FR2969743A1 - Connecting element i.e. extension for frame to support solar panels on roof of building, has support rails fixed perpendicularly against longitudinal axis of rafters, and base secured to slide that is attached to rafters - Google Patents

Abstract

The connecting element i.e. extension (50) has rafters (11) placed over a cover (30) attached to ridges (20), where the ridges are perpendicular to the profile of a metal frame (10) that supports solar panels (40). Support rails (12) are fixed perpendicularly against a longitudinal axis of the rafters. A base is secured to a slide attached to the rafters, where the slide is adapted to slide on the base along the longitudinal axis of the rafters, and the slide is secured to the base in two orthogonal directions to the longitudinal axis of the rafters. An independent claim is also included for a frame comprising a clamp.

Description

1

The invention relates to an assembly element for a metal frame particularly adapted to support solar panels and more particularly such a framework with expansion compensation. The invention also relates to a frame using such an assembly element to compensate for expansion. The installation of solar panels, and especially photovoltaic solar panels, on the roof of a building must satisfy many sealing and mechanical resistance conditions (eg snow and wind), particularly when it comes to a large-scale installation for surfaces of several hundred square meters as is the case for industrial buildings or agricultural sheds, for example. In most cases, the roof of these buildings is made on a metal frame or, where appropriate wood, having at least a plurality of substantially horizontal parallel failures, starting with a failure at the top of the roof and ending with a sand pit fault at the bottom edge of the roof. The cover ensuring the watertightness of the roof is generally made by plates of ribbed sheet, galvanized steel and / or lacquered, sometimes called "steel tray", or even aluminum. These plates are generally in accordance with the DTU 40.35 and standardized dimensions, for example meeting the standards NF-P-34 401 (steel sheets) or NF-P-34 411 (aluminum sheets). The cover can also be made with "sandwich" plates comprising two sheet metal plates, at least one of which is ribbed separated by an insulator such as polyurethane foam or rockwool, for example. These plates are placed so that the ribs are in the direction of the slope of the roof, ie perpendicular to the purlins of the frame to improve the bending resistance of the cover. However, these cover plates are made from metal sheets of reduced thickness, generally a few tenths of a millimeter and are not able to directly support the weight of the solar panels. In addition, it was noted that the cover plates were likely to deform slightly when mounted on the purlins, which is likely to introduce subsequent dimensional errors annoying the accuracy of the fixing pattern of solar panels. In addition, depending on the construction on which the installation of photovoltaic solar panels is to be developed, the spacing of the purlins is not always adapted to the size of the panels, which prevents the weight and efforts to be taken up again. directly on the breakdowns. Thus, except for using much thicker and more expensive sheets, it is necessary to provide a support frame to support the weight of the panels and the constraints induced by the climatic conditions applied thereto.

Such a support frame includes in particular profiles, said support rails, usually extruded aluminum, in which are provided grooves adapted to accommodate clamps for fixing solar panels. The longitudinal axis of these rails is perpendicular to the slope of the roof and therefore parallel to the purlins. However, the gauge of the rails is conditioned by the size of the panels and does not always correspond to the spacing of the purlins. In order to prevent some of the support rails from resting directly on the cover plates, it is necessary to complete the supporting framework with profiles, called counter-chevrons, having a longitudinal axis perpendicular to the purlins, resting on the failures and serving back support of the support rails.

This support frame nevertheless has certain disadvantages, such as for example the problems of expansion of metal parts, particularly when they are large as is the case for rails and counter-chevrons. In order not to induce additional stress in the roof, it is necessary to take into account not only the problem of the expansion of the elements of the supporting framework, but also the reciprocal influences with the failures and the metal roofing of the building. In addition, due to the attachment of the support frame through the cover, the above-mentioned problems of expansion can also cause sealing problems of the cover when the fasteners undergo efforts and / or movements that can to reach a few millimeters (or even centimeters) during strong temperature variations over long lengths of counter-chevrons. It has also been found that when the solar panels are very close to the roof, as is the case when the support frame is directly fixed on it, the natural ventilation of the underside of the panels may be insufficient and cause problems of overheating or moisture stagnation particularly harmful for photovoltaic panels. In addition, the passage of the cables connecting the photovoltaic solar panels (or pipes in the case of solar panels) to treatment devices and / or use requires an available space on the underside of the panels. The invention therefore proposes an assembly element of a solar panel support frame which makes it possible to respond to the problems posed in the prior art, and in particular that makes it possible to compensate for the expansion of the elements of the framework. The invention also relates to an assembly element which makes it possible to fix and, where appropriate, to adjust the position of the support frame above the cover. The invention also relates to an assembly element 25 capable of adapting to all kinds of existing covers, ribbed sheets or where appropriate, corrugated sheets. The invention also extends to a support frame for solar panels economic and efficient, relatively independent of the underlying roof.

