EP2743418A1

EP2743418A1 - Sound insulation structures

Info

Publication number: EP2743418A1
Application number: EP13197033.7A
Authority: EP
Inventors: David Bignell; Iain MAIR
Original assignee: Isomass Ltd
Current assignee: Isomass Ltd
Priority date: 2012-12-13
Filing date: 2013-12-12
Publication date: 2014-06-18
Also published as: GB201222520D0; GB2508878A

Abstract

A sound insulator, particularly for installation beneath a floor, comprises a sound-absorbent foam 1 within a flexible membrane 2. Part of the external surface is curved around a longitudinal axis. Advantageously, the membrane 2 comprises a partial cylinder.

Preferably, the sound insulator comprises interengageable, hemi-cylindrical modules which may be secured to the floor joists or other frames.

Description

Field of the Invention

This invention relates to the provision of sound proofing separating floors, between commercial properties and/or dwellings or simply between two dwellings. These dwellings are commonly multiple occupancy such as a block of flats, hotels or hospitals. The invention is intended to be used primarily, although not exclusively to enhance the sound insulation of timber or steel frame structures within buildings such as timber/steel joisted floors, walls and ceilings.

Background of the Invention

It is known that to overlay or underline these different timber or steel structural sub floors with combinations of sound absorbing structures will improve the acoustic performance to varying degrees. This is a common method to achieve a specified minimum performance. All present applications in this field result in increasing the depth of the floor by introducing a flexible or rigid interlayer or board system to cover or replace either or both the ceiling and the floor.
There are many known acoustic damping systems for floors, which commonly comprise a particle board composite panel (such as chipboard or MDF) that performs by being suspended or floated above the structural subfloor with the use of a foam or textile resilient layer. Latterly these systems are now often accompanied by additional suspended ceiling boards because in many cases the particle board composite floor covering or suspended ceiling is not good enough to achieve the specified acoustic performance.
In addition to the composite panels that are commonly used either side of the structural floor, it is also known that the introduction of soft absorbent material within the structural floor void may be beneficial because it stops an unwanted echo in the floor void and can improve the floor's overall performance by up to 1dB.
JP2000038780 (A ), Sekisui Chemical Co Ltd, describes a rectangular sound absorbing block for installation between a floor and an underlying ceiling. A face and side surfaces of the block are covered by a high density sheet material and the assembly is secured to the floor joists or ceiling supports so as to leave clearance between the block and the respective floor and ceiling surfaces by lugs co-planar with a face of the block and projecting from the sheet material.
US 3729879, Andrew T Franklin , describes fibre insulation wool within a paper pocket. The outer edges of the pocket incorporate a particular configuration of a self-adhesive strip for securing the package to floor joist of wall studs.

Summary of the Invention

This invention is directed primarily to reduction of airborne noise. The invention facilitates the ability to improve the sound insulation of a separating structural floor more than that of the soft insulation currently used. A further feature is that it will increase the overall performance of the floor sufficiently so as to only require one additional acoustic system to be added to one side of the structural floor, in order to achieve a commonly specified acoustic performance.
A feature of the invention is that it can enable improvement of the acoustic performance of a floor while being installed from one side only of the floor structure. The weight is supported by the floor joists and not the ceiling or the floorboards.
According to one aspect of the present invention, we provide a sound insulator comprising a sound-absorbent core within a flexible membrane characterised in that part of the external surface of the resultant composite structure is curved around a longitudinal axis.
According to another aspect of the present invention, we provide a method of reducing transmission of airborne sound through a planar frame structure, which method comprises:

a) locating a sound-absorbent core within a flexible membrane in such a manner that: i) part of the external surface of the resultant composite structure is curved around a longitudinal axis; ii) a generally flat face extends in a longitudinal direction and is opposed to the curved surface; and iii) there is formed a pair of substantially parallel and planar flanges, each of which extends beyond the flat face from a corresponding edge of a curved surface of the membrane in a plane substantially perpendicular to the flat face;
b) placing the resultant composite insulating structure between longitudinal frame members; and
c) securing each flange to an adjacent longitudinal frame member.

