GB2336390A

GB2336390A - Roofing framework

Info

Publication number: GB2336390A
Application number: GB9907906A
Authority: GB
Inventors: Richard Joseph Oldroyd
Original assignee: DIBSA
Current assignee: DIBSA
Priority date: 1998-04-17
Filing date: 1999-04-08
Publication date: 1999-10-20
Anticipated expiration: 2019-04-08
Also published as: GB9907906D0; GB2336390B

Abstract

A roofing framework is provided for use in the conversion of an existing flat or undulating roof 1 into a pitched roof. The framework comprises a plurality of base members 2 for attachment to the existing roof 1, a plurality of props 3 of graded height and a plurality of rafter members 4. The rafter members 4, props 3 and base members 2 define a plurality of tilt frames 5 spaced across the flat roof 1 for supporting a roofing covering. The props 3 are adjustable in height to facilitate of adjustment of the roof pitch. In a further embodiment, hip and valley support assemblies (figures 8 and 11) are provided comprising at least one prop connected via a rotational bracket to a base member.

Description

1 A ROOFING FRAMEWORK 2336390 The present invention relates to a roofing

framework and in particular to a roofing framework for converting a flat or undulating roof into a pitched roof.

Flat roofed building structures have the disadvantage that they are prone to leak. Often the only way in which such leaks can be rectified permanently is to convert the flat roof into a pitched roof.

The object of the present invention is therefore the provision of a roofing framework which can be used for such a conversion.

According to the present invention there is provided a roofing framework for use in the conversion of an existing flat or undulating roof into a pitched roof comprising a plurality of base members for attachment to the existing roof, a plurality of props of graded height for connection at spaced intervals to the base members, and a plurality of rafter members for attachment to and between adjacent props to define with the props and the base members a plurality of tilt frames spaced across the flat roof for supporting a roofing covering, the props being of adjustable height whereby adjustment of the pitch of the rafter members.and thereby that of the pitched roof is facilitated.

Preferably, the props are each of e.onstruction.

telescopic Preferably also, adjacent rafter members are lap jointed to one another over the props.

2 Advantageously, each prop comprises a sleeve adapted for attachment to a base member and an insert adapted for attachment directly or indirectly to a rafter member, the insert being slidable within and attachable to the sleeve to enable the length of the prop to be extended or shortened.

Preferably also, the sleeve and the insert are both of channel section.

Preferably also, the insert of at least one prop frictionally engages with the sleeve whereby the insert can be frictionally retained at a predetermined height after being when pulled upwardly to project out of the sleeve.

Preferably also, one side of the insert is splayed outwardly and bears against the inner surface of the sleeve in order to create said frictional engagement.

Preferably, the framework also comprises a hip or valley support assembly comprising at least one prop connected at one end via its sleeve to a rotational bracket for attachment to a base member.

Preferably also, the insert of said one at least one prop is connected at the other end of the prop to at least one rotatably mounted bracket.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:- Fig. 1 is a side view of a roofing framework according to the invention shown attached to a flat roof, which is shown in section; 3 Fig. 2 is a perspective view from above of the framework shown in Fig. 1; Figs. 3a and 3b are diagrams showing the cross sectional profile of a sleeve bracket and an internal leg respectively; Fig. 4 is a diagram showing the cross-sectional profile of a purlin; and Fig. 5 is a diagram showing the cross-sectional profile of a base member or a rafter member.

Fig. 6 is a plan view of a roofing framework according to the invention which is adapted to provide a ridged pitched roof defining hips and a valley; Fig. 7 is a transverse sectional view, but to a reduced scale, along the line VII-VII of Fig. 6; Fig. 8 is a side diagrammatic view of a hip support assembly when attached to an existing flat roof, which is shown in cross-section; Fig. 9 is a cross-sectional diagrammatic view of an adjustable height hip prop; Figs. 10a and 10b are diagrams showing the crosssectional profile of a sleeve and an insert forming two members of the hip prop shown in Fig. 9; and Fig 11 is a side diagrammatic view of a valley support assembly.