To do this, the invention relates to an assembly element, said riser, of a metal frame supporting solar panels on a roof, the frame comprising first sections, said counter-chevrons, adapted to be placed above a cover fixed on faults parallel to a failure, perpendicular to the purlins and second profiles, said support rails, fixed on said counter-chevrons perpendicularly to a longitudinal axis thereof, characterized in that said connecting element comprises at least a first portion, said base, adapted to be fixed to the failure and a second portion, said slide, adapted to be fixed to the counter-chevron, said slide being adapted to slide on the base along the longitudinal axis of the counter-chevron and to be secured to the base in the two directions orthogonal to this axis. Thus, it is sufficient to fix the counter-chevron at a single point, for example at the edge of the sewer of the roof and fix it on each slide of each riser over the entire height of the roof to compensate for the expansion of the counter- chevron along its axis while maintaining a solid attachment of the counter-chevron vis-à-vis the lifting forces or lateral pressures, for example due to wind on the structure of the solar panels and their supporting framework. In addition, the support efforts of the counter-rafter on the roof are fully taken over by the extensions, by the breakdowns of the roof without exerting effort on the cover. Advantageously and according to the invention, the base comprises a lower part, said foot, having a transverse profile adapted to fit a profile of a rib of the cover and receive at least one screw, said base screw, fixing the the base on a breakdown, through the cover. The base can thus be made to adapt to all kinds of existing covers, whether it is ribbed sheet with trapezoidal ribs of various sizes or even corrugated sheet. Advantageously, the inner part of the foot comprises a flat gasket adapted to be pressed between the foot and the top of the rib. This seal can be glued, overmoulded or fixed by any other means. Thus, drilling the top of the rib by the base screw does not present a risk of leakage between the foot and the rib. Advantageously and according to the invention, the base comprises an upper part, said head, comprising a sole covering the foot, extending parallel to the plane of the cover and having lateral flanges protruding from either side of the foot and adapted to guide the slide along the longitudinal axis thereof. Advantageously and according to the invention, the head of the base also comprises at least one flange, orthogonal to the sole and the longitudinal axis of the base and having a shape adapted to cooperate with an inner profile of the slide. Advantageously and according to the invention, the head and the foot of the base are two separate parts fixed to one another by the base screw. This allows, if necessary, to adjust the position of the head in a direction normal to the roof, by inserting wedges between the head and the foot. Alternatively and always according to the invention, the head and the foot of the base form a single piece. The base in one piece is then easier and more economical to ask. Advantageously and according to the invention, the slide is formed by a section section whose cross section has a central portion of shape adapted to fit below the counter-chevron and two folded side tabs adapted to pass under the side flanges of the head of the base. The slide is thus engaged on the base, the end of the lateral tabs folded under the flanges of the base preventing the slide to move upwardly in translation, in a direction normal to the plane of the roof. The lateral tabs passing on either side of the flanges of the base also prevent lateral translations. The movements of the slide are thus limited to a translation along the longitudinal axis thereof. Advantageously, the slide comprises, in the vicinity of one of its ends, a stop projecting towards the inside of the slide 6

and adapted to cooperate with a flange of the base. This stop temporarily immobilizes the slide on the base during assembly. Advantageously and according to the invention, the slide is made integral with the counter-chevron by at least one screw, said slide screw, passing through the counter-chevron and the slide and whose part of the body projecting inside the slide serves as abutment in translation to limit the sliding of the counter-chevron relative to the base. The counter-chevron is thus fixed to the slide and can move only along its longitudinal axis. It is therefore maintained in position against the forces of lifting or lateral displacement that may be exerted on the support frame. In addition, the slide can also serve as a connecting piece between two profiles if the length required for the counter-chevron exceeds the standard length of the profile. The invention also extends to a metal support frame of solar panels, in particular photovoltaic, adapted to be mounted on a roof above a cover fixed on failures parallel to a failure, the type comprising first sections, said counter-chevrons, adapted to be placed perpendicular to the purlins and second profiles, said support rails, fixed on said counter-chevrons perpendicular to the longitudinal axis thereof, characterized in that the counter-chevrons are fixed to the purlins, over the cover, by means of assembly elements, said extensions, comprising at least a first part, said base, fixed to the failure and a second part, said slide, attached to the counter-chevron, said slide being adapted to slide on the base along a longitudinal axis of the counter-chevron and to be secured to the base in the two directions orthogonal to this axis.

