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Title:
OUTER-WALL PROTECTION SYSTEM
Document Type and Number:
WIPO Patent Application WO/2001/023688
Kind Code:
A1
Abstract:
A system for erecting a temporary protection along an outer wall of a structure, in particular a multi-story building, comprising one or more vertical webs (11-15, 72) of a protective material which are to be positioned next to one another at a distance from the outer wall and a plurality of web-guidance members which are intended to be arranged vertically at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place. The system also comprises suspension members (5, 70) which can be supported on the structure and from which the top end of each of the web-guidance members (10, 71) can be suspended. Tensioning weights (74) can be hung from the bottom part of one or more web-guidance members for creating a tension in the web-guidance members. The system also comprises means (20, 73) for fixing the bottom part of each web-guidance member and/or the tensioning weight in the horizontal direction.

Inventors:
Klijnstra, Tjipke Gerard (33 Martensweg KJ Nunspeet, NL-8071, NL)
Application Number:
PCT/NL2000/000698
Publication Date:
April 05, 2001
Filing Date:
September 29, 2000
Export Citation:
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Assignee:
ALTREX B.V. (71 Industrieweg CS Nunspeet, NL-8071, NL)
Klijnstra, Tjipke Gerard (33 Martensweg KJ Nunspeet, NL-8071, NL)
International Classes:
E04G3/30; E04G5/12; E04G21/28; (IPC1-7): E04G21/28
Domestic Patent References:
WO1997048863A11997-12-24
Foreign References:
US4979589A1990-12-25
US4738335A1988-04-19
DE29517897U11996-02-01
NL7305038A1973-10-16
Attorney, Agent or Firm:
Brookhuis H. J. A. (Exter Polak & Charlouis B.V. P.O. Box 3241 GE Rijswijk, NL-2280, NL)
Download PDF:
Claims:
CLAIMS
1. System for erecting a temporary protection along an outer wall (1; 60) of a structure, in particular a multistorey building, comprising: one or more vertical webs (1115; 72) of a protective material which are to be positioned next to one another at a distance from the outer wall, a plurality of webguidance members (10; 71) which are intended to be arranged vertically at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place, characterized in that the system comprises suspension members (5; 70), from which the top end of each of the webguidance members can be suspended, and in that the system also comprises one or more tensioning means (20; 74) for creating a tension in the webguidance members.
2. System according to claim 1, in which the tensioning means comprise one or more tensioning weights (74) which can be suspended from the bottom part of one or more webguidance members.
3. System according to claim 1 or 2, in which the system comprises fixing means (20; 73) for fixing the bottom part of each webguidance member and/or the tensioning weight in the horizontal direction.
4. System according to claim 3, in which the fixing means for fixing the bottom part of the webguidance member and/or the tensioning means in the horizontal direction are designed as a platform (20) which is to be arranged along the outer wall.
5. System according to claim 1, in which the tensioning means are at least partially formed as a platform (20) which is to be arranged along the outer wall.
6. System according to claim 4 or 5, in which the platform is provided with a pivot attachment (21), in such a manner that the platform (20) can pivot about a substantially horizontal pivot axis with respect to a support structure, a scaffold or the outer wall.
7. System according to claim 6, in which the webguidance members (10) can be attached to the platform (20) at a distance from the pivot axis, in such a manner that the platform can hang from the said webguidance members (10) and can thus tension the webguidance members (10).
8. System according to one or more of the preceding claims, in which the webguidance members are cables (10).
9. System according to one or more of the preceding claims, in which the suspension members (5) are designed to be supported on the structure, preferably to be positioned on the roof (2) of the structure.
10. System according to claim 9, in which the suspension members (5) are of mobile design.
11. System according to one or more of the preceding claims, in which a separate suspension member is provided for each web guidance member (10; 71).
12. System according to one or more of the preceding claims, in which the system furthermore comprises rails which can be arranged on the structure, and the suspension members are designed to move along the rails.
13. System according to one or more of the preceding claims, in which the platform (20) can be walked on, and is preferably continuous.
14. System according to one or more of the preceding claims, in which the system also comprises a bearing rail (40) which can be arranged along the outer wall, and a cradle device (41,42, 43) which can be hung from the bearing rail.
