AU4986993A

AU4986993A - Method and apparatus for improving sound insulation

Info

Publication number: AU4986993A
Application number: AU49869/93A
Authority: AU
Inventors: Godfrey Wynn Hall
Original assignee: Woolhouse International Ltd
Current assignee: WOOLHOUSE INTERNATIONAL Ltd
Priority date: 1992-09-11
Filing date: 1993-09-09
Publication date: 1994-04-12
Also published as: WO1994006976A1

Description

METHOD AND APPARATUS FOR IMPROVING SOUND INSULATION

TECHNICAL FIELD

This invention relates to apparatus and methods for improving sound insulation.

BACKGROUND ART

Reference throughout this specification will be made to use of the present invention with conventional building constructions, however it should be appreciated that the present invention has applications outside this field.

A standard parameter that indicates the amount of sound transmission through an object is the Sound Transmission Class (STC). The greater the STC, the less sound (particularly in the speech frequency range) that is transmitted through that object. Recently in New Zealand, a law has come into effect which states generally that a common wall between habitable dwellings should have minimum STC of 55.

In particular, it is now a concern that the noise of human occupation including speech, radio, television and other household activities does not transfer between walls.

A typical wall construction has fibreglass situated in the cavity between noggins and the studs. Typically the fibreglass is in the form of pads. With this arrangement and two layers of material such as plasterboard nailed directly to each side of the studs, an STC of approximately 45 is achieved. The density of fibreglass used in this situation is higher than a compressible blended polymer-woollen blanket. Further, although fibreglass does reduce sound passing through the wall, the fixing of plasterboard directly to the noggins and studs assists sound to pass therethrough. It is also expensive to use two layers of plasterboard each side of the stud to provide additional sound insulation to achieve more than STC 45. In an attempt to further lower the level of sound transmission, a resilient rail is used to separate the plasterboard from the studs and noggins. Using the set-up described previously in combination with a resilient rail, an STC of approximately 50 can be achieved. However, use of the resilient rail is an additional cost and this construction still cannot be used as a common wall between dwellings as the STC is not high enough.

Currently, to achieve an STC of 55 or more, two possible constructions are available.

The first construction is a solid concrete wall approximately 150mm thick which is understandably expensive and heavy.

The second construction is two separate walls having no point of contact between them. A fibreglass blanket is placed between the walls. The outer surfaces of the walls require plasterboard lining. It can be seen that this construction can also be expensive to produce and takes up space (approximately 220mm).

It is an object of the present invention to address the above problems, or at least to provide the public with a useful choice.

Further objects and advantages of the present invention will become apparent by the following description which is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a method of improving the sound insulation of a wall having cavities therein characterised by the steps of: a) attaching a compressible material to an outer surface of the frame of the wall, and b) placing a lining against the compressible material, and c) attaching the lining to the frame of the wall, wherein the construction of the compressible material is such that it at least partially fills the cavities in the wall yet is compressed between the lining and the outer surfaces of said wall. The term "wall" in this specification shall be taken to mean not only vertical partitions, but also floors and ceilings.

The cavities in the wall shall be now referred to as the gaps between the noggins and the studs, however it should be appreciated that the present invention can be used with walls having different types of cavities. For example, the cavities may be between joists or beams of floors and ceilings.

The lining which is attached to the wall shall now be referred to as plasterboard, however it should be appreciated that many other types of material may be used in accordance with the present invention. For example, other linings such as hardboard or particle board may be used. Preferably the lining chosen assists in the improvement of sound insulation as well. For example, dense linings are particularly effective.

The compressible material may be made from a variety of materials, for example Dacron™, other polyester fibres and other compressible insulatory materials for example rubber.

One compressible material that the applicant has found to be particularly suitable is a composite material invented by the applicant which is a mixture of wool and polymer and has sound and thermal insulation properties. The material is constructed so that it does not collapse under its own weight, yet is highly compressible with a ratio greater than 10 to 1.

