Suspended ceiling tile system

A method for refurbishing a suspended acoustical tile ceiling when the tiles become soiled comprises inserting a tile insert beneath each soiled tile to provide a new face to the suspended ceiling. The tile insert comprises a thin layer of substantially rigid material with an acoustical pattern of holes extending therethrough. The tile insert has a front face which is of washable material. In this manner, an entire suspended ceiling system can be refurbished without the need to remove the existing tiles. The tile insert may include a moisture barrier on the rear face of the tile insert. The moisture barrier improves washability of the tile and significantly enhances the noise reduction properties of the refurbished suspended ceiling.

FIELD OF THE INVENTION 
This invention relates to acoustical tile suspended ceilings and method and 
product for refurbishing suspended acoustical tile ceilings. 
BACKGROUND OF THE INVENTION 
Suspended tile ceilings have been used extensively in industrial, office 
and home building construction. Suspended ceilings are particularly useful 
in areas where it is not desirable to close off the space between the 
ceiling level and the floor above. This provides access to wiring, 
heating, plumbing and other service installations. Over an extended period 
of time, acoustical ceiling tile normally become soiled, particularly in 
industrial areas, commercial cooking establishments and offices. In 
addition, air conditioning outlets, particularly those extending through 
the suspended ceiling, distribute a considerable amount of soot over the 
panel surfaces. 
It is very difficult to clean acoustical tiles. Normally acoustical tiles 
have holes extending through the face and into the acoustical layer behind 
the face. Should one attempt to wash the acoustical tile, the wash water 
passes up through the holes into the water absorptive acoustical backing 
and leaches dirt back to the face of the tile. This can result in spotting 
of the tiles after they have been washed. People have attempted to paint 
the tile face instead of washing. However, this normally plugs the holes 
of the acoustical tile reducing its acoustical properties. Attempts have 
also been made to bleach the suspended ceiling tile to bring it back to 
its natural white color. However the bleach, if not properly applied, can 
be corrosive to the suspending T-bar members and can discolor the 
suspended ceiling tile. A system has been developed which successfully 
paints the ceiling tile without clogging the acoustical holes. The paint 
is a highly loaded titanium dioxide base. However, in spraying this paint 
onto the tile, it is necessary to cover all of the suspended T-bars with 
tape to prevent overcoating the metal. This becomes a very time consuming 
and labour intensive job. 
Attempts have been made in providing vinyl coated acoustical tile. However 
because of the holes provided through the vinyl, wash water can leach dirt 
from the acoustical padding of the tile back through the porous vinyl 
coating onto the surface and thereby discoloring the washed panel face. An 
example of this type of tile is disclosed in U.S. Pat. No. 4,040,213 which 
consists of an acoustical prefabricated panel having a thin flexible 
laminated facing adhesively secured to the fiberglass acoustical panel. To 
provide for sound absorption, holes are provided through the thin flexible 
laminated facing to expose the sound absorption fiberglass panels. The 
thin flexible laminated facing is made up of laminate layers of thin, 
impact resistant, metallic film laminated to glass fiber scrim which is, 
in turn, laminated to a synthetic film. If no holes were provided in the 
face of this panel, the panel would be washable. However, its acoustical 
properties would be very poor, thereby necessitating the acoustical 
pattern of holes and in turn precluding washing. A further example of this 
type of acoustical suspended ceiling tile is disclosed in U.S. Pat. No. 
4,487,793. The acoustical tile includes a base structure of fibrous 
material with another face of vinyl material. A plurality of apertures are 
provided in the outer vinyl layer. Such relationship provides for 
satisfactory acoustical noise reduction properties, however, when any 
attempts are made to wash the panel, the wash water passes through the 
apertures in the outer vinyl coating and leaching dirt back down to the 
face of the panel. Such leaching action may occur over a number of hours 
or days making it impossible to properly clean the face of the acoustical 
panel. 
Examples of suspended ceiling tiles, which have washable metal faces, are 
disclosed in U.S. Pat. Nos. 1,972,563 and 3,695,395. The difficulty with 
each of these panel arrangements is that wash water can pass through the 
apertures in the metal panel mixing with dirt on the inside of the metal 
panel and, eventually by capillary attraction, reappearing on the face of 
the panel after it is wiped down to resoil the panel face. 
Plastic panels, which provide washability of the face of the panels, are 
disclosed in U.S. Pat. No. 2,966,954. The panel is a composite of two or 
more plastics which include apertures offset from one another to define a 
tortuous path and thereby provide sound deadening properties. The 
difficulty with this system is that wash water used in cleaning the face 
of the panel can flow to within the several spaces between the panel 
portions and eventually run back resulting in resoiling of the panel face 
even after the washed panels have been wiped down. 
