CEILING

Abstract: A ceiling construction, which comprises one or several layers (5, 7) of a heat insulating and sound absorbing material as well as a false ceiling (6), which is a stretched fabric, which conceals said heat insulating material and means (3) for suspending said material and which fabric (6) at the same time permits high as well as low frequency sound to pass into said layers (5, 7). These properties of the fabric are attained by giving its loop holes a specified side size and a specified total area. The fabric is suitably made of artificial fibers and is treated with a fire suppressing coating.

Description: CEILING -The present invention " relates to a ceiling construc¬ tion above a heated room in a building. The ceiling con¬ struction comprises a heat insulation means, which consists of at least two layers of a heat insulation material, the layers being placed on top of each other, but also a dif¬ fusion barrier and a false ceiling in the shape of a fabric. The heat insulating layers of known ceiling constructions ordinarily are strongly sound-absorbing. However, it is customary to cover the heat insulating layers with a false ceiling or a decorative surface layer, partly to conceal them, since they usually do not have a pleasing surface, and partly to keep them in place between the beams. Ceilings with perforated metal bays are also known, the bays holding heε.t insulating layers. Examples of known decorative suf- face layers, which have been used to conceal heat insula¬ ting layers, are perforated fiber boards and gypsum boards, mounted on spaced boards, as well as stretched fabrics or sheets, woven or non-woven, of celluiose or -a plastic mate¬ rial. However, such false ceiling materials usually are not satisfactory, because a great portion of the sound generated in the rooms, particularily the high frequency sound, is reflected despite the perforating of the materials and can not be absorbed by the heat insulating layers, which are placed above the false ceiling or the decorative surface layer. It is also known, that a high frequency sound, which has penetrated a ceiling material, readily is reflected by a diffusion barrier, of a plastic material or a impregnated cellulose material which is placed adjacent the ceiling ma¬ terial, and returns through the false ceiling material to the room. The object of the present invention is to improve the sound absorbing capacity and the acoustic qualities of a ceiling construction, which comprises a heat insulating material, a diffusion barrier as well as a false ceiling in the sha of a stretched fabric, and to attain this by simple means and substantially without any additional materials. We have now found, quite surprisingly and in accordance with the present invention, that the sound absorbing capa city of a ceiling construction of the type described abov is improved considerably, provided a) the false ceiling, which is a stretched fabric, has su ■ qualities, that a considerable portion of the sound, whic is generated in the room, also high frequency sound, is allowed to pass through the fabric; b) at least the heat insulating layer adjacent the fabric is made of a soft and porous material, preferably mineral wool, and has sound absorbing qualities; c) the heat insulating layer adjacent the fabric is place between the diffusion " barrier and the fabric to act also a sound absorbing material; and d) at least a second heat insulting layer is placed above the diffusion barrier and has such heat insulating qualit es, that water condensation below the diffusion barrier i prevented, and also acts as a sound absorbing material fo low frequency sound, which passes the diffusion barrier. The sound absorption capacity of the ceiling construction is improved, since the high as well the low frequency sou generated in the room passes the false ceiling without be ing strongly reflected. The high frequency sound is refle ted to quite a large extent, as compared to the low frequ cy sound, by the diffusion barrier above the first heat i sulating layer but is then weakened and the rest of it, which may penetrate said first heat insulating layer, pa es the false ceiling and enters the room, can hardly be experienced as disturbing. OMP , W1P Thus, the basic idea of the present invention is, a) that the acoustic qualities of a ceiling construction as descri¬ bed in the preamble of claim 1, the one side of which is cold (often freezing temperatures) and the other side of which is warm, can be improved substantially without using any additional materials but by utilizing a limited portion of the required amount of heat insulating material as an ab¬ sorbing material for high frequency sound, and b) that, de¬ spite this utilization, it is possible to prevent water from condensing in the sound absorbing material, a most important accomplishment, because