GB2300203A

GB2300203A - A timber-frame panel

Info

Publication number: GB2300203A
Application number: GB9508459A
Authority: GB
Inventors: Luke Richard John Whale; Julian Philip Marcroft
Original assignee: Gang Nail Systems Ltd
Current assignee: Aldershot GNS Ltd
Priority date: 1995-04-26
Filing date: 1995-04-26
Publication date: 1996-10-30
Also published as: GB2300237A; GB9508459D0; GB9608498D0; GB9608496D0; GB2300204A; IE960318A1; GB2300204B

Abstract

A framework panel (10) for use in the construction of a timber-frame building, comprises a plurality of timber members (12-26) connected together to form a substantially rectangular frame, by means of nail plates (28) such that the addition of sheathing is rendered unnecessary. The panel may include at least one inclined bracing member inside the frame for strengthening such that the addition of sheathing is rendered unnecessary. Nail plates of non-rectangular cross section may be used.

Description

A TIMBER-FRAME PANEL The invention relates to a timber-frame panel, particularly but not exclusively to a prefabricated timber-frame wall panel.

Two main methods of wall construction are generally used in the UK: masonry construction and timber-frame construction. In the former, bricks or blocks of masonry are used to construct walls which carry the load imposed by the structure itself and additional loads imposed thereon by external forces such as snow loading, wind loading, etc. In timber-frame construction, a timber-frame is constructed to carry the majority of the weight of the structure and loads imposed thereon, although facings of brickwork, tiles, rendering or other suitable materials can be used to cover the timber framework. However, the vast majority of the loads concerned are carried by the timber-frame and not by the facing.

Prefabricated panels are commonly used in timber-frame construction. The panels generally consist of a substantially rectangular frame having a height of approximately one storey of a building (approximately 2. 4m) and a width which where possible is made a multiple of 0. 6m. This is necessary because vertical studs are required to be located at 0. 6m intervals within the wall to accommodate the fixing of internal wall facing material such as plasterboard sheets. The panel will therefore usually consist of generally horizontal top and bottom members, two upright side members and two or more further upright members usually spaced at intervals of 0. 6m between the upright side members.

A panel consisting purely of the members described above and fixed by nails would have very little in-plane resistance and would be prone to racking or sideways distortion. Also, forces applied to the panel substantially perpendicular to the plane thereof would result in distortion and buckling of the upright members. It is therefore common practice to apply sheathing to one side of the panel primarily to provide resistance to racking but also to prevent torsional instability of the studs acting as beams under wind loads normal to the panel. This increases the panel's ability to carry in-plane and out-of-plane loading.

However, the application of sheathing, which is typically formed from plywood or similar wood-based materials, increases the overall weight of the panel and also adds considerably to the material cost thereof.

Furthermore, the labour costs involved in manufacturing a completed panel with sheathing are substantially higher than the cost of producing an unsheathed panel.

Furthermore a sheathed panel requires the inclusion of a vapour control layer to prevent condensation forming inside the panel. The vapour control layer usually consists of a sheet of plastics material which is awkward to position and is easily punctured which adds to the difficulties of manufacture and transportation.

An unsheathed panel requires no such vapour control layer.

It has long been recognised that it would be desirable to produce a timber-frame panel which does not require sheathing. However, to provide the required strength, the joints of the frame itself require to be strengthened to a significant extent. Various proposals for strengthening the joints have been made, but all require elaborate manufacturing or construction methods and do not substantially reduce the overall cost of the timber-frame panel.

It is an object of the present invention to provide a timber-frame panel which is sufficiently strong to obviate the need for sheathing and which can be manufactured in a simple and cost effective manner.

A first aspect of the present invention provides a panel as set out in claim 1. A second aspect of the present invention provides a panel as set out in claim 2. The invention also provides a method of constructing a timber-frame building as set out in claim 16 and a building comprising a panel according to the invention as set out in claim 19. A third aspect of the invention provides a nail plate for connecting the timber members of a panel according to claim 20. Further improvements and advantageous features are set out in the subsidiary claims.

The first aspect of the invention provides a panel whose timber members are connected together by means of nail plates. It has been discovered that the use of suitably disposed nail plates to connect the timber members together can provide sufficient in-plane strength to resist racking. Also, the strength of the joints, particularly in combination with the provision of transverse timber members, is sufficient to resist any bowing of the upright members when forces are applied to the panel perpendicular to the plane thereof. The need for sheathing is thereby avoided, substantially reducing the cost and overall weight of the panel and obviating the need to spend time applying the sheathing or the vapour control layer during the manufacture thereof. The nail plates are also applied to the joints of the timber-frame only from the planar faces thereof.Insertion of screws, nails, dowels etc.

within the plane of the panel is not required. The timber can therefore be manufactured relatively easily by means of a commonly available automatic pressing machine with reduced labour costs and increased speed.