4 As shown in Figs 1 and 2, a roofing framework according to the invention for converting a flat or undulating roof 1 into a pitched roof comprises a plurality of base members 2 to which are attached a plurality of props 3 of graded height. A plurality of rafter members 4 are attached to and between adjacent props 3 to def ine with the props 3 and the base members 2 a plurality of tilt frames 5 spaced across the flat roof 1. Purlins 6 are then attached between the rafter members 4 of adjacent tilt frames 5. A roofing covering (not shown) can then be attached to the rafter members 4 and purlins 6 in a conventional fashion.

Preferably, all of the components of the framework are made from a lightweight galvanised steel. These components are preferably made in standardized sizes and lengths in order that any particular size or shape of framework can be erected on site.

As shown in Fig. 5, the base members 2 have a 90' angle section and they are laid across the flat roof in parallel lines at right angles to the direction of the existing roof joists 7 of the flat roof 1.

It should be appreciated that in the present example the base members 2 are orientated in the same vertical planes as the rafter -members 4 so that the tilt frames 5 comprise substantially triangular frames. However, dependent on the direction of the roof joists 7, the orientation of the base members 2 may not be the same as that of the rafter members 4. In any event, the parallel lines made by the rafter members 4, and therefore the tilt frames 5, preferably have a spacing A which is approximately 1500 mm apart as shown in Fig. 2. However, in alternative but similar constructions, the spacing A may be arranged to be 120Omm, 1800 mm or 2000 mm apart.

The base members 2 are secured to the joists 7 with suitable fixings, which can be selected on site to suit the existing roof structure and which are screwed through the existing roof covering, which is left in place. Typically this covering comprises roofing felt or a similar flexible sheeting material. The base members 2 thus support the rest of the roofing framework and new roof covering, as will be described, the load being spread over the joists 7 of the existing roof. For this reason, the length of the base members 2 should be selected, for any particular roof, so that two or more joists 7 are spanned by a single base member as shown in Fig. 1. Usually, it will be sufficient to supply the base members 2 in 1000 mm lengths as roof joists 7 are normally spaced around 600 mm apart.

Along the edge of the roof 1 which will support the lower end of the new pitched roof a line 8 of base members 2 can be laid above and parallel to the end joist or a wall plate (not shown) which may lie therebeneath.

Once the base members 2 have been located in position, the props 3 are attached thereto. The lengths of the props 3 are graded along lines where the tilt frames 5 are to be constructed in order to clef ine the pitch of the new roof. Preferably, adjacent props 3 in each frame 5 have a spacing B which is approximately 1500 mm. To this end, the props 3 are provided in a range of lengths but each is also of telescopic construction in order that the exact length of prop 3 required can be provided for any particular job, adjustment of the pitch of the roof being thereby facilitated. The spacing B may also be adjusted in alternative but similar constructions to vary up to a maximum of 2000 mm.

6 Each prop 3 comprises a sleeve 9 which is adapted for attachment to a base member 2, and an insert 10 which is adapted for attachment to the rafter members 4. As shown in Figs. 3a and 3b, the sleeves 9 and inserts 10 are both of channel section with the inserts 10 being slidable within the sleeves 9. However, the edges 11 of the sleeves 9 are curved inwardly of the channel section and around the edges 12 of the inserts 10 in order that the inserts 10 are retained within the sleeves 9 except at their ends.

