WO2008065385A1

WO2008065385A1 - Wall coping

Info

Publication number: WO2008065385A1
Application number: PCT/GB2007/004535
Authority: WO
Inventors: Liam Clear
Original assignee: Wembley Innovation Ltd
Priority date: 2006-11-29
Filing date: 2007-11-27
Publication date: 2008-06-05
Also published as: GB2444258A; GB2444258B; GB0623889D0

Abstract

A coping unit comprises a portion (44) configured to underlie an adjacent coping unit to form a lap joint. A channel (47a, 47b) formed on the upper surface of the underlying portion is arranged to direct rainwater penetrating the lap joint laterally of the unit. An undersurface of the unit is configured to form a drip point or edge spaced from a face of a wall on which the unit is installed, whereby water emerging from the channel falls off the drip point or edge away from the wall face. The drip point may comprise inset strips (48) or depending ridges (18, Fig.2) cast or moulded together with the coping unit, or a drip channel.

Description

WALL COPING

Field of the Invention

This invention concerns building units for constructing a rain penetration resistant wall coping.

Background of the Invention

Copings used in buildings, for example on parapet walls, must not only protect the masonry below from weathering, but must also prevent damp penetration into the building interior, or into the wall cavity in the case of a cavity wall construction. A masonry unit well known for use as a wall coping is substantially rectangular in plan with a generally flat underside dimensioned to jut out slightly beyond both faces of the wall below. The overhanging underside portions of the unit are often provided with a drip channel running parallel to and spaced from the adjacent wall face. The top surface of the unit may slope symmetrically from a raised centre portion towards lower side edges so as to shed water evenly to either side, or may slope wholly or predominantly to one side, so as to direct water from a parapet wall onto an adjacent roof or into a gutter, for example.

Such units are made inter alia from hard fired clay (brick "specials"), natural or artificial stone, concrete or the like, having relatively low water absorbency. The units are laid on a mortar bed with the joints between neighbouring units also filled with mortar. These joints are vulnerable to cracking, erosion and damp penetration. Therefore to prevent water from seeping further into the wall or building below, a damp proof course or cavity tray must be incorporated into the wall immediately below the coping. However this in turn introduces a slip plane into the wall structure. The mortar bond between the coping and the wall below is therefore weak or absent. As the coping units are not weighed down by masonry above, they can easily be dislodged. Due to poor workmanship or ageing, the damp proof course or cavity tray is also vulnerable to leaks. Further, the drip channel to the overhanging underside portion of the unit is generally such that it can be easily bridged or surpassed by running/dripping water, which then reaches the top face of the wall and can penetrate into the cavity via cracks in the mortar or result in concentrated wetting of the wall. US2246615 discloses fired clay wall coping sections with drain members positioned beneath their adjacent ends for conveying moisture, which may pass through the joint, to points laterally of the wall, so that moisture may fall along the sides of the wall without engaging the top of the wall. However, in the arrangement shown, water seeping through the coping joints emerges from either end of the drain members into respective gaps formed between depending side flanges of the coping sections and the adjacent wall faces, hi the absence of an adequate damp proof course this can result in concentrated wetting of the wall surfaces and damp penetration into the wall. Even in the case of a coping unit having an overhanging, generally flat underside provided with drip channels, it has been observed that during heavy or prolonged rainfall the overhanging underside portions can become wetted to an extent that allows water droplets to cling to and run along the underside and even "jump" the drip channel to reach the face of the wall. This is believed to be due to surface tension / capillary effects. Once a water droplet has established a flow path or runnel, subsequent water droplets or flows tend to follow the same path. Without a damp proof course, water penetration into the wall is again possible. Prolonged wetting can result in erosion of the mortar and masonry and damp penetration into and through the wall.

US2233308 relates to a flanged wall coping of arcuate contour in transverse cross-section between the flanges. One higher end portion of a coping unit is arranged to overlap a seat formed by a lower end portion of an adjacent coping unit. The seat also comprises thinned continuations of the flanges at the lower end portion. The overlapping higher end portion has complementary thinned flange continuations which engage over the seat thinned flange continuations so as to provide a substantially uniform outer profile for the interengaged coping units. The seat has a transversely extending groove on its upper surface, which extends down its flange continuations. The overlapping higher end portion has a complementary key extending transversely across its underside and down the inside of its flange continuations, for engagement in the seat groove. Rainwater penetrating the joint between adjacent coping units will therefore be directed by the groove and key to emerge mainly from the crack in the lower face of the flanges formed between the juxtaposed faces of the thinned flange continuations. As there is no drip channel on each flange lower face, from there water droplets can easily cling to and run across the flange lower faces to cause concentrated wetting of the adjacent wall. Mortar in which the coping units are bedded is also squeezed into lower parts of the joints between the coping unit ends, causing blockages that can redirect water penetrating the joints onto the top surface of the masonry below the coping. In either case, damp can penetrate into the wall.