The same effect can be achieved according to the second aspect of the invention, wherein inclined bracing members are provided inside the substantially rectangular frame of the panel. The inclined bracing provides triangulation of the frame and this triangulation provides resistance to racking and also reduces the risk of bowing of the upright members.

Preferably, the frame and inclined bracing members are connected together by means of nail plates which also increase the in-plane strength of the panel. Sheathing is therefore rendered unnecessary by the provision of triangulating bracing members.

This new application of nail plates to unsheathed timber-frame panels has led to a development in nail plates themselves. To date, nail plates have always been manufactured with a generally rectangular overall shape with the nail projections themselves being pressed out of the sheet metal from which the plate is manufactured. Nail plates of different sizes and different width-to-length ratios are known but nail plates have always been manufactured in rectangular shapes.

It was found during tests carried out on frames as described above and held together by nail plates, that the overall strength and stiffness of the frame could be improved if the nail plates were increased in size so as to provide an increased area of connection between each nail plate and the respective timber member or members.

However, a mere increase in size of the nail plates produced situations wherein sharp corners of nail plates projected beyond the timber members themselves. It was perceived that this would be hazardous during manufacture and subsequent handling and nail plates of different shapes were then contemplated. Nail plates according to the third aspect of the invention were developed.

The invention therefore provides a nail plate which is non-rectangular in overall shape. Preferably, the nail plate has two opposing sides of unequal length.

This is advantageous when connecting timber members at right angles to one another. The side of the shorter length can be placed on one member whilst the side of the longer length can be placed on the second member located transversely thereto. The increase in connecting area could previously only be achieved using a rectangular plate of greater area and therefore cost, which would have sharp corners projecting beyond the timber members and which would be hazardous.

Embodiments of the various aspects of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 is an elevation view of a panel according to a first aspect of the present invention; Figure 2 is an elevation view of an alternative panel illustrating the second aspect of the present invention; Figure 3 is an elevation view of a second embodiment of both the first and second aspects of the present invention; and Figures 4a to 4i illustrate nail plates according to the third aspect of the present invention.

Figure 1 illustrates a timber-frame wall panel according to the first aspect of the present invention.

The wall panel 10 comprises horizontal upper and lower members 12, 14 and upright side members 16, 18. Upright members 20,22 are positioned between the upright side members 16, 18 at regular spacings of substantially 0. 6m. Transverse strengthening members 24,26 extend between the upright members 16 and 20 and between the upright members 18 and 22 respectively.

Each member 12-26 is connected to at least one other member by means of nail plates 28. For the avoidance of doubt, nail plates are substantially planar plates of metal out of which have been pressed a plurality of nail-like projections such that the projections extend substantially perpendicular to the plane of the plate itself. Commonly, the projections extend over substantially the entire area of the plate and are arranged in rows.

One nail plate 28 is provided on either face of the panel 10 at each joint. At each corner joint, ie. at each joint between an upright member 16, 18 and one of the top and bottom members 12, 14, an enlarged plate 28 is provided. This provides additional strength and stability to the panel's corner jointS. In order to avoid a potentially hazardous projecting corner of these plates 28, it is possible to replace these plates with an alternatively shaped nail plate such as those shown in any of Figures 4(c), 4(e) and 4(f). At other joints larger nail plates can be used to add strength and stiffness. These can be replaced by plates such as those shown in any of Figures 4(a), 4(d), 4(g), 4(h) and 4(i).

The panel 10 illustrated in Figure 1 has sufficient strength and stiffness due to the presence of the nail plates 28 to avoid the need for the provision of sheathing. The panel 10 will not rack unduly under normal in-plane loading and the members 12-26 are joined together in a simple and easily achieved manner. The overall cost of manufacturing the illustrated frame is estimated at around 70% of the cost of the present standard sheathed frame.

Figure 2 illustrates a second aspect of the present invention. In Figure 2, a panel 30 is illustrated which comprises top and bottom members 32, 34 and upright side members 36,38. Upright members 40,42 are provided spaced between the side members 36,38 at 0. 6m intervals.

Inclined bracing members 44a, 44b, 44c extend between the junction of the top and upright members 32, 38 and the upright member 42, between the upright members 42 and 40, and between the upright member 40 and the junction between the bottom member 34 and the upright member 36. The bracing members 44a,44b,44c are aligned so as to be colinear with one another. The inclined bracing members 44a, 44b, 44c extend along a diagonal of the frame 30. This bracing member effectively triangulates the frame 30 so as to prevent racking as a result of in-plane forces being applied to the panel.