Advantageously and according to the invention, each counter-chevron has a transverse cross section with a trapezoidal central portion bordered on either side by two flat wings parallel to the longitudinal axis of the counter-chevron. The flat wings of the counter-chevron reinforce its rigidity in torsion and allow, if necessary, to fix pipes or electrical cables coming out of the panels in the direction of the slope of the roof. 7

Advantageously and according to the invention, each counter-chevron carries, at regular intervals along its longitudinal axis, stirrups adapted to receive and guide the support rails with a degree of freedom in translation along the longitudinal axis of the rails. In this way, the expansion of the support rails is also compensated and the support frame is not subjected to stresses likely to damage it. The invention also relates to an assembly element and a support frame for solar panels characterized in combination by all or some of the characteristics mentioned above or below.

Other objects, features and advantages of the invention will become apparent from the following description and the appended drawings in which: FIG. 1 represents a partial view of a roof comprising a solar panel support frame in accordance with FIG. the invention, - Figure 2 is a section of a riser according to the invention by a plane orthogonal to its longitudinal axis; - Figure 3 is a longitudinal section through a vertical plane of a riser according to the invention; - Figures 4, 5 and 6 are exemplary embodiments of the base 20 of a riser according to the invention. The roof 1 shown in Figure 1 is an example of an industrial building roof, such as a shed for example. It is conventionally constituted by a blanket 30 of ribbed sheets 31 placed and fixed on metal purlins extending perpendicularly to the slope of the roof. In the rest of the text, the terms "longitudinal" are used to define the axes in a reference frame attached to the roof, for a direction extending in the direction of the slope of the roof, "lateral" for an orthogonal direction. to the previous, in the plane of the roof and "normal" for a direction orthogonal to the plane of the roof. In order to simplify the description, these terms are also used to define the orientation of elements or parts 2969743 s

elements with reference to the position they occupy relative to the roof without this being considered as a limitation to the assembled element on the roof. The steel or aluminum sheets constituting the cover 5 have a reduced thickness of a few tenths of a millimeter to limit the weight of the cover and to minimize the cost thereof. In order to give them sufficient rigidity not to bend over the span between the purlins 20, the ribbed plates 31 comprise at regular intervals ribs 32 extending parallel to the slope of the roof. These ribs 32 generally have a trapezoidal profile obtained by folding the sheet according to a standardized profile. If the cover 30 is capable of sealing the building, it is not rigid enough to carry the additional weight represented by a solar panel installation 40 on the roof. The cover 30 is thus reinforced by a support structure 10 for supporting the solar panels 40. This framework 10 comprises first sections, called counter-chevrons 11, installed in the direction of the slope of the roof and second sections, said support rails 12. , placed orthogonally against the chevrons 11 and carried by them. The solar panels 40 are fixed, generally by clamping, on the support rails 12.

Counter-chevrons 11 are made from a metal profile, preferably galvanized steel, whose cross section profile and thickness to ensure a flexural strength adapted to the weight to bear. By way of example, the counter-chevrons can be made from a section comprising a central part, called body 110, of trapezoidal cross-section (FIG. 2) extended on either side by plane parallel wings 111 (FIG. to the axis of the counter-chevron and extending towards the outside of the body. For a given section, the number and spacing of the counter-rafters are calculated according to the rules of construction (eg snow and wind rules and / or other standards) applicable to the building on which the installation of solar panels is to be carried out. .

Each counter-chevron 11 bears directly on the purlins 20 through the cover 30, preferably in line with the ribs 32 so as to maintain the tightness of the cover, by so-called assembly elements 50. rafters 11 are generally fixed at the bottom of the slope, on the sand pit fault, the extensions 50 ensure a maintenance against-rafters on other failures in the direction normal to the roof, to support the weight of the installation in one direction and fight against any lifting of the frame (in case of wind for example) in the other direction. The extensions 50 also provide lateral support against the chevrons.

