GB2067229A

GB2067229A - A structural assembly having a water-seal element in a joint

Info

Publication number: GB2067229A
Application number: GB7837380A
Authority: GB
Original assignee: Radway Plastics Ltd
Current assignee: Radway Plastics Ltd
Priority date: 1978-09-19
Filing date: 1978-09-19
Publication date: 1981-07-22
Also published as: GB2067229B; GB2030191B; GB2030191A

Abstract

The assembly comprises a water- pervious structural element such as a brick or concrete wall, and a frame of timber, metal or plastics material butted up to the structural element with a water seal element (Fig. 1) engaging between the frame and the structural element. The water seal element comprises a strip of water- impermeable material such as extruded plastics material having a part which enters the joint between the frame and the structural element, and also having a rib 22 along a longitudinal edge of the joint-entering part, this rib bridging and sealing the joint on the outside of the assembly. The part of the water seal element which enters the joint may be a membrane 20, and may have flange(s) 24, 26 projecting therefrom. Applications Nos: 37394/78 and 37379/78 are referred to. <IMAGE>

Description

SPECIFICATION A structural assembly Wherever a window or door frame is fitted into an outside wall of a building mastic pointing is required to protect the joints between the frame and the surrounding water-pervious structural elements. The expression "water-pervious structural elements" is used herein to describe building bricks or blocks, with any mortar used between them, solid concrete, timber or plaster walls. The mastic used sometimes comprises a resin mixed with linseed-oil, which is usually applied with a special mastic trowel, but more often nowadays comprises a synthetic plastics material, which has the property of retaining its elasticity for a long period, and which is generally applied by squeezing from a gun.

Mastic pointing is a tedious operation and is quite expensive because it has to be carried out after all other building operations (except painting) have been completed, and frequently involves working from ladders or scaffolding. Moreover, the operation requires skilled operatives, and if the synthetic plastics material is used by ejecting it from a gun, it is difficult to obtain a neat appearance. It is the primary object of the present invention to provide a structural assembly which obviates the need for mastic pointing with its attendant disadvantages.

According to this invention a structural assembly comprises a water-pervious structural element (as herein defined) having a surface on the outside of the structure and a frame of timber, metal or plastics material butted up to the structural element with a water seal element engaging between the frame and the structural element, the water seal element comprising a strip of water impermeable material having a part which enters the joint between the frame and the structural element, and also having a rib along a longitudinal edge of the joint-entering part, this rib bridging the joint on the outside of the assembly to provide a water seal protecting the joint.It will be appreciated, that the water seal element is fitted during construction of the assembly, and in fact, as will hereinafter appear, it will normally be fitted by the bricklayer in the same way that he would fit a damp-proof course. Once fitted however, the water seal element carries out the function of the mastic seal, and hence mastic pointing is no longer required.

Preferably, the part of the water seal element which enters the joint is a membrane. In a preferred construction, at least one flange projects from a face of the membrane, so that the membrane and flange splay apart in the joint or on the inside of the joint, to provide an additional barrier against moisture travelling through the joint.

According to other preferred features of the invention, the rib of the water seal element is of hollow cross-section, and it may be of hollow cylindrical form. It is to be understood however, that the shape of the rib is immaterial, so long as it forms an effective seal between the frame and the water-pervious structural element, in the assembly.

The water seal element may be made of plastics material, such as the plastics materials used for the manufacture of damp-proof courses (e.g. polyethylene). If the water seal element is made of plastics material, it may conveniently be formed by an extrusion process. Several structural assemblies each in accordance with the invention, will now be described by way of examples only, with reference to the accompanying drawings, in which:: Figure 1 isba transverse section through a water seal element, Figure 2 is a horizontal section through a structural assembly comprising a cavity wall adjacent to a window frame opening, Figure 3 is a view similar to Figure 2, but showing an arrangement in which the window frame bridges the end of the cavity, Figure 4 is a view similar to Figure 3, but showing an alternative arrangement of the window frame, Figure 5 is a transverse section through another form of water seal element, being regarded as a single flange projecting from the membrane.