Suspended ceiling panels, which include a continuous washable surface, are 
disclosed in U.S. Pat. Nos. 4,241,806 and 4,248,647. In U.S. Pat. No. 
4,241,806, a panel construction consists of an outer decorative layer of 
plastic which is very light and thin. Underlying the decorative plastic 
layer is a perforated steel plate which is also relatively thin. The 
perforated steel plate transmits sound waves which pass through the outer 
decorative film into an acoustic absorption layer. Due to the outer layer 
being continuous, it is possible to wash down the panel without causing 
any soil behind the perforated metal plate leaching out onto the outer 
surface of the panel. 
U.S. Pat. No. 4,248,647 discloses an acoustical suspended ceiling tile 
which has a washable, distortion-free, decorative plastic film on the 
front face of the panel, such decorative film may be of Mylar polyester 
films (trade mark). The tile has a frame which defines a recessed area 
providing an acoustical base portion. The plastic film is adhered to the 
frame and heat-shrunk to provide a taut distortion-free film across the 
face of the panel. Such panels are not practical for most types of 
suspended ceilings because the film can be readily punctured, due to it 
being spaced from the recessed acoustical base, thereby ruining the 
appearance of the panel. 
Other types of suspended ceiling tiles which include an outer plastic film 
or metal foil to provide for washability of the tiles are disclosed in 
U.S. Pat. Nos. 3,204,380 and 3,771,213. Plastic film as disclosed in U.S. 
Pat. No. 3,204,380 is applied to the face of each interlocking acoustical 
tile. The film is drawn tightly to the face of the tile by the use of 
vacuum or the like, and with heating the softened film edges are secured 
by adhesive to the tile edges. The plastic sheet overlying the tile face 
acts as a vibrating member to transmit the sound waves to the underlying 
base which absorbs the sound energy sufficiently to appreciably reduce 
noise. The plastic film face is washfast and water impervious, to provide 
tiles which can be cleaned or washed without damage to the ceiling or 
other surface to which the tiles are applied, and without impairment of 
their acoustical properties. In U.S. Pat. No. 3,771,213 a metal foil is 
applied to the face of the tile. To ensure that the metal foil tightly 
fits the face of the tile and preventing sagging in the centre portion of 
the tile face, mechanical embossing of the foil is used to draw the foil 
tightly between the edges of the tile. Sound waves will strike against the 
foil and cause the foil to vibrate, whereby the sound is transmitted to 
the punched fibre-board backing where the sound vibrations are absorbed 
within the holes of the fibre-board backing of the suspending ceiling 
tile. However, both of these tile systems are not useful in a practical 
sense because the plastic film or metal foil can be readily punctured due 
to normal wear and tear in an office, industrial or home environment, 
hence rendering it impossible to clean the tile face. Furthermore, with 
the stretching or tightly fitting of the plastic film or metal foil to the 
face of the acoustic panel, the face can reflect by vibration more sound 
than it transmits through to the fibrous sound-absorbing backing material, 
hence requiring the use of holes or the like in the outer facing, thereby 
suffering from the drawbacks of the aforementioned U.S. Pat. No. 
4,040,213. 
In view of these difficulties with the existing expensive constructions 
which do offer washability of the panel for purposes of refurbishing, in 
most installations the acoustical ceiling tiles are simply replaced with 
new tiles, rather than any attempt made to refurbish the existing tiles 
with more expensive washable type. 
According to this invention, a system is provided for refurbishing an 
existing suspended ceiling tile without the need to replace the existing 
tile and, in turn, provide a system which is washable and can enhance the 
acoustical properties of the tile ceiling. 
SUMMARY OF THE INVENTION 
According to an aspect of the invention, a method for refurbishing a 
suspended acoustical tile ceiling comprises inserting a tile insert 
beneath each soiled tile. The soiled tiles are suspended by a plurality of 
suspended tile supporting members arranged in a grid formation. The 
supporting members support each tile by engaging a perimeter portion of 
the tile. The standard size tile insert may be cut to a size to correspond 
with the size of the soiled tile, whereby the supporting members support 
the tile insert beneath and thereby covering the soiled tile. The tile 
insert comprises a thin layer of substantially rigid material with a 
plurality of holes extending therethrough in the form of an acoustical 
pattern of holes. The tile insert has a front face which is of washable 
material. According to a preferred aspect of the invention, a moisture 
barrier layer is affixed to a rear face of the tile insert whereby the 
barrier layer covers the holes and isolates the insert tile rear face from 
the soiled acoustical tile. The moisture barrier may be affixed to the 
rear face of the insert in a manner which considerably enhances the 
acoustical sound absorption properties of the ceiling. 
