JP2001152590A - Soundproof floor structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soundproof floor structure to effectively suppress the impact sound of a floor in a hung ceiling structure of a wooden house. SOLUTION: The soundproof floor structure comprises a floor member 4 including a vinyl chloride resin sound insulating mat 8, a beam 12 to support a lower side of a periphery of the floor member 4, a first floor joist 14 to support an intermediate portion of the floor member 4 from a lower side, a hanging wood member 40 in which an upper end portion thereof is joined with the first floor joist 14, a lower end portion thereof is joined with the second floor joist 18, and the upper end portion is connected to the lower end portion via vibration control members 50 and 52, a hung ceiling member 20 including a vibration control and sound insulating board with the second floor joist 18 joined with an upper surface, and a vibration control and sound insulating sheet 30 to be fitted between an outer peripheral end of the hung ceiling member 20 and the beam 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a soundproof floor structure, and more particularly, to a soundproof floor structure in a suspended ceiling of a wooden house.

[0002]

2. Description of the Related Art In wooden houses, impacts on flooring caused by operations such as walking on floors, opening and closing doors, moving furniture, and the like cause ceiling materials to vibrate, and this vibration may generate floor impact sounds. It is a problem. The floor impact noise is reduced by increasing the density of the flooring material while increasing the thickness of the flooring material. However, the thickness and density of the flooring material are limited and are not sufficient measures.

[0003] For this reason, for example, as a soundproof floor structure, as described in Japanese Patent Application Laid-Open No. 9-78751, a ceiling material is suspended from a floor material installed on the floor via a vibration-proof rubber. Sound insulation measures have been taken. In such a soundproof floor structure, when an impact is applied to the floor, vibration of the ceiling material can be suppressed by elastically deforming the vibration isolating rubber.

[0004] However, in the above structure, although vibration of the ceiling material is suppressed, it is necessary to increase the size of the vibration-proof rubber in order to enhance the soundproofing effect. And the ceiling downstairs was lowered.

[0005] Further, a structure has been reported in which ceiling vibration is suppressed by deforming an elastic caulking material sandwiched between ceiling materials in a shearing direction. However, even if such a structure is adopted, there is a problem that the vibration of the ceiling material cannot be sufficiently suppressed from being transmitted to the downstairs via beams or walls provided below the floor material.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a soundproof floor structure capable of effectively suppressing the impact sound of a floor in a suspended ceiling structure of a wooden house by solving the above problems. It is in.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and as a result, have found that a portion of a wooden house in which a beam and a ceiling material come into contact with each other is formed of a vinyl chloride resin composition. It has been found that by sandwiching the formed vibration-damping and sound-insulating sheet and fixing it with joists, the vibration sound transmitted downstairs can be effectively reduced, and based on this new finding, the present invention has been completed.

In other words, the soundproof floor structure according to the present invention comprises a floor member formed by laminating sound insulating mats, a beam for supporting a lower part of the periphery of the floor member, and a first member for supporting an intermediate portion of the floor member from below.
A joist, a suspension member having an upper end portion joined to the first joist, a lower end portion joined to a second joist, and the upper end portion and the lower end portion connected via a vibration isolating member; A second ceiling joist is joined to the upper surface, a suspended ceiling material including a vibration-damping sound-insulating board and a vibration-damping material sheet, and a vibration-damping sound-insulating sheet mounted between an outer peripheral end of the suspended ceiling material and the beam. Having.

[0009] It is preferable that a damping material sheet is interposed at a joint between the beam and the wall material and / or column material of the room located below the suspended ceiling material.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings. As shown in FIG. 1, the vibration isolating floor structure 2 according to the present embodiment has a floor member 4 on a floor higher than the first floor (including a basement) in a wooden building. The flooring material 4 has a floor base material 6 made of plywood and the like, and a floor surface material 10 made of flooring material and the like, and a vinyl chloride resin-based sound insulation mat 8 is interposed between them. . The material of the sound insulating mat 8 will be described later. The thickness of each of the floor base material 6, the sound insulation mat 8, and the floor surface material 10 is not particularly limited.
0 to 20 mm, preferably about 3
８8 mm, preferably about 5-1 for the floor surface material 10.
5 mm.