Referring now to Figure.2, there is shown part of a cavity wall of a building, which has an outside leaf 30 and an inside leaf 32, with a cavity 34 between them. In this particular arrangement, it is assumed that the inner and outer leaves of the wall are made from building bricks joined by mortar, and that the building bricks are of standard metric dimensions. In that case, the cavity 34 will usually be about 50 mm wide. It is to be understood however, that the invention is equally applicable to other types of wall construction, for example walls formed by pouring concrete.

The end of the cavity adjacent to a window or door opening has to be closed, by fitting T and T cut bricks, in adjacent courses of the inside leaf, these cut bricks being laid transversely of the wall, so that they project across the end of the cavity as indicated at 36. A standard vertical damp-proof course 38 has to be fitted between the outside leaf 30 and the closure bricks 36, in order to prevent moisture travelling from the outside leaf, which by virtue of its water-pervious nature, may be quite damp, to the inside leaf. If water does cross from the outside leaf to the inside leaf, then it usually forms damp patches on the plaster inside the building, and the only way of dealing with this problem is to dismantle the part of the wall where the damp is appearing, and to remove any mortar which is creating a moisture bridge.

The damp-proof course 38 essentially comprises a strip of bitumen impregnated felt, or a strip of polyethylene. A more precise explanation of the method of closing the end of a cavity in a cavity wall, is found in the specification of our copending United Kingdom Patent Application No. 37394/78. However, this method of closing the end of the cavity wall is entirely conventional.

The stile of a timber window frame is indicated at 40 and whilst in general, this abuts against the end of the outer leaf 30, it will be noted that in fact it bridges the joint in which the damp-proof course 38 is fitted, and extends slightly onto the closure bricks 36. Plaster 42 is normally applied to the inside reveal of the window opening, and the window frame has to bridge the end of the joint in which the damp-proof course 38 is fitted, in order to ensure that the plaster 42 does not extend on to the outside leaf 30 of the wall. This is to ensure that moisture cannot travel from the waterpermeable outside leaf 30, directly into the plaster 42.

It will be appreciated however, that it is necessary to take steps to ensure that there is no ingress of moisture through the joint between the stile 40 and the outside leaf 30. Some architects specify that a vertical damp-proof course should be fitted in this joint, to protect the window frame itself from moisture in the outer leaf, but whatever form of jointing is used, it is invariably required to form a mastic-pointing across the corner between the outer face 44 of the stile 40, and the end face 46 of the outside leaf 30. In the present arrangement however, it will be noted that the water seal element shown in Figure 1 has been fitted in the joint between the stile 40 and the outer leaf 30.

When the wall has been built-up to a position at which the window frame can be fitted, a piece of the water seal element equal in length to the total height of the window frame (i.e. the length of the stile plus the depth of the head and the depth of the sill of the window frame) is cut-off, and this strip is applied to the end face of the window frame which butts the end face 46 of the outer leaf, and secured thereto by nails 48. The tubular rib 22 is pressed against the outer face 44 of the stile during fitting of the water seal element, and this has the effect of correctly locating that element on the window frame. The flange 26 will be pressed towards the plane of the membrane 20, but by virtue of its resilience will tend to press against the end face of the stile 40.In fact, as illustrated in Figure 2, this flange 26 will probably enter the vertical groove 50 which is almost invariably provided in the stile of a timber window frame. It will be appreciated therefore, that the rib 22 acts as a water seal, to prevent the ingress of water between the water seal element and the stile 40, and if any water manages to pass the rib 22, it then has to creep by capillary action between the membrane 20 and the stile 40, and furthermore it has to pass the region where the flange 26 is pressing against the stile 40.

When the water seal element has been secured to the window frame, the latter is offered up to the wall, and then the wall is built-up with the window frame in position. Since there is an almost negligible gap between the stile 40 and the end 46 of the outer leaf (this gap has been exaggerated in the drawing) the rib 22 will be pressed tightly against the face 46 of the outer leaf, and indeed the rib 22 may well be placed under slight compression. Furthermore, the flange 24 by virtue of its resilience will tend to press tightly against the end face 46. Thus, a seal is formed preventing the ingress of water between the outer leaf 30 and the membrane 20, by the rib 22, and if any water manages to pass this seal, it still has to pass the secondary seal formed by the flange 24 pressing against the end 30.In other words, a quite effective water seal is formed in the corner between the face 44 on the stile 40 and the end face 46 on the outer leaf of the wall, which protects the joint between the window frame and the outer leaf, in exactly the same manner as mastic-pointing. Since the rib 22 has an appearance which is aesthetically acceptable, in the finished building - and indeed due to its smooth nature will be superior in appearance to most mastic-pointing - there is no necessity for any pointing operation across this joint.