According to another aspect of the invention, a composite suspended tile 
ceiling is provided which comprises in combination a tile insert beneath 
an acoustical panel. The suspended tile ceiling comprises a plurality of 
suspended tile supporting members arranged in a grid formation. The tile 
insert comprises a thin layer of substantially rigid material with a 
plurality of holes extending therethrough in the form of an acoustical 
pattern of holes. The tile insert has a front face which is of washable 
material. The tile insert is supported about its perimeter edges by the 
grid of supporting members with an acoustical panel lying and unattached 
to the tile insert. 
According to another aspect of the invention, a tile insert for use in 
refurbishing soiled acoustical tiles of a suspended tile ceiling comprises 
a thin layer of substantially rigid material with a plurality of holes 
extending therethrough in the form of an acoustical pattern of holes. The 
tile insert has a front face which is of washable material. The tile 
insert is sized to fit beneath the soiled tile of a suspended tile ceiling 
and is supported by supporting members of a suspended tile ceiling. 
According to another aspect of the invention, a method for manufacturing 
the tile insert for use in refurbishing a suspended tile ceiling comprises 
forming a thin layer of substantially rigid material. A plurality of holes 
are formed through the tile insert layer which are positioned to form an 
acoustical pattern in the tile insert. The front face of the tile insert 
is provided with a washable surface. To the rear face of the tile is 
affixed a moisture barrier film for covering at least the acoustical 
pattern of holes. The method may further comprise extruding the thin layer 
of substantially rigid material from an extrudable plastic material. The 
extruded layer is allowed to cool and the acoustical pattern of holes is 
punched from the extruded layer. The moisture barrier film is affixed to 
the rear face of the punched extruded layer and cut to form the tile 
insert. The method may also comprise thermoforming the tile insert from a 
sheet of substantially rigid plastic material. A plurality of 
criss-crossing strengthening ribs may be thermoformed into the layer of 
rigid plastic material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Suspended ceilings can be provided in many forms, such as exemplified in 
FIG. 1. The suspended ceiling 10 comprises a plurality of individual 
ceiling panels or tile 12 supported about their peripheral edges 14 by a 
gridwork of intersecting T-bars 16. The T-bars are suspended from the 
ceiling by wires 18 which are fastened to the existing ceiling (not shown) 
and then hooked through an appropriate aperture 20 in the upright leg 
portion 22 of the T-bar. The panel peripheries 14 rest on the flange 
portions 24. Normally, the ceiling tiles 12 are self-supporting and may be 
of standard sizes of two feet by four feet, or two feet by two feet 
square. The particular ceiling tile shown in FIG. 1 is of the acoustical 
type having a planar sound absorptive surface 26 with an acoustical 
pattern of holes 28 formed therein which extend into the acoustical 
absorptive material 26 to the extent shown at 28a. 
The ceiling tile 12 may be formed of a variety of materials. Commonly, the 
outer face is provided with a decorative coating which is usually white 
and may be of a variety of forms of coatings which can include fire 
retardants and smoke suppressants. The sound absorptive layer 30, into 
which the acoustic holes are formed, may consist of compressed fiberglass 
or other compressed fibres such as a wood fibres and composite mineral 
board, where the intention is that the material 30 provides sound 
absorptive characteristics and adds self-supporting characteristics to the 
ceiling tile 12. 
The outer face 26 of the ceiling tile can become soiled over time due to 
installation in industrial areas, commercial cooking establishments and 
offices. Dirt, soot, and smoke in the area and handling of tiles can soil 
the ceiling tile from the underside. Flooding from above the tile can 
cause staining on the tile face 26. 
The ceiling tile insert, according to this invention, is placed beneath the 
ceiling tile 12 to immediately refurbish the suspended tile ceiling 10 
without the need for painting or other techniques, such as washing, in 
attempting to refurbish the tile 12. Dirt and soot can collect in the 
holes 28 of the acoustical type of tile. Any attempt to wash the face 26 
of the tile 12 results in water passing into the holes and then leaching 
dirt down from the holes which will simply necessitate rewashing of the 
tile panel after it was initially cleaned. 
By use of the ceiling tile insert 32, as shown in FIG. 2, the outer face 26 
of the existing suspended ceiling tile 12 is immediately refurbished. The 
ceiling tile insert 32 is sized to correspond with the size of the 
existing tile 12. For example with the suspended ceiling 10 of FIG. 1, the 
tiles 12 are two feet by four feet. The ceiling tile insert 32 is of 
corresponding size. To refurbish the ceiling 10, the ceiling tile inserts 
32 are placed beneath the existing tiles 12 to rest on the flange portions 
24 of the respective suspended T-bars 16. To place the ceiling tile insert 
32, existing tile 12 is simply elevated sufficiently to allow placement of 
the insert 32 within the space defined by the gridwork of the suspended 
T-bar 16 and releasing the insert to allow the pre-existing panel 12 to 
fall back down on top of the insert 32 which is now supported about its 
periphery 34 by the suspended T-bars 16. 