A lower part of the outer periphery of the floor member 4 is formed by beams 12.
Is supported from below, and the middle part of the flooring 6 is
It is supported from below by first joists 14 arranged at predetermined intervals. The end of the first joist 14 is joined to the beam 12 with a nail or the like, the floor material 4 and the first joist 14 are joined with a nail or the like, and the beam 12 and the floor material 4 are joined with a nail or the like. I have. The beam 12 is supported on a wall member 28 (including a column member, hereinafter the same) of a room located downstairs, and has the same composition as that used for a ceiling member 20 described later. A vibration damping material sheet 32 adjusted from an object is interposed, and transmission of vibration from the beam 12 to the wall material 28 and / or the column material is suppressed. The vibration damping material sheet 32 also has a function of maintaining airtightness between the beam 12 and the wall material 28. The thickness of the damping material sheet 32 is not particularly limited, but is preferably about 0.5 to 5 mm. The width of the damping material sheet 32 is preferably substantially the same as the cross-sectional width of the beam 12 and / or the wall material 28.

In the present embodiment, the ceiling material 20 is formed of the first material.
The joist 14 is suspended from the joist 14 via the hanging wooden member 40 and the second joist 18. The ceiling material 20 is a sandwich type vibration damping structure in which two vibration damping and sound insulating boards 22 and 26 and a butyl rubber-based damping material sheet 24 are stacked therebetween. Generally, such a sandwich type vibration damping structure preferably has a loss coefficient at 23 ° C. and 500 Hz of 0.08 or more, and is 0.2 in the present embodiment.
The vibration damping and sound insulating boards 22 and 26 are made of, for example, a gypsum board. The material of the damping material sheet 24 will be described later. The thickness of the vibration damping sound insulating boards 22 and 26 may be the same or different and is not particularly limited.
It is preferably in the range of 2 mm. The thickness of the damping material sheet 24 is also not particularly limited, and is preferably about 0.5 to 3 mm. The second joist 18 is fixed to the upper surface of the upper board 26 with nails or the like.

In this embodiment, the vibration damping and sound insulating sheet 30 is used.
Is the second joist 1 between the outer edge of the ceiling material 20 and the beam 12.
8, is fixed to the beam 12 by a nail or the like.
In the present embodiment, a vinyl chloride resin-based vibration damping sheet is used. In addition, depending on the positional relationship between the ceiling material 20 and the wall material 28, the vibration damping sound insulation sheet 30
May extend between the outer peripheral end portion of the base material and the wall material 28. The thickness of the vibration damping and sound insulating sheet 30 is not particularly limited, and is 1 to 4 m.
m is preferable. The width of the vibration-damping and sound-insulating sheet 30 is preferably about the same as the dimension obtained by adding the overall thickness of the ceiling member 20 to the cross-sectional height of the second joist 18. The material of the vibration damping and sound insulating sheet 30 will be described later.

In the soundproof structure of the present invention, it is most necessary that the vibration-damping and sound-insulating sheet 30 be mounted between the outer peripheral end of the suspended ceiling material and the beam. With such a structure, it is possible to effectively reduce the transmission of the vibration of the ceiling material to the downstairs via the beam or the wall surface.

As shown in FIG. 2, the hanging member 40 used in this embodiment includes a hanging stopper 42 fixed to the first joist 14 with a nail or the like, and a hanging member 42 for the second joist 18. And a ridge receiving portion 48 fixed by the like. A male screw 44 is formed at the lower end of the suspension portion 42, and the male screw 44 is screwed to a tightening nut 45 fixed to the upper end of the buckle ring 46. By adjusting the axially threaded position of the tightening nut 45 and the male screw 44, the axial length of the hanging member 40 can be adjusted in accordance with the distance between the first joist 14 and the second joist 18. I can do it.