Each sleeve 9 is attached to one of the base members 2 in a vertical position by a pair of self-drilling, selftapping screws 13 which are screwed through the upright portion of the base member 2 and into the channel section of the sleeve 9. With the base members 2 extending in the direction shown in Figs 1 and 2, the screws 13 are screwed through the central face 14 of the sleeves 9. However, in cases where the base members 2 normally to those shown in Figs. 1 and 2, the screws 13 are screwed through one of the side faces of the sleeves 9. In both of these cases the sharp pointed tips of the screws 13 are safely enclosed within the sleeve 9. The inserts 10 are then secured within the sleeves 9 in a similar fashion by pairs of self-drilling, self-tapping screws 15. The inserts 10 are adapted to project upwardly out of the sleeves 9 in accordance with the length of prop 3 required. However, it is important for the rigidity of the framework as a whole that the overlap between the sleeve 9 and the insert 10 is sufficient. Therefore, the sleeves 9 are provided with at least two holes along their length through which the screws 15 must pass. In this way, although no similar holes are provided in the inserts 10 it is ensured that a sufficient overlap between the inserts 10 and the sleeves 9 is made. It will be appreciated in this regard, that with shorter props 3, the holes will be located relatively close together near one end of the sleeve 9, overlaps of 7 around 50 mm being sufficient. However, with longer props 3, the holes may be located closer to the middle and to one end of the sleeve 9 respectively, an overlap of around 150 mm being more appropriate.

After the props 3 have been located in position, the rafter members 4 are attached thereto. The rafter members 4 are lap jointed to one another and attached to and between adjacent props 3 at the desired roof slope to form the tilt frames 5.

The rafter members 4 have an identical crosssectional 90 angled profile to the base members 2, as shown in Fig. 5 and are laid over the props 3 so that a vertical portion 16 of the angled profile lies adjacent the central side 14 of the insert 10 and the other tilted portion 17 of the profile covers the end of the insert 10. One end of each rafter member 4 is provided with a pair of pre-drilled holes and this end of the member 4 is lapped over an adjacent member 4 above the insert 10. These holes are then used to locate self-drilling, self-tapping screws 18 which are screwed through the overlapping rafter members 4 and into the channel section of the inserts 10 to secure the members 4 in position, the sharp tips of the screws 16 again being enclosed by the props 3.

Once the rafter members 4 have been located in position, the purlins 6 are attached thereto along spaced lines at right angles to the rafter members 4 and spanning across adjacent tilt frames 5. The purlins 6 are of splayed channel section as shown in Fig. 4 and adjacent purlins 6 are lap jointed to one another over the rafter members 4. Holes are provided at each end of the purlins 6 and those of adjacent purlins 6 are aligned and used to locate self-drilling, self-tapping screws 19 which attach them to the tilted portions 18 of the rafter members 4. To 8 this end, therefore, the purlins 6 are preferably made approximately 1550 mm long to span between the tilt frames 5, which are spaced at 1500 mm intervals and to allow for a 25 mm overlap at each end. The holes for the screws 19 are therefore located within the 25 mm overlap at each end of the purlin 6. If the framework has the exemplary dimensions as proposed herein, then preferably the rows of purlins 6 down the tilt frames 5 have a spacing C which is preferably a maximum of 2000 mm.

A framework erected as aforesaid can then be covered with a suitable conventional roofing covering, which is attached to the purlins 6. The roof conversion can then be completed by the attachment of appropriate guttering to the structure.

It will be appreciated that the arrangement described above provides a pitched roof but not one comprising a ridged pitched roof defining hips or valleys. However, the framework can be readily adapted when required to provided these features as will now be described.

Shown in Figs. 6 and 7 are plan and transverse sectional views of a more sophisticated roofing framework 20 than that described above. This framework 20 comprises an L-shaped pitched roofing framework with ridges 21, hips 22 and a valley 23 at the angle of the L- shape.

As previously described with reference to Figs. 1 and 2, the framework 20 comprises a plurality of spaced parallel base members 2 which are attached to the existing roof deck 24 at right angles to the direction of the existing roof joists. Props 3 of graded height are attached to the base members 2, as before, and rafter members 4 are attached to and between adjacent props 3 to 9 define the tilt frames 5 spaced across the deck 24. Purlins 6 are then attached between the rafter members 4 of adjacent tilt frames 5.