For example, one embodiment of this material has an uncompressible thickness of 40mm but can compress down to 2-3mm. A blanket of this material 75mm thick can compress to 4-5mm. A full description of this composite material is given in PCT Patent Application No. NZ/PCT 00024.

In preferred embodiments of the present invention, the composite material has a high proportion of wool to provide the required softness and compressibility. Possible ratios of wool and polymer are given below, however it should be appreciated that other ratios could be used.

For example, in a preferred embodiment of the compressible material a percentage of wool may be between 70% and 100%, a percentage of low melt polymer between 0% and 30% by weight. This mixture may be baked in an oven with a temperature of between 100°C and 200°C, with the preferred temperature being approximately 160°C.

The present invention overcomes a number of problems associated with the prior art. Compression of the same material between the plasterboard and the studs/noggins, provides a resilient material which separates the plasterboard from direct contact with the studs/noggins. This reduces the transmission of sound which has been a problem with previous wall constructions. The un-compressed material can substantially fill in the wall cavities and reduces the transmission of high frequency sound. This also obviates the need to use a resilient rail, making this method less expensive than previous methods.

A further advantage of the present invention is that the method of construction is also simpler and less consuming than previous methods. Instead of cutting pads of fibreglass to size to place in the cavities, a single blanket of compressible material can be attached to the top of the wall and draped downwards.

The applicant has found that the use of nails, screws and other rigid fixing means commonly used to attach the plasterboard to the studs is also responsible for a considerable amount of sound transmission. Therefore, in preferred embodiments of the present invention the method of construction uses only a few rigid fixing means such as nails, rivets and screws, if any. Typically, nail spacings are in the order of 150mm. With the present invention nail spacings in the order of 300mm can be used.

According to a further aspect of the present invention there is provided a method of improving sound insulation as described characterised by the further step of attaching a lining to a wall frame with an adhesive. A resilient adhesive, for example Gibfix™ adhesive can isolate vibration and act to isolate the plasterboard from the studs. This occurs, as vibration of the plasterboard is absorbed, and not directly transmitted through rigid fixing means into the studs. Gibfix™ adhesive has particularly suitable properties in reducing sound transmission as it remains slightly soft and pliable once set.

To attach the plasterboard to the resilient adhesive, there may be holes created in the compressible blanket through which the adhesive can attach to the studs and to the plasterboard. With this construction, fewer nails and screws can be used to attach the plasterboard to the wall. In some embodiments using this method, it may be possible to totally eliminate the requirement for the rigid attachment means.

It is envisaged that there will be many variations on how a wall can be constructed using the present invention. It has been found by the applicant that it is important that the compressible blanket is attached to the top plate and the bottom plate of the wall (if it is vertical) and that there is little or no gap in those regions. With 'walls' that are floors or ceilings, the blanket should be securely attached to the sides of these with minimal gaps.

If two layers of plasterboard are used on each side of the wall with the present invention, it is envisaged that in a preferred embodiment the boards be glued together. Once the glue has set, any rigid fixing means holding the boards together can then be removed. This is another method by which sound transmission can be reduced. However other methods of fixing may be used provided that the sheets of plasterboard are not connected rigidly to the frame of the wall. Rigid fixing means could be used to hold the two boards together provided these do not also connect the boards to the studs and noggins.

Some examples providing an indication of how well the present invention compares with the prior art are given below. Example One

A compressible wool mix blanket of approximately 30mm in width with a composition substantially as described above was draped over studs and noggins. A single layer of plasterboard was attached using the combination of Gibfix™ adhesive and nails. This achieved an STC of 46. In comparison, previous methods required the use of fibreglass which is a more expensive material as well as an extra sheet of plasterboard on each side of the wall to achieve an STC of 45.