The extensions 50 are particularly adapted to allow the compensation of the expansion of the counter-chevrons in the longitudinal direction. Indeed, given the length of the counter-rafters that can reach several tens of meters, and temperature differences that can reach several tens of degrees, a rigid attachment of them on the purlins could introduce a warping of the frame due to the expansion of the counter-rafters. To this end, the extensions 50 comprise a first part, said base 520 adapted to be fixed on a fault 20 by means of at least one base screw 528 and a second so-called slide portion 510, adapted to be fixed against the chevron 11 by at least one slide screw 514 and to slide on the base 520 along the longitudinal axis of the counter-chevron. The base 520 comprises a lower part or foot 525 whose cross section has a profile adapted to fit the profile of the rib 32. In this case, for a ribbed steel sheet 31 having trapezoidal ribs 32, the foot 525 comprises two flanks 527 and a base 526 forming a homothetic profile of that of the rib 32. The foot 525 also comprises a flat 529 seal, for example EPDM, extending on the base 526 and optionally on a portion of the flanks 527 facing the rib 32. The seal 529 is preferably bonded at the factory to the base but could also be fixed in any other manner known to those skilled in the art, for example by overmolding or 2969743 io

other mechanical fixing means such as mechanical jamming, engagement of tongues in appropriate slots, etc. Of course, the foot 525 can be adapted to other cover plate profiles. For example, for a corrugated sheet having sinusoidal corrugations, the foot 525 may be formed in the same waveform to fit a peak of the sheet profile. The base 520 also comprises an upper part or head 521 comprising a sole 522 covering the foot 525. In the case where the base 520 is formed of two parts (head 521 and foot 525) separated as shown in FIG. 522 sole is parallel to the base 526 and fixed thereto by means of the base screw 528 during attachment of the base on the tip, which allows, if necessary, to adjust the height of the plane the sole 522 in a direction normal to the roof plane by inserting shims of the desired thickness between the base 526 and the sole 522. Alternatively, the base 520 may be formed in one piece as in the examples shown in Figure 2, 5 and 6. In this case, the sole 522 is partially confused with the base 526 of the foot. In all cases, the sole 522 has flanges 523 projecting laterally on either side of the foot and at least one flange 524 orthogonal to the sole 522 and to the longitudinal axis of the base. This flange 524 has a shape corresponding to the inner profile of the slide 510 and serves, as described below, guide and stop for the slide. When the base 520 is made in one piece, the flanges 523 may be formed by a fold of the sidewalls 527 of the foot which are folded flat 25 under the plane of the sole 522 and then bent at the angle suitable for matching the flanks of the rib 32 as shown in FIG. 5. Alternatively, the flanks 527 can be directly folded at the appropriate angle, but only over a fraction of the length of the flange 522, leaving two flange portions 522 with flanges 30 remaining. 523 protruding from both sides of the base 526.

The base 520, whether in one or more parts, is preferably made of sheet steel with a thickness of 2 to 3 mm, preferably 2.5 mm, galvanized or protected against corrosion by another means. The length of the base, along the axis of the rib, is between 70 and 150 mm, for example 130 mm in the example of a base according to Figure 6 (flanges 523 separated by flanks 527). The base 520 cooperates with a slide 510 which is formed of a section section, also preferably made of steel sheet thickness of 2 to 3 mm (preferably 2.5 mm), protected against corrosion by appropriate treatment, such as galvanizing, plasticizing, etc. The slide 510 has a length greater than the length of the base, for example between 100 and 200 mm, and preferably of the order of 180 mm to cooperate with a base according to Figure 6 above. The slide 510 has a cross section orthogonal to the common longitudinal axis of the slide and against-chevron having a central portion 511 of shape and dimensions adapted to allow this central portion to engage below the counter-chevron 11 In the example shown, the central part 511 has a trapezoidal shape homothetic of the trapezoidal shape of the inner part of the body 110 of the counter-chevron 11. Other shapes are also possible provided that the central part of the slide can to lodge inside the body of the counter-chevron 11, such as rounded shapes, half-wave, etc. The central portion 511 of the slide 510 ends on each side with a lug 513 returned to the inside of the slide and adapted to surround the flange 523 of the base 520. In this way, the flanges 523 of the base are trapped in the slide 510 by the tabs 513 and the end of the tabs 513 is guided parallel to the intersection between the flanges 523 of the soleplate 522 and the flanks 527 of the foot 525. Thus, the relative movement of the slide relative to the base is limited to a translation along a common longitudinal axis of the slide and the base, orthogonal to the plane of their cross section.