The ridges 21 are formed at the apex 25 which is defined by two adjacent "back to back" tilt frames 5 along the junction of the two sloping sides of the frames 5 (see Fig.7). At the apex 25, the upper ends 26 of the sloping rafter members 4 on each side of the frame 5 lie adjacent to one another and may be joined by a screw (not shown). However, in addition the ends 26 are each supported by a prop 27, which props 27 therefore lie in close proximity on either side of the ridge 21, typically between 150 mm apart. Where the base members 2 run in a direction which is perpendicular to the line of the ridge 5, as shown in Fig. 7, the props 27 can be connected to the same base member 2. However, where the base members 2 lie parallel to the ridge 21, for example as is the case along the longer arm of the L-shaped roof shown in Fig. 6, then the same base member cannot support both props 27 and one or two base members 28, as shown in Fig. 6, may have to be specifically provided at a closer spacing than would otherwise be the case to which the props 27 can be respectively connected on either side of the ridge 21. Adjacent props 27 an either side of the ridge may also be tied together by means of cross- braces (not shown) located approximately 200 mm below the apex 25 in order to give further rigidity to the framework 20.

The hips 22 of the framework 20 are formed by using specially designed hip support assemblies 29 which are attached to the base members 2 at intervals along the line of the hips 22, wherever the projected line of the hip overlies a base member 2. These support assemblies will now be described in more detail with reference to Fig. 8.

Each hip support assembly 29 is connected to the underlying base member 2 by means of a rotational bracket 30 which enables the orientation of the assembly 29 to be varied and aligned as required according to the particular layout of the roofing framework 20. The bracket 30 comprises a short length of square section tube 31 which is attached to the base member 2 by means of selfdrilling, self-tapping screws which are drilled through the upright portion of the base member 2 into the tube 31 at the positions labelled 32. The square section tube 31 has similar dimensions to that of the base member 2 and fits neatly into the angle of the member as shown in Fig. 8. Attached to the top face of the square tube 31 by means of a rotational bolt 33 is an angle bracket 34. The square section tube 31 and the angle bracket 34 are pre-assembled with the rotational bolt 33 in order that after the tube 31 has been rigidly attached to the base member 2 the angle bracket 34 can be rotated and appropriately angled along the hip line. The angle bracket 34 is then secured to the tube 31 at this orientation by self drilling, self tapping screws at the positions labelled 35.

An adjustable height hip prop 36 is then attached to the bracket 34. Each hip prop 36 is of telescopic construction and comprises an outer sleeve 37, which is adapted for attachment to the angle bracket 34, and an insert 38, which is slidably located within the sleeve 37. As shown in Figs. 10a and 10b, the sleeve 37 and the insert 38 are both of channel section. However, one edge 39 of the sleeve 37 is curved inwardly of the channel section and around one edge 40 of the insert 38 in order that the insert 38 is retained within the sleeve 37 except at its ends. In addition, the side 41 of the insert 38 adjacent the edge 40 is splayed outwardly in order that it bears against the inner surface of the sleeve 37 in order to create sufficient friction to enable the insert 38 to 11 be pulled upwardly out of the sleeve 37 and be frictionally retained at this position. This facilitates height adjustment of the hip prop 36. Once an insert 38 has been pulled out of its sleeve 37 to project at the correct height, it is secured within the sleeve 37 by self-drilling, self- tapping screws (not shown) in a similar manner as for the props 3.

The upper end of each insert 38 is adapted to support L-he ends of the purlins 6 which terminate on the line of the hip 22. To this end, the hip prop 36 is pre-assembled by the provision of two inverted U-shaped brackets 42 which are attached respectively at each side of the upper projecting end of the insert 38 by means of a pivot bolt 43. Once the hip prop 36 has been suitably adjusted for height, the brackets 42 are adjusted to the correct angle for the roof slope and then fixed in this position by means of self-drilling, self-tapping screws (not shown) to the insert 38. When all the hip props 36 along the line of a hip 22 have been located in position and appropriately adjusted, two Z-section rafter members 43 are attached to each bracket 42 along each side respectively of the props 36. Thus, in this arrangement the inserts 38 indirectly support the specially shaped rafter members 43 via the brackets 42.

