GB2360811A

GB2360811A - Method of constructing wooden frames

Info

Publication number: GB2360811A
Application number: GB0007947A
Authority: GB
Inventors: Stephen Charles Wright
Original assignee: George Barnsdale & Sons Ltd
Current assignee: George Barnsdale & Sons Ltd
Priority date: 2000-04-01
Filing date: 2000-04-01
Publication date: 2001-10-03
Also published as: GB0007947D0

Abstract

A joint, figure 4, for a wooden frame comprising first and second frame members adapted to be fixed together to form an angled joint which also comprises a wooden corner piece 18 with first and second ends configured for attachment to the adjacent ends of the first and second members. A joint may comprise a wooden corner piece 28, 38, 48 which joins three frame members, fixed together to form a T-joint. A joint may also comprise a wooden corner piece 58 which joins four frame members, fixed together to form an X-joint. These corner pieces may be made from a single piece of wood so that when in place there is substantially no exposed end-grain. The ends of the frame members may be butt-jointed to the respective corner piece and this may be such that the mating faces of the corner piece and members have closely spaced grooves. A wooden frame consisting of members defining a rectangle or square, figure 5, may incorporate a plurality of these three types of joint. A method of constructing a wooden frame in which at least two wooden frame members are joined to one another by a wooden corner piece. The ends of the corner piece may have substantially the same profile as the ends of the frame members it is fixed to.

Description

2360811 METHOD OF CONSTRUCTING WOODEN FRAMES

Field of the Invention

This invention relates to the construction of wooden frames, such as used for doors and/or windows, especially in the construction industry.

Background to the Invention

In the area of traditional wooden door and window frames, one of the most troublesome aspects of using a "living" medium is that of water penetration into the end-grain of the profiles or mouldings used in the assembly of a frame.

In the past, the moulding destined to become the cill of a window or the threshold of a door would be a continuous, horizontal strip to which would be attached the upright members, ie the stiles or mullions, of a door or window respectively. These uprights would be attached to the upper surface of the horizontal frame member. As a consequence, the ends of the horizontal member would be exposed to the elements.

Water in the form of rain or run-off from other parts of the building in which the win dow was fitted would enter the end-grain of the horizontal member and, over a period of time, would eventually lead to rotting and decay of the wood, unless other costly and/or time-consuming measures were taken to minimise water ingress.

More importantly, there would be exposed end-grain within the joint itself that could not be treated by the application of a water-proof barrier, such as paint or var nish. In the above case, the bottom ends of the uprights would be purely end-grain and would merely be butted against the top surfaces of the cills.

The same situation could apply to the head or upper horizontal member of a frame, in which the tops of the uprights would be joined to the undersides of the head.

One way of tackling this problem was to attach the uprights to the horizontal frame members by means of a comb joint. A typical example of such a joint is illus trated in Figure 1 of the drawings. As the name implies, both parts of the joint would be formed, eg by hand or by machining, with a series of teeth 1, as in a comb. The size and spacing of the teeth was such that when the two parts were fitted together, the teeth would inter-fit to form a strong joint in which the surface area of the end-grain at the ends of the horizontal member was considerably reduced compared to the basic butting together of the uprights on top of the horizontal members in the earlier joints mentioned above. However, there still remained the problem that, within the joint, there were surfaces consisting entirely of end-grain which could not be reached once the joint had been made. Decay through water ingress was inevitable unless those sur faces had been specially treated beforehand, thereby adding to costs.

With the advent of more complex profiles for the members making up the frame, the act of cutting the comb joints itself became far more complex A partial solution to this problem was seen in the development of jointcutting machines which were capable of producing elaborate joints which were designed to cut down on the amount of end-grain exposed. A typical example of such a joint is shown in Figure 2. It can be seen that the joint is essentially a comb joint but the spacing and size of the teeth has been adjusted from the regular array in Figure 1 to one which takes account of the relative size and strength of the cross-sections of the component parts, based on their respective profiles.