The upper end of the ridge receiving portion 48 is connected to the lower end of the buckle ring 46 via vibration isolating rings 50 and 52 as a vibration isolating member by a slider washer 54 and a snap ring 56. Vibration transmitted from 14 to the second joist 18 via the suspended ceiling member 40 is attenuated. The thickness of each of the vibration isolation rings 50 and 52 is not particularly limited, but is preferably 1 to
It is about 5 mm. The material of the vibration isolation rings 50 and 52 is not particularly limited, but is made of a vibration isolation rubber such as natural rubber or synthetic rubber. The material of the suspension member 42, the buckle ring 46, and the ridge receiving portion 48 is not particularly limited, but is preferably made of a reinforced plastic material such as FRP.

Glass wool or other heat insulating material may be provided in the gap between the floor material 4 and the ceiling material 20.

The sound insulating mat used in the present invention is a powder of a vinyl chloride resin or rubber, a metal or a metal oxide, and has a specific gravity of 4.
The above is a sheet-like molded product obtained from the composition obtained by blending the tackifier. The molded body has a hardness (JIS) of 70 to 95 and an areal density of 15 to 25 kg / m ^2.
Those prepared in the range described above are preferable. The proportion of each component in the compounding composition is not particularly limited, but is usually a powder of metal or metal oxide having a specific gravity of 4 or more per 100 parts by weight of a vinyl chloride resin or rubber.
２０００2000 parts by weight, preferably 400-1000 parts by weight, and 5-50 parts by weight of a tackifier, preferably 8-30 parts by weight.

The vinyl chloride resin is a homopolymer of vinyl chloride or a copolymer of vinyl chloride and a monomer copolymerizable therewith.
500, preferably in the range of 800 to 1500 can be used. These can be produced by a known method such as suspension polymerization, bulk polymerization or emulsion polymerization.

The monomers copolymerizable with vinyl chloride include vinyl acetate, vinylidene chloride, acrylonitrile,
Representative examples include, but are not limited to, ethylene, propylene, butadiene, styrene, acrylic acid, methacrylic acid, acrylates, methacrylates, and the like. One of these copolymerizable monomers or a mixture of two or more thereof may be used as appropriate. Specific examples of the vinyl chloride resin include polyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-ethylene-vinyl acetate copolymer, and the like. Conventionally, in the field of vinyl chloride resin molding, extrusion molding,
The same vinyl chloride resin as used in various molding applications such as injection molding and calendar molding can be used. Furthermore, in order to reuse the recovered vinyl chloride resin, it is possible to use a recycled vinyl chloride resin.

Examples of the rubber include natural rubber, isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), and ethylene-propylene rubber (E
PDM), styrene-isoprene block copolymer rubber (SIS), styrene-butadiene block copolymer rubber (SBS) and the like can be used. These may be used in combination of two or more. Among these, vinyl chloride resins are preferred.

Examples of the metal or metal compound powder having a specific gravity of 4 or more include those conventionally known as fillers for vinyl chloride resins or rubbers.
Average particle size is 0.1 to 300 μm, preferably 1 to 100
Those having a range of μm can be used. Examples of the metal compound include an oxide, a carbonate compound, and a sulfate compound. Specific examples of such metal or metal compound powders include powders of simple metals such as copper, iron, zinc, lead, chromium, molybdenum, manganese, nickel, and tungsten; cuprous oxide, cupric oxide, and oxides. Powders of metal oxides such as zinc, lead oxide, chromium oxide, molybdenum oxide, ferric oxide and nickel oxide; powders of carbonate compounds such as zinc carbonate, lead carbonate, barium carbonate; lead sulfate, barium sulfate, etc. Sulfuric acid compound powder and the like can be mentioned.

Examples of the tackifier include, but are not particularly limited to, natural resins such as rosin and dammar; modified rosins such as polymerized rosin and partially hydrogenated rosin; rosins such as glycerin ester rosin and pentaerythritol ester rosin; Derivatives; polyterpene resins such as pinene polymers; terpene modified products such as terpene phenols; aliphatic hydrocarbon resins such as olefin polymers and modified products thereof; cyclopentadiene resins, aromatic petroleum resins, phenolic resins, Known tackifiers such as alkylphenol-acetylene resin, styrene-based resin, xylene-based resin, coumarone-indene resin, vinyltoluene-methylstyrene copolymer resin and the like can be mentioned. Among these, 90 to 50% by weight of cyclopentadiene monomer
And a vinyl monomer having an ester bond or a monomer mixture comprising 10 to 50% by weight of a monomer having a hydroxyl group.
A cyclopentadiene resin at 110 ° C. is desirable.