The slide 510 also comprises along its longitudinal axis and in the vicinity of one of its ends, a stop 512 projecting towards the inside of the slide. This abutment is for example made by a stamping point on the upper part of the slide but could also be formed by a folded folded inwards or any other embodiment having no overtaking above the upper part. of the slide capable of hindering the fitting thereof under the counter-chevron 11. In order to limit the translational movement of the slide 510 on the base 520, the latter comprises at least one flange 524, parallel to a plane orthogonal to the translation axis and extending above the sole 522, whose shape is adapted to cooperate with the profile of the cross section of the slide. In the example shown in FIG. 2, the flange 524 has a trapezoidal shape of dimensions making it possible to inscribe it inside the central part 511 of the slide and to retain a sufficient sliding clearance. The height of the flange 524 is adapted to cooperate (at least temporarily) with the abutment 512 when the slide 510 is engaged on the base 520, before fixing the counter-chevron on the slide. The support frame is assembled as follows, the roofing failures are first located and, depending on a mechanical strength calculation of the framework, a base 520 of a riser 50 is placed at the right of each failure, straddling a rib 32, according to a spacing of an integer number of ribs calculated according to the number of counter-rafters necessary to support the installation of solar panels. Each base is fixed by at least one base screw 528 which passes through the top of the rib 32 and comes to drill and tap a wing of the tip 20. The base screw comprises a sealing collar to prevent infiltration water at the point of attachment. The seal 529 prevents any runoff on the rib from seeping between the rib and the base until the drilling made by the base screw in the cover, thus ensuring the integrity of the seal.

In the case of a ribbed sheet of "sandwich" type, particularly if the insulation (rock wool for example) does not have sufficient rigidity, it may be appropriate to insert a spacer in the core of the panel in order to limit the crushing of the rib under the clamping forces of the base screw. On each base, a slide 510 is slid around the head of the base, the tabs 513 engaging below the flanges 523 and the central portion 511 engaging the flange or flanges 524. The abutment 512 is placed on the side of the top of the slope and comes into contact with the flange 524 closest to this top to limit the movement of the slide down. It is thus possible to position a plurality of slides without the risk of seeing them slide out of their respective base. The extensions 50 are then formed and ready to accommodate a counter-chevron. A counter-chevron 11 is then placed on one or more extensions 50, preferably from the bottom of the slope of the roof. The counter-chevron is fixed on each riser 50 by means of sliding screws 514 adapted to drill and tap simultaneously the counter-chevron 11 and the slide 510 without penetrating the base 520. The counter-chevron is thus integral with the slide and can move in translation along its axis. In order to limit the possible deflection of the counter-chevron, the slide screws 514 may advantageously be placed at a predetermined distance from the flanges in order to form a stop in translation by the part of their body protruding inside the slide. The counter-chevron 11 is fixed at the bottom of the slope at the level of the sill plate by means of a riser 50 by using fastening screws of a sufficient length to pass through the counter-chevron 11, the slide 510 and the base 520, thus preventing any translation of the counter-chevron on this particular riser. A possible slipping of the counter-chevron along the slope is thus avoided without limiting the possibility of expansion of the latter to the top of the slope.

When the length of the slope of the framework 10 is such that it is necessary to join several sections together to form a counter-rafter of sufficient length, the connection between profiles is performed on a slide by fixing the end of each of profiles, overlapping, on the same slide.

In addition, in case of very long slope lengths of the roof, the counter-rafters 11 could be divided along their length, each section being fixed in its lower part on a fixed extension. Once the counter-rafters 11 fixed on the roof, stirrups 13 are fixed on the top of the body 110 of the counter-chevrons, at predetermined longitudinal intervals according to the layout for laying the solar panels. These stirrups 13, known in themselves, make it possible to fix the support rails 12 transversely to the counter-chevrons. The support rails are then threaded into the stirrups and mounted free in translation along a transverse axis of the roof. Alternatively, the stirrups 13 are first slidably threaded onto the support rails 12, these are presented in position on the counter-chevrons 11 and a stirrup 13 is fixed at each cross. In this way, the support rails 12, generally made of extruded aluminum, do not present any risk of warping of the framework because of the expansions that may affect them. The solar panels are then assembled on the frame 10, respecting the planned layout and flanged on the support rails. Advantageously, the electrical cables (for photovoltaic panels) or the connection pipes (for heat-transfer solar panels) can be fixed along the counter-rafters by using for example clamps fixed on the wings 111. This arrangement makes it possible to perform a flow of cables or pipes from the top to the bottom of the slope without having to pierce the cover 30 and thus endanger the sealing thereof. Of course, this description is given by way of illustrative example only and the skilled person can make many modifications without departing from the scope of the invention, such as for example to modify the profiles of the straight sections of the various elements (base , slide and counter-chevron) to adapt to different cover styles (corrugated sheets, ribbed sheets other than trapezoidal, etc.). Similarly, the slide / base functional connection could be made differently, for example by providing a sole 522 of the wrapping base by appropriate tabs a rim placed on the slide, without departing from the scope of the invention.

