CA1229462A - Monolithic ceiling for manufactured housing - Google Patents
Monolithic ceiling for manufactured housingInfo
- Publication number
- CA1229462A CA1229462A CA000478460A CA478460A CA1229462A CA 1229462 A CA1229462 A CA 1229462A CA 000478460 A CA000478460 A CA 000478460A CA 478460 A CA478460 A CA 478460A CA 1229462 A CA1229462 A CA 1229462A
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- Canada
- Prior art keywords
- ceiling
- tape
- plasterboards
- latex
- plaster
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
MONOLITHIC CEILINGS FOR MANUFACTURED HOUSING
Abstract of the Disclosure A crack resistant, monolithic looking ceiling and/or wall in a manufactured house is fabricated on an assembly line. A veneer of set-accelerated plaster is sprayed onto a subtract of plasterboards rein-forced at the joints with glass fiber mesh tape and a single layer of setting-type joint compound which is flush with the tape. The steps of taping, application of joint compound, plaster spraying, and, optionally, paint spraying serially overlap so that a one-thousand square foot area may be reinforced and surfaced in about one hour.
Abstract of the Disclosure A crack resistant, monolithic looking ceiling and/or wall in a manufactured house is fabricated on an assembly line. A veneer of set-accelerated plaster is sprayed onto a subtract of plasterboards rein-forced at the joints with glass fiber mesh tape and a single layer of setting-type joint compound which is flush with the tape. The steps of taping, application of joint compound, plaster spraying, and, optionally, paint spraying serially overlap so that a one-thousand square foot area may be reinforced and surfaced in about one hour.
Description
MONOLITHIC CEILINGS FOR ~NUFACTURED HOUSING
This invention relates to the factory construction of mobile homes and modular housing units. It relates particularly to the problem of providing such buildings with walls and ceilings having an esthetically pleasing monolithic surface like those in conventional, site-built residences.
The manufacturers and buyers of modular homes and mobile homes have long desired a more esthetically pleasing appearance for the walls and ceilings of their homes as delivered from the factories. Truly monolithic surfaces on long expanses of ceiling and walls have not been available in such homes because of the co-existing demands for a method amenable to assembly line constraints for finishing one 1000 square foot ceiling unit every hour, for units which are crack resistant on the assembly line and on the road, for units having a surface which is handle able within an hour or less, and for units which are easily touched up in case of damage.
In the manufacture of mobile homes, or example, the ceiling structure is built by fastening 4-foot wide plasterboards to the lower chords of a row of roof trusses spaced apart at 16 or I inch intervals. Staples, screws and/or adhesives may be used as the fasteners. The plaster-boards are from 10 to 14 feet long, depending on the desired width of the unit Thus, in a 48 foot long unit where are 12 panels and 11 joints to be concealed. The walls of a mobile home are built in a similar manner, stapling the plasterboards to the framework Ox studs, plates and runners to form an array of mutually abutting panels. Such ceilings and 25 walls must be able to withstand the considerable flexing and twisting which are normally encountered during their fabrication and placement at the economically feasible rates of an assembly line. They must also be $
durable under the severe racking forces encountered during transport-lion ox the housing units over the road.
Until the present invention, the industry has not been able to produce housing units with durable, seamless ceilings within the time constraints of an assetnbly line. It has been and continues co be common 6 practice to conceal Joints and fasteners with batten strips and rosettes.
Systems have been proposed whereby the fasteners are located on the occluded face of the plasterboard. There still is a seam between such back fastened boards, however, and although careful butting of the boards will produce an appearance more pleasing than batten strips and rosettes, a truly monolithic appearance can only be achieved by con-coaling the joints in some unobtrusive manner. Joint tapes covered by several layers of joint compounds are obviously not unobtrusive. The obvious expedient of covering the taped and filled surface with paint is impractical in the manufactured housing industry because of the long drying time of the paint as jell as of drying and setting times of the joint compounds.
The acceleration of the setting of joint compounds when used in the factory construction of homes is the subject of US. Patent No.