water condensation re¬ sults in sharply reduced heat insulation and also reduced sound absorption. We have also found, in accordance with the present inven¬ tion, that if the fabric used as a false ceiling has holes in it with an average side size of at least 0,05 mm, it will also permit high frequency sound (> 1000 Hz) to readily pass, ^ the total amount of holes preferably covering at least 0,3% of the total area of the fabric. Thus, we have found that it is possible to adjust by trial and error the amount of fabric holes, their average surface area and their total surface area and thereby achieve the result, that high as well as low frequency sound to a great extent pass the fabric while at the same time the visual covering power of the fabric is satisfactorily maintained, i e a capacity to cover the first heat insulating layer placed above the fabric and possibly means to fasten this layer. The major portion of the high frequency sound, which passes the fabric, is absorbed in the first heat insulating layer and the major portion of the rest of it is absorbed in the same layer after a reflexion against the diffusion barrier. The low frequency sound is also partly absorbed by the first heat insulating layer but is not reflected to a large extent by the diffusion barrier but passes it readily and is absorbed to a great extent by the heat insulating mate- rial placed above the diffusion barrier. In a preferred embodiment of the present invention the fa bric is a knitted fabric with artificial fibers, e g rayo fibers reinforced by nylon fibers, having a fiber diamete of 0,05 to 0,40 mm and a hole side size of 0,05 - 0,50 mm The fabric has, before it has been subjected to a treatme an average hole side size of e g 0,18 x 0,18 mm, 0,10 x 0, mm and 0,05 x 0,40 mm and is treated with a fire suppress plastic paste, suitably containing an acrylic polymer as well as fire suppressing additives and pigments as main i gredients, in such a way that said holes mainly have been left open but that the holes between the fibers have been closed. Such a treatment provides the fabric with fine po res and at the same time it is made fireproof and elastic and in case it has selfstretching properties, these will be adversly influenced. The small curls of the one side o the fabric, by which the fabric is tied, determine the vi al covering power and the porosity. Such a low porosity 2 as 0,3% of the total area and 100 pores per cm of the plastic paste treated fabric can be attained, depending o the pressure exerted when treating the fabric with the plastic paste, the flow properties of the plastic paste e while, as a comparison, it can be noted that it is not practical and economical to perforate sheet and plate at rials using standard technics to a porosity of less than 10%.- An ordinary porosity is 28% for a hole diameter of 1,8 mm and a center distance of 3 mm, i.e. 11 holes per c or 20% for a hole diameter of 2,5 and a center distance 2 of 5 mm, i.e. 4,1 holes per cm . However, it . is entirely possible, in accordance with the invention, to use as a fabric a perforated sheet of a plastic material or the li provided it is produced in a suitable manner. A knitted stretched fabric composed of rayon fibers and p pared in the way described above permits high as well as frequency sound to pass but completely conceals layers of sound absorbing materials placed above the fabric. More¬ over, the small pores prevent dust from penetrating the fabric and accumulating between the fabric and the heat insulation. In another preferred embodiment of the present invention the fabric, which constitutes the false ceiling, is stret¬ ched in such a way that an air gap is provided between the fabric and the first heat insulating and sound absorbing layer and is thus not affected by possible uneveness and joints of said layer. In this way valuable additional heat insulation is attained due to the small total area of the fabric holes and the insignificant air convection in the gap caused by the holes in the fabric. Swedish patent application 7304368-9 gives examples of false ceilings in the shape of a stretched fabric or a de¬ corative weave, which can be used according to the present invention. A knitted rayon weave was used instead of the cotton cloth mentioned in Example 2. It was coated on 'its one side with a paste diluted with water and having rough¬ ly the same composition as the paste described in Example 2 and was dried, thereby making the weave fireproof. Weaves, produced in this way, were tested in a ceiling construction according to the present invention, but we found (see the chart, plotting 1) , that the porosity and the holes in the weave had been reduced so sharply due to the paste coating that an effect, which works according to the invention, could not be attained. The sound absorption was not at all satisfactory. The