The ceiling tile insert 32 is provided with an acoustical pattern of holes 
36. As shown in FIG. 3, these acoustical holes 36 extend through the 
thickness of the tile insert 32. The pattern of these acoustical holes may 
be random, as shown in FIG. 2, and thus will not necessarily align with 
the acoustical holes 28 in the sound absorptive material 30 of the 
pre-existing panel 12. The ceiling insert tile 32 is provided with an 
outer face 38 which is of washable material. This permits washing of the 
refurbished ceiling when the tile inserts 32 become soiled. Due to the 
tile insert being independent of the acoustical tile, the insert can be 
readily withdrawn from the ceiling for washing and then returned to the 
ceiling. This avoids dirt in the acoustical holes causing a problem. 
Another washing technique is to use a fine spray of wash water on the 
inserts while they remain in the ceiling. The wash mist can be wiped off. 
A moisture barrier 40 may be used to provide for easy washing of the tile 
insert 32 and prevent the wash water due to a capillary attraction drawing 
dirt from the existing tile 12 on to the face 38 of the tile insert. The 
moisture barrier is affixed to the rear face 42 of the tile insert. The 
moisture barrier 40 prevents any moisture applied to the face 38 of the 
tile insert from leaching dirt out of the soiled tile onto the face of the 
tile insert 32. The moisture barrier 40 precludes any moisture which may 
fall onto the panels 12 from draining through the tile insert and further 
soiling the tile insert face. The moisture barrier 40 also precludes dirt 
from within the room permeating through the acoustical tile insert and 
into the pre-existing tile 12. Normally, the insert 32 is sufficiently 
thin that washing of its exterior face 38 clears out any dirt which may 
collect within the acoustical apertures 36. 
As shown in FIG. 4, if particularly thin non-self-supporting material is 
used for the tile insert 32, it will tend to droop or sag as shown at 32a 
resulting in a bulge in the face of the tile insert and a space 44 between 
the rear face 42 of the tile insert and the acoustical panel 12. Although 
the tile insert has to be of substantially rigid material, i.e. a plastic 
panel which will flex along its length and width to allow insertion in the 
ceiling, it has to have sufficient rigidity to permit placement within the 
ceiling. Thus the insert cannot be of a thin flexible material such as 
polyethylene film since it would be very difficult to place that type of 
insert. If the tile insert 32 is essentially self-supporting, a slight 
bulge in the face of the tile insert is acceptable. However, the extent of 
bulging as shown in FIG. 4 may in some situations be unsatisfactory from 
an aesthetics point of view. To overcome this problem, fasteners may be 
used to affix the tile insert 32 to the acoustical panel 12. As shown in 
FIG. 6, a bifurcated fastener 46 may be pushed through the aperture 48 
provided in panel 12 and aperture 50 provided in tile insert 32. The 
bifurcated fastener, as shown in FIG. 6, can be reduced in width dimension 
as shown at 46a and inserted in the direction of the arrow 52, so as to 
extend through the aperture 48 in the panel 12. The lug portions 54 spread 
outwardly once their undercut portions 56 clear the upper surface 30 of 
the acoustical panel 12. The head portion 58 then draws the tile insert 32 
against the underside 26 of the self-supporting acoustical panel 12. Thus 
unsightly bulges in the tile insert can be eliminated, where normally for 
a panel such as two feet by four feet, only one or two fasteners need be 
used. The head portion 58 of the fastener 46 may be formed of transparent 
material or of a material which is colored to match the color of the 
exterior face 38 of the tile insert. When it is desired to leave a small 
spacing between the insert and the acoustical panel to enhance its 
acoustical properties in a manner to be discussed, spacer washers may be 
used about the perimeter of the insert and at the locations for the 
fasteners. 
An alternative arrangement for connecting the tile insert 32 to the 
supportive acoustical panel when the insert is not self-support, is to use 
an adhesive. Various forms of adhesives may be employed, such as hot melts 
which have a set-up time of approximately one half a minute to allow 
proper placement of the insert into position before firmly adhering to the 
acoustical panel 12. Pressure sensitive adhesives may be used which permit 
movement of the panel before setting up and adhering to the acoustical 
tile 12. Any other form of adhesive would be acceptable which can be used 
in association with the tile insert rear face, which will not affect the 
moisture barrier and affix the interior surface of the panel insert to the 
acoustical tile. Examples of other types of adhesives include contact 
adhesives, rubber based adhesives, polyvinyl acetate adhesives, tapes 
which have double sided adhesive and adhesives with transfer films where 
removal of the film exposes the adhesive for adhering to the acoustical 
panel 12. 