In the composition, various fillers such as calcium carbonate and carbon black; phthalic acid ester, aliphatic dibasic acid ester, trimellitic acid ester and phosphorus are used as long as the object of the present invention is not impaired. Acid esters,
Various plasticizers such as polyester plasticizers; reinforcing agents such as glass fibers and carbon fibers; and various additives such as flame retardants, ultraviolet absorbers, antioxidants, antistatic agents, lubricants, and pigments are added as necessary. be able to. Further, when rubber is used, a vulcanizing agent such as sulfur organic peroxide can be blended.

The method of manufacturing the sound insulating mat may be a conventionally known method. For example, after each component such as a vinyl chloride resin is mixed in a tumbler, Henschel mixer, ribbon blender, etc., the mixture is kneaded with an extruder, a Banbury, a roll, etc., and the obtained composition is, for example, an extruder, a calenderer. It is formed into a sheet shape by using the method described above.

Damping sheet 24 and 32 The damping sheet used in the present invention is a composition comprising an ethylene-vinyl acetate resin or rubber and a tackifier,
Alternatively, it is a sheet-like molded product obtained from a composition obtained by blending a polyacrylate and a plasticizer. The vibration damping material sheet preferably has a loss coefficient at 250 Hz of 0.1 or more at a hardness (JIS) of 40 to 60 and 23 ° C.

The ratio of the ethylene-vinyl acetate resin (EVA) or rubber to the tackifier is not particularly limited,
Usually, plasticizer 10 is added to 100 parts by weight of EVA or rubber.
１００100 parts by weight. Examples of EVA include an ethylene-vinyl acetate copolymer, a modified ethylene-vinyl acetate copolymer, and an ethylene-vinyl acetate-vinyl chloride graft copolymer. Examples of the rubber include butyl rubber (IIR) in addition to those exemplified in the sound insulation mat. Particularly, butyl rubber is preferable. The butyl rubber preferably has an unsaturation of 0.5 to 2.5 mol% and a Mooney viscosity at 100 ° C. of 35 to 70.

As the tackifier, a viscosity at a temperature of 20 ° C. is 10 ³ to 10 ⁵ cps, preferably 5.0 ×.
Those having a density of 10 ^{3 to} 5.0 × 10 ⁴ cps are exemplified. As a tackifier having such a viscosity range,
Although not particularly limited, petroleum hydrocarbons such as polybutene, atactic polypropylene, liquid polybutadiene, and low molecular weight butyl rubber; rosin derivatives such as hydrogenated rosin methyl ester and hydrogenated rosin triethylene glycol ester; turpentine tackifier And the like.

[0029] Asphalt can also be used as a tackifier obtained by dissolving asphalt in a paraffinic or naphthenic process oil and adjusting the viscosity to the above viscosity range.

The above-mentioned composition may further contain other softeners and reinforcing agents such as carbon black for the purpose of improving moldability, etc .; inorganic fillers such as calcium carbonate, talc, clay and calcium sulfate; Flame retardants such as antimony, zinc borate hydrate, aluminum hydroxide; heat stabilizers,
Lubricants, anti-blocking agents, coloring agents, UV inhibitors and the like can be added. Further, in order to improve durability, a vulcanizing agent such as sulfur may be added.

The method of forming the damping material sheet according to the present invention is not particularly limited, but generally, it may be formed by kneading with a Banbury mixer or the like and then forming the sheet with a calendar or the like.

The ratio of the polyacrylate to the plasticizer is usually 50 to 100 parts by weight of the plasticizer per 100 parts by weight of the polyacrylate. Examples of polyacrylates include polyethyl acrylate, polymethyl acrylate, 2-ethylhexyl polyacrylate,
Polybutyl methacrylate and the like can be mentioned.

Examples of the plasticizer include tricresyl phosphate, acetyltributoxy citrate, dioctyl phthalate, dioctyl adipate, dibutyl phthalate, butyl benzene phthalate and the like.