Furthermore, the water seal provides a secondary seal due to the operation of the flanges 24 and 26, which would not normally be provided by masticpointing.

It will be appreciated, that the water seal element is also fitted across the top of the head of the frame, and under the sill of the frame, so that there is all round protection of the joints between the window frame and the surrounding waterpervious structural element, which is at least as effective as that which would be provided by mastic pointing in these areas.

In an even simpler form, which is not illustrated, the water seal element could simply comprise the membrane 20, and the rib 22. In that case, the rib 22 would still provide the mastic seal effect, but there would be no secondary sealing effect as provided by the flanges 24 and 26.

Turning now to Figure 3, there is illustrated a modified structural assembly, in which there is an outer leaf 60 and an inner leaf 62, with a cavity 64 between them. In this case, the inside leaf extends further into the window opening than the outside leaf, forming an outer reveal. The window frame is fitted into the reveal, the stile of the frame being shown at 66. The inside face 68 of the stile abuts against the outer face 70 of the inner leaf 62, but the outer portion of the stile 68 abuts the end face 72 of the outer leaf 60. It will be seen that the stile 68 completely bridges the end of the cavity 64, and because of this, it is unnecessary to close the end of the cavity by the use of cut T and T bricks.

With this construction, which is known, it is still necessary to provide mastic-pointing in the corner between the outer face 74 of the stile 68 and the end face 72 of the outer leaf 60 in order to prevent moisture passing through the joint between the stile 68 and the outer leaf 60 and then travelling across the stile to the inner leaf. However in this construction, the mastic-pointing is replaced by the water seal element of the type shown in Figure 1, which is secured to the stile 68 by nails 76, in exactly the same manner as described with reference to Figure 2. When the window frame is in position, the rib 22 acts to prevent ingress of water into the joint between the window frame and the outer leaf of the wall as described with reference to Figure 2, and the flange 26 is pressed against the stile of the window frame as previously described.In this construction however, the flange 24 is pressed against the inside corner of the outer leaf 60, part of the flange actually entering the cavity 64.

Figure 4 illustrates another cavity wall construction adjacent to a window frame opening, in which there is an outer leaf 80 and an inner leaf 82, with a cavity 84 between them. In this construction however, the outer leaf 80 projects further into the window opening than the inner leaf 82, so that an inside reveal is formed, and the window frame is fitted into this inside reveal, the stile of the frame being shown at 86. Part of the stile abuts the end of the inside leaf 82, and part of its outer face 88 abuts the inside (cavity) face of the outer leaf 80. Again, instead of using masticpointing, the water seal element illustrated in Figure 1 is used, but in this construction, the membrane 20 is nailed to the outer face 88 of the stile 86, in a position such that the rib 22 forms the required seal in the corner between the outer face 88 and the end face of the outer leaf 80.The membrane 20 passes through the joint formed between the face 88 and the inside face of the outer leaf, and the flanges 24 and 26 engage respectively against the inside face of the outer leaf, and the corner of the stile 86 which is in the cavity 84. Again therefore, it will be seen that the mastic-pointing is obviated by the water seal element, and that in addition there are moisture barriers presented by the flanges 24 and 26. It will also be understood, that with both the constructions illustrated in Figures 3 and 4, the water seal element is used across the heads and under the sills of the window frames as described with reference to Figure 2.

A somewhat more sophisticated water seal element is shown at 110 in Figure 5, and again, this element is formed as an extrusion in plastics material, in a similar fashion to that in which the previously described element shown in Figure 1 is produced. In this construction, there is a membrane 112, formed with a tubular rib 114 along one longitudinal edge, but the membrane 112 has an overall width of some 82 mm. There are six flanges 116, 118, 120, 122, 124 and 126 arranged in three pairs as illustrated, and it will be noted that the flanges 124 and 126 have their roots coinciding with the longitudinal edge of the membrane 112 which is opposite to the rib 114.