According to a further aspect of the present invention, we provide a preformed, flexible membrane to contain a sound-absorbent core and so shaped that, in use, part of the external surface of the resultant composite structure is curved around a longitudinal axis and includes: i) a generally flat face extending in a longitudinal direction and opposed to the curved surface; and ii) a pair of substantially parallel and planar flanges each of which extends beyond the flat face from a corresponding edge of a curved surface of the membrane in a plane substantially perpendicular to the flat face.
A particularly effective configuration includes a generally flat face extending in a longitudinal direction and opposed to the curved surface. The curved surface should be continuous, for example cylindrical, without discontinuities or sharp cusps.
The composite structure preferably includes a pair of substantially parallel and planar flanges each of which extends beyond the flat face from a corresponding edge of a curved surface of the membrane in a plane substantially perpendicular to the flat face.
A preferred configuration of the curved surface comprises a partial cylinder and particularly a hemi-cylinder.
This invention preferably utilises a polymer or fibrous material for the core, such as a resilient polymer foam. Preferably but not exclusively at least the bulk of the core is an open cell foam structure. The membrane may be a natural or synthetic rubber or a high density polymer, such as polyvinyl chloride (PVC).
The density of the absorbent core should not exceed 400kg.m^-3 and is preferably in the range from about 30kg.m^-3 to 200kg.m^-3. The absorbent material core is either cut from a block or extruded or moulded to form the desired shape. The absorbent core may be a resilient polymer such as reconstituted / virgin open cell foam of varying densities from about 64kg.m^-3 to 200kg.m^-3 or a compressed mineral wool of varying densities from about 30kg.m-³ to 120kg.m^-3.
Conveniently, the thickness of the high density membrane ranges from about 2mm to 6mm and the corresponding weight from about 4kg to 16kg per square metre. Preferably, the two components are bonded together.
Alternatively, particularly when a trough-shaped membrane is secured to floor joists, as described below, the absorbent core can be a granular material such as crumbed foam, which fills the shaped membrane after it is secured in position. In contrast to the known technique of pugging, the partial curve can enable an appropriate acoustic performance without imposing an excessive load on the ceiling.
Preferably, the membrane is the major proportion, say at least 70%, of the mass of the composite structure.
The absorbent core can be altered in height and depth according to the spacing between the supporting members to which it is fixed.
Preferably, the sound insulator has a generally longitudinal axis and at least part of the edge of the core in section transverse to the longitudinal axis comprises a curve. Such a sound insulator preferably includes a generally flat face extending in a longitudinal direction and opposed to the curved surface.
The sound insulator may be adapted to be located alongside a longitudinal support and particularly but without limitation between floor joists. Preferably, the sound insulator is adapted to be secured to at least one support and, in particular, between adjacent floor joists. It may be so supported or secured by means of an extended carrier or flap on each side through which mechanical fixings can be driven, such as by including at least one flange adapted to abut a support.
A particularly preferred configuration includes: (i) a generally flat face extending in a longitudinal direction and opposed to the curved surface; and (ii) a pair of substantially parallel and planar faces forming flanges, each of which extends beyond the flat face from a corresponding edge of a curved surface of the membrane in a plane substantially perpendicular to the flat face. Thus, the sound insulator is generally cup- or trough-shaped in transverse section. Conveniently, the curved portion is a partial cylinder and especially a hemi-cylinder.
In use, the flanges abut longitudinal supports, such as wall studs or floor joists, in the structure being insulated and may readily be secured to such supports in any convenient manner. The flexibility of the flanges may be sufficient to compensate for variations in spacing between adjacent supports.
The sound insulator may comprise a plurality of interconnecting modules. Each module may be shaped specifically so as to allow the foam to slot into the next unit (see Fig. 4) to form a continuous structure. By way of example, each module may include at least one portion of foam projecting beyond the flexible membrane and adapted to engage in a recess in a second adjoining module.
Without limitation, it is believed that the invention improves acoustic insulation by absorbing and deflecting airborne sound energy in many different directions. The acoustic insulation is created from the combination of reflective scattering of the sound energy from the flexible high mass membrane layer, and absorption from the shaped core fillet on one side of the membrane. The carrier membrane may also absorb some sound energy through its flexibility.
The invention may be applied to reduce sound transmission through any planar structure, such as a floor, wall or ceiling. It is particularly useful between pairs of adjoining panels such as: a cavity wall; wall panels on opposing sides of studs or a frame; a floor and the underlying ceiling; or the underside of a floor and a suspended ceiling.
The sound insulation can be manufactured in specific sizes to cater for different floor construction ranges (for example the joists could be 200mm deep and 450mm apart or upto 300 mm deep and upto 600mm apart), by altering the physical thickness/weight and shape of the membrane, always being sure to limit the contact with the structural elements of the floor.
It is well-known that the absorption of airborne noise is a function of the mass of the intervening material and, indeed, building regulations often prescribe a minimum mass per unit area. The curved surface enables a greater quantity of material and therefore greater mass to be located in the same spacing between longitudinal supports. For example, 600 mm of carrier membrane and the enclosed absorbent core can be suspended between floor joists on a 400 mm spacing.

Brief Description of the Drawings

Figure 1 is a transverse section of a sound insulation structure according to the present invention installed under floor boards from below before the ceiling is replaced;
Figure 2 is a transverse section of a sound insulation structure according to the present invention installed above a ceiling before the floor is replaced;
Figure 3 is a perspective view of a sound insulation structure according to the present invention being installed above a ceiling;
Figure 4 is a partial view of two modules of a sound insulation structure according to the present invention showing adaptation of the foam to enable interconnection of the two modules.