Aside from the use of fasteners and adhesives for affixing the tile insert 
to the acoustical panel, it is appreciated that one or more metal or 
plastic struts spanning the T-bars may be placed intermediate the tile 
insert to support it adjacent the acoustical panel. Another alternative is 
to provide an elastic member secured between opposing T-bars of the 
suspended grid network which can be used to support the tile insert 
intermediate its ends and sides. 
It is appreciated that thicker tile inserts may be used which in themselves 
would be self-supporting, particularly of the two foot by two foot size, 
or the ceiling tile insert when formed may include strengthening ribs 
which provide a self-supporting ceiling tile insert. As shown in FIG. 7, 
the ceiling tile insert 32 may include a plurality of strengthening ribs 
60 which are formed in the tile insert 32 during the manufacturing 
process. As shown in more detail in the section of FIG. 8, each of the 
strengthening ribs 60 is defined by a ridge 62 extending from the 
underside 38 of the tile insert 32. In forming the ridge 62, a trough 64 
is formed on the upper side 42 of the tile insert. The acoustical 
apertures 36 may be either formed into the tile insert before or after the 
formation of the strengthening ribs 60. The moisture barrier 40 is affixed 
to the rear face 42 of the tile insert after the formation of the 
strengthening ribs 60. As shown in FIG. 7, the strengthening ribs 60 
traverse the width of the tile insert to avoid the sag or droop in the 
insert as shown in FIG. 4. By a judicious choice of rib designs, a pattern 
can be added to the face of the tile to strengthen the tile, render it 
self-supporting and also add a decorative appearance to the tile insert 
exterior. 
To enhance the decorative effect of the suspended tile ceiling, a 
dish-shaped tile insert 66 may be inserted beneath an existing tile 12 as 
supported by the T-bars 16. The tile insert 66 has a front face 68 with 
inwardly extending side walls 70 and laterally projecting flange edge 
portions 72 which are supported by the suspended T-bar gridwork 16. As 
shown in FIG. 12, the ceiling tile insert 66 has a pattern of acoustical 
apertures 74 extending through the tile insert 66. A moisture barrier 76 
is affixed to the rear surface 78 of the panel insert and, in this 
embodiment, overlaps the side wall portions 70 and the lateral flange 72. 
The weight of the panels 12 hold the flange portion 72 against the T-bar 
flanges 24. By this arrangement, a space 80 is provided between the bottom 
face 26 of the acoustical panel 12 and the moisture barrier 76. This space 
80 enhances the acoustical absorption properties of the tile insert 66 as 
demonstrated in the following example, as well as providing a decorative 
refurbishing aspect to an existing suspended ceiling tile system. 
The tile insert may be formed of a variety of materials which have an 
exterior washable face and provide for the fixing of the moisture vapor to 
the tile insert rear face. Rigid and semi-rigid plastics, which have 
sufficient flex to allow placement of the tile insert within the suspended 
ceiling T-bar grid work, are acceptable. Materials other than plastics, 
such as aluminum and other rust-resistant metals, and pressboard may also 
be used. Representative plastics include acrylonitril-butadiene-styrene 
polymers, acrylic polymers, phenolic polymers, Nylon (trademark), 
polycarbonates, polyesters, high and low density polyethylene and 
copolymers thereof, polyimides, polypropylene, polystyrene and 
polyvinylchloride. The moisture barrier may be any suitable film which 
acts as a barrier to moisture passing beyond the tile insert and 
impregnating the existing acoustical panel or like suspended ceiling tile. 
Suitable materials for the moisture barrier, therefore, include plastic 
film, thin rubber, rubber foam, plastic foam, waterproof flame retardant 
paper, aluminum foil. A variety of plastics are acceptable for the plastic 
film, including polyethylene, polyvinylchloride and polystyrene. 
The composite pre-existing acoustical tile and tile insert generally 
designated 82 as shown in FIG. 9 has the acoustical panel 12 resting on 
top of the tile insert peripheral edges 34 supported by the flanges 24 of 
the respective suspended ceiling T-bars 16. The patterned array of 
acoustical apertures 36 in the ceiling tile insert 32 provide for rows of 
sets of apertures in the manner shown in FIG. 6. According to a preferred 
embodiment of this invention, the portions of the ceiling tile insert 
between the rows of apertures designated 84 may be affixed to the 
pre-existing acoustical panel 12. The insert may be affixed by means of 
fasteners such as shown in FIG. 5, or according to this preferred 
embodiment, at least some of the blank portions 85 of the insert with the 
moisture barrier on the rear are affixed to the acoustical panel 12 by an 
adhesive 87. In this arrangement, the moisture barrier 40 is affixed to 
the rear face of the insert 32 by use of adhesive 89. The moisture barrier 
is affixed to the rear face of the insert in a manner to provide for an 
unstretched, loose fitting of the moisture barrier over the sets of 
apertures. Then, by affixing the moisture barrier to the acoustical panels 
with a hot melt adhesive or the like, a predetermined amount of sag occurs 
in the tile insert to the extent shown in FIG. 9 between the spaced-apart 
locations of the adhesive which affix the insert to the acoustical panel 
12. In this manner, a slight gap 91 of approximately 1/4 inch is provided 
between the tile insert below the underside of the acoustical panel 12. 