Referring now to Figure 6, there is illustrated a wall comprising an outer leaf 130 and an inner leaf 132 with a cavity 134 between them, there being the usual closure bricks 136. The stile 138 of a standard window frame is illustrated, in the conventional position, i.e. the position illustrated in Figure 2 of the drawings. Furthermore, a conventional bitumen impregnated felt dampproof course 140 is fitted between the inside face of the outer leaf 130, and the end face of the closure bricks 136. All this therefore rrepresents the traditional method of closing the cavity at the end where there is a window opening.

However, during the construction of the building, a length of the water seal element 110 equal to the total height of the window frame is cut-off, and secured to the end of the stile 138 as illustrated in Figure 6. The rib 114 is engaged with the outer surface of the stile 1 38, and thereby provides a location for the water seal element, and nails 116 are used to secure the water seal element to the stile. The flange 122 is bent at right angles, and nailed to the inside face of the stile 138, and the flange 120 is also bent at right angles and fitted into the joint between the outer leaf 130 and the closure bricks 136. The portion of the water seal element on the inside of the flanges 120 and 122 simply extends inwardly of the window frame, and becomes embedded in the plaster 142, when that is applied to the inside of the window reveal.

It will be appreciated that the water seal element 110 illustrated in Figure 5, provides an effective damp-barrier between the outer leaf 130 and the window frame, and a further damp-barrier between the outer leaf and the plaster 142. In additional however, its rib 11 4 provides the necessary joint protecting seal across the corner between the outer face of the stile 1 38, and the end face of the outer leaf 130, so that it is not necessary to apply mastic-pointing in this corner.

Turning now to Figure 7, there is illustrated a structure comprising an outer leaf 150 and an inner leaf 152 with a cavity 154 between them.

The end of the cavity adjacent to a door opening is closed by the usual 4 and 4 closure bricks 156, and in this construction, a bitumen impregnated felt damp-proof course 1 58 provides the vertical moisture barrier between the outer leaf 150 and the closure bricks 156. Up to this point therefore, the construction is entirely conventional. The stile 1 58 of a standard timber door frame is shown in position against the end of the outer leaf 1 50, and it will be observed that the inner face of the stile 1 58 is in the same plane as the inside face of the outer leaf 150. The water seal element 110 is fitted to the stile 1 58, in similar fashion to the fitting of that water seal element to the window frame stile 138 described with reference to Figure 6. However, because the stile of the door frame is wider than that of the window frame, the outer flange 126 has to be bent at right angles and engaged against the inside face of the stile 1 58, and the corresponding flange 124 has to be bent at right angles and fitted into the joint between the outer leaf 150 and the closure bricks 156.

Otherwise, the water seal element 110 is fitted to the stile 158 in the same manner as has been described with reference to Figure 6, and it functions in exactly the same manner as that described with reference to Figure 6.

A still more sophisticated water seal element. is illustrated at 240 in Figure 8, and again this element is extruded in long lengths, in water impermeable plastics material. It will be observed that the water seal element 240 comprises essentially a membrane 242, ribs 244 and 245 extending respectively along the longitudinal edges of the membrane 242 and a series of flanges 246, 248,250, 252,254, 256, 258, 260, 262,264,266 and 268 each of which extends outwardly from a respective face of the membrane 242. It will be observed from Figure 8, that these flanges are in fact arranged in pairs, in similar manner to the flanges described with reference to Figure 5.

All the water seal elements which have been described, are generally quite flexible, and the flanges can be folded flat against the membrane or bent from the position which they occupy as extruded. Clearly, it is also possible to coil the water seal element on itself, as with conventional damp-proof courses. It will be appreciated, that during coiling, the flanges tend to be compressed towards the membrane.