15. System according to claim 14, in which the bearing rail (40) can be mounted on the suspension members (5) of the web guidance members.
16. System according to one or more of the preceding claims, in which the system comprises a platform (20) which is to be arranged at the level of the bottom section of the webguidance members and along the outer wall, in which the platform (20) is provided with a pivot attachment (21), in such a manner that the platform can pivot about a substantially horizontal pivot axis with respect to a support construction, for example a scaffold, or the outer wall, in which the webguidance members (10) can be attached to the platform at a distance from the pivot axis, in such a manner that the platform can hang from the said web guidance members (10) and therefore can tension the webguidance members (10), in which the platform is provided with an attachment member (22) for each webguidance member, and in which the distance to the pivot attachment of the platform is adjustable.
17. System according to one or more of the preceding claims, in which the system comprises a platform (20) which is to be arranged at the level of the bottom section of the webguidance members and along the outer wall, in which the platform (20) is provided with a pivot attachment (21), in such a manner that the platform can pivot about a substantially horizontal pivot axis with respect to a support construction, for example a scaffold, or the outer wall, in which the webguidance members (10) can be attached to the platform at a distance from the pivot axis, in such a manner that the platform can hang from the said web guidance members (10) and therefore can tension the webguidance members (10), and in which the system furthermore comprises ballast weights which can be placed on top of the platform or can be mounted on the platform.
18. System according to one or more of the preceding claims 16 or 17, in which the platform (20) is provided with a compartment (25) for accommodating one or more removable webs (1115).
19. System according to one or more of the preceding claims, in which the system also comprises hoist means (30; 80) for raising the web or webs.
20. System according to claim 19, in which the hoist means can be attached to the suspension members (5; 70).
21. System according to claim 19 or 20, in which the hoist means (30; 80) are provided with a motor drive, preferably an electric drive.
22. System according to one or more of the preceding claims, in which the system furthermore comprises detection means for detecting one or more parameters which are related to the load on and/or performance of the system.
23. System according to claim 22, in which the detection means are designed to detect the wind, in particular the wind speed, and/or one or more parameters relating to the system which are dependent on the wind, for example the movement of the platform or the forces acting on the webguidance members.
24. System according to claim 22 or 23, in which the detection means are designed to detect icing (black ice) on the system.
25. System according to one or more of claims 2224, in which the detection means are coupled to means for the automatic removal of one or more of the webs.
26. System according to one or more of the preceding claims, in which the webs are made from netting or the like.
27. System according to one or more of the preceding claims, in which the webs (1115) are provided on their vertical longitudinal edges with coupling means (16) for coupling the webs to the webguidance members (10).
28. System according to one or more of the preceding claims, in which the coupling means are eyelets (16) which can slide over the webguidance members.
29. System according to one or more of the preceding claims, in which each web (1115), in the vertical direction, is composed of a plurality of segments, and in which a horizontal connecting section (35) is provided between two segments.
30. System according to claim 29, in which connecting sections (35) of adjacent webs can be connected to one another.
31. System according to one or more of the preceding claims, in which a web is provided with diagonal reinforcement members (36).
32. System according to one or more of the preceding claims, in which the system furthermore comprises detection means for detecting one or more parameters which are related to the load on and/or the performance of the system.
33. System according to claim 32, in which the detection means are designed to detect weather influences.
34. System according to claim 33, in which the detection means are designed to detect the wind, in particular the (expected) wind speed and wind direction.
35. System according to claim 33, in which the detection means are designed to detect icing.
36. System according to claim 32, in which the detection means are designed to detect movements of and/or loads on components of the system under the influence of the weather conditions.
