GB2305946A - Sound insulation of floors - Google Patents

Abstract

A floor component includes a foam material 3 made up of a mixture of open cell and closed cell foam particles attached to an elongate batten 2 to be laid on to an existing floor 11 and a floor deck 12 laid on top. The foam has acoustic and vibration insulating properties and can be used in the refurbishment of existing floors. The batten / foam composite can be laid foam side down (Fig 2) or foam side up (Fig 3).

Description

SOUND INSULATING FLOOR CONSTRUCTION The present invention relates to the field of floors for buildings, and particularly to floor components and floor constructions having vibration insulating properties.

In commercial and residential buildings, for example block of flats, office blocks, hospitals, hotels etc. it is known to refurbish an existing concrete or wooden floor by overlaying a new floor skin on top of the existing floor, the new floor having vibration absorbing properties and particularly acoustic vibration absorbing or sound absorbing properties.

A known method of floor refurbishment comprises laying on to an existing floor a sound deadening floor construction comprising a plurality of elongate wooden battens, for example of square cross.section 50mm x 50mm, on top of the existing floor and on top of the battens laying either floor boards, or tongue and groove chipboard floor panels. The wooden battens are faced on a lower surface with a strip of foam, such that the batten rests on top of the foam strip, the foam strip being in contact with the existing floor.

A known sound deadening floor construction is disclosed in GB 2,192,913, in which there is provided a flooring raft construction comprising a plurality of floor boards nailed or screwed to a plurality of battens, each batten having on a lower face thereof, a laminated foam strip comprising a separate layer of higher density closed cell foam of thickness around lOmm, and a layer of lower density open cell foam of thickness around lOmm.

The closed cell foam is directed at absorbing low frequency vibrations, for example as caused by shock loads on the floor e.g. dropping a desk, jumping on the floor, or dropping some other heavy article on the flooring raft. The open cell foam layer is directed at absorbing higher frequency vibrations in the audible range. The open cell foam may absorb airborne acoustic vibrations by dissipation of the vibrations within the interstices of the open cell foam.

In use, since the open cell foam is much less dense then the closed cell foam, the open cell foam may compress to less than its original thickness.

For example a strip of open cell foam of height iOmm, may compress under loading to a thickness of between 4 and lOmm. The open cell foam layer compresses to a much greater extent than the closed cell foam layer.

According to one aspect of the present invention there is provided a floor construction comprising: a plurality of battens each having a layer of foam material on one side; and a plurality of floor boards laid on said plurality of battens, characterised in that said foam material comprises a plurality of open cell foam particles and a plurality of closed cell foam particles.

Preferably, said open cell foam particles and said closed cell foam particles are mixed together in substantially random orientation.

Preferably, said mixture may comprise a composition of 10% to 50% by volume of said open cell foam particles and 10% to 50% by volume of said closed cell foam particles.

Preferably, said open cell foam particles and said closed cell foam particles are bonded together.

Preferably, said foam has a density in the range 50 to 120 kgm3.

Preferably, said foam layer is of thickness in an un-compressed state in the range lOmm to 30mm, and suitably of around 20mm.

Preferably, each said foam layer is adhered to one face of the respective said batten.

Preferably, said battens may be laid such that said foam layers are presented upwardly.

Preferably, said foam layers are positioned between said floor boards and said respective battens.

Preferably, said floor boards may be adhered directly to one or more said foam layers.

Preferably, said floor construction may comprise a plurality of strips having a thickness less than a thickness of a said floor board, said strips being positioned between a said foam layers and one or more said floor boards.

According to a second aspect of the present invention there is provided a floor construction comprising: a plurality of battens each having a layer of foam material on one side; and a plurality of floor boards laid on said plurality of battens, characterised in that said foam layers are positioned between said battens and said floor boards.

The invention includes a component for a vibration insulating floor construction, said component comprising: an elongate batten having one side thereof faced with a layer of foam material, characterised in that said foam material comprises a mixture of open cell foam particles and closed cell foam particles.

Preferably, said foam layer is bonded directly to a face of said batten.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 shows a flooring component according to a first specific embodiment to the present invention; Figure 2 shows a first floor construction; Figure 3 shows a second floor construction; Figure 4 shows a transfer characteristic of acceleration transmissibility versus frequency for the floor component; Figure 5 shows a characteristic of phase difference versus frequency for the floor component; and Figure 6 shows a theoretical characteristic of transmissibility versus frequency ratio.