With reference to FIG. 10, the gap 91 is demonstrated where the moisture 
barrier 40 is also free from the underside 42 of the ceiling tile insert 
32. Sound waves directed towards the ceiling tile insert 32 pass through 
the acoustical apertures 36 and induce vibration in the unstretched, loose 
moisture barrier 40 in the direction of arrows 93. The loose fitting 
moisture barrier then acts to dampen the energy of the sound waves passing 
through the acoustical apertures 36, and in turn transmitting the sound 
waves into the acoustical panel 12 which serves to further dampen and 
absorb the energy of the sound waves. However, due to the loose, 
unstretched nature of the moisture barrier 40 and the provision of a small 
gap 91 between the insert and the acoustical tile, it has been found that 
there is a considerable marked increase in the sound absorptive or sound 
deadening capacity of the composite acoustical tile and tile insert 
compared to normal acoustical panels. It is believed that the loose 
fitting of the moisture barrier 40, which may for example be a thin film 
of polyethylene of a thickness in the range of one-half to 3 mil, absorbs 
a considerable portion of the energy of the sound waves as they are 
transmitted through the moisture barrier into the acoustical panel 12, 
unlike systems which have moisture barriers which are taut, and transmit 
the sound wave energy to the acoustical panel and at the same time reflect 
or retransmit the sound waves. It is appreciated, however, that film 
thicknesses in the range of one-half to 10 mils are useful. 
A variety of techniques may be used in manufacturing the ceiling tile 
insert. When quantities warrant, the ceiling tile insert can be injection 
molded, particularly if complicated shapes are desired. However, 
thermoforming techniques and extrusion techniques are equally useful on 
mass production economic basis. Referring to FIG. 14, an extruder 82 is 
used to extrude the plastic in forming the sheet material or metal alloy 
sheet may be formed by rolling. For example, the plastic resin pellets 84 
are introduced via the hopper 86 and extruded by screw 88 through 
extrusion die 90 to produce a sheet 92 of a width equal to the length of 
the ceiling tile insert to be formed. The sheet 92 is passed over rollers 
94, 96 and 98 to cool and form the sheet into a uniform thickness sheet 
material 100. The acoustical pattern of holes may be punched into the 
cooled sheet 100 by mating punch dies 102 and 104 or a punch press to 
produce a continuous sheet 106 having the acoustical pattern of apertures 
repetitively formed therein. The moisture barrier 108 is withdrawn from a 
supply roll 110 and passed over idler roller 112 and fed between 
compression rollers 114 and 116 to affix the moisture barrier to the 
surface of the sheet 106. The moisture barrier 108, if of a plastic 
material, may be heat sealed to a heat sealable plastic material for the 
sheet 106. On the other hand if heat sealing cannot be employed, adhesive 
may be used. A variety of different types of adhesives may be used which 
are sprayed or applied by an applicator device on idler roller 112. With 
adhesive techniques, the moisture barrier may be affixed to a majority of 
the surface area of the sheet, thus enclosing or being affixed to the 
periphery of the majority of apertures in the sheet 106. If heat sealing 
techniques are used, the moisture barrier film is affixed to the periphery 
of essentially all of the holes in the insert. 
It is appreciated, however, that when it is desired to make the ceiling 
tile insert of FIG. 9, where the moisture barrier is affixed to selective 
portions of the insert, glue applicator wheels or the like may be used to 
apply adhesive to the planar regions 85 of the ceiling tile insert. The 
moisture barrier is then laid onto the ceiling tile insert inside surface 
42 and by pressure roller affixes the moisture barrier to these portions 
of the ceiling tile insert between the rows of sets of acoustical 
apertures. The moisture barrier is then left free, and in an unstretched 
manner loosely overlies the apertures of the ceiling tile insert. 
Similarly, heat sealing of a plastic moisture barrier to a plastic tile 
insert at areas 85 may be used in place of hot melt adhesives. 