results was almost the same as if a weave without any porosity and holes had been used (see plotting 2) . However, the rayon weave treatment now was modified to the extent that pastes being increasingly diluted were used and/or " that increasing coating pressures were used. We found, quite surprisingly, that a certain relatively large dilution and/or a relatively heavy coating pressure made it possible to attain mainly the same sound absorption (see plotting 3) as when a weave without any paste coatin at all was used (plotting 4) or when no weave at all was used (plotting 5) and yet at the same time attain satisfa tory visual covering power, which certainly was not the case, when a weave without any paste coating at all was used (plotting 4) . Rayon weaves having sound absorption qualities according to the present invention (plotting 3) were examined in a microscope. The thin paste coating had given the weaves a conspicuously open structure. Each fib was completely covered with paste but any complete brid¬ ging of the square or rectangular weave holes could only be observed in a few instances. However, the oblong holes between fibers close to each other and having the same di rection had been plugged. Nevertheless, a satisfactory visual covering power of the weaves had been attained. Mi neral wool boards, their joints and metal wires holding the boards against a safety net could not be visually de- tected through the weave. The -second heat insulating layer is according to another preferred embodiment of the present invention divided int fillings, placed between the beams of the ceiling constru tion and possibly also above the beams, while the first heat insulating and sound absorbing layer adjacent the false ceiling mainly covers the fillings as well as the undersides of the beams. The diffusion barrier is according to another preferred e bodiment of the present invention a thin and flexible, steamtight sheet, preferably a sheet made of LD-polyethy- lene, having a thickness of less than 0,25 mm. It can be thinner, in case it is made of HD-polyethylene, since thi material has superior strength. Such a choise of material and thickness results in vibrations of the diffusion barrier, when it is subjected to sound waves, which reach it through the first heat insulating and sound absorbing layer. Thus, sound energy can also in this way be absorbed in the ceiling construction. However, it is desirable that also the second heat insulating layer placed above the diffusion barrier is a porous sound absorbing material, suitably mineral wool. A polyethylene sheet having a thick¬ ness of 0,1 mm permits sound having a frequency of up to about 690 Hz to readily pass, a polyethylene sheet having a thickness of 0,2 mm up to about 345 Hz. In another preferred embodiment of the invention the first as well as the second heat insulating and sound absorbing layer are supported by a net. This net is held in place by the beams of the ceiling and preferably it is extended be¬ low them and fastened to the undersides of the same. The diffusion barrier and the second heat insulating and sound " " absorbing layer are supported by the net and placed on top of it, while the first heat insulating and sound ab¬ sorbing layer is suspended from the " net. According to another embodiment of the net the first heat insulating and sound absorbing layer is suspended in the net by means of a multitude of wireshaped suspension attach¬ ments pushed through the layer. These attachments are pro¬ vided with carrying surfaces to touch the underside of the layer and their upper end portions are fastened to the net. The carrying surfaces are obtained by bending the lower end portions of the suspension attachments or are heads, suit¬ ably ringshaped, attached to the suspension attachments. The present invention also relates to means which are used to produce the new ceiling construction in case it also comprises a net of metal wire, from which a heat insulating and sound absorbing layer is suspended. This means is characterized in that the net in addition to the two grou of metal wires, which are crossing each other transversly and together form an at least roughly regular structure having a loop hole size of under 100 mm, also is provided with a few metal wire elements roughly equally spaced ov the "~ net surface. These elements are fastened to the rest the net in such a manner, that portions of them, possibly produced by cutting of the elements at certain points, ca be bended outwardly from the net surface and form projec- ' tions to be used as suspension means. The bendable metal wire elements can according to a particular embodiment of the suspension net be selected metal wires of the net i.e the ordinary two groups of metal wires constituting the n itself and transversly crossing each other. It is also possible to fasten