Description of an Embodiment

A sound insulator module comprises a sound-absorbent foam infill 1, commonly reconstituted or virgin open cell foam or mineral wool, such as reconstituted polyurethane foam. Foam infill 1 is constrained into a hemi-cylinder by an outer membrane 2 of PVC or natural or synthetic rubber or similar polymeric materials bonded to the foam infill 1. A flat face of the composite structure is indicated at 8.
Typical dimensions are:

Length - 1.2m - 2m
Overall horizontal width - upto 600mm

Width around the curved face of the carrier membrane - normally upto 750mm but, depending on the spacing between floor joists, can be as much as 900mm.

Membrane thickness - 2mm - 6mm
Membrane density - 200kg.m-³
Membrane weight - 7-10 per square metre
Core density -
- (a)Foam 64kg.m^-3 to 96kg.m^-3
- (b)Mineral wool 30kg.m^-3 to 60kg.m^-3

Figures 1 and 2 show the sound insulator module located between floor joists 3, below floor boards 4 and above ceiling 5. Figure 3 shows two adjoining modules of the sound insulator being positioned between floor joists 3, with the hashed lines indicating the final position of the sound insulator modules.
The edges of outer membrane 2 extend beyond the flat surface 8 of the hemi-cylindrical foam infill 1 to form a pair of longitudinal flanges 6 which may be secured to the floor joists 3 by conventional fixings 7 such as screws or bolts.
Figure 4 shows two complementary sound insulator modules A and B. In module A an offset portion 1a of the foam infill extends longitudinally beyond the membrane 2. In module B a portion 2a of the membrane extends longitudinally beyond the end of the foam infill 1. In use, offset portion 1a of the foam infill of module A abuts the adjoining end of foam infill 1 of module B and slots into a corresponding recess formed by portion 2a of the membrane of module B.

Claims

A sound insulator comprising a sound-absorbent core (1) within a flexible membrane (2) characterised in that part of the external surface of the resultant composite structure is curved around a longitudinal axis.
A sound insulator as claimed in Claim 1 including a generally flat face (8) extending in a longitudinal direction and opposed to the curved surface.
A sound insulator as claimed in Claim 2 including a pair of substantially parallel and planar flanges (6) each of which extends beyond the flat face (8) from a corresponding edge of a curved surface of the membrane (2) in a plane substantially perpendicular to the flat face (8).
A sound insulator as claimed in Claim 3 wherein, in use, at least one flange (6) is secured to an adjacent longitudinal support (3).
A sound insulator as claimed in any one of the preceding claims wherein the curved surface is hemi-cylindrical.
A sound insulator as claimed in any one of the preceding claims wherein the membrane (2) is at least 70% of the mass of the composite structure.
A sound insulator as claimed in any one of the preceding claims wherein the thickness of the membrane (2) ranges from about 2mm to about 6mm and the corresponding weight from about 4kg to about 16kg per square metre.
A sound insulator as claimed in any one of the preceding claims wherein the membrane (2) is a natural or synthetic rubber or a high density polymer.
A sound insulator as claimed in Claim 8 wherein the membrane (2) is polyvinyl chloride.
A sound insulator as claimed in any one of the preceding claims wherein the density of the core (1) ranges from about 30kg.m^-3 to about 200kg.m^-3.
A sound insulator as claimed in Claim 10 wherein the absorbent core is a reconstituted or virgin open cell foam of density from about 64kg.m^-3 to 96kg.m^-3 or a compressed mineral wool of density from about 30kg.m-³ to 60kg.m^-3.
A sound insulator as claimed in any one of the preceding claims comprising a plurality of interconnecting modules (A, B).
A sound insulator as claimed in Claim 12 comprising a module (A) including at least one portion of absorbent core (1a) projecting beyond the flexible membrane (2) and adapted to engage in a recess (2a) in a second adjoining module (B).
A method of reducing transmission of airborne sound through a planar frame structure, which method comprises:
a) locating a sound-absorbent core (1) within a flexible membrane (2) in such a manner that: i) part of the external surface of the resultant composite structure is curved around a longitudinal axis; ii) a generally flat face (8) extends in a longitudinal direction and is opposed to the curved surface; and iii) there is formed a pair of substantially parallel and planar flanges (6) each of which extends beyond the flat face (8) from a corresponding edge of a curved surface of the membrane (2) in a plane substantially perpendicular to the flat face (8);

b) placing the resultant composite insulating structure between longitudinal frame members (3); and

c) securing each flange (6) to an adjacent longitudinal frame member (3).
A preformed, flexible membrane (2) to contain a sound-absorbent core (1) and so shaped that, in use, part of the external surface of the resultant composite structure is curved around a longitudinal axis and includes: i) a generally flat face (8) extending in a longitudinal direction and opposed to the curved surface; and ii) a pair of substantially parallel and planar flanges (6) each of which extends beyond the flat face (8) from a corresponding edge of a curved surface of the membrane (2) in a plane substantially perpendicular to the flat face (8).