GB 6145/04 relates to a ridge tile that may also be used as a wall coping. The tile has a projection at one end, over which the complementary end of an adjacent tile may be placed to form a joint. A small channel or groove is provided on the upper sides of the projection, to conduct away any moisture which may pass into the joint, and prevent it from entering the roof. Water emerges from the ends of the channel inwardly of drip edges formed by the lowermost edges of the tile, and can easily run onto, or be drawn by capillary action into, a wall on which the ridge tile is mounted.

The present invention aims to provide a coping unit which forms a joint with an adjacent coping unit having improved moisture penetration resistance.

Summary of the Invention

Accordingly, the present invention provides a coping unit comprising: a portion configured to underlie an adjacent coping unit to form a lap joint; a channel formed on the upper surface of the underlying portion and arranged to direct rainwater penetrating the lap joint laterally of the unit towards an end termination of the channel, and a ridge depending from an undersurface of the unit configured to form a drip point or edge; characterised in that the ridge is positioned in use between the end termination and a face of a wall on which the unit is installed, whereby water emerging from the channel falls off the drip point or edge away from the wall face.

In one embodiment, the channel terminates at a side face of the underlying portion. Such units are easily cast, or easily formed by working natural stone. The depending ridge may be positioned between the side face and the wall face in use, to form the drip point or edge and to prevent water from running along the undersurface to the face of the wall. Alternatively, the channel terminates at the undersurface of the underlying portion. This provides a neater appearance, as the underlying portion can be almost completely hidden in a complementary recess formed in the adjacent coping unit. The visible joint between the side faces of the two units can therefore appear as a simple vertical line.

The undersurface may slope upwardly from the channel termination towards the adjacent wall face and slope downwardly from the channel termination towards the adjacent outer edge of the unit. This ensures that water draining from the channel tends to run down the undersurface away from the wall face.

The ridge may be cast or moulded with the rest of the coping unit, or may comprise an insert secured to project from the undersurface. For example, the insert may be a strip that has a projecting edge, preferably projecting outwardly and downwardly from the undersurface. The ridge may extend along the entire length of the unit undersurface.

In one form, the coping unit comprises an opposed pair of the underlying portions, each cooperating in use with a complementary overlying portion of an adjacent coping unit, to form a said lap joint. In an alternative form, the coping unit comprises a complementary recess for reception of an underlying portion of a similar coping unit.

Illustrative embodiments of the invention and some of their preferred features and advantages are described below with reference to the drawings.

Brief Description of the Drawings Figure 1 is a perspective view of a coping unit forming a first embodiment of the invention;

Figure 2 corresponds to Figure 1 but shows the unit inverted;

Figure 3 is a side view of a joint formed between two of the previously illustrated coping units installed abutted end-to-end on a wall;

Figure 4 is a transverse cross-section through the joint shown in Figure 3; Figure 5 is a perspective view of a second coping unit embodying the invention;

Figure 6 corresponds to Figure 5 but shows the unit inverted;

Figure 7 corresponds to Figure 3, but showing two of the second coping units; Figure 8 is a transverse cross-section through the joint shown in Figure 7; Figure 9 is a perspective view of a third coping unit embodying the invention; Figure 10 corresponds to Figure 9 but shows the unit inverted;

Figure 11 is a transverse cross-section through a joint formed using the coping unit of Figure 9.

Description of the Illustrated Embodiments

The coping unit 10 shown in Figure 1 comprises an elongate main body part 12 from one end of which projects an underlying portion 14. The opposite end of the main body part 12 is provided with a projecting overlying portion 16. The portions 14, 16 are of complementary shape to each other, so that the underlying portion 14 of a first unit 10 can co-operate with the overlying portion 16 of an identical unit to form a lap joint as shown in Figure 3. In this way, a series of units 10 can be fitted together to form a wall coping. The units are secured to the wall on a bed of mortar, but the joints between units are dry, i.e. mortar free. Additional fixings can be used to secure the units to the wall, for example metal angle brackets plugged and screwed to the wall and to the exposed end of the underlying portion 14, in similar manner to known masonry coping units. The end face of the underlying portion may be do welled to the co-operating surface of the adjacent unit, again in similar manner to known units. For simplicity, such fixings are omitted from the drawings.