Referring to figure 1 of the accompanying drawings, there is shown a flooring component 1 according to a specific embodiment of the present invention. The flooring component 1 comprises an elongate timber batten 2 of substantially square or rectangular cross-section having width and height of comparable dimensions, for example 45mm X 45mm, or 45mm X 60mm.

Along one face of the batten is provided an elongate foam layer 3, the foam layer being bonded to the batten.

The foam layer 3 comprises a reconstituted foam material formed of a plurality of particles of open cell foam material mixed substantially randomly with a plurality of particles of closed cell foam material. The particles vary in size, but are suitably chopped up particles of reclaimed foam, which may have dimensions in the range 0.5mm to 20mm. The particles of open cell foam and closed cell foam are bonded together to form a unitary foam layer, under conditions of elevated temperature and pressure above room temperature and pressure. A conventional bonding agent may be mixed in with the particles prior to subjecting to the elevated temperature and pressure.

Suitably the density of the reconstituted foam is of the order of 85 kgm 3, and may be in the range 50 to 120 kgm3.

For a batten having an elongate foam layer of width 45mm and height 20mm in un-compressed form, it was found experimentally that for an evenly distributed weight of 120kgm, compression of the foam layer by 0.3 to 0.5mm was experienced. For a weight of 240kgm, the foam layer compressed by 2mm + 0.33mm. For a weight of 360kgm-2 the foam layer was found to compress by 4mm + 0.5mm.

For a weight of 480kgm2, the foam was found to compress by about Smm and for a weight of 600kgm-2, the foam was found to compress by about 6mm, giving a compressed foam layer thickness of about 14mm.

For higher pressures, the foam layer compressed significantly. For a weight of 8750kgm the foam layer of 20mm thickness in un-compressed state was found to compress to a thickness of around 2mm.

On a small scale laboratory test of a floor component having a 20mm thick reconstituted foam layer, as compared with a similar floor component having an 18mm thick reconstituted foam layer, a transfer function of acceleration transmissibility versus frequency was measured. The transfer function 100 for 20mm foam and (solid line) 18mm foam (dotted line) are shown in figure 4 herewith. A low transfer function, i.e. low value of acceleration transmissibility is desirable for isolation of vibration.

The transfer function 4 of figure 4 demonstrates an average acceleration transmissibility for 20mm thick foam layer to be lower than that for an 18mm thick foam layer, over a range 300Hz to 2kHz.

The same floor components were then tested for input/output phase difference. Referring to figure 5, the phase difference between input/output signals for 18mm and 20mm foam thickness samples was relatively low, in the range 20 to 50Hz. For applied frequencies in the range 60 to 100Hz the phase differences became significantly higher.

A natural frequency for the floor components is arbitrarily taken to be the frequency at which a phase difference between an input and output vibration is equal to 900. As compared to a control batten, the thicker the foam layer, the lower the frequency at which a high input-output phase difference was achieved, and the lower the natural frequency.

For a floor component having a 20mm thick reconstituted foam layer, the natural frequency is around 6 to 8Hz lower than for a floor component having a 18mm thick foam layer, and around 10 to 13 Hz lower than the natural frequency of the control batten.

A relatively low natural frequency is beneficial for the reasons explained in Appendix 1 herewith.

Referring to figure 2 of the accompanying drawings, there is shown a first floor construction comprising a plurality of floor components 10 each as described with reference to figure 1, laid substantially in parallel to each other on an existing convention floor surface 11, for example a concrete or wooden floor and with the foam layers 3 underneath the battens. Laid on top of the plurality of flooring components 10 is a floor deck 20 comprising a plurality of floor boards 12. Preferably the floor boards 12 are bonded directly to the battens 2 of the first components 10. The foam layers 3 are preferably loose laid onto the surface 11, to allow some movement for expansion.

Referring to figure 4 of the accompanying drawings, a second floor construction is shown. The second floor construction comprises a plurality of the flooring components 10 each arranged substantially in parallel, and laid upon a conventional flooring surface 21, e.g. a concrete or wooden floor.

The flooring components 10 are laid with the wooden battens 2 in direct contact with the conventional floor 11 and with the foam layers 3 on top of the battens 2. A floor deck 20 comprising a plurality of floor boards 12 are laid on top of the first flooring components, in direct contact with the foam layers 3. The floor boards may be directly adhered to an upper surface of the foam 3 using conventional adhesive.