the first heat insulating a sound absorbing layer to the net by strings or the like, which are sewed onto the net, or by various hook means, which are pushed through the layer from below. The present invention is described in more detail in the following and reference is made to the attached drawing, which Fig. 1 is a vertical cross section of a ceiling con struction according to the invention, Fig. 2 is a perspec tive view of a ceiling construction according to the in¬ vention showing two different embodiments of metal wires designed for the suspension of mineral wool boards from a safety net and Figs. 3 and 4 show preferred embodiments o a safety net according to the invention. ~ - ±g. 5 is a diagra In Fig. 1 of the drawing a ceiling construction is shown having two beams 1, under which a polyethylene sheet 4 an a safety net are fastened. Between the beams two layers o mineral wool boards 7 are placed. The safety net consists of stiff metal wires (2,2) welded to each other. Short st metal wires 3 are attached to the safety net 2 and are OMPI A pointed downwards. Mineral wool boards 5 have been pushed upwards against the safety net 2 and thereby the metal wi¬ res 3 have penetrated the boards 5. The metal wires 3 have been bended or means, e g wire rings (not shown in detail), have been attached to the metal wires in order to retain the boards 5 in place. When the boards 5 have been fastened under the safety net 2 a fabric or a weave 6 has been stret¬ ched and fastened under the boards. The fabric 6 lets in accordance with the present invention sound waves readily pass through it and yet its covering power is so great, that it is substantially impossible to see the mineral wool boards 5, the joints between the boards and the metal wires 3 through the fabric with one's own eyes. Fig. 2 shows a safety net 2 according to the present in- vention, produced of metal wires 2,2 welded to one another. It is fastened to beams 1' (only one shown) with braces 8. At the welding points short stiff metal wires 3 are faste¬ ned and pointed downwards. Two mineral wool boards 5a and - ~" 5b (drawn with dots. as if they were translucent for the- sake of clearness) have been pushed upwards against the safety net 2 and thereby they have been penetrated by the downwardly pointed metal wires 3. Metal wire rings 9 are, in order to hold board 5a in place, firmly attached to the lower portions of the metal wires 3 with suitable means (not shown) . The mineral wool board 5b is hold in place by stiff downwardly pointed metal wires 3, which are somewhat longer than the thickness of the mineral wool boards, and hence the lower portions of these metal wires 3, after the pene¬ tration of the board, can be bent to be pointed in a hori- zontal direction (the dotted lines 10) and hold the board in place without any additional means. This results in a simpler construction-, less work, when the mineral wool boards are to be mounted, and cost efficiency. Fig. 3 shows an embodiment of a safety net according to the present invention, which has been produced by welding met wires (2a,2b) to each another, rectangular openings betwe the wires being formed. In this embodiment additional met wires (11, black) have been welded onto ordinary wires (2a, 2b, white) in the positions shown, besides every thi or, depending on the mutual metal wire distance and the mineral wool board thickness, every fourth etc ordinary wire (2a, white) , in any one of the two wire directions o the net. When the mineral wool boards (not shown) are to fastened under the safety net, wires 11 are cut at suitab points with pliers or the like. Cut ends are bent downwar from their closets welding points, the mineral wool board are pushed upwards and those portions of the cut downward ly bent wires, which after a complete penetration have pe netrated and appeared under the lower surfaces of the boards, are bent upwardly into a horizontal position to be able to hold the boards in place. It is also possible to do without attaching additional wi res 11 ' on the net by welding and instead cut and bend ordinary wires 2a or 2b of the net and use these wires to hold the mineral wool boards against the net. Such a net embodiment is shown in Fig. 4, one wire 2a being cut, whe it crosses one wire 2b. The next wire 2b, which said wire 2a crosses, is cut in two places to free said wire 2a fro it. Where the third wire 2b crosses said wire 2a, said cu wire 2a is bent downwards. A mineral wool board (not show is pushed upwardly and that portion of the downwardly pointed cut wire 2a, which after a complete penetration h been pushed out of the lower surface of the board, is ben upwards to a horizontal position to be able to keep the board in place. In the same manner a suitable number of w res 2a or 2b are cut free and bent and used to hold miner wool boards in place (not shown) .