A variation in the construction of corner joints for frames was contemplated for wooden frames. This variation, as shown in Figure 3 of the drawings, makes use of a simple mitre joint but with a significant exception. As can be seen in Fig 3, the horizon tal and upright members are mitred along surfaces 4 and 5 and those surfaces are formed, eg by machining, with a parallel array of grooves, notches, striations etc 6. This form of joint is termed a finger mitre joint. When the two parts are brought together, there is virtually no end-grain exposed in either part and the use of modern, strong ad hesives on the faces of the mitres means that there is little or no opportunity for the ingress of water. The relatively large area of the surfaces 4, 5 means that adhesive in the grooves etc 6 occupies a correspondingly large surface area and leads to a very strong joint.

The major hurdle with this kind of joint is that it cannot readily be adapted for use with the kind of complex profiles used in making frames since the profiles of the uprights and the horizontals are different and their mitred surfaces would not conform with one another.

Sumrnary of the Invention Accordingly, the invention resides in a new style of joint which overcomes the problems of water penetration into end-grain but without costly and/or time-consuming machining of complex joints and without requiring much skill from the average fabrica5 tor.

To this end, in one aspect the invention provides a joint for a wooden frame, comprising a first frame member and a second frame member adapted to be fixed together to form an angled joint, the joint further comprising a wooden corner piece having first and second ends configured for attachment to the adjacent ends of the first and second frame members.

In a second aspect, the invention provides a joint for a wooden frame, compris ing a first frame member, a second frame member and a third frame member adapted to be fixed together to form a T-joint, the joint further comprising a wooden corner piece having first, second and third ends configured for attachment to the adjacent ends of the first, second and third frame members.

In a third aspect, the invention provides a joint for a wooden frame, comprising a first frame member, a second frame member, a third frame member and a fourth frame member adapted to be fixed together to form an X-joint, the joint further com prising a wooden corner piece having first, second, third and fourth ends configured for attachment to the adjacent ends of the first, second, third and fourth frame members.

Each of the said corner pieces is preferably made from a single piece of wood such that, when in place, there is substantially no exposed end-grain.

In a corner joint according to the invention, the ends of the frame members are preferably butt-jointed to the respective corner piece.

In this case, the butt-joint is preferably of the kind in which the mating faces of the ends of the frame members and of the corner piece are provided with closely spaced grooves in the manner of a finger joint.

The frame may consist of an upper and a lower horizontal frame member and a left and right upright frame member, the said members defining a rectangle or square, and four corner pieces as aforesaid placed at the corners of the frame and joined to the respective ends of the adjoining frame members.

Where a frame according to the preceding paragraph has a further horizontal frame member located between said upper and lower horizontal frame members, said left and right vertical frame members are each subdivided into respective upper and lower sections, and two additional corner pieces of generally T-shape are interposed between the adjacent ends of the upper and lower subdivided sections and the adjacent end of the further horizontal frame member.

Where a frame according to the next preceding paragraph but one has a fur ther vertical frame member located between said left and right vertical frame mem bers, said upper and lower horizontal frame members are each subdivided into respec tive left and right sections, and two additional corner pieces of generally T-shape are interposed between the adjacent ends of the left and right subdivided sections and the adjacent end of the further vertical frame member.

Where a frame comprises at least one further horizontal frame member and at least one further vertical frame member according to both of said preceding para graphs, each of said further frame members is subdivided into two respective sections and a yet further corner piece of cruciform shape is interposed between the ends of the respective said subdivided sections.

The invention also provides, in a further aspect, a method of constructing a wooden frame in which at least two wooden frame members are joined to one another by means of a wooden corner piece.

Preferably, the ends of the corner piece have substantially the same profile as the ends of the frame members to which it is attached.

The method may be applied to frames having a variety of shapes and sizes and may include doors, windows etc with one or more openings. For example, the method can be used to make window frames with mullions and transoms or door frames de signed to accommodate more than one door.