For the composition, it is preferable to use a polyacrylate having a glass transition temperature of -20 ° C. or lower, but it is preferable to blend a polyacrylate having a glass transition temperature of -20 ° C. or higher with the plasticizer. In addition, those prepared by adjusting the glass transition temperature of the composition to -20 ° C or lower can also be used. If necessary, a tackifier may be added to form a sheet.

The vibration-damping and sound-insulating sheet 30 used in the present invention is a composition comprising a vinyl chloride resin or rubber, a filler and a tackifier, and has a specific gravity of 1 to 2. The prepared product is formed into a sheet. The sheet has an areal density of 10 to 15
It is preferable that the loss coefficient at 250 Hz is 0.05 or more at kg / m ² , hardness (JIS) of 70 to 90 and 23 ° C. The proportion of each component is 100 to 400 parts by weight of a filler, preferably 150 to 300 parts by weight, and 3 to 3 parts by weight of a tackifier based on 100 parts by weight of a vinyl chloride resin or rubber.
It is preferable to add 30 parts by weight, preferably 5 to 20 parts by weight.

As the vinyl chloride resin, rubber and tackifier, the same as those exemplified in the above-mentioned sound insulating mat can be used.

Examples of the filler include various fillers such as calcium carbonate and carbon black. In addition, as other components, various plasticizers such as phthalic acid esters, aliphatic dibasic acid esters, trimellitic acid esters, phosphoric acid esters, and polyester plasticizers; reinforcing agents such as glass fibers and carbon fibers are also included. can do. In addition, flame retardants, ultraviolet absorbers, antioxidants, antistatic agents, lubricants,
Various additives such as pigments can be added as needed.

As a method of manufacturing the vibration damping and sound insulating sheet, a conventionally known method may be adopted. For example, after mixing each component with a tumbler, Henschel mixer, ribbon blender, or the like,
The composition obtained is kneaded with an extruder, a Banbury, a roll, or the like, and the resulting composition can be molded using various molding machines, and is particularly preferably molded using an extrusion molding machine or a calendar molding machine.

[0039]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. (Sound insulation performance test) In the floor structure shown in FIG.
3000 mm x 4000 mm according to A 1418
The impact sound source is placed on the floor material 4 of the upper floor room of the size of the room at the center of the room and the vicinity of the four corners, and also on the floor of the lower room,
The sound receivers were placed at the same five positions as the sound source, and the sound insulation performance of the sound sources having the frequencies shown in Table 1 was measured. The improvement effect amount in Table 1 indicates a value obtained by subtracting a floor impact sound level value for each frequency after soundproofing from a floor impact sound level value for each frequency in a floor structure where no soundproofing work is performed. The greater the effect, the greater the improvement effect (unit: dB).

The floor structure in which no soundproofing work is performed means that the flooring 4 shown in FIG. 1 is a flooring made of a flooring material and a plywood without the sound insulation mat 8 being laminated. , Using a suspension tree that does not use anti-vibration rubber,
The ceiling material 20 has a structure in which two gypsum boards that do not sandwich the damping material sheet 24 are used, and the damping sound insulation sheet 30 and the damping material sheet 32 are not used. The soundproofing grade of the lightweight impact sound in this case is LL-80.

Example 1 As the flooring material 4 shown in FIG. 1, a flooring material 6 made of plywood having a thickness of 15 mm, a sound insulation mat 8 having a thickness of 6.5 mm and a surface density of 21 kg / cm ² , and a flooring material having a thickness of 12 mm were used. A laminate with the floor surface material 10 was used. The sound insulation mat 8
100 parts of vinyl chloride resin, 30 parts of plasticizer, iron oxide 440
And 10 parts of a tackifier. As the hanging tree member 40, an earthquake-resistant hanging tree T-01 (manufactured by Joto Chemical Co., Ltd.) using vibration-proof rubber was used. As the ceiling material 20, a gypsum board 22 having a thickness of 9 mm
And 26, with a thickness of 1 mm and an areal density of 14 kg / cm ²
Of a sandwich type vibration damping structure sandwiching the butyl rubber type vibration damping material sheet 24 is used. The damping material sheet was prepared from a composition containing 100 parts of butyl rubber, 60 parts of polybutene, 25 parts of carbon black, and 75 parts of calcium carbonate.