37. System according to claim 32, in which the detection means are arranged at a distance from the structure, in particular at a meteorology centre, and in that data transmission means are associated with the system, these means being designed at least to transmit data to the automatic web removal means.
38. System for erecting a temporary protection along an outer wall (1) of a structure, in particular a multistorey building, comprising: one or more vertical webs (1115) of a protective material which are to be positioned next to one another at a distance from the outer wall, a plurality of webguidance members (10) which are intended to be arranged vertically at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place, characterized in that the system comprises suspension members (5), from which the top end of each of the webguidance members can be suspended, and in that the system also comprises a platform (20) which is to be arranged horizontally along the outer wall and is provided with a pivot attachment (21), in such a manner that the platform can pivot about a substantially horizontal pivot axis with respect to a support construction or the outer wall, and in that the webguidance members (10) can be attached to the platform at a distance from the pivot axis, in such a manner that the platform can be hung from the said webguidance members (10) and can thus tension the webguidance members (10).
39. Structure having an outer wall and provided with a temporary protection along the outer wall, which protection comprises: one or more vertical webs of a protective material which are to be positioned next to one another at a distance from the outer wall, a plurality of webguidance members which are intended to be arranged vertically at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place, characterized in that the system comprises suspension members which are supported on the structure and from which the top end of each of the web guidance members is suspended, and in that the system also comprises a platform which is arranged horizontally along the outer wall and is provided with a pivot attachment, in such a manner that the platform can pivot about a substantially horizontal pivot axis with respect to a support construction or the outer wall, and in that the web guidance members are attached to the platform at a distance from the pivot axis, in such a manner that the platform hangs from the said webguidance members and therefore tensions the web guidance members.
40. Construction according to claim 39, in which the platform hangs freely at a distance above the ground.
41. Structure according to claim 39 or 40, in which the platform is situated at a height of at least 2 metres above the ground.
42. Structure according to one or more of claims 3941, in which the pivot attachment of the platform is fixed to the outer wall.
43. System for erecting a temporary protection along an outer wall of a structure, in particular a multistorey structure, preferably a system according to one or more of the preceding claims, comprising: one or more webs of a protective material which are to be positioned next to one another at a distance from the outer wall, a plurality of webguidance members which are intended to be arranged at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place, characterized in that the system also comprises detection means for detecting one or more parameters which are related to the load on and/or the performance of the system.
44. System according to claim 43, in which the detection means are designed to detect weather influences.
45. System according to claim 44, in which the detection means are designed to detect the wind, in particular the (expected) wind speed and wind direction.
46. System according to claim 44, in which the detection means are designed to detect icing.
47. System according to claim 43, in which the detection means are designed to detect movements of and/or loads on components of the system under the influence of the weather conditions.
48. System according to claim 43, in which the detection means are arranged at a distance from the structure, in particular at a meteorology centre, and in that data transmission means are associated with the system, these means being designed at least to transmit data to the automatic web removal means.
Description:
Outer-wall protection system The present invention relates to a system for erecting a temporary protection along an outer wall of a structure, in particular a multi-storey building, comprising: -one or more vertical webs of a protective material which are to be positioned next to one another at a distance from the outer wall, -a plurality of web-guidance members which are intended to be arranged vertically at a distance from the outer wall and which guide the web or webs while they are being fitted and removed and hold the fitted webs in place.