Brief Description of the Drawings

The invention is best understood by reference to the Figures of the Drawing in which:

Fig 1 shows a typical comb joint; Fig 2 shows a comb joint between an upright and a horizontal frame member; Fig 3 shows a finger mitre joint; and Fig 4 shows a joint in accordance with the invention for location between an up right and a horizontal frame member Fig 5 shows the application of the invention to a window having several lights.

Detailed Description of the Illustrated Embodiments

Referring first to Fig 2, a comb joint is illustrated between a horizontal member 7 and an upright member 8. The members 7 and 8 are shown in section as indicated by the broad arrows 16 and 17 but section lines have been omitted for the sake of clarity.

The member 7 could be the cill of a window frame or the threshold of a door frame. It should also be noted that the same type of joint would occur at the upper end of a frame where the upper ends of the uprights would be joined to a horizontal frame member forming the head of the door or window.

It can be seen that there are many grooves and channels, such as indicated at 9, 10, 11 and 12 in one or other of the frame members, which serve essential purposes in the frame. Typical examples would be channels for glazing bars or beads and for draught-excluding devices When further grooves are cut into the ends of the frame members by a cutting machine in order to produce the typical comb joint as previously discussed with reference to Fig 1, it can be seen that there are three major areas 13, 14 and 15 at the end of the lower, horizontal member 7 where the end-grain is exposed.

There will also be corresponding areas at the underside of the upright members where the end-grain will likewise be exposed. Moreover, within the joint there are inevitably passageways which are not visible from the outside and which are, therefore, not acces sible from outside, Consequently, they cannot be protected by paint, varnish or the like but they are nevertheless open to water ingress. Where these surfaces consist of end grain, water is more likely to be drawn into the joint by capillary action.

Turning now to Fig 4, in the embodiment illustrated, the comb joint of Fig 2 is replaced by a single corner piece indicated generally at 18. The corner piece is substan tially identical in outer appearance to the comb joint of Fig 2 but, instead of being cre ated by machining the ends of the members 7 and 8 in Fig 2, the corner piece according to the invention is made from a single piece of wood. The corner pieces may best be manufactured by plural axis CNC machines. The ends 19, 20 of the corner piece are intended to be butt-jointed to the mating ends of the adjoining frame members 7, 8, not shown in Fig 4. When the joint is complete, there is substantially no end- grain of any of the frame members or the corner piece actually exposed to water ingress and clearly there is no internal exposed end-grain.

In order to make as strong a joint as possible, the end faces 19, 20 of the corner piece and of the adjoining frame members are preferably formed with closely spaced grooves such as those marked 6 in Fig 3. The pieces can then be assembled and held together with adhesive which runs into the grooves and occupies a large enough surface area to form a very strong joint.

Thus far, only relatively simple square or rectangular frames have been under consideration. However, there is no reason why the same principles of construction cannot be applied to frames which either do not have rectangular corners and/or whose precise orientation does not fit the terms "upright" and "horizontal" as used in this specification. In such cases, it is intended that the invention will cover such ar is rangements, provided there is a corner piece which is used to join two or more frame members to one another.

Referring now to Fig 5, there is shown an example of a window design which in cludes a transom 21 and two mullions 22 and 23. In this example, respective corner pieces 18 are provided at each corner of the frame. The corner pieces 18 at the bot tom would be of the same configuration as that shown in Fig4 whereas those at the top would be configured to match the profile of the head 24 and the sides 8.

Where the mullions meet the head and the cill, a variation of the corner piece is provided, generally indicated at 28 and consisting of three limbs in the shape of a letter T. The main limbs of the T are configured to match the respective ends of sections 7a, 7b, 7c of the horizontal cill member 7 whilst the branch limb is configured to match the lower end of an upright, mullion frame member 22 or 23 as appropriate. A similar construction is applied to the joints between the upper ends of the mullions 22, 23 and the horizontal sections 24a, 24b, 24c of the head frame members, except that the T pieces 38 will be configured to match the upper ends of the mullions 22, 23 and the sections 24a, 24b, 24c of the head 24.

