hollow body 402 is to be attached may comprise a fixing mechanism 704 for attaching the hollow body 402 to the pitched roof 100. The fixing mechanism 704 may attach the hollow body 402 to the upstand 102 through the top surface 105, a bottom edge 108, and / or side edges 110 of the upstand 102. In particular, the fixing mechanism 704 may comprise drive bolts which are used to screw the hollow body 402 to the upstand 102.

[0064] The roof element 602 shown in Figure 6 is attachable to the hollow body 402 shown in Figure 5. When attached, the hollow body 402 and roof element 602 form a building structure 1 , in particular, a dormer window. As shown in the Figures, the roof element 602 comprises a surrounding portion 605, which in the embodiment shown comprises a fascia 606. The surrounding portion 605 may also comprise a soffit, such as the vented soffit 806. Preferably, when the roof element 602 is installed on the hollow body 402, the surrounding portion 605 surrounds the upper edge 514 of the hollow body 402 and a further portion of an outer wall of the hollow body 402.

[0065] 17683793 MDN MDNThe roof element 602 comprises a plurality of removable loops 604 for attaching lifting straps 510. In the embodiment of Figure 6, the removable loops 604 are eyebolts. The eyebolts may be thread into sockets on the corners of the fascia 606 of the roof element 602 to enable connection to lifting straps 510. The removable loops 604 are removed once the roof element 602 has been lowered onto the hollow body 402. The sockets into which the removable loops 604 are inserted may be covered with covering elements such as fascia covers so as not to be visible post-installation.

[0066] The roof element 602 is fixed to the hollow body 402 through an attachment mechanism 908. The attachment mechanism 908 may comprise drive bolts which are used to fix the roof element 602 to the hollow body 402.

[0067] In particular, the attachment mechanism 908 may be a screw or drive bolt which is inserted through the fascia 606 of the roof element 602, and further into the side of the hollow body 402, just below the upper edge 514. Where removable loops 604 are connected to the roof element 602 through sockets for lifting the roof element 602 into position, these same sockets may be used for connecting the roof element 602 to the hollow body 402 by inserting a connecting rod through the roof element 602 sockets into complementary sockets on the hollow body 402. Alternatively, the roof element 602 may be fixed to the hollow body 402 through other means, such as screwing or nailing down through the top face 608 of the roof element 602 into the upper edge 514 of the hollow body 402.

[0068] In any embodiment, the attachment mechanism 908, such as the screw or drive bolt is advantageously covered by a covering, such as a fascia covering such that it is not visible once the building structure 1 has been installed.

[0069] Additionally, the roof element 602 shown in Figure 9 has a metal roof element covering 902. This comprises an installed section 904, fixed to the roof element 602, leading to an attachment section 906 folded back over the installed section 904 and deployable, in use, to cover part of the pitched roof 100. The installed section 904 may be nailed to a timber frame of the roof element 402, for example, with an attachment section 906 rolled back or folded back over the roof element 402. As shown in Figure 9, the installed section 904 may be a separate piece of metal to that of the attachment section 906. In particular, in the Figure 9, the installed section 904 is fixed to an upper surface of the roof element 602, and

[0070] 17683793 MDN MDNthe attachment section is connected to a rear edge of the roof element 602 which contacts the pitched roof structure 10 when installed.

[0071] This enables the roof element 602 to be lowered onto the hollow body 402 without the attachment section 906 adversely interacting with the pitched roof structure 100 while remaining rapidly attachable to the pitched roof structure 10 without requiring additional metal cladding to be taken onto the pitched roof structure 10.

[0072] Once the roof element 602 has been lowered onto the hollow body 402, the installation of the metal roof element covering 902 may be quickly completed by deploying the attachment section 906 over the pitched roof 100 and attaching (such as by nailing) the metal roof element covering 902 to the pitched roof 100. This technique reduces the opportunity for metal theft and decreases the installation time of a building structure 1 having a metal roof element covering 902 on a pitched roof 100. In particular, as the metal roof element covering is pre-cut to size and quick to attach to the pitched roof 100, the need for skilled metal workers on site following installation is reduced.

[0073] Although the building structure 1 shown in the Figures is a dormer window having a flat roof element 602, the present invention allows for various roof shapes, including curved roofs and apex roofs. The same applies for alternative building structures 1 according to the first aspect such as chimneys, ventilation louvres, dovecotes and the like.

[0074] Additional advantages of building structures 1 installable on an upstand 102 is that they may be vented, thereby reducing condensation and corrosion. Figure 7 illustrates a vented embodiment of a hollow body 402 according to the present disclosure. A double wall structure defines a second void 706. The width of the second void 706 may be from 25 mm to 50 mm. The outermost wall 708 of the double wall structure does not extend fully down to the gutter 106, but instead extend partially down towards the gutter 106, leaving a hollow body cheek vent 710 for encouraging airflow, indicated by arrow 712, through the double wall structure. The outermost wall 708 of the double wall may be metal cladding 302, preferably lead cladding.