Outer-wall protection systems of this nature are intended in particular to create a working space which is more or less protected from the environment, so that work can be carried out on the outer wall during adverse weather conditions, for example painting work. Protection arrangements are known in which the protective material is a canvas and completely sealed protection is obtained, but there are also screens with an open design, such as a mesh or netting, so that above all the wind and rain along the outer wall are reduced.

A system according to the preamble of claim 1 is known, for example, from WO 97/48863. In this known system, the web- guidance members are profiled strips with grooves for holding the edges of the webs. The vertical strips are attached to an interim frame of horizontal bars which, in turn, are fixed to vertical bars. It is shown in WO 97/48863 that the latter bars form part of the building, but this situation is only seldom encountered. Much more often, as is also mentioned, a scaffold structure will first be positioned alongside the outer wall, and then the protective system will be attached to the outside of the scaffold.

One of the drawbacks of this known system is the laborious assembly and dismantling of the protective system, particularly for a large building.

A first object of the present invention is to provide an improved protective system for an outer wall of a structure.

Another object is to provide a protection system which can be assembled and dismantled easily and quickly.

Another object is to provide a protection system which offers a considerable degree of safety with respect to forces resulting from the wind.

According to a first aspect, the present invention provides a system according to claim 1. The system comprises suspension members from which the top end of each of the web- guidance members can be suspended. The system also comprises one or more tensioning means for creating a tension in the web- guidance members.

In an advantageous embodiment, the tensioning means comprise one or more tensioning weights which can be suspended from the bottom part of one or more web-guidance members. As an alternative, particularly in systems of limited height, such as those which are positioned along the outer wall of a single- family dwelling, the tensioning means can be designed with a (steel cable) tensioner and/or spring.

Preferably, the system comprises fixing means for fixing the bottom part of each web-guidance member and/or the tensioning weight in the horizontal direction.

The system preferably comprises a platform which is to be arranged along the outer wall and is used for fixing the bottom part of each web-guidance member in the horizontal direction and which can also serve as a tensioning weight for tensioning the web-guidance members.

In another advantageous embodiment, the platform is provided with a pivot attachment, in such a manner that the platform can pivot about a substantially horizontal pivot axis with respect to a support structure or the outer wall. In this embodiment, the vertical web-guidance members are therefore held under tension by the platform hanging from it, which can pivot about a horizontal axis. This firstly allows a simple design, and secondly the suspension of the platform from the web- guidance members provides automatic security against the system being overloaded as a result of wind, since in the event of a high wind the platform can pivot upwards slightly and therefore the protection can yield slightly to the load from the wind.

This advantage also applies when using tensioning weights attached to the web-guidance members.

In another preferred embodiment, the web-guidance members are flexible in such a way that they can be rolled up for transportation and storage. The flexibility of the web- guidance members also makes it easy to adapt to the height of the building, in which case, for example, a residual length is stored in a coil. In particular, the web-guidance members are (steel) cables.

In a further preferred embodiment, the suspension members for the said cables are designed to be positioned on the roof of the structure. In this case, it is possible for the weight of the suspension members to be sufficient to provide secure attachment for the cables, with ballast weights which make the suspension members heavier possibly being used.

In an advantageous embodiment of the system according to the invention, there is no need for a scaffold construction to be set up alongside the outer wall in order for work to be carried out on the outer wall. The system may in this case also comprise a bearing rail and a cradle device which can be hung from the said bearing rail and can be moved along the bearing rail.

Preferably, the bearing rail can be fitted to the suspension members which also support the web-guidance members.

The cradle device may be of a generally known design with a working floor which is suspended from the bearing rail by way of one or more controllable hoists and can be moved both sideways and up and down along the outer wall.

The invention also relates to a system which also comprises a scaffold which is set up alongside the outer wall of the structure. In this case, in one possible embodiment the suspension members of the outer-wall protection system can be supported on the scaffold. This design is advantageous, for example, for structures of relatively low height, such as for example single-family dwellings, or if the structure, in particular the roof, cannot support the suspension members.

According to a second aspect, the present invention relates to a structure where an outer-wall protection system according to a preferred embodiment of the invention is set up alongside one of the outer walls. Preferably, it is possible to walk beneath the platform, requiring a height of approximately

2 metres above the ground. Furthermore, it is preferable for there to be no support construction or the like beneath the platform, so that completely free passage beneath the platform is possible. This embodiment is highly advantageous, for example, for buildings in which the bottom storey is provided, for example, with garages for parking vehicles or accommodates shops or businesses.