Depending upon the direction of the in-plane force acting on the panel 30, the bracing members 44a,44b,44c can operate under tension or under compression. Also, further inclined bracing members can be provided; for example, parallel but spaced from the bracing members 44a,44b,44c, or inclined in the opposite direction, ie.

extending along a line joining the top left and bottom right corners of the frame as seen in Figure 2. Where an elongate panel is provided having a width of greater than three or four upright member spacings, a plurality of diagonal bracing members can be arranged within the frame. These diagonals can be arranged substantially parallel or cross bracing can be provided.

As described in connection with Figure 1, each member 32-44c is connected to at least one other member by means of nail plates 46. The presence of the nail plates 46 further increases the strength and stiffness of the panel 30, both in the in-plane direction and the out-of-plane direction. At the junction of the inclined members 44a,44b,44c with the upright members 40,42, different arrangements can be provided. As illustrated at the junction with the upright member 40, an elongate rectangular nail plate extending in the general direction of the inclined members 44b,44c can be provided. A corresponding nail plate 46 will also be provided on the reverse face of the panel 30. However, in order to improve stability and strength still further, a wider nail plate 46a can be provided as illustrated in dotted lines at the junction with the upright member 42.In this arrangement the nail plate 46a is still generally rectangular but it is arranged such that it comes into contact with a greater length of the upright member 42. The arrangement illustrated has the advantage that no potentially hazardous corners project beyond the timber members and the joint between the upright member 42 and the inclined bracing members 44a, 44b is exceptionally strong and stiff.

Alternative shapes of nail plate can be utilised at other parts of the panel 30. A triangular nail plate 46c is illustrated in dotted lines at the junction between the bottom member 34 and the upright member 38.

The size of the triangular nail plate 46c can be varied according to the strength and stiffness requirements.

When a panel 10,30 as illustrated in either of Figures 1 and 2 is to be used in a construction, it is essential that the panel 10,30 is securely anchored to the foundation. Commonly, timber-frame panels have been secured to foundations merely by nailing. It has been found advantageous to use field splice plates located at least at either end of the bottom member 14,34 to secure the timber-frame panel 10,30 to the foundation.

Ideally, the field splice plate which would be used is of considerable size (for example, 0. 15m x 0. 3m) and have nail projections located in substantially half of the area of the field splice plate. These nail projections are used to secure the connector to the panel 10, 30 during prefabrication and the lower half of the field splice plate, which contains a plurality of holes, will then be nailed to the foundation or sole plate fixed thereto during erection on-site.

Figure 3 illustrates an alternative timber-frame panel 50. The panel 50 essentially comprises a top member 52, a bottom member 54 and upright members 56, 58. In this particular embodiment, the top member 52 overhangs the upright members 56,58 and additional upright members and horizontal bottom members 60, 60a are provided so as to render the overall shape of the frame generally rectangular. However, the presence of the upright member 60 and horizontal bottom members 60a are of little structural significance and they can be omitted altogether if desired. This arrangement differs dramatically from known arrangements because substantial side areas previously needed to prevent racking are no longer necessary. This means that windows positioned in the new unsheathed panels can be placed closer to one another or to corners of buildings.

A transverse member 62 extends substantially horizontally between the upright members 56, 58. Upright members 64 extend between the horizontal member 62 and the bottom member 54 at regular intervals of substantially 0. 6m. Inclined bracing members 66 are then located between the upright members 56, 58 and the upright members 64 to provide triangulation of the panel 50.

An opening 68 is located between the upright members 56, 58 and above the horizontal member 62. The opening 68 is suitable for receiving a window frame. Above the opening 68, a second horizontal member 70 is provided and upright members 72 are located between the second horizontal member 70 and the upper member 52 at regular spacings of substantially 0. 6m between the upright members 56,58.

Each of the members forming the frame 50 is joined to at least one other member by means of a nail plate as described above. The presence of the triangulating bracing members 66 and the nail plates 74 gives the panel 50 sufficient strength and stiffness in both the in-plane and out-of-plane directions for sheathing to be rendered unnecessary.

The above specific embodiments have been directed to panels which are of a standard width of substantially 1. 8m in the case of Figures 1 and 2 or 3. Om in the case of Figure 3. However, it will be appreciated that, in some cases, prefabricated panels of greater length are desirable and panels of any practical length or height can be produced. When inclined bracing members are provided, the bracing members can be inclined in either direction and at any desired angle. Preferred angles of inclination are between 35 and 75- but are most effective at around 52-. Also, cross bracing can be introduced and inclined bracing members can also be arranged to overlap with one another.

A panel as described above can be used in the following manner in the construction of a building.

Firstly the panel 10, 30, 50 is manufactured according to the desired specifications. The manufacture can take place at a location remote from the site of construction of the building. The panel 10,30,50 is then transported to the site of construction and positioned in place.