[0075] The roof element 602 may additionally or alternatively have a double wall structure which defines a first void 802, and may be vented as shown in Figure 8. Figure 8 shows a further cross-sectional view of an installed building structure 1 with a roof element vent 804. In this

[0076] 17683793 MDN MDNembodiment, the roof element vent 804 is a vented soffit 806. The roof element vent 804 encourages airflow through the first void 802. Exemplary airflow paths through the building structure are illustrated with arrows 808. Preferably, the roof element vent 804 is present on both of the sides of the roof element 602 which correspond to the side edges 110 of the upstand 102 to enhance the airflow. There may be a vented soffit 806 on the side of the roof element 602 which corresponds to the bottom edge 108 of the upstand 102.

[0077] Preferably, at or near the roof element vent 804 and / or the hollow body cheek vent 710, insect mesh may be provided to prevent the entry of insects or other animals into the first and second voids 802, 704.

[0078] A method for installing the building structure 1 (as described above) on the pitched roof 100 is now provided.

[0079] In order to prepare the roof, upstand 102 is formed on the pitched roof 100 around the opening 104. The upstand 102 may be fixed to a timber frame of the pitched roof 100 using nails for example.

[0080] The gutter 106 is installed by fixing a piece of plywood between joists 304, as shown in Figure 3. Although described herein as plywood, other appropriate materials may be used as a gutter substrate between joists 304. The installation of the gutter 106 may involve attaching the gutter substrate supporting timbers 308 to the joists 304 to provide support for the gutter substrate.

[0081] A runner batten 112 is attached to joist 304 at a suitable distance from the upstand 102 to define the outer edges of the gutter 106. Preferably, the distance from the inner edge of the runner batter 112 to an outer face of the upstand 102 is at least 230 mm. The gutter 106 is then covered with the metal cladding 302, which also covers the upstand 102 and runner batten 112.

[0082] The pitched roof 100 is tiled prior to lifting the hollow body 402 onto the upstand 102, and the tiles 702 partially cover the gutter as shown in Figure 7. This tiling may also be performed following the lifting of the hollow body 402 onto the pitched roof 100, but tiling in advance of this step may be advantageous for efficient construction.

[0083] 17683793 MDN MDNThe hollow body 402 is then lifted onto the pitched roof 100 such that the oblique lower edge 406 contacts the upstand 102. The lifting may be done by attaching straps connected to a crane hook to a removable bar 504 spanning an interior 506 of the hollow body 402, and the hollow body 402 may be reinforced with a temporary supporting beam 512 during lifting.

[0084] The hollow body 402 is then fixed to the upstand 102, and any removable bar 504 or temporary supporting beams 512 in the hollow body 402 may be removed. The hollow body 402 may be fixed to the upstand 102 using screws, nails, or other fixing mechanisms known in the art.

[0085] The roof element 602 is then lifted onto the hollow body 402 such that the upper edge 514 of the hollow body 402 is covered. The roof element 402 may be lifted using a plurality of removable loops 604 to which lifting straps 510 are attached. Once the roof element 602 is on the hollow body 402, these removable loops 604 (if used) may be removed.

[0086] Both the hollow body 402 and / or the roof element 602 may be lifted onto the roof with a crane, and lowered into position.

[0087] Preferably, the surrounding portion 605 of the roof element 602 surrounds the upper edge 514 of the hollow body 402. If a separable building structure 1 is being installed, the roof element 602 is then fixed to the hollow body 402; this may be through screws. The screws may be inserted through the sockets in which the removable loops 604 were inserted. The sockets may then be covered so as not to be visible post-installation.

[0088] The method described above may also be adapted for the installation of a single-piece building structure, in which the hollow body 402 and the roof element 602 are attached together prior to being lifted onto the pitched roof 100, such as during prefabrication offsite. In this case, many of the advantages of the installation method described above for a separable building structure 1 can be retained; the method requires the installation of a gutter 106 and upstand 102 prior to lifting the building structure onto the upstand 102 such that the oblique lower edge 406 contacts the upstand. This achieves the corresponding advantages of the method for installing a separable building structure 1; namely the prefabrication and pre-installation of a gutter reducing overall installation time of a building structure.

[0089] 17683793 MDN MDNA single-piece building structure may require a modified lifting apparatus, as the singlepiece building structure has a roof element 602 pre-attached to the hollow body 402 which would prevent the use of a removable 504 bar as described above. In this case, one such modified lifting apparatus may be the use of a plurality of removable loops 604 thread into sockets on the fascia 606 of a dormer window (or similar structure) prefabricated as a single piece. Alternatively, and particularly for dormer window single piece building structures, a single-piece building structure may be lifted using a device similar to a pallet lifting device attached to a crane. Such a pallet lifting device comprises a plurality of forks which contain a right-angled bend, as are well-known in the art. The forks may be inserted into a gap at the front of the dormer window single-piece building structure which defines the opening for a window. The load is then supported by multiple forks as the forks contact both an upper edge of the gap and an interior face of the roof element 602 of the dormer window single-piece building structure.