Preferably, a platform of this nature is sealed, so that any waste dropping downwards during the work does not reach the public area.

In a preferred embodiment, the platform is pivotably attached to the outer wall, but it is also conceivable, for example, for a construction to be positioned on the ground alongside the outer wall and for the platform to be pivotably attached to this construction.

According to a third aspect of the present invention, an outer-wall protection system, which is preferably designed according to the first or second aspect of the invention, comprises detection means for detecting one or more parameters which are related to the load on and/or performance of the system.

In an advantageous embodiment, the detection means are designed to detect weather influences, for example the wind speed and the wind direction. The detection means could also be designed, for example, to detect icing, for example in the event of black ice.

In a variant, the detection means could be designed to detect movements of and/or loads on components of the system under the influence of the weather conditions, for example the pivoting movements of the platform in the above-described design of the system.

The detection means are preferably coupled to means for the automatic removal of one or more of the webs. In this way, it is possible, for example, to prevent overloading by the wind by means of the timely removal of one or more webs.

It will be clear that the latter aspect of the invention can be used not only for protection with vertical webs, but also for all other arrangements and designs of a protection for an outer wall of a structure.

The invention will be explained in more detail below with reference to the drawing, in which: Fig. 1 shows a diagrammatic side view of a building provided with a first exemplary embodiment of the outer-wall protection system according to the invention, Fig. 2 shows a front view of the building with outer- wall protection system as shown in Figure 1, Fig. 3 shows a plan view of the suspension members positioned on the roof and the bearing rail of the cradle installation, Fig. 4 shows a detail from Figure 1 on an enlarged scale, Fig. 5 shows another detail from Figure 1 on an enlarged scale, and Fig. 6 shows a diagrammatic side view of a building provided with a second exemplary embodiment of the outer-wall protection system according to the invention.

Figure 1 shows a highly diagrammatic view of a building, for example an apartment building or a multi-storey office building, the reference numeral 1 denoting an outer wall of the building and the reference numeral 2 denoting the flat roof.

Reference numeral 3 indicates the ground level.

To carry out work on the outer wall 1, for example renovation or painting work, a temporary protection is set up alongside the outer wall 1, use being made of the system according to the present invention.

In the embodiment shown, the system comprises a number of suspension members 5 which are positioned on the roof 2.

These suspension members 5 each comprise a stable beam 6 with roof supports 7,8 which are situated at a distance from one another and are in this case provided with one or more wheels so that the suspension member can be moved over the roof. The beam 6 has a projecting part 9 which extends beyond a roof support 8.

If the suspension member 5 is positioned with the beam 6 at right angles to the outer wall 1 and with its wheels 8 along the edge of the roof 2, the projecting part 9 projects a distance beyond the outer wall 1. It will be clear that blocking means, for example on the wheels, may be provided in order to prevent the suspension members from moving unexpectedly.

In an advantageous embodiment, the system may comprise rails which are to be laid on the roof 2 and along which the suspension members can travel. The blocking means can then fix the suspension members with respect to the rails. The rails may, for example, be positioned at right angles to the edge of the roof, so that work on the projecting part 9 can be carried out in safety on top of the roof, after which the suspension members are moved towards the edge of the roof. Obviously, it is also conceivable for the rails to allow the suspension members to move parallel to the outer wall in order, for example in the case of a long building, to move the protection system at intervals.

If appropriate, the projecting part 9 is of telescopic design.

A steel cable 10 hangs vertically downwards at the end of the projecting part 9 of each suspension member 5, at a distance from the outer wall 1. The cables 10 serve as guide members for a plurality of vertical webs 11-15 of a suitable protective material which are to be positioned next to one another at a distance from the outer wall. The webs 11-15 fit between the cables 10 and, at their vertical edges, are provided with eyelets 16, through each of which a cable 10 fits. In this way, the cables 10 hold the webs 11-15 vertical at a distance from the outer wall 1. Furthermore, the cables 10 serve as a guide for the webs 11-15 during fitting, in this case raising, and removal, in this case lowering, of the webs 11-15.