The upper surface of the main body part has a pair of pitched or downwardly and outwardly sloping planar surfaces meeting at a central longitudinal ridge line, so as to shed rainwater to either side. The upper surface of the underlying portion 14 is similarly shaped, so that rainwater entering the joint between abutting units 10 is directed laterally so as to run down the sides of the underlying portion 14. A channel 17 extends laterally across the upper surface so as to catch any water running towards the free end of the underlying portion 14. This water is therefore redirected laterally so as also to run down the sides of the underlying portion 14, so being prevented from running over the free end and prevented from reaching the top surface of the wall. The undersurface of the unit 10 on either side of the wall slopes downwardly and outwardly so as to form outer drip edges 18. Any water droplets clinging to the undersurface will therefore run downwardly away from the face of the wall and fall off the drip edge 18 away from the wall 22.

The coping unit 40 shown in Figures 5 to 8 is similar to that of the preceding figures, the following being the main differences:

1) The upper surfaces of the main body 42 and underlying portion 44 have a single slope, so as to direct water towards one side of the unit only (the right hand side as illustrated in Figure 5).

2) The underlying portion 44 does not extend across the full width of the unit 40, but stops short to form an inward step on either side.

3) Two grooves 47a, 47b are provided in the top surface of the underlying portion 44. This surface is also pitched to slope downwardly towards the main body 42 of the unit 40, so that the entire top surface of the underlying portion 44 may be regarded as the base of a channel that directs water entering the joint between two neighbouring coping units laterally to one side of the wall 22. The groove 47a extending across the upper surface and down the sides of the underlying portion 44 is positioned immediately adjacent to the main body part 42 ofthe unit 40.

4) The overlying portion 46 is provided with depending side walls which also form continuations of the sides of the main body 42. The side walls together with the overlying portion -46 define a complementary recess for reception of the underlying portion 44. The rainwater channel so formed thus extends down the sides of the underlying portion 44 within the recess 47 so as to terminate at the undersurface of the unit 40. This area of the undersurface slopes upwardly away from the end of the channel, towards the adjacent wall face, and downwardly and outwardly away from the end of the channel, towards a drip edge 48.

5) The drip edge 48 is positioned slightly inward of the sides of the unit 40, but water emerging from the end of the channel defined between the sides of the underlying portion 44 and the opposing sides of the recess 47, still falls off the drip edge 48 away from the adjacent face of the wall 22.

6) The undersurface of the unit 40 is generally flat. The depending parts and drip edges 18 shown in Figures 1 to 4 are replaced by strips of waterproof material partially embedded in the undersurface. These provide a downwardly and outwardly projecting longitudinal edge forming a drip edge. The strips may be of corrosion resistant metal such as stainless steel, brass, bronze or aluminium; or of plastics, such as uPVC. They may be cast into the unit 40 or grouted into grooves moulded or cut into the unit undersurface. As shown, the strips are angled outwardly and downwardly at approximately 45 degrees. However other angles are also effective in preventing droplets of water clinging to the unit undersurface from running towards the adjacent wall surface, and instead shedding them away from the wall surface. The relatively sharp lower corner of the strip acts as a drip edge. Other moulded or cast in features can be used as a drip promoting formation positioned between the channel terminations and the wall face, such as drip channels provided in the coping unit undersurface. However it has been found that a relatively sharp, depending drip edge is particularly effective. Materials which are not easily wetted (or even which are water repellent) are preferred, such as metal or plastics.

The upper surface of the underlying portion shown in Figures 5 to 8 slopes predominantly to one side, so that water is shed substantially to one side only. However, other upper surface profiles are readily possible which direct water to either side in any proportion between 0 and 100%. For example, one or more corners or edges of the underlying portion may be rounded.