A cutting device 118 cuts the continuous sheet 106 with the moisture 
barrier 108 laminated thereto by way of a travelling knife 120. The 
movement of the travelling knife 120 is timed to cut the sheet into 
separate ceiling tile inserts with moisture barrier affixed thereto and 
stacked in the packaging station 122. The tile inserts are cut from the 
sheet so that the repetitive acoustical pattern is preferably symmetrical 
on each severed tile insert. In the extrusion process, the strengthening 
ribs, such as shown in FIG. 7, may be extruded in the sheet since the 
strengthening ribs extend across the width of the ceiling tile insert 32 
which is the direction of travel of the extruded sheet 100. The 
strengthening ribs may be formed at the extrusion die 90 or by appropriate 
mating ridges and grooves in the rollers 94, 96 to work the extruded sheet 
before cooling over roller 98. 
An alternative approach to forming the ceiling tile insert is schematically 
shown in FIG. 15. Individual sheets 124 are removed from a pile and 
transferred to a thermoforming oven 126. The sheet 124 is heated by 
heating element 128. The sheet 124 is held by clamps 130 and lowered onto 
the thermoforming device 132 having a manifold 134 with an outlet 136. A 
vacuum is drawn on the outlet 136. The plastic sheet 124, as raised to 
thermoforming temperature by heater 128, is placed over the cavity 138. By 
vacuum, the heated sheet 124 takes on the shape of the cavity 138 to 
produce a part 140 which is the shape of the ceiling tile insert of FIG. 
11. To provide self-support for the dished portion of the ceiling tile 
insert, cross-strengthening ribs 142 are formed in the part by way of 
appropriate grooves formed in the vacuum forming cavity 138. The 
acoustical pattern of apertures is formed in the exterior face 144 of the 
formed part 140 by a punch 146. The part 140 with the acoustical apertures 
therein is then inverted and the moisture barrier 148 is applied to the 
inverted part 140 and subsequently packaged at station 158. As shown in 
more detail in FIG. 13, an adhesive may be applied to the interior of part 
140. The barrier material 148 is supported by clamps 152. Before the 
adhesive is set, the moisture barrier 148 is lowered in the direction of 
arrow 154 onto the part 140 to form a seal about the perimeter. A vacuum 
is drawn through the apertures 156 formed in the face 144 of the part to 
draw the film and adhere it against the interior surface of the part 
bottom 144, thereby forming the completed ceiling tile insert 66 of FIG. 
11. 
The ceiling tile insert, in order to be self-supporting without 
strengthening ribs, can be manufactured, for example, from polystyrene to 
a thickness of approximately 1/16 inch. It is appreciated that thinner 
inserts of the same or different material may be used having thicknesses 
ranging from 0.010 inches up to 0.60 inches. In working with these 
thicknesses of tiles, not only can ornamentation be added to the face of 
the tile by strengthening ribs and decorative acoustical patterns for the 
apertures, but also coloring may be incorporated in the plastic tile to 
provide a variety of colors in refurbishing the suspended tile ceiling. 
The coloring of the tile inserts can be coordinated with the wall and 
floor colorings. 
Due to the use of a ceiling tile insert having a surface which may be 
printed, such as the surface of plastic material, decorative effects on 
the face of a plastic insert can be created. For example, various patterns 
may be lithographed onto the outer face of the ceiling tile insert to 
enhance the overall appearance of the room in which the inserts are 
placed. Should the walls include a type of wallpaper with a textured 
finish such as "grass cloth", the ceiling tile insert may be lithographed 
to provide a surface with a straw colored tint and having printed thereon 
a design which complements the appearance of the grass cloth. Furthermore, 
the moisture barrier as positioned on the rear face of the tile insert can 
be of various colors to blend in with the surface color of the ceiling 
tile insert. 
The tile insert can be formed of materials having acceptable fire ratings 
on flame spread and smoke generation. A treated polyvinylchloride material 
with fire retardants may be used which has a rating of twenty-five for 
flame spread and fifty for smoke development in accordance with the 
National Building Code, which is a class 1 AMA flame spread index. 