[0090] The single-piece building structure may retain compatible advantages of the separable building structure 1 described above. For instance, the hollow body 402 and roof element 602 may have the ventilation features (including the hollow body cheek vent and roof element vents) described above. Similarly, the roof element of a single-piece building structure may similarly have a metal roof element covering 902 as described above, wherein the folded back attachment section 906 allows the single-piece building structure to be lowered onto the upstand 102 without the attachment section 906 interacting with the pitched roof structure 100.

[0091] 17683793 MDN MDN

Claims

CLAIMS:

1. A building structure for attachment to a pitched roof, the building structure comprising:a hollow body with an oblique lower edge for attachment to the pitched roof and an upper edge opposite to and diverging from the lower edge;a roof element attachable to the upper edge of the hollow body; and an attachment mechanism on at least one of the hollow body and / or roof element;wherein the oblique lower edge of the hollow body is fixable to the pitched roof, and the roof element is lowerable onto the upper edge of the hollow body and attachable to the hollow body via the attachment mechanism.

2. A building structure according to claim 1, wherein the hollow body comprises a lifting point for a crane.

3. A building structure according to claim 2, wherein the lifting point comprises a bar spanning an interior of the hollow body.

4. A building structure according to claim 3, further comprising a temporary supporting beam spanning the interior of the hollow body.

5. A building structure according to any preceding claim wherein the roof element comprises a plurality of removable loops for attaching lifting straps.

6. A building structure according to any preceding claim wherein the roof element further comprises a surrounding portion which surrounds at least part of the hollow body when the roof element is attached to the hollow body.

7. A building structure according to claim 6, wherein the attachment mechanism attaches the roof element to the hollow body through the surrounding portion.

8. A building structure according to either of claims 6 or 7, wherein the roof element comprises a double wall structure creating a first void within the roof element for allowing air flow.17683793 MDN MDN9. A building structure according to claim 8, wherein the surrounding portion further comprises a roof element vent for encouraging airflow through the first void.

10. A building structure according to any preceding claim wherein the hollow body comprises a double wall structure creating a second void around the hollow body.

11. A building structure according to any preceding claim wherein the building structure has a metal covering.

12. A building structure according to claim 11, wherein the metal is lead, copper, zinc, aluminium, or steel.

13. A building structure according to any preceding claim, further comprising a metal roof element covering, wherein the metal roof element covering comprises an installed section, fixed to the roof element, leading to an attachment section folded back over the installed section and deployable, in use, to cover the pitched roof.

14. A building structure according to any preceding claim, wherein the building structure is a dormer window.

15. A roof structure comprising a building structure according to any preceding claim and a pitched roof to which the building structure is attached.

16. A roof structure according to claim 15, wherein the pitched roof further comprises an upstand surrounding an opening, the building structure being received on the upstand.

17. A roof structure according to claim 16 wherein the upstand is covered in a metal sheet.

18. A roof structure according to either of claims 16 or 17, further comprising a gutter which is recessed relative to the upstand and extends around at least a portion of the oblique lower edge of the building structure.17683793 MDN MDN19. A roof structure according to claim 18, wherein the building structure comprises a double wall structure, and an outermost wall extends down below the upstand towards the gutter.

20. A method for installing a building structure on a pitched roof comprising:creating an upstand on the pitched roof around an opening;prior to lifting the building structure onto the pitched roof, creating a gutter on the pitched roof adjacent to the upstand, such that the gutter is on the opposite side of the upstand from the opening;lifting a building structure onto the roof, the building structure comprising: a hollow body with an oblique lower edge for attachment to the pitched roof and an upper edge opposite the lower edge; anda roof element on the upper edge of the body,such that the oblique lower edge of the building structure contacts the upstand; andfixing the building structure to the upstand.

21. A method according to claim 20, further comprising a step of:covering the upstand and gutter with a metal sheet prior to lifting the building structure onto the roof such that the oblique lower edge rests on a metal sheet covering the upstand.

22. A method according to claim 21, further comprising a step of:tiling the pitched roof to partially cover the gutter prior to lifting the building structure onto the pitched roof.

23. A method according to any of claims 21 to 22 wherein the metal sheet is a lead sheet.

24. A method according to any of claims 20 to 23 wherein the building structure is lifted onto the roof in at least two parts:the hollow body with an oblique lower edge for attachment to the pitched roof and an upper edge opposite the lower edge; andthe roof element attachable to the upper edge of the body;17683793 MDN MDNthe building structure further comprising an attachment mechanism on at least one of the hollow body and / or roof element;wherein the oblique lower edge of the hollow body is fixed to the pitched roof, and the roof element is lowered onto the upper edge of the hollow body and attached to the hollow body via the attachment mechanism.

25. A method according to any of claims 20 to 24 wherein the building structure is a dormer window.17683793 MDN MDN

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