The coping unit 50a shown in Figures 9 to 11 is configured to be completely covered by an abutted pair of further coping units 50b (only one of which is shown in Figures 9 and 10). Respective longitudinal halves of the unit 50a are received in recesses 57 formed in the undersides of the ends of the units 50b. Each unit 50b has a recess 57 at either end, so that a series of units 50a and 50b can be assembled to form the coping, with the units 50b adjacent to one another end to end, and the units 50a beneath the joints thus formed. The joints between units 50a, 50b and between adjacent units 50b are assembled dry, i.e. without mortar. The units 50a, 50b are however fixed to the wall by a bed of mortar and optionally other fixings, as discussed above. To prevent them from sinking too far into the wet mortar bed, the units 50a are provided with support feet 51 which rest on the uppermost course of the wall (not shown). The upper surface of the unit 50a is curved, so as to direct rainwater entering the joints between units 50b laterally to either side of the wall. Other top surface profiles for the unit 50a are readily possible, for example directing water to only one side of the wall, or in differing proportions to either side of the wall. The unit 50a has upstanding ribs 55 at both longitudinal ends, to prevent water from running off those ends and onto the top surface of the wall. The entire top surface of the unit 50a between the ribs 55 thus may be regarded as a channel. However, the upper surface of the unit 50a is further provided with transverse grooves 57 which also help to direct water laterally to either side of the wall. The undersurfaces of the units 50a, 50b are (apart from the support feet 51) generally flat. The units 50a, 50b are respectively provided with partly embedded strips 58a, 58b configured and arranged similarly to the strips 48 shown in Figures 5 to 8, to act as drip edges that prevent water droplets clinging to the unit undersurfaces from running inwards and wetting the faces of the wall.

Numerous variations and modifications are readily possible within the scope of the claims. For example, the different features of the various embodiments may be combined in ways not specifically illustrated. For example, the various drip edge features may be interchanged, or replaced with others such as drip channels. Likewise the different underlying portion upper surface profiles may be interchanged or replaced with others not shown. A series of ridges may be positioned between the channel end termination and the adjacent wall face in use. The ridge may comprise a projection formed between a pair of generally parallel channels. The unit 50a may be as wide as the unit 50b shown in Figures 9 to 11, so that the channels terminate at the side faces of the units, somewhat as shown in Figures 1 to 4.

The coping units of the invention provide improved resistance to damp penetration into the top of an associated wall, and therefore allow the usual damp proof course to be dispensed with. Prior masonry copings drip at the joints between units, which is precisely where drip shedding features such as drip grooves are absent. The underlying wall is therefore subjected to concentrated wetting adjacent to the coping joints. The masonry and/or mortar in these regions becomes eroded after repeated wetting/drying freezing/thawing cycles and can eventually allow damp penetration of the wall. The present invention, by effectively preventing rainwater from reaching the upper course of masonry in the wall, including at the joints between adjacent coping units, avoids these problems.

Claims

1. A coping unit comprising: a portion configured to underlie an adjacent coping unit to form a lap joint; a channel formed on the upper surface of the underlying portion and arranged to direct rainwater penetrating the lap joint laterally of the unit towards an end termination of the channel, and a ridge depending from an undersurface of the unit configured to form a drip point or edge; characterised in that the ridge is positioned in use between the end termination and a face of a wall on which the unit is installed, whereby water emerging from the channel falls off the drip point or edge away from the wall face.

2. A coping unit as defined in claim 1, in which the channel terminates at a side face of the underlying portion.

3. A coping unit as defined in claim 1, in which the channel terminates at the undersurface of the underlying portion.

4. A coping unit as defined in claim 3, in which the undersurface slopes upwardly from the channel termination towards the adjacent wall face.

5. A coping unit as defined in claim 3 or 4, in which the undersurface slopes downwardly from the channel termination towards the adjacent outer edge of the unit.

6. A coping unit as defined in any preceding claim, in which the ridge is cast or moulded with the rest of the coping unit.

7. A coping unit as defined in any of claims 1 - 5, in which the ridge comprises an insert secured to project from the undersurface.

8. A coping unit as defined in claim 7, in which the insert comprises a strip that has a projecting edge.

9. A coping unit as defined in claim 8, in which the edge projects outwardly and downwardly from the undersurface.

10. A coping unit as defined in any preceding claim, in which the ridge extends along the entire length of the unit undersurface.

11. A coping unit as defined in any preceding claim, comprising a series of such ridges positioned between the channel end termination and the adjacent wall face in use.

12. A coping unit as defined in any preceding claim, in which the ridge comprises a projection formed between a pair of generally parallel channels.

13. A coping unit as defined in any preceding claim, comprising an opposed pair of the underlying portions.

14. A coping unit as defined in claim 13, in combination with a further coping unit having a recess for accommodating one of the underlying portions.

15. A coping unit as defined in any of claims 1 to 12, comprising a complementary recess for reception of an underlying portion of a similar coping unit.