The spacing between some of the pairs of flanges is significant. Thus, between the roots of the flanges 248 and 260 on the one hand and the rib 244 on the other hand, there is a distance of approximately 70 millimetres, which corresponds to the width of the stile of a standard window frame as conventionally used in the United Kingdom. Similarly, the flanges 254 and 266 on the one hand and the rib 245 on the other hand are spaced by a distance equal to the width of a standard window frame stile. The distance between the roots of the flanges 250 and 262 on the one hand and the rib 244 on the other hand, is approximately 82 millimetres, that is to say it is equivalent to the width of the standard door frame stile used in the United Kingdom.Similarly the distance between the roots of the flanges 252 and 264 on the one hand and the rib 245 on the other hand is approximately 82 millimetres. The distance between the rib 244 and the roots of the flanges 246 and 258 is approximately 12 millimetres, and similarly the roots of the flanges 256 and 268 are spaced 12 millimetres from the rib 245. An important feature of the damp-proof course 240 is that it is entirely symmetrical about the plane of the membrane 242, and also about a plane perpendicular to the membrane 242, and passing through the damp-proof course along its longitudinal axis. This is a useful feature of the invention, because it means that no special precautions have to be taken in fitting the water seal element, since it is in no way handed.

Figure 10 illustrates the end of a cavity wall comprising an outer leaf 270 and an inner leaf 272, with a cavity 274 between them, the end of the cavity being closed by a bricks and T bricks as indicated at 276. The stile 278 of a standard timber window frame is shown applied to the end 280 of the outer leaf 270 of the wall, and it is to be noted that in this instance, the inside face of the stile 278 is in alignment with the inner face 282 of the outer leaf 270 (that is the face of the outer leaf which is in the cavity 274). Many builders would prefer this position for a window frame, because it allows the sill of the window frame to overhang the outer face of the outer leaf 270, by a slightly greater distance, than if the window frame is required to bridge the joint between the outer leaf 270, and the closure bricks 276.

The water seal element 240 which has been described with reference to Figure 8, is shown fitted between the stile 278 and the end face 280 of the outer leaf 270, and also between the inside face 282 of the outer lead and the facing end of the closure bricks 276.

During construction of the building, when the courses of the wall reach the level at which the window frame can be fitted, a length of the dampproof course 240 equal to the total height of the window frame is cut off, and secured to the stile 278, and to the ends of the head and sill of the frame, which form continuations of the end face of the stile 278, so that the entire end face of the frame is protected by part of the water seal element 240. The rib 244 is pressed against the outer face of the stile 278, and this provides a means of locating the water seal element 240 relatively to the window frame, this in itself ensuring that fitting can be carried out neatly and accurately. The water seal element is secured to the stile 278 by nails 284 driven through the membrane 242 of the water seal element.The "free" edges of the flanges 246 and 258 will be splayed to some extent from the membrane 242 as is illustrated in Figure 10.

The flange 260 is located in such a position, that it can be bent at right angles to the portion of the membrane 242 which extends along the side of the stile 278, so that it locates on the inside face of the stile 278, where it can be secured by nails 286 driven into the stile. Now this not only ensures that the water seal element is effectively secured to the window frame, it also provides a moisture barrier, between the window frame, and the plaster 288, which is eventually applied inside the reveal of the window opening.

It will be appreciated, that when the water seal element is secured to the stile of the window frame, the remainder of the water seal element will extend inwardly from the stile 278, in continuation of that part of the water seal element which has been secured to the stile. The window frame is then placed in position, and the end of the wall is built-up in the conventional manner, but the part of the water seal element 240 which was extending inwardly from the stile, is bent through 900, and laid against the inside face 282 of the outer leaf 270. The cavity closing bricks 276 hold the water seal element in this bent condition, the mortar squeezed out from between the courses of the bricks in the outer leaf 270 and in the closure bricks 276, will tend to enter the slightly splayed formations provided by the flanges 252, 264 and 254, 266. This assists in keying the mortar to the water seal element.

It will be appreciated therefore, that the water seal element 240 provides the usual vertical damp-proof course required between the outer leaf 270 and the closure bricks 276, and since the membrane 242 extends completely across the width of the closure bricks 276, this damp-proof course should prove very effective. Furthermore, the rib 245 rests against the inside face 282 of the outer leaf 270, and any moisture attempting to cross the cavity 274 from the face 282 of the outer leaf, would have to creep around the rib 245. This is a further barrier to the travel of moisture across the cavity. In addition, the flange 268 is engaged against the inside face 290 of the closure bricks 276, and this provides yet another location for the water seal element.