The rafter members 43 are attached to one of the side faces of the brackets 42 respectively by screws 44, their uppermost flanges 45 overlying the open top of each bracket 42. The lowermost flanges 46 of the members 43 thereby form two sloping shelves along the line of the hip 22, which support the ends of the purlins 6 which terminate along the both sides of the hip 22. The load of the hip 22 formed by the abutting purlins 6 on each side 12 of the hip 22 is therefore transferred via the adjustable brackets 42 directly to the single hip props 36 of each assembly 29 located therebeneath.

The purlins 6 are of splayed channel section as shown in Fig. 4 and their ends are attached to the lowermost flange 46 of the members 43 by means of self-drilling, self-tapping screws (not shown). The depth of the Ushaped brackets 42 and the Z-section rafter members 43 is arranged to be comparable with the height of the purlins 6 in order that the uppermost flange 45 of the members 43 also acts as an additional sloping purlin to which the final roof covering, for example the cut edges of roof sheeting, can be attached.

The valleys of a framework, such as the valley 23 of the framework 20 are formed by using valley support assemblies 47 which are attached to the base members 2 at intervals along the line of the valley 23, wherever the projected line of the valley 23 overlies a base member 2. These valley support assemblies 47 are similar but not identical to the hip support assemblies 29 and will now be described in more detail with reference to Fig. 11 wherein identical components of both assemblies 29, 47 have been given the same reference number.

The main difference between the two assemblies is that each hip assembly 29 comprises a single prop 36 whereas each valley assembly 47 comprises two spaced props 48 which are tied together in the finished framework 36 by means of an angle section brace 49.

As with the hip support assemblies 29, each prop 48 of a valley support assembly 47 is connected to an underlying base member 2 by means of a rotational bracket 30 which enables the orientation of the props 48 to be 13 varied and aligned as required according to the particular layout of the roofing framework. In this case, not only are the props 48 aligned along the line of the valley 23 but they must also be correctly spaced and aligned with regard to one another. The brackets 30 again comprise short lengths of square section tube 31 which are attached to the base member 2 and to which angle brackets 34 are attached, by means of rotational bolts 33. As before, after the tubes 31 have been rigidly attached to the base member 2 the angle brackets ' 23 are rotated and appropriately angled respectively along the line of the valley. The brackets 34 are then secured to the tube 31 at this orientation by self drilling, self tapping screws.

The two adjustable height valley props 48 of each assembly 47 are then attached respectively to the brackets 34. Each prop 48 is of similar construction to the props 36 described above and this construction will not be described again in detail here. However, only one U-shaped bracket 42 is attached to each insert 38. The props 48 of assembly 47 are orientated with regard to one another so that their brackets 42 project in opposite directions outwardly of the assembly along the line of the valley 23.

Once each prop 48 has been appropriately adjusted and secured at the correct height, the two props are tied together by means of the angle section brace 49. The braces 49 have a 90' angle section angle and they are orientated to define an inverted L-section, the vertical leg 50 of the L-section being rigidly attached to the projecting insert 38 of each prop 48 and the horizontal arm 51 of the L-section projecting outwardly from the props 48 and overlying the legs 50. In this way along the line of the valley 23, the arms 51 of each brace 49 form a series of spaced supports and are intended to be used to 14 support guttering (not shown) which is laid along the valley 23 between the two roof sections adjoining the valley.

The brackets 42 of the props 48 are adjusted to the correct angle for the roof slope and then fixed in this position by means of self-drilling, self-tapping screws (not shown) to the inserts 38 in the same way as in the hip props 36. When all the prop assemblies 47 along the line of the valley 23 have been located in position and appropriately adjusted, two Zsection rafter members 43 are attached to each bracket 42 along each side respectively of the assemblies 47, one member 43 being attached to each prop 48 as indicated in Fig. 11.

As with the hip props 36, the rafter members 43 are attached to the brackets 42 by screws 44 and their lowermost flanges 46 form two sloping shelves along the line of the valley 23 to support the ends of the purlins 6 which terminate along the both sides of the hip valley 23. The uppermost f lange 45 of the members 43 again acts as a sloping purlin to which the final roof covering, for example the cut edges of roof sheeting, can be attached after the guttering, mentioned above, has been secured in position.