The system also comprises a platform 20 which is arranged horizontally alongside the outer wall 1. The platform 20 is in this case fixed to the outer wall 1 via an associated pivot attachment 21, in such a manner that the platform 20 can pivot about a horizontal pivot axis with respect to the outer wall. At a distance from the pivot axis, the platform 20 is attached to the cables 10, for which purpose cable attachments 22 are provided. The cable attachments 22 allow the active length of the cables 10 to be adjusted and therefore enable them to be adapted to the height of the outer wall which is to be protected. The platform 20 hangs from the cables 10, with the result that the cables 10 are tensioned. If appropriate, the

distance between the cable attachments 22 and the pivot axis of the platform may be of adjustable design.

In this arrangement, the platform 20 is situated at least 2 metres above the ground 3 and, since no further support is required beneath the platform 20, it is possible to use the space beneath the platform as a walkway which is protected from above.

The weight of the suspension members 5 may in this case be insufficient to provide a stable attachment point for the cables 10, and therefore in this case use is made of a ballast weight 27 which in this case is attached to that end of the suspension member 5 which is remote from the outer wall 1.

The platform 20 has a floor 23 and can therefore be walked on by the maintenance staff. Furthermore, there is a railing 24.

It can be seen in the drawing that the platform 20 projects beyond the cables 10, where it forms an open compartment with a raised wall 26 for accommodating the lowered webs 11-15.

To raise the webs 11-15, hoist means 30 are provided for each web. It is preferable to provide electric winches which can be used to operate one or more hoist cables attached to each web 11-15.

To lower the webs 11-15 it is sufficient to operate the winches 30 in the opposite direction, so that the webs 11-15 are lowered along the cables 10 under the influence of their own weight and reach the compartment 25. If desired, it is possible for the raising and lowering to be carried out for each web 11-15 or for each section of a plurality of webs. Consequently, in practice, the work will always take place at a defined location of the outer wall 1, and if it is not necessary to screen off the entire outer wall for this purpose, the residents of the building will appreciate the fact that part of the protection is lowered.

In this example, the winches 30 are suspended from the suspension members 5 for the cables 10. If appropriate, the winches 30 may be of the low-tension type.

The system according to the invention may advantageously be used without a scaffold construction or the like positioned

against the outer wall 1. In order in this case to still allow every point of the outer wall 1 to be reached, the system also comprises a bearing rail 40 which extends parallel to and at a distance from the outer wall 1 and is mounted on the projecting parts 9 of the suspension members 5.

A cradle 42 hangs from the bearing rail 40 by means of two trolleys which can move along the bearing rail and two cables 41 (not shown). The cradle 42 is of a generally known type and has a working floor and two winches 43, by means of which the height of the cradle 42 can be moved.

The cradle 42 may be parked on the platform 20 when it is not in use and when people are getting on and off.

To gain access to the platform 20, it is possible to provide one or more (closable) hatches in the platform 20.

In the system, the cables 10 are tensioned by the weight of the platform 20. If necessary, for example if the platform 20 is of lightweight design, it may be desirable to increase the weight of the platform 20 using ballast weights. If appropriate, the ballast weights may be directly attached to the cables 10.

Tensioning the cables 10 by means of the platform 20, in addition to rapid and easy assembly and dismantling of the system, also provides an advantage with regard to the safety of the protection system against overloading from the wind, for example gusts of wind. As is known, the wind may impose very great loads on the protection. In the system described here, the cables 10 which hold the webs 11-15 in place are not fixed at their bottom end, but rather can move more or less freely in the vertical direction, although under the load of the weight of the platform. This weight is such that, under normal wind loads, the platform hangs in a virtually stationary position. In the event of a high wind load, the cables 10 will pull on the platform 20 in such a manner that this platform 20 pivots upwards slightly, so that the screen yields slightly to the wind. As a result, the tension in the cables 10 remains limited, and therefore so does the mechanical load imposed on the other components of the protection system.