3,984,269. To avoid the problems arising from the mixing of an acceder-atop with the joint compound before application, the patentees spray the joint tape with a solution of the accelerator before the joint come pound is applied and then over each layer of joint compound aster it has been spread and feathered. The patentees say that a wall section thus treated can be moved and further assembled abut 15 minutes after the accelerator is sprayed over the final layer of joint compound. Further time is required, however, for painting or otherwise covering the broad bands of joint compound on the surface of the plasterboard.
Hobson, in US. Patent No. 3,035,940, advocates doing away with joint tapes and join compounds in favor of spraying combine streams of plaster and an accelerator directly over the entire surface I the plasterboard, newlyweds and all. Outstanding advantages of the method are said to accrue in thee there is no nail popping and painting is possible some hours after the plasterboard is installed. Suck a volleyer of plaster would not be expected to survive the severe racking conditions encountered by a ~anufact~lred housing unit during and aster its fabrication.
McNulty, on the other hand, teaches in US. Patent No. 3,391,037 the use of adhesive-edged glass fiber mesh tape as a joint reinforcement along with an over layer of Joint compound when the plasterboard wall is to be painted or without the joint compound when a veneer of plaster is to be applied. Neither ~cNulty nor Hobson is addressed to the racking problems that are unique to manufactured housing.
It is an object of this invention, therefore, to provide an answer to the long felt need for affordable monolithic looking ceilings and walls in manufactured housing.
lo It is a related object of this invention to provide mass produced ceilings and walls for modular and mobile homes that are durable in transit and monolithic in appearance.
It it a further object of this invention to provide a method for manufacturing housing having seamless ceilings and walls which are resistant to cracking while being lifted, turned and twisted on an assembly line.
It is still another related object of this invention to provide a method for the production of seamless, crack-resistan~ ceilings and walls in a manufactured housing unit in which the steps of reinforcing the joints of the plasterboard substrate, spraying a veneer of plaster onto the reinforced substrate, and painting the plastered surface serially overlap one another.
It is a related object of this invention to provide a method for reinforcing the joints in an array of mutually abutting plasterboards and applying a monolithic veneer of plaster to the reinforced array to produce ceilings and walls for modular and mobile homes at a rate of about 1000 square feet per hour.
It will be understood that a manufactured housing unit may be an individual module of a modular home, one of two or more rooms of a mobile home to be joined after separate transportation to a buyers lot, or it may be the complete mobile home. The term "plasterboard" includes gypsum board and cement board or other building boards where their use is appropriate and desirable. The term "plaster," however, refers either to a paste of water and koalas sulfate hemihydrate or the set gypsum, as the context requires. The term "seamless", as used herein to describe a surface, means that the surface is virtually devoid of any evidence of underlying seams or bands of joint compound. The term "structural panel ~:Z~34~
assembly" includes ceiling and walls, that is, the framework and plaster-boards attached thereto which constitute the substrate of a coiling or a Hall; joint reinforcing tape, joint compound filling the tape; a veneer of plaster; and, optionally, a coat of paint.
The monolithic ceiling surface of this invention is created by taping the joints with a glass fiber mesh type, pressing a single layer of a latex-modified, setting type joint compound into the voids of the tape, covering staples in the field of the board with a joint compound or its equivalent, and, while the latex-modified joint compound is still wet, spraying a coat of latex-modified, set-accelerated plaster over the entire surface. Preferably, a first coat is sprayed with a steady sweeping motion along successive paths parallel to the joints to build up a thickness of about one-sixteenth of an inch and, after about I to about 2/3 of the surface has been sprayed and while the first coat is still wet, spraying a second coat with a similar sweeping motion along successive paths at fight angles to the joints. one-thousand square foot ceiling substrate is thus covered with a one-eighth inch thick veneer of hard, durable plaster in from about 45 to about 50 minutes after taping of the joints is commenced. color variation caused by a high moisture level in the joint areas is noticeable initially but this dissipates upon drying so that a seamless, truly monolithic appearance is achieved.