Besides providing the usual vertical damp-proof course, the arrangement also provides a dampproof course between the stile 278 and the outer leaf 270 of the wall, which as has been previously mentioned is highly desirable. The rib 244 bridges the outer edge of the joint between the outer leaf 270 and the stile 278, and prevents water entering that joint. In this way, the water seal provides a substitute for the conventionally used mastic-pointing. If any moisture does pass the rib 244, it can then only travel inwardly by capillary action. If moisture manages to travel between the membrane 242 and the stile 278, it will have to pass the region where the water seal element is nailed to the stile, which represents a severe barrier, and it will then have to pass the region where the flange 258 is pressed against the stile 278.Following that, moisture will have to traverse the usual groove 292 formed in the stile 278. Any moisture which manages to evade the rib 244 on the wall side of the membrane 242, can do no harm, because it is prevented from reaching the stile 278, or the plaster 288 or the closure bricks 276, by the water seal element itself.

It is also to be noted, that the flanges 248, 250 and 262 provide reinforcing to the damp-proof course, at the position where the latter is bent through 900 in order to provide the three moisture barriers previously described.

As a result of the construction which is shown in Figure 10, the following advantages have been achieved over the traditional constructional methods: (a) The elimination of expensive and inconvenient mastic pointing at the joint between the stile and the end of the outer leaf.

(b) The prevention of cavity bridging by mortar crossing the inner longitudinal edge of the vertical damp-proof course.

(c) The provision of protection for the window frame itself from moisture contained in the outer lead of the wall.

(d) The provision of three moisture barriers, namely (i) that between the outer leaf and the stile, (ii) that between the inner and outer leaves, and (iii) that between the outer leaf and the plaster in a single water seal element.

The water seal element which is illustrated in Figure 8, is quite versatile, because it is possible to fit it in positions where the 900 bend has to be made at the roots of the flanges 250 and 262, in the case of a window or door frame which is wider than that illustrated in Figure 10.

Although the ribs 22, 114 and 244 on the three water seal elements which have been described, are all of cylindrical tube form, it will be appreciated, that any form of rib which provides a protruberance out of the plane of the membrane, and which is capable of forming the bridge required to protect the joint will be satisfactory. An alternative cross-section is illustrated in Figure 9 of the drawings. The membrane 242 is illustrated by way of example, and this has the flanges 246 and 258, and also the tubular rib 244. However, between the rib 244 and the flanges 246 and 258, there is a membrane 294 of tapering crosssection, so that there is a smooth interchange between the thick cross-section of the rib, and the thinner cross-section of the membrane.

The water seal elements illustrated in Figures 5 and 8 of the drawings, are also described in the specification of our co-pending Patent Applications Nos: 37394/78 and 37379/78.

Claims

1. A structural assembly comprising a waterpervious structural element (as herein defined) having a surface on the outside of the structure and a frame of timer, metal or plastics material butted up to the structural element with a water seal element engaging between the frame and the structural element, the water seal element comprising a strip of water impermeable material having a part which enters the joint between the frame and the structural element, and also having a rib along a longitudinal edge of the joint entering part, this rib bridging the joint on the outside of the assembly to provide a water seal protecting the joint.

2. A structural assembly as claimed in Claim 1, in which the part of the water seal element which enters the joint is a membrane.

3. A structural assembly as claimed in Claim 2, in which at least one flange projects from a face of the membrane, so that the membrane and flange splay apart in the joint, or on the inside of the joint, to provide an additional barrier against moisture travelling through the joint.

4. A structural assembly as claimed in any one of Claims 1 to 3, in which the rib is of hollow cross-section.

5. A structural assembly as claimed in Claim 4, in which the rib is of hollow cylindrical form.

6. A structural assembly as claimed in any one of Claims 1 to 5, in which the water seal element is made of plastics material.

7. A structural assembly as claimed in Claim 6, in which the water seal element is formed by an extrusion process.

8. A structural assembly constructed and arranged substantially as herein described with reference to any one of Figures 2, 3, 4, 6, 7 and 10 of the accompanying drawings.