In another advantageous embodiment (not shown), the protection against overloading by the wind could be improved further by providing wind detection means, for example a device

for measuring the wind speed and direction, and by coupling these wind detection means to the control unit of the winches 30 in such a manner that one or more webs 11-15 is/are automatically lowered fully or partially when the wind load threatens to exceed an acceptable level. In this way, it is possible, to obtain protection against the situation in which the wind rises at night. The wind detection may take place in the immediate vicinity of the building, but the data concerning the actual or expected wind could also be derived from a meteorology centre which transmits this data in a suitable way, for example via a (wireless) connection, to a control unit associated with the system. It will be clear that this safety measure can also be used in combination with protection systems which are of completely different design.

Instead of or in combination with detection of the wind, the outer-wall protection system could also comprise detection means which detect one or more other weather influences. In particular, consideration may be given to the detection of deposits of ice or snow on the system, in particular on the webs of protective material.

The detection means could also be designed, for example, to detect the movements of and/or loads on components of the system. For example, it would be possible to provide detection of the movements of the platform 20 which could indicate a high wind load. It would also be possible to detect the movement of the cables.

The webs 11-15 may be made form any suitable material, for example may be designed as mesh or canvas, but the invention in particular envisages the webs being made from netting.

In this example, the webs 11-15 are not made from one piece, but rather from segments with a length of, for example, 10 metres which are arranged in succession in the vertical direction. Between adjacent segments there is in each case a horizontal connecting section 35 with a groove on both sides, into which the segment is pushed or clamped. The connecting sections 35 of the adjacent webs 11-15 may, if appropriate, be coupled to one another. This latter variant is of interest in particular if the hoist means of the adjacent webs are synchronized even if they are each provided with their own drive

motor. Synchronization of this nature can be achieved successfully in practice with an electric drive motor. In this way, it is possible for a plurality of webs to form a unit and to be raised and lowered as a unit. To increase the rigidity in the plane of the webs 11-15, it is possible for a web to be provided with diagonal reinforcement members 36.

Figure 6 shows a highly diagrammatic view of a building, in this case a single-family dwelling with two storeys, the reference numeral 60 denoting an outer wall of the building and the reference numeral 62 denoting the sloping roof. Reference numeral 63 indicates ground level.

To carry out work on the outer wall 1, for example renovation or painting work, a scaffold 65 is positioned alongside the outer wall 60, with three working platforms 66, 67,68 which can be walked on, at different heights.

A temporary protection is arranged alongside the outer wall 1, along the vertical outer side of the scaffold 65, use being made of the system according to the present invention.

In the embodiment shown, the system comprises a number of suspension members 70 which are fixed to the top of the scaffold 65 at regular intervals. These suspension members 70 each comprise a stable bar which is positioned at right angles to the scaffold 65 and projects slightly beyond the latter.

A steel cable 71 hangs vertically downwards from the end of the projecting part of each suspension member 70. The cables 71 are used as guide members for a plurality of vertical webs 72 made from a suitable protective material which are to be positioned next to one another.

The system also comprises fixing supports 73 which are attached to the scaffold 65 and each fix the bottom end of the associated cable 71 in the horizontal plane. By way of example, each. support 73 is provided with a hole through which the cable 71 fits. A tensioning weight 74 hangs from the bottom end of each cable 71, so that a vertical tensioning force is generated in the cable 71.

To raise the webs, hoist means 80 are provided for each web. It is preferable to provide electric winches which can be used to actuate one or more hoist cables attached to each web.

In this example, the hoist means 80 are suspended from the suspension members 70 for the cables 71.

In a variant which is not shown, the webs are fixedly attached at the top and the hoist means 80 act on the bottom edge of the webs.