Claims: CLAIMS 1. Celling construction above a heated room of a building and comprising a heat insulating and sound absorbing layer (5) as well as a false ceiling (6) consisting of a stret¬ ched fabric, which permits a considerable amount of the sound which is created in the room to pass the fabric and into the heat insulating and sound absorbing layer, charac¬ terized in that said fabric (6) has holes having an average side size of at least 0,05 mm, said holes perferably hav¬ ing a total area, which is at least.0,3% of the total area of the fabric, and said fabric (6) visually covering said heat insulating and sound absorbing layer (5) . 2. The ceiling construction of claim 1, characterized in that said fabric (6) is a weave of artificial fibers having a fiber thickness of 0,05 - 0,40 mm and a loop width of 0,05 - 0,50 mm, which weave is treated with a fire suppres¬ sing coating in such a manner that the loops sustantially are left open with sligntly reduced size. 3. The ceiling construction of claim 1 och 2, characterized in that said fabric (δ) is stretched with a distance between the fabric and the above-positioned heat insulating and sound absorbing layer (5) . 4. The ceiling construction of claim 1, 2 or 3, comprising also a diffusion barrier, characterized in that said heat insulating and sound absorbing layer (5) is in a horizon- tal direction divided into at least two layers (5,7), said diffusion barrier (4) is positioned between said two layers (5,7) and the upper one of said two layers (7) has such thickness, that water condensation under said diffusion barrier (4) is prevented, and at the same time serves as a sound absorbing means, particularity for low frequency sound, which quite- readily passes said diffusion barrier (4) 5. The ceiling construction of claim 4, characterized in that said upper heat insulating and sound absorbing layer (7) is divided into fillings (7) positioned between and possibly also above said beams (1) in the ceiling constru tion, while said lower heat insulating and sound absorbin layer (5) substantially covers the undersides of the beam (1) as well as said fillings (7) . 6. The ceiling construction of claim 4 or 5, characterize in that said diffusion barrier (4) is such a thin and flexible vaportight sheet, preferably a polyethylene shee having a thickness of not more than 0,25 mm, that the dif fusion barrier (4) itself vibrates, when it is subjected to the sound waves, which reaches it through the lower heat insulating and sound absorbing layer (5) . 7. The ceiling construction of any of the claims 4-6, characterized in that the lower (5) as well as the upper (7) heat insulating and sound absorbing layers are held i • place by a net (2), which in its turn is held in place by said beams (1) and preferably'is spread under the beams and fastened to the undersides of the beams. 8. The ceiling construction of claim 6 and 7, characteriz in that said diffusion barrier (4) and said upper heat in sulating and sound absorbing layer (7) are supported by said net (2) , while said lower layer (5) is suspended fro the underside of the net. 9. The ceiling construction of claim 8, characterized in that said lower heat insulating and sound absorbing layer (5) is suspended from the underside of said net (2) by means of a multitude of wirelike suspension attachments ( which are pushed through said layer (5) , on the underside of the layer form carrying surfaces and the upper portion of which are attached to the net (2) , said carrying surfa ( OMPI being formed by bending of the lower end portions (10) of said suspension attachments (3) or being heads (9) , which are attached to said suspension attachments, suitably ring- shaped. 10. Means for the manufacture of the ceiling construction of el-aim 9, comprising a metal wire net, characterized in that said net besides two groups of metal wires (2a,2b) , transversally crossing each another and forming an at least substantially regular loop hole structure having a hole width less than 100 mm, comprises a multitude of metal wi¬ re elements (11) , substantially uniformly distributed over the net surface and attached to the proper net (2) in such a manner that portions of them, possibly attained by cut¬ ting the metal wire elements (11) at selected points, can be bended out from the plane of the proper net to form pro¬ jections suitable as suspension attachments for said layers. 11. The means of claim 10, characterized in that said bend- able metal wires (11) are metal wires selected from one or both of the groups of the metal wires (2a,2b) , which transversly cross each other and constitute the proper net (2) . OMPI fa wipo >.

Inventors: ANDERSSON K, THELANDER B
Applicants: ANDERSSON K, EUROC DEVELOPMENT AB, THELANDER B, EUROC DEV AB
Application year: 1979
Main classification: E04B1
IPC codes: E04B1, E04B9