The still wet but setting plaster may be spray coated with a water-based latex paint to provide a still Gore uniform appearance and allow for fast touch-up of the finished ceiling if damaged or marred during subsequent phases of construction ox the housing unit. Spraying of the paint may be commenced at one end of the ceiling while the opposite end is still being sprayed with plaster. Rapid drying of the paint is effected by the absorb-lion of water by the setting plaster. Due to the overlapping ox the plaster and paint sprawling operations, one thousand square feet of ceiling surface may be completely finished and decorated in from about 55 to about I minutes.
Because setting of the plaster is occurring while the pollinating it in pro~resst the finished ceiling structure may ye hoisted into place atop the upright walls in from about 5 to about 15 minutes after the painting is completed. Thus, the elapsed time from the commencement of taping to the placement, not including fastening, of the painted ceiling s~rtlcture in the housing unit is from about 60 to about 75 minutes. If painting is omitted, eke cPilin~ structure may be hoisted into place about 60 to 65 minutes after the first tape is touched to the gypsum board. Actually, there is very little time lost in waiting for eke plaster to set sufficiently to allow movement of the ceiling if the ridge plates which tie the trusses together are not in-stalled until Just before the structure Lo hoisted.
All of the manipulative steps in the reinforcing and surfacing of assailing may serially overlap, that is, application of joint compound may be started while taping Lo being completed, plaster spraying may be started while joint compound is still being spread, and painting may be stated 10 while plaster is still being applied.
The operations involved in fabricating a monolithic appearing wall are substantially the same as for a ceiling, except for the overhead spraying of a ceiling as opposed to the horizontal spraying of an upright wall. Thus, the rates given above for a ceiling may also be achieved in the fabrication of seamless, crack-resistant walls.
The industry desires a plaster application rate of about 2000-4000 square feet per hour or about one average ceiling every 15 minutes.
Spraying of the plaster at such a rate is possible, however, the critical step in the fabrication of the ceilings and walls of this invention is 20 the reinforcement ox the joints between the plasterboards making up the substrate for the ceiling or wall. Because the stresses at these joints are more severe in housing units constructed on an assembly line and destined for movement over highways and byways than in conventially built, stationary homes, reinforcement of these joints is a special 25 problem on the assembly line.
In this invention, the total thickness of the filled glass mesh tape is from about 0.008 to about 0.015 inch. The tape itself, preferably adhesive-backed, is that thick and the skim coat of the joint compound is just thick enough to fill the voids of the mesh. The outline of the 30 fiber network is still visible before the plaster veneer is applied.
The coat of Joint compound may be slightly thicker but this is not considered beneficial; its application would be more time consuming be-cause the use of the tape as a gauze would be forfeited. A setting type of joint compound such as that sold under the trademark Durabond by the 35 United States Gypsum Company or as described in US. Patent Jo. Rev 2~,753 provides the slip, water-retention, and flow properties desired for the purposes of this invention. A preferred compound is made by adding a supplementary amount of a latex binder to the mix water before the joint ~.2~9~-~62 compound powder is stirred in. us mixed, the wet joint compound is easily spread upon and pressed into the voids of the tape but it stiffens in place within a few minutes so that the spraying of an aggregate-filled plaster does not cause pock marking of the still wet mud. The S preferred compound contains prom about 6.1% to about 7.1% latex solids based on the total dry weight of the compound but the latex solids con-tent may range from about 3.2% to about 10.9%.
The manipulative steps of taping and spreading joint compound in the reinforcement of 100 lineal feet of plasterboard, using 2.5 inch wide tape at the joints, are complete in from about 10 to about 12 minutes.
The setting time of the joint compound may be, nevertheless, retarded so that a three hour supply or more may be mixed before the taping is begun. joint compound having a 45 minute setting time is preferred.