With the first floor construction of figure 2, the floor deck 20 and floor components 10 are secured to each other and form a raft which can move relative to the underlying original floor surface 11. Impact vibrations are absorbed between battens and the original floor.

With the second floor construction of figure 3, the floor deck is isolated from the battens 2 by the foam strips 3 and vibrations are absorbed within the raft comprising the floor components 10 and the floor deck 20.

Specific embodiments of the present invention may have the property that severe shock loading, for example by heavy weights falling on the floor boards of the floor construction, are isolated from the underlying original conventional floor by the reconstituted foam layers 3. As the reconstituted foam layer comprises a substantially homogenous, substantially random mixture of foam particles of open cell construction and closed cell construction, bonded together, the closed cell particles may absorb heavy shock loadings, whilst the open cell particles may absorb and/or attenuate higher frequency vibrations, such as general background noise, voices, audible noise from televisions or computer equipment.

Because of the substantially random positioning of closed cell particles within the foam structure, the foam may have a more linear characteristic of compressibility against pressure loading than prior art laminate foams. Under shock load conditions, the homogeneous nature of the reconstituted foam may lead to a reduced movement of the floor deck as compared to prior art floor constructions having the conventional dual layer laminate foam.

Under compression, primarily the closed cell foam particles bear the weight of the floor deck, and the open cell foam particles occupy the spaces between particles of closed cell foam. Because the open cell foam particles and closed cell particles are randomly interspersed and orientated, provided sufficient proportion of closed cell particles, and each of sufficient size are included, the open cell particles can be substantially prevented foam compressing to a great extend and the interstices in the open cell foam can remain open to a greater extent under vertical loading of the floor, as compared with a prior art layer of purely open cell foam.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Appendix 1 Transmissibility for a single degree of freedom system is given by equation 1.

T = 1 1-(ff) fn where ff = forcing frequency.

= natural frequency.

A graph of transmissibility against the ratio (f:fJ transmissibility is illustrated in figure 6 herewith.

It can be seen from equation 1 and figure 6 that when the forcing frequency (f) is equal to the natural frequency (fn) transmissibility goes to infinity although in real situations this does not occur because of damping present. When transmissibility falls below 1 then there is an element of isolation in the floor component. A perfect isolator would show transmissibility equal to zero. Figure 6 shows that as the ratio (ff:f) increases above a value of 1 then transmissibility falls and thus isolation increases. For good vibration isolation therefore one usually looks for a flooring construction or flooring component with a natural frequency as low as possible.

Claims (14)

1. A floor construction comprising: a plurality of battens each having a layer of foam material on one side; and a plurality of floor boards laid on said plurality of battens, characterised in that said foam material comprises a plurality of open cell foam particles and a plurality of closed cell foam particles.

2. A floor construction according to claim 1 in which said open cell foam particles and said closed cell foam particles are mixed together in substantially random orientation.

3. A floor construction according to claim 1 or 2, in which said mixture comprises a composition of 10% to 50% by volume of said open cell foam particles and 10% to 50S6 by volume of said closed cell foam particles.

4. A floor construction according to any one of the preceding claims, in which said open cell foam particles and said closed cell foam particles are bonded together.

5. A floor construction according to any one of the preceding claims, in which said foam has a density in the range 50 to 120 kgm-3.

6. A floor construction according to any one of the preceding claims, in which said foam layer is of thickness in an un-compressed state in the range 10mm to 30mm, and suitably of around 20mm.

7. A floor construction according to any one of the preceding claims, in which each said foam layer is adhered to one face of the respective said batten.

8. A floor construction according to any one of the preceding claims, in which said battens are laid such that said foam layers are presented upwardly.

9. A floor construction according to claim 8, in which said foam layers are positioned between said floor boards and said respective battens.

10. A floor construction according to claim 8 or 9, in which said floor boards are adhered directly to one or more said foam layers.

11. A floor construction according to claim 8 or 9, comprising a plurality of strips having a thickness less than a thickness of a said floor board, said strip being positioned between a said foam layer and one or more said floor boards.

12. A floor construction comprising: a plurality of battens each having a layer of foam material on one side; and a plurality of floor boards laid on said plurality of battens, characterised in that said foam layers are positioned between said battens and said floor boards.

13. A component for a vibration insulating floor construction, said component comprising: an elongate batten having one side thereof faced with a layer of foam material, characterised in that said foam material comprises a mixture of open cell foam particles and closed cell foam particles.

14. A component according to claim 13, in which said foam layer is bonded directly to a face of said batten.