Should the tile insert be formed of plastic, its face portion is inherently 
washable. However with other surfaces, such as aluminum or pressboard, the 
face may be provided with a laminated layer which is washable or a paint 
layer which provides for washability. The surface of the plastic tile 
insert may be treated with antistatic compounds to resist the accumulation 
of dust on the faces of the tile inserts. The face of the tile insert is 
readily cleaned by use of a damp cloth or a fine spray of cleaning 
solution which can be wiped with a sponge. By use of the moisture barrier, 
there is little if any likelihood of moisture in the holes bleeding dirt 
down onto the face of the tile which would require subsequent washing. The 
tile inserts are sufficiently thin that washing will normally clean out 
dirt from the acoustical holes. The tiles are particularly useful in areas 
requiring sanitary conditions, such as cooking areas, hospitals and 
environment controlled rooms. The ceiling tile inserts are long lasting 
and may be cleaned any number of times by mild chemicals to maintain the 
fresh look of the refurbished suspended ceiling. The tile, due to the 
acoustical pattern of holes, retains the acoustical values of the existing 
ceiling without requiring replacement of the existing tiles. The tiles, 
when made particularly of the planar type as shown in FIG. 2, can be 
readily cut to the size of ceiling tile in the suspended grid network 
which is to be refurbished. The moisture barrier as optionally affixed to 
the rear of the ceiling insert readily provides for custom cutting of the 
tile pieces and insertion where required in the suspended ceiling. 
EXAMPLE 1 
The noise reduction coefficient (NRC) which is a measure of the sound 
absorptive characteristics, was determined for composite ceiling tile 
insert and acoustical panel of this invention compared to a normal 
acoustical panel. The samples tested were an acoustical panel normally 
used in suspended ceilings, the ceiling tile insert of this invention in 
direct contact with the acoustical panel, and the ceiling tile insert of 
this invention at a distance of approximately 1/4 inch from the acoustical 
panel. The noise reduction co-efficient is the arithmetic mean of the four 
absorption co-efficients calculated for frequencies of 250, 500, 1,000 and 
2,000 Hz. The value so obtained is rounded off to the nearest multiple of 
0.05. The absorption co-efficient represents the ratio of sound absorbing 
effectiveness, at a specific frequency, of a unit area of acoustical 
absorbent to a unit area of perfectly absorptive material. The tests were 
conducted in accordance with ASTM C-423-81A Standard using the type E-400 
mounting. 
The acoustic absorption co-efficient for each of the 1/3 of octave 
frequency band was calculated by the following equations: 
EQU X=(A.sub.s -A.sub.e)/S (1) 
where 
x=Absorption co-efficient 
A.sub.s =Absorption of room with sample in (metric sabin) 
A.sub.e =Absorption of empty room 
S=Total sample area (ft.sup.2) 
The absorption is given by: 
EQU A=0.9210.sub.c.sup.vd (2) 
where 
v=Volume of the reverberation room (ft.sup.3) 
d=Rate of decay (db/s) 
c=Speed of sound in air (1130 ft/s) Since recorded time is for a 60 db drop 
one can write d=n/t=60/t 
##EQU1## 
The results of the tests are as follows: 
______________________________________ 
Sample Tested NRC (Noise reduction co-efficient) 
______________________________________ 
Acoustic panels 
0.50 (0.5230) 
Plastic inserts in 
0.50 (0.4964) 
contact with 
acoustic panels 
Plastic inserts at a 
0.60 (0.6095) 
distance of 1/4" from 
acoustic panels 
______________________________________ 
A plot of the acoustic absorption co-efficient for each 1/3 of octave 
frequency band was calculated in accordance with the above formulae. The 
values of the absorption co-efficient versus the frequencies for the 
acoustic panel alone, the plastic insert in contact with the acoustic 
panel and a 1/4" gap between the acoustic panel and the insert are shown 
in FIGS. 16 and 17. FIG. 16 illustrates that with the insert in contact 
with the acoustic panel, the absorption co-efficient is less than with the 
uncovered acoustic panel, whereas 1/4" gap between the plastic insert and 
the acoustic panel provides absorption co-efficients which are 
considerably higher for the system with the insert spaced from the 
acoustic panel. 
From these results it is apparent that a gap between the ceiling tile 
inserts and the acoustic panels provide very high absorption co-efficients 
relative to the standard type of acoustic panel. Such gap may be provided 
in a variety of ways such as illustrated in FIGS. 9 and 12. Furthermore, 
with respect to the particular absorption co-efficients versus frequency 
as shown in FIG. 17, the system with the gap between the ceiling tile 
insert and the acoustic panel provides significant improvements 
particularly in the higher frequencies in the range of 2.5 kHz. This 
system provides greatly improved sound absorption characteristics in the 
range most needed, particularly in office environments where word 
processing equipment, telephone, and other machines generate sounds in 
this range which are considerably dampened by this system. 
The ceiling tile inserts according to this invention with moisture barrier 
not only provide a system for enhancing or refurbishing an existing 
suspended ceiling tile system, but also, when used in accordance with a 
preferred embodiment of this invention and spaced to a slight degree from 
the acoustic panels, provide significant improvements in sound absorption 
characteristics in the ceiling. 
Although preferred embodiments of the invention have been described herein 
in detail, it will be understood by those skilled in the art that 
variations may be made thereto without departing from the spirit of the 
invention or the scope of the appended claims.