Similar T-pieces 48, matching the profiles of sections 8a, 8b, of the side uprights and of sections 21 a and 21 c of the transom 21 are used to join together the sides 8 and the transom 21. Where the mullions 22, 23 and the transom 21 cross, corner pieces 58 of generally cruciform shape are interposed between the sections 22a, 22b of the mullions 22 and sections 21a, 21b, 21c of the transom 21. The ends of the corner pieces 58 are configured to match the ends of the sections of the transom and the mul lions to which they are joined.

It will be appreciated that the cill and head are no longer constructed from a sin gle piece of appropriate profile but are now constructed from individual sections joined to one another through the various designs of corner pieces shown and discussed above Of course, as many difFerent configurations of corner piece as are necessary to create the intended window design will be provided and joined to the appropriate num ber and size of the various frame sections constituting the frame edges and any of the frame sections making up the final design.

The invention thereby provides a modular system for constructing wooden frames. Although the description has concentrated solely on door and window frames, the same principles of construction may be applied to other environments where frames are required to be made.

Claims

1. A joint for a wooden frame, comprising a first frame member and a sec ond frame member adapted to be fixed together to form an angled joint, the joint fur ther comprising a wooden corner piece having first and second ends configured for at tachment to the adjacent ends of the first and second frame members.

2. A joint for a wooden frame, comprising a first frame member, a second frame member and a third frame member adapted to be fixed together to form a T joint, the joint further comprising a wooden corner piece having first, second and third ends configured for attachment to the adjacent ends of the first, second and third frame members.

3. A joint for a wooden frame, comprising a first frame member, a second frame member, a third frame member and a fourth frame member adapted to be fixed together to form an X-joint, the joint further comprising a wooden corner piece having first, second, third and fourth ends configured for attachment to the adjacent ends of the first, second, third and fourth frame members.

4. A joint according to any of the preceding claims, wherein each of the said corner pieces is made from a single piece of wood such that, when in place, there is substantially no exposed end-grain.

5. A joint according to Claim 1, wherein the ends of the frame members are butt-jointed to the respective corner piece.

6. A joint according to Claim 5, in which the butt-joint is of the kind in which the mating faces of the ends of the frame members and of the corner piece are provided with closely spaced grooves in the manner of a finger joint.

7. A wooden frame incorporating a plurality of joints according to any of the preceding claims, wherein said frame consists of an upper and a lower horizontal frame member and a left and a right upright frame member, the said members defining a rectangle or square, and four said corner pieces located at the corners of the frame and joined to the respective ends of the adjoining frame members.

8. A frame according to Claim 7, having a further horizontal frame mem ber located between said upper and lower horizontal frame members, wherein said left and right vertical frame members are each subdivided into respective upper and lower sections, and wherein two additional corner pieces of generally T-shape are interposed between the adjacent ends of the upper and lower subdivided sections and the adjacent end of the further horizontal frame member.

9. A frame according to Claim 7, having a further vertical frame member located between said left and right vertical frame members, wherein said upper and lower horizontal frame members are each subdivided into respective left and right sec tions, and wherein two additional corner pieces of generally T-shape are interposed be tween the adjacent ends of the left and right subdivided sections and the adjacent end of the further vertical frame member.

10. A frame according to Claims 8 and 9, having at least one said further horizontal frame member and at least one said further vertical frame member, wherein each of said further frame members is subdivided into two respective sections and a yet further said corner piece of cruciform shape is interposed between the ends of the re spective said subdivided sections.

11. A method of constructing a wooden frame in which at least two wooden frame members are joined to one another by means of a wooden corner piece.

12. A method according to Claim 11, wherein the ends of the corner piece have substantially the same profile as the ends of the frame members to which it is at tached.

13. A joint for a frame substantially as described with reference to Figures 4 and 5.

14. A frame incorporating a joint substantially as described with reference to Figures 4 and 5.

15. A method of forming a frame substantially as described with reference to Figures 4 and 5.

16. A method of forming a frame incorporating a joint substantially as de scribed with reference to Figures 4 and 5.