Abstract:
A building unit of generally diamond shape which includes flange members along its edges, the flange members adapted to interlock with those of an adjacent unit to construct a building structure for example a dome structure. The units are simple to manufacture and assemble to provide inexpensive domes and other structures.

Description:
SUMMARY OF THE INVENTION 
     The present invention relates to building units, a plurality of which can be assembled to form building structures of various shapes and dimensions. The particular design of the unit is simple and as such, they are inexpensive to manufacture and easy to assemble by unskilled persons. 
     The invention is a building unit which consists of a panel of quadrilateral shape. Upstanding walls extend along the edges of the panel, one pair of walls being simple flanges and the other pair being inverted U-shaped flanges. Although each pair of flanges converge towards each other they remained spaced apart because the apices are truncated. A plurality of these building units can be assembled in horizontal courses to form a structure. The U-shaped flanges engage the simple flanges of a contiguous panel in a lower course while the lower end of a higher panel overlaps the upper end of a panel two courses below. The unit is particularly suitable for the fabrication of dome structures as will be described, although it is contemplated that such units can be utilized in the fabrication of various wall and roof structures. 
     An advantage of the structure is that it is essentially water tight in a rain storm. This is because water is shed from the building units since adjacent ones overlap where assembled. An additional advantage is that in a dome structure, no additional structural members are necessary to provide support. The units themselves may be manufactured from various materials including metal and plastic or fiberglass. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     For the purpose of illustration but not of limitation, embodiments of the invention will be hereinafter described with reference to the drawings, in which: 
     FIG. 1 is a plan view of a building unit according to the invention; 
     FIG. 2 shows a cross-section along line 2--2 in FIG. 1; 
     FIG. 3 shows a cross-section along line 3--3 in FIG. 1; 
     FIG. 4 shows a portion of a structure comprising a plurality of interconnected units; 
     FIG. 5 is a section on the line 5--5 in FIG. 4; 
     FIG. 6 shows a dome structure; and 
     FIG. 7 shows a group of building units prior to assembly. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     As shown in FIG. 1, the building unit comprises a panel 1 of generally diamond shape with a first pair of adjacent edges 2 being of equal length and converging towards a first apex 4 of the panel. A second pair of edges 3 converge towards a second apex 5 which is opposite the first apex 4. Two pairs of upstanding walls 6, 7 are connected to or integral with the panel portion 1 at its edges 2 and 3 respectively. These upstanding walls may be substantially orthogonal to the adjacent portion of the panel or at a small obtuse angle. The upstanding walls 6 are simple flanges which extend the length of the first pair of edges 2. The other two upstanding walls 7 are inverted U-shaped flanges which extend the length of the second pair of edges 3. The cross-sectional shape of the flanges is seen more clearly in FIGS. 2, 3 and 5. 
     As is evident from FIGS. 2 and 3, the walls 6 and 7 are at a small obtuse angle to the adjacent portions of the panel, so that when assembled, contiguous panels are angled with respect to each other as is best seen in FIG. 5. 
     The first apex 4 and second apex 5 are truncated and, as a result, the pair of simple flanges 6 connected to the converging edges 2, approach each other but remain spaced apart at their ends proximal the first apex 4. In the same manner, the inverted U-shaped flanges 7 along the converging edges 3 remain spaced apart at the second apex 5. 
     In the illustrated embodiment, the panel 1 consists of two roughly triangular planar portions 1a, 1b, which are angularly offset about line 8 which joins the points 9 where the first pair of edges 2 meet the second pair of edges 3. Alternatively, the panel portion 1 could be slightly curved. 
     The units are assembled in courses as shown in FIG. 4 to form a dome as in FIG. 6, the U-shaped flanges 7 of a unit in one course engaging the simple flanges 6 of contiguous units in the adjacent course. As seen in FIGS. 2 and 3 the spacing between the walls 7a and 7b of the U-shaped flange corresponds to the thickness of the simple flanges 6 such as to provide a tight interlocking engagement. Fastening means for the mating upstanding walls (e.g. bolts rivets or by welding or otherwise) is also contemplated and is shown in FIG. 5 as bolt 10. In addition, fasteners 10a (FIG. 4) are passed through registering holes 12c, 13 (FIG. 7) in the overlapped apices of the assembled units. 