Because the plaster is applied by spraying, a monolithic surface having a hubby texture is preferred. uniform texture is provided by the addition of an aggregate such as puerility to the calcium sulfate hemlhydrate in an amount appropriate to the desired texture. The volume to weight ratio of aggregate to hemihydrate is from about 1.5 to 6, preferably prom about 2.5 to about 3.5, cubic feet per hundred pounds. Bonding of the aggregate in the set plaster as well as in the freshly sprayed plaster is improved by the addition of polyvinyl acetate, polyvinyl alcohol, starch, mixtures and equivalents thereof to the plaster. The hardness and flexural strength of the set plaster are improved, also. moreover the bond of the plaster to the paper on the plasterboard is improved, especially when the paper has a low suction. Retention of moisture in the sprayed plaster is prolonged so that hydration of the hemihydrate in the thin layer is ensured. The polyvinyl acetate or its equivalent may be incorporated as a powder in the dry plaster or it may be added as a latex to the plaster mix, i.e., the mixture of hemihydrate, aggregate, a retarder, and water. The weight ratio of dry polyvinyl acetate, for example, to the total weight of hemihydrate and aggregate is from about 0.75:100 to about 1.5:100.
The retarder is added in an amount sufficient to give a setting time of about 9 to 12 hours so that a batch may be mixed in a hopper and pumped to a spraying tool such as a pole gun for a full work shirt and residual amounts in the equipment may be flushed out easily. An even more extended setting time is desirable so that daily cleaning of the equipment is not necessary.
22~z The setting of the plaster is accelerated as it issues from the nozzle of the pole gun by entraining a solution of aluminum, potassium, or ferrous sulfate or their equivalents in a stream Ox atomizing air which it injected into the stream of plaster just before the plaster leaves the nozzle. The setting of the plaster is accelerated su~Eiciently to allow the ceilillg or wall assembly to be hoisted into position within about 15 to about I minutes after completion of the spray application of the plaster. To attain such a rapid setting rate, a solution containing from about 18% to about 50% by weight of the accelerator is injected into the plaster stream at a rate ox from about 40 mls to about 320 mls. per minute. The flow rate of the plaster stream through the nozzle is from about 5.9 liters to about 11.8 liters per minute. Thus, the volume ratio of the accelerator solution to the plaster mix is from about 1:140 to about 1:40. The setting time ox the plaster as thus accelerated is preferably from about 9 to about 15 minutes.
The square edged, 5/16 inch thick plasterboard having a manila face paper commonly used in the mobile home industry is satisfactory as the substrate for the monolithic ceiling surface ox this invention even though it has less suction than the plasterboard that is usually used as a veneer base.
Further details of the imTent:Lon are revealed in the following example but this is not to be taken as a limitation thereof.
Example 1 A ceiling assembly measuring 13.5' x 66', having a 45' long vaulted area, for a mobile home was constructed by the staple and screw attachment of sixteen and a half 4' x 13.5' square edged, 5/16" thick plasterboards to the lower chords of a row of 50 wooden roof trusses spaced 16 inches apart on center. The assembly was hoisted above a work station and was supported on a jig while reinforcing and spraying of the assembly were on performed, joint compound mud was prepared by mixing Durabond 45 joint compound powder with water and a polyvinyl acetate latex (55% solids;
sold under the trademark Elves JC~I by Reich hold Chemicals in the proportion: 25 pounds of the powder, 1.4 gallons of water, and one quart of the latex. The joints between the plasterboards were taped with a I
This invention relates to the factory construction of mobile homes and modular housing units. It relates particularly to the problem of providing such buildings with walls and ceilings having an esthetically pleasing monolithic surface like those in conventional, site-built residences.
The manufacturers and buyers of modular homes and mobile homes have long desired a more esthetically pleasing appearance for the walls and ceilings of their homes as delivered from the factories. Truly monolithic surfaces on long expanses of ceiling and walls have not been available in such homes because of the co-existing demands for a method amenable to assembly line constraints for finishing one 1000 square foot ceiling unit every hour, for units which are crack resistant on the assembly line and on the road, for units having a surface which is handle able within an hour or less, and for units which are easily touched up in case of damage.