Field splice plates as described above are used to secure the bottom member 14, 34, 54 of the panel 10, 30, 50 to the foundations of the building to hold the panel in place. Additional panels are similarly located and fixed together as required. An outer facing or veneer of brick, tiles or other suitable material is then applied in a known manner.

It has been mentioned above that nail plates of non-rectangular shape can be advantageously used in the construction of timber-frame panels as described above.

A variety of non-rectangular shapes of nail plate are illustrated in Figure 4. These nail plates are advantageously used when two timber members are to be joined to one another at right angles. The nail plates illustrated in Figures 4(a), (d), (g) and (i) are suitable for use at a "T junction"; eg. where a vertical stud meets an upper or lower member or a transverse member meets an upright or vertical member. The nail plates illustrated in Figures 4(c), (e), (f) and (h) are suitable for use at "corner junctions'; eg. where a lower or bottom member meets an upright member. The presence of one side which is longer than the opposing side improves the transmission of forces through the nail plate and also increases the area of contact between the nail plate and at least one of the members to be connected without rendering significant amounts of plate area inutile.

Claims

1. A panel for use in the construction of a timber-frame building, comprising a plurality of timber members connected together to form a substantially rectangular frame, wherein the timber members are connected together by means of nail plates such that the addition of sheathing is rendered unnecessary.

2. A panel for use in the construction of a timoer-frame building, comprising a plurality of timber members connected together to form a substantially rectangular frame, wherein at least one inclined bracing member is provided inside the frame such that the addition of sheathing is rendered unnecessary.

3. A panel as claimed in claim 2, wherein the timber members and the or each bracing member are connected together by means of nail plates.

4. A panel as claimed in claim 2 or 3, wherein the bracing member or members extend over only part of the height of the panel.

5. A panel as claimed in claim 4, wherein the bracing member or members extend over no more than half of the height of the panel.

6. A panel as claimed in claim 4 or 5, wherein the panel incorporates an opening for accommodating a window or door.

7. A panel as claimed in claim 6, wherein the opening is located above the bracing member or members and additional strengthening members are located within the frame above the opening.

8. A panel as claimed in claim 7, wherein the additional strengthening members comprise a transverse member connected to the frame by a plurality of upwardly extending members.

9. A panel as claimed in claim 8, wherein the strengthening members are connected to one another and to the frame by means of nail plates.

10. A panel as claimed in claim 2 or 3, wherein the bracing member or members extend over the entire height of the panel.

11. A panel as claimed in claim 10, wherein a plurality of bracing members are provided, the bracing members being arranged colinearly with or substantially parallel to one another.

12. A panel as claimed in any one of claims 2 to 11, wherein the angle of inclination of the or each bracing member with respect to the horizontal is between 35 and 75-.

13. A panel as claimed in claim 12, wherein the angle of inclination of the or each bracing member with respect to the horizontal is substantially 52-.

14. A panel as claimed in any one of the preceding claims, wherein connectors are provided at the lower region of the frame for connecting the panel to supporting means, the connector comprising a field splice plate.

15. A panel for use in the construction of a timber-frame building substantially as hereinbefore described with reference to any one of the embodiments shown in Figures 1 to 3 of the accompanying drawings.

16. A method of constructing a timber-frame building comprising the steps of: (a) connecting a plurality of timber members together to form a panel according to any one of the preceding claims; and.

(b) positioning the panel in the building without attaching sheathing to the panel.

17. A method as claimed in claim 16, wherein no vapour control layer is positioned adjacent the panel.

18. A method as claimed in claim 16 or 17, wherein the formation of the panel is carried out remote from the site of construction of the building.

19. A building comprising at least one panel according to any one of claims 1 to 15.

20. A nail plate for connecting the timber members of a panel according to any one of claims 1 to 15, wherein the overall shape of the nail plate is non-rectangular.

21. A nail plate as claimed in claim 20, wherein the nail plate has two opposing sides of unequal length.

22. A nail plate as claimed in claim 20 or 21, wherein the overall shape of the nail plate is that of a trapezium, parallelogram or rhombus.

23. A nail plate as claimed in claim 20 or 21, wherein the overall shape of the nail plate is T-shaped or L-shaped.

24. A nail plate as claimed in claim 20 or 21, wherein the overall shape of the nail plate is triangular.

25. A nail plate as claimed in claim 24, wherein the overall shape of the nail plate is that of a right-angled triangle.

26. A nail plate as claimed in claim 24, wherein the overall shape of the nail plate is that of an isosceles triangle.

27. A nail plate substantially as hereinbefore described with reference to any one of the embodiments shown in Figures 4(a) to 4(g) of the accompanying drawings.