It will be appreciated that the hip and valley support assemblies 29 and 47 have been designed with preassembled, rotational, height-adjustable props 36 and 48 respectively in order to facilitate the adjustment of the roof place angles at both locations. This construction has the advantage over the prior art that it removes the requirement to calculate the dihedral angles formed by the angular relationship between the two roof planes as they come together at the hips 22 and the valleys 23. It also allows rotation of the props 36 and 48 in relation to the base members 2 to which they are attached. Construction of a roofing framework is thereby greatly facilitated and can be easily adjusted on- site during the actual construction of the framework.

Whilst the construction of the props 36 and 48 has been specially designed for use with the hip and valley support assemblies 29 and 47 as described above, where the height of the props 36 and 48 may vary between 2 metres and 5 metres, it is possible to use props similar to those described with particular reference to Figs. 10a and 10b in place of the props 3 for lower pitched roofs.

16

Claims

1. A roofing framework for use in the conversion of an existing flat or undulating roof into a pitched roof comprising a plurality of base members for attachment to the existing roof, a plurality of props of graded height for connection at spaced intervals to the base members, and a plurality of rafter members for attachment to and between adjacent props to define with the props and the base members a plurality of tilt frames spaced across the flat roof for supporting a roofing covering, the props being of adjustable height whereby adjustment of the pitch of the rafter members and thereby that of the pitched roof is facilitated.

2. A framework as claimed in Claim 1, wherein the props are each of telescopic construction.

3. A framework as claimed in Claim 1 or Claim 2, wherein adjacent rafter members are lap jointed to one another over the props.

4. A framework as claimed in any one of Claims 1 to 3, wherein the base members and the rafter members are fabricated with a 90' angle-section.

5. A framework as claimed in any one of Claims 1 to 4, wherein at least one prop comprises a sleeve adapted for attachment to a base member and an insert adapted for attachment directly or indirectly to a rafter member, the insert being slidable within and attachable to the sleeve to enable the length of the prop to be extended or shortened.

6. A framework as claimed in Claim 5, wherein the sleeve and the insert are both of channel section.

17 7. A framework as claimed in Claim 5 or Claim 6, wherein the insert of said one prop frictionally engages with the sleeve whereby the insert can be frictionally retained at a predetermined height after being when pulled upwardly to project out of the sleeve.

8. A framework as claimed in Claim 7, wherein one side of the insert is splayed outwardly and bears against the inner surface of the sleeve 37 in order to create said frictional engagement.

9. A framework as claimed in any one of Claims 1 to 8, comprising a hip or valley support assembly comprising at least one prop connected at one end via its sleeve to a rotational bracket for attachment to a base member.

10. A framework as claimed in Claim 9, wherein the insert of said one at least one prop is connected at the other end of the prop to at least one rotatably mounted bracket for attachment to a rafter member.

11. A framework as claimed in Claim 10, wherein the support assembly comprises a hip support assembly with a single prop comprising an insert to the projecting end of which are rotatably mounted two brackets for attachment to rafter members.

12. A framework as claimed in Claim 11, wherein two Zsection rafter members are provided, each for connection between adjacent brackets of props forming part of hip support assemblies located along one side of the line of a hip defined by the framework.

18 13. A framework as claimed in Claim 10, wherein the support assembly comprises a valley support assembly comprising a pair of props comprising inserts to each of which is connected a rotatably mounted bracket and between which is connected a brace.

14. A framework as claimed in Claim 13, wherein a plurality of valley support assemblies are provided along the line of a valley defined by the framework and guttering is provided between along the valley located between the pair of props of each valley support assembly and is supported by the brace.

15. A framework as claimed in any one of Claims 1 to 'wherein purlins are provided for attachment between tne rafter members of adjacent tilt frames.

16. A framework as claimed in Claim 15, wherein the purlins are lap jointed to one another over the rafter members.

17. A framework as claimed in Claim 15 or Claim 16, wherein the purlins are of splayed channel section.

18. A roofing framework for use in the conversion of an existing flat or undulating roof into a pitched roof substantially as described herein with reference to any one of the accompanying drawings.