In the manufacture of mobile homes, or example, the ceiling structure is built by fastening 4-foot wide plasterboards to the lower chords of a row of roof trusses spaced apart at 16 or I inch intervals. Staples, screws and/or adhesives may be used as the fasteners. The plaster-boards are from 10 to 14 feet long, depending on the desired width of the unit Thus, in a 48 foot long unit where are 12 panels and 11 joints to be concealed. The walls of a mobile home are built in a similar manner, stapling the plasterboards to the framework Ox studs, plates and runners to form an array of mutually abutting panels. Such ceilings and 25 walls must be able to withstand the considerable flexing and twisting which are normally encountered during their fabrication and placement at the economically feasible rates of an assembly line. They must also be $
durable under the severe racking forces encountered during transport-lion ox the housing units over the road.
Until the present invention, the industry has not been able to produce housing units with durable, seamless ceilings within the time constraints of an assetnbly line. It has been and continues co be common 6 practice to conceal Joints and fasteners with batten strips and rosettes.
Systems have been proposed whereby the fasteners are located on the occluded face of the plasterboard. There still is a seam between such back fastened boards, however, and although careful butting of the boards will produce an appearance more pleasing than batten strips and rosettes, a truly monolithic appearance can only be achieved by con-coaling the joints in some unobtrusive manner. Joint tapes covered by several layers of joint compounds are obviously not unobtrusive. The obvious expedient of covering the taped and filled surface with paint is impractical in the manufactured housing industry because of the long drying time of the paint as jell as of drying and setting times of the joint compounds.
The acceleration of the setting of joint compounds when used in the factory construction of homes is the subject of US. Patent No.
3,984,269. To avoid the problems arising from the mixing of an acceder-atop with the joint compound before application, the patentees spray the joint tape with a solution of the accelerator before the joint come pound is applied and then over each layer of joint compound aster it has been spread and feathered. The patentees say that a wall section thus treated can be moved and further assembled abut 15 minutes after the accelerator is sprayed over the final layer of joint compound. Further time is required, however, for painting or otherwise covering the broad bands of joint compound on the surface of the plasterboard.
Hobson, in US. Patent No. 3,035,940, advocates doing away with joint tapes and join compounds in favor of spraying combine streams of plaster and an accelerator directly over the entire surface I the plasterboard, newlyweds and all. Outstanding advantages of the method are said to accrue in thee there is no nail popping and painting is possible some hours after the plasterboard is installed. Suck a volleyer of plaster would not be expected to survive the severe racking conditions encountered by a ~anufact~lred housing unit during and aster its fabrication.
McNulty, on the other hand, teaches in US. Patent No. 3,391,037 the use of adhesive-edged glass fiber mesh tape as a joint reinforcement along with an over layer of Joint compound when the plasterboard wall is to be painted or without the joint compound when a veneer of plaster is to be applied. Neither ~cNulty nor Hobson is addressed to the racking problems that are unique to manufactured housing.
It is an object of this invention, therefore, to provide an answer to the long felt need for affordable monolithic looking ceilings and walls in manufactured housing.
lo It is a related object of this invention to provide mass produced ceilings and walls for modular and mobile homes that are durable in transit and monolithic in appearance.
It it a further object of this invention to provide a method for manufacturing housing having seamless ceilings and walls which are resistant to cracking while being lifted, turned and twisted on an assembly line.
It is still another related object of this invention to provide a method for the production of seamless, crack-resistan~ ceilings and walls in a manufactured housing unit in which the steps of reinforcing the joints of the plasterboard substrate, spraying a veneer of plaster onto the reinforced substrate, and painting the plastered surface serially overlap one another.
It is a related object of this invention to provide a method for reinforcing the joints in an array of mutually abutting plasterboards and applying a monolithic veneer of plaster to the reinforced array to produce ceilings and walls for modular and mobile homes at a rate of about 1000 square feet per hour.
It will be understood that a manufactured housing unit may be an individual module of a modular home, one of two or more rooms of a mobile home to be joined after separate transportation to a buyers lot, or it may be the complete mobile home. The term "plasterboard" includes gypsum board and cement board or other building boards where their use is appropriate and desirable. The term "plaster," however, refers either to a paste of water and koalas sulfate hemihydrate or the set gypsum, as the context requires. The term "seamless", as used herein to describe a surface, means that the surface is virtually devoid of any evidence of underlying seams or bands of joint compound. The term "structural panel ~:Z~34~
assembly" includes ceiling and walls, that is, the framework and plaster-boards attached thereto which constitute the substrate of a coiling or a Hall; joint reinforcing tape, joint compound filling the tape; a veneer of plaster; and, optionally, a coat of paint.