Example Two

To achieve an STC of greater than 55, a similar construction is used to that above, however a further wool mix blanket was used on the other side of the wall along with two layers of plasterboard on each side. This construction is considerably easier to construct than the previous construction outlined earlier in the specification which was required to achieve an STC of 55 or more. Further, a greater living surface area is achieved as more floor space becomes available by constructing one wall only.

BRIEF DESCRIPTION OF DRAWINGS

Aspects of the present invention will now be described by way of example only with reference to the accompanying figure in which:

Figure 1: is a diagrammatic cross-section of one embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

With respect to the drawing, there is provided a method of wall construction generally indicated by arrow 1.

It should be appreciated that the wall construction 1 is not necessarily shown as being dimensionally accurate. Further, the material used are given by way of example only, for example the top plate 2 and noggin 3 may not necessarily be constructed of timber and may be made of steel or some other material.

A wool mix compressible blanket 4 is fastened to the top of the top plate 2 to ensure that there is no bare timber through which sound can be transmitted.

The blanket 4 hangs downwards and is pressed against the outer surfaces of the top plate 2 and noggin 3 by plasterboard 5.

In the gap 6 between the top plate 2 and noggin 3, the blanket 4 is in its un-compressed state, thus filling a considerable proportion of the gap 6.

The plasterboard 5 is not attached by nails as previously, but is attached to the noggin 3 by a resilient adhesive 7 which passes through a hole which has been created in the blanket 4.

The profile of the wool blanket 4 is such that it provides a dense compressed material that isolates the plasterboard 5 from the top plate 2 and noggin 3, as well as providing a filling material for the cavity 6. This has the dual property of absorbing sound in the cavity and isolating vibration transmission from the frame of the wall to the plasterboard lining. Further, there is no need to cut individual pieces of fibreglass (which is expensive and potentially a safety hazard as safety equipment is usually required). There is also no requirement for a resilient rail and the second sheet of plasterboard is not always required.

It should be appreciated that the blanket 4 is also securely attached to the bottom plate (not shown) of the wall.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE;

1. A method of improving the sound insulation of a wall having cavities therein characterised by the steps of: a) attaching a compressible material to an outer surface of the frame of the wall, and b) placing a lining against the compressible material, and c) attaching the lining to the frame of the wall, wherein the construction of the compressible material is such that it at least partially fills the cavities in the wall, yet is compressed between the lining and the outer surfaces of the wall.

2. A method of improving the sound insulation of a wall as claimed in claim 1 wherein the material has sound and thermal insulation properties.

3. A method of improving the sound insulation of a wall as claimed in either claim 1 or claim 2 wherein the compressible material includes wool.

4. A method of improving the sound insulation of a wall as claimed in either claim 1 or claim 2 wherein the compressible material includes a polymer.

5. A method of improving the sound insulation of a wall as claimed in either claim 1 or claim 2 wherein the compressible material is comprised of: a) a percentage of wool in between 70% and 100%, and b) a percentage of low melt polymer between 0% and 30%.

6. A method of improving the sound insulation of a wall as claimed in either claim 1 or claim 2 wherein there is no or fewer rigid attachment means than conventional methods used to a affix a lining to the frame of the wall.

7. A method of improving the sound insulation of a wall as claimed in either claim 1 or claim 2 characterised by the further step of attaching the lining to the wall with an adhesive.

8. A method of improving the sound insulation of a wall as claimed in claim 7 characterised by the further step of creating holes in the compressible material through which the adhesive can attach to the lining and the frame of the wall.

9. A method of improving the sound insulation of a wall as claimed in claim 1 characterised by the further step of using two linings fixed together.

10. A method of improving the sound insulation of a wall as claimed in claim 9 characterised by the further step of: a) gluing the two linings together, and b) removing any rigid fixing means that were holding the linings together.

1 1. A method of improving the sound insulation of a wall as claimed in claim 1 wherein the compressible material is in the form of a blanket.

12. A method of improving the sound insulation of a wall substantially as herein described with reference to and as illustrated by the accompanying drawing.