As the vibration damping and sound insulating sheet 30, 100 parts of a vinyl chloride resin, 80 parts of a plasticizer, and 350 parts of calcium carbonate
And a sheet having a surface density of 14 kg / cm ² and a width of 20 cm and a thickness of 3 mm were used from a composition containing 10 parts of an adhesive and 10 parts of an adhesive. As the vibration damping material sheet 32, the same material as that used for the ceiling material 20 was used.

The distance between the upper surface of the ceiling material 20 and the lower surface of the floor material 4 was 30 to 40 mm. Glass wool having a thickness of 50 mm and a density of 24 kg / cm ³ was laid on the upper surface of the ceiling material 20.

A sound insulation performance test was performed on such a floor structure. Table 1 shows the results. As shown in Table 1, the soundproofing grade of the light impact sound was LL-60, and it was confirmed that the soundproofing was excellent.

[0045]

[Table 1]

Example 2 A sound insulation performance test was performed under the same conditions as in Example 1 except that the damping material sheet 32 shown in FIG. 1 was not used. Table 1 shows the results. As shown in Table 1, the soundproofing grade of the lightweight impact sound was LL-65, and it was confirmed that the soundproofing was excellent.

COMPARATIVE EXAMPLE 1 As the hanging member 40 shown in FIG. 1, a hanging tree which does not use a vibration-proof rubber is used.
A sound insulation performance test was performed under the same conditions as in Example 1 except that two gypsum boards not sandwiching No. 4 were not used and the vibration damping and insulating sheet 30 and the vibration damping material sheet 32 were not used. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 As the flooring material 4 shown in FIG. 1, a flooring material made of a flooring material and a plywood without using a sound insulating mat 8 was used.
The sound insulation performance test was performed under the same conditions as in Example 1 except that two gypsum boards that did not sandwich the damping material sheet 24 were used, and the damping sound insulation sheet 30 and the damping material sheet 32 were not used. went. Table 1 shows the results.

COMPARATIVE EXAMPLE 3 As the ceiling material 20 shown in FIG. 1, two gypsum boards without sandwiching the damping material sheet 24 were used.
The sound insulation performance test was performed under the same conditions as in Example 1 except that the vibration damping material sheet 32 was not used. Table 1 shows the results.

COMPARATIVE EXAMPLE 4 The same procedure as in the above-mentioned Example 1 was carried out except that the hanging tree member shown in FIG. A sound insulation performance test was performed under the same conditions. Table 1 shows the results.

As shown in Table 1, the soundproofing grades of the lightweight impact sounds in Comparative Examples 1 to 4 are all low, and it can be seen that the soundproofing effect is not improved as compared with Examples 1 and 2.

[0052]

As described above, according to the present invention, in a suspended ceiling structure of a wooden house, a soundproof floor structure capable of effectively suppressing a floor impact sound can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a vibration isolating floor structure according to an embodiment of the present invention.

FIG. 2 is a detailed view of the hanging member shown in FIG.

[Explanation of symbols]

 2 ... soundproof floor structure 4 ... floor material 6 ... floor base material 8 ... vinyl chloride resin-based sound insulation mat 10 ... floor surface material 12 ... beams 14 ... first joists 18 ... second joists 20 ... ceiling materials 22, 26 ... boards 24 , 32 ... damping material sheet 28 ... wall material 30 ... damping sound insulation sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) E04B 5/58 S

Claims (1)

[Claims] A floor member formed by stacking sound insulation mats; a beam supporting a lower part of the periphery of the floor member; a first joist supporting an intermediate portion of the floor member from below; and an upper end with respect to the first joist. Parts are joined, the lower end part is joined to the second joist, the upper end part and the lower end part are connected to each other via a vibration isolating member, and the second joist is joined to the upper surface, A soundproof floor structure including a suspended ceiling material including a vibration-damping and sound-insulating board and a vibration-damping material sheet, and a vibration-damping and sound-insulating sheet mounted between an outer peripheral end of the suspended ceiling material and the beam.