The monolithic ceiling surface of this invention is created by taping the joints with a glass fiber mesh type, pressing a single layer of a latex-modified, setting type joint compound into the voids of the tape, covering staples in the field of the board with a joint compound or its equivalent, and, while the latex-modified joint compound is still wet, spraying a coat of latex-modified, set-accelerated plaster over the entire surface. Preferably, a first coat is sprayed with a steady sweeping motion along successive paths parallel to the joints to build up a thickness of about one-sixteenth of an inch and, after about I to about 2/3 of the surface has been sprayed and while the first coat is still wet, spraying a second coat with a similar sweeping motion along successive paths at fight angles to the joints. one-thousand square foot ceiling substrate is thus covered with a one-eighth inch thick veneer of hard, durable plaster in from about 45 to about 50 minutes after taping of the joints is commenced. color variation caused by a high moisture level in the joint areas is noticeable initially but this dissipates upon drying so that a seamless, truly monolithic appearance is achieved.
The still wet but setting plaster may be spray coated with a water-based latex paint to provide a still Gore uniform appearance and allow for fast touch-up of the finished ceiling if damaged or marred during subsequent phases of construction ox the housing unit. Spraying of the paint may be commenced at one end of the ceiling while the opposite end is still being sprayed with plaster. Rapid drying of the paint is effected by the absorb-lion of water by the setting plaster. Due to the overlapping ox the plaster and paint sprawling operations, one thousand square feet of ceiling surface may be completely finished and decorated in from about 55 to about I minutes.
Because setting of the plaster is occurring while the pollinating it in pro~resst the finished ceiling structure may ye hoisted into place atop the upright walls in from about 5 to about 15 minutes after the painting is completed. Thus, the elapsed time from the commencement of taping to the placement, not including fastening, of the painted ceiling s~rtlcture in the housing unit is from about 60 to about 75 minutes. If painting is omitted, eke cPilin~ structure may be hoisted into place about 60 to 65 minutes after the first tape is touched to the gypsum board. Actually, there is very little time lost in waiting for eke plaster to set sufficiently to allow movement of the ceiling if the ridge plates which tie the trusses together are not in-stalled until Just before the structure Lo hoisted.
All of the manipulative steps in the reinforcing and surfacing of assailing may serially overlap, that is, application of joint compound may be started while taping Lo being completed, plaster spraying may be started while joint compound is still being spread, and painting may be stated 10 while plaster is still being applied.
The operations involved in fabricating a monolithic appearing wall are substantially the same as for a ceiling, except for the overhead spraying of a ceiling as opposed to the horizontal spraying of an upright wall. Thus, the rates given above for a ceiling may also be achieved in the fabrication of seamless, crack-resistant walls.
The industry desires a plaster application rate of about 2000-4000 square feet per hour or about one average ceiling every 15 minutes.
Spraying of the plaster at such a rate is possible, however, the critical step in the fabrication of the ceilings and walls of this invention is 20 the reinforcement ox the joints between the plasterboards making up the substrate for the ceiling or wall. Because the stresses at these joints are more severe in housing units constructed on an assembly line and destined for movement over highways and byways than in conventially built, stationary homes, reinforcement of these joints is a special 25 problem on the assembly line.
In this invention, the total thickness of the filled glass mesh tape is from about 0.008 to about 0.015 inch. The tape itself, preferably adhesive-backed, is that thick and the skim coat of the joint compound is just thick enough to fill the voids of the mesh. The outline of the 30 fiber network is still visible before the plaster veneer is applied.