     For water tightness, it is necessary that the building unit be oriented in such a manner that the apex 5 is lowermost and the simple flanges 6 are above the inverted U-shaped flanges 7. The inverted U-shaped flanges 7 of a unit in one course will engage the simple flanges 6 of contiguous units of the adjacent lower course. At the same time, the lower end portion 19 of panel portion 1 in one course will overlap the upper end portion 18 of a panel portion 1 in the next but one lower course. In the dome type structure shown this overlapping arrangement allows the rainwater to shed from one panel down onto the next panel and not into the joint. Similarly, there is no gap between the flanges presented to water flowing down the lower portion 1b of the panel. The joint gap where the flanges 6 and 7 of contiguous panels overlap, is present along the upper edges of the lower panel and is thus largely protected from rainwater. In the assembled structure, an inverted U-shaped flange 7 always overlies a simple flange 6 and there is little likelihood of rainwater penetrating the overlapped flanges. However, if desired, additional weather-sealing means can be employed between the flanges. 
     In the dome structure, the panels of each successive course are smaller than the preceding lower course in order to provide the convergence of the hemisphere. This is evident from FIGS. 6 and 7. Since the lower edge of the dome is flat, there are triangular gaps between the units 1&#39; of the lower most course. These gaps are filled by triangular shaped building units 11 similar in design to the upper half of a building unit 1 bounded by simple flanges 6 and line 8. Thus the triangular unit 11 (FIG. 7) has inclined edges bearing simple flanges 6c and apex 4c with a hole 12c therethrough. The lower edge of the unit 11 is strengthened by an angled flange 15 forming a base for the dome. A simple circular cap 14 can seal the top of the dome structure. 
     The lower apex 5&#39; of each building unit 1&#39; of the lowest course has an extension 16 of a shape corresponding to that of the flange 15. In the assembled condition the extension 16 overlaps the gaps between the flanges 15 of adjacent units 11 and prevents the egress of rainwater. Suitable fastening means (not shown) may be provided to secure the extension 16 to the flanges 15. 
     As has been discussed, the cooperating configuration of the U-shaped flanges 7 and simple flanges 6 prevents entry of water into the joints between the building units. To enhance this weather-proofing, the lower end of each U-shaped flange 7 has a curved flared extension 17 as seen best in FIG. 4. In the assembled condition the flared extension overlaps the upper edge of the flange 7 of the contiguous building unit of the adjacent lower course, thus preventing entry of water at that point. Similarly, as is also shown in FIG. 4, the lower apex of the unit has an extension 19 to increase the degree of overlap and weather-proofing at this location. 
     A major advantage of the building unit as described above is that it is capable of being assembled into self-supporting free-standing structures such as the dome shown in FIG. 6 without the need for any additional supporting or bracing structure other than the building units themselves. By suitably selecting the dimensions of the units, domes of any size can be constructed, but only in domes of the largest sizes or those subject to abnormal loading conditions would any additional bracing be required. The dome as described herein derives its strength from the configuration of the mating flanges 6 and 7. Thus, while the unit 1 may be fabricated by bending and folding from light gauge sheet metal, such as aluminum, steel etc, the overlapped flanges form a series of zig-zag strengthening ribs extending up the wall of the dome, and resisting deflection of the dome structure. This strengthening effect is enhanced by the provision of fastening means securing together the overlapped flanges. Any suitable fastening means may be employed for this purpose, for example nut-and-bolt fasteners or where the dome is not intended to be dis-assembled after erection, more permanent fastening means such as rivets or spot or seam welding. 
     While in the above described example the building units are fabricated in sheet metal, it will be evident that other materials can be employed, and that numerous details of the structure of the invention can be modified, within the scope of the appended claims. Thus the building units 1 could be fabricated by moulding in plastics, glass fibre or other suitable material. Particularly when formed by moulding, the units could be formed with panels which are spherically curved rather than, as shown, with two flat triangular sections 1a, 1b. 
     Furthermore, the dome could be provided with doors, windows etc. by replacing or modifying various units or groups of units. The surface of the dome can be covered with various coatings such as plastic or paint. Insulation can also be applied either by affixing it directly onto the surface or by blowing it between the outer surface of the dome and a plastic or other covering over the dome.