Claims (1)

CLAIMS1 / - Assembly element, said riser (50), a frame (10) support metal solar panels (40) on a roof (1), the frame comprising first sections, said contre-chevrons (11). ), adapted to be placed above a cover (30) fixed on failures (20) parallel to a failure, perpendicular to the purlins and second profiles, said support rails (12), fixed on said counter-chevrons perpendicularly to a longitudinal axis thereof, characterized in that said connecting element comprises at least a first portion, said base (520), adapted to be fixed to a failure and a second portion, said slide (510) adapted to be fixed to the counter-chevron (Il), said slide being adapted to slide on the base along the longitudinal axis of the counter-chevron and to be secured to the base in the two directions orthogonal to this axis. 2 / - assembly element according to claim 1, characterized in that the base (520) comprises a lower part, said foot (525), having a transverse profile adapted to fit a profile of a rib (32) of the cover and receive at least one screw, said base screw (528) for fixing the base on a fault (20), through the cover (30). 3 / - Fitting element according to claim 2, characterized in that the inner part of the foot (525) comprises a seal (529) flat sealing adapted to be pressed between the foot and the top of the rib (32) . 4 / - connecting element according to one of claims 1 to 3, characterized in that the base (520) comprises an upper part, said head (521), having a sole (522) capping the foot (525). , extending parallel to the plane of the cover and having lateral flanges (523) protruding from either side of the foot and adapted to guide the slide (510) along the longitudinal axis thereof. 5 / - Fitting element according to claim 4, characterized in that the head (521) of the base (520) also comprises at least 17 a flange (524), orthogonal to the sole (522) and the longitudinal axis of the base and having a shape adapted to cooperate with an inner profile of the slide (510). 6 / - Fitting element according to claims 2 and 4, characterized in that the head (521) and the foot (525) of the base (520) are two separate parts fixed to one another by the base screw (528). 7 / - Fitting element according to claims 2 and 4, characterized in that the head (521) and the foot (525) of the base (520) form a single piece. 8 / - Fitting element according to one of claims 1 to 7, characterized in that the slide (510) is formed by a profile section whose cross section has a central portion (511) of shape adapted to s' nesting below the counter-chevron (11) and two folded lateral tabs (513) adapted to pass under the flanges (523) side of the head of the base. 9 / - Fitting element according to one of claims 5 to 8, characterized in that the slide (510) comprises, in the vicinity of one of its ends, a stop (512) projecting towards the inside of the slide and adapted to cooperate with a flange of the base. 10 / - Fitting element according to one of claims 1 to 9, characterized in that the slide (510) is secured to the counter-chevron (11) by at least one screw, said slide screw (514), traversing the counter-chevron and the slide and whose body portion projecting into the interior of the slide serves as translation stop to limit the sliding of the counter-chevron relative to the base. 11 / - Support (10) metal support solar panels (40) including photovoltaic, adapted to be mounted on a roof (1) above a cover (30) fixed on failures (20) parallel to a failure, of the type comprising first sections, said counter-chevrons (11), adapted to be placed perpendicular to the purlins and second sections, said support rails (12), fixed on said counter-chevrons perpendicular to the axis 2969743 ls longitudinal of those characterized in that the counter-chevrons (11) are fixed to the purlins (20), over the cover, by means of assembly elements, said extensions (50), comprising at least a first part, said base (520), fixed to the failure and a second part, said slide (510), attached to the counter-chevron, said slide being adapted to slide on the base along a longitudinal axis of the counter-chevron and to be secured the base in both directions ort hogonal to this axis. 12 / - A frame according to claim 11, characterized in that each counter-chevron (11) has a transverse cross section comprising a central portion (110) trapezoidal lined on either side by two wings (111) planes parallel to the longitudinal axis of the counter-chevron. 13 / - Frame according to one of claims 11 or 12, characterized in that each counter-chevron (11) carries, at regular intervals along its longitudinal axis, stirrups (13) adapted to receive and guide the support rails (13). 12) with a degree of freedom in translation along the axis of the rails.