The coat of Joint compound may be slightly thicker but this is not considered beneficial; its application would be more time consuming be-cause the use of the tape as a gauze would be forfeited. A setting type of joint compound such as that sold under the trademark Durabond by the 35 United States Gypsum Company or as described in US. Patent Jo. Rev 2~,753 provides the slip, water-retention, and flow properties desired for the purposes of this invention. A preferred compound is made by adding a supplementary amount of a latex binder to the mix water before the joint ~.2~9~-~62 compound powder is stirred in. us mixed, the wet joint compound is easily spread upon and pressed into the voids of the tape but it stiffens in place within a few minutes so that the spraying of an aggregate-filled plaster does not cause pock marking of the still wet mud. The S preferred compound contains prom about 6.1% to about 7.1% latex solids based on the total dry weight of the compound but the latex solids con-tent may range from about 3.2% to about 10.9%.
The manipulative steps of taping and spreading joint compound in the reinforcement of 100 lineal feet of plasterboard, using 2.5 inch wide tape at the joints, are complete in from about 10 to about 12 minutes.
The setting time of the joint compound may be, nevertheless, retarded so that a three hour supply or more may be mixed before the taping is begun. joint compound having a 45 minute setting time is preferred.
Because the plaster is applied by spraying, a monolithic surface having a hubby texture is preferred. uniform texture is provided by the addition of an aggregate such as puerility to the calcium sulfate hemlhydrate in an amount appropriate to the desired texture. The volume to weight ratio of aggregate to hemihydrate is from about 1.5 to 6, preferably prom about 2.5 to about 3.5, cubic feet per hundred pounds. Bonding of the aggregate in the set plaster as well as in the freshly sprayed plaster is improved by the addition of polyvinyl acetate, polyvinyl alcohol, starch, mixtures and equivalents thereof to the plaster. The hardness and flexural strength of the set plaster are improved, also. moreover the bond of the plaster to the paper on the plasterboard is improved, especially when the paper has a low suction. Retention of moisture in the sprayed plaster is prolonged so that hydration of the hemihydrate in the thin layer is ensured. The polyvinyl acetate or its equivalent may be incorporated as a powder in the dry plaster or it may be added as a latex to the plaster mix, i.e., the mixture of hemihydrate, aggregate, a retarder, and water. The weight ratio of dry polyvinyl acetate, for example, to the total weight of hemihydrate and aggregate is from about 0.75:100 to about 1.5:100.
The retarder is added in an amount sufficient to give a setting time of about 9 to 12 hours so that a batch may be mixed in a hopper and pumped to a spraying tool such as a pole gun for a full work shirt and residual amounts in the equipment may be flushed out easily. An even more extended setting time is desirable so that daily cleaning of the equipment is not necessary.
22~z The setting of the plaster is accelerated as it issues from the nozzle of the pole gun by entraining a solution of aluminum, potassium, or ferrous sulfate or their equivalents in a stream Ox atomizing air which it injected into the stream of plaster just before the plaster leaves the nozzle. The setting of the plaster is accelerated su~Eiciently to allow the ceilillg or wall assembly to be hoisted into position within about 15 to about I minutes after completion of the spray application of the plaster. To attain such a rapid setting rate, a solution containing from about 18% to about 50% by weight of the accelerator is injected into the plaster stream at a rate ox from about 40 mls to about 320 mls. per minute. The flow rate of the plaster stream through the nozzle is from about 5.9 liters to about 11.8 liters per minute. Thus, the volume ratio of the accelerator solution to the plaster mix is from about 1:140 to about 1:40. The setting time ox the plaster as thus accelerated is preferably from about 9 to about 15 minutes.
The square edged, 5/16 inch thick plasterboard having a manila face paper commonly used in the mobile home industry is satisfactory as the substrate for the monolithic ceiling surface ox this invention even though it has less suction than the plasterboard that is usually used as a veneer base.
Further details of the imTent:Lon are revealed in the following example but this is not to be taken as a limitation thereof.
Example 1 A ceiling assembly measuring 13.5' x 66', having a 45' long vaulted area, for a mobile home was constructed by the staple and screw attachment of sixteen and a half 4' x 13.5' square edged, 5/16" thick plasterboards to the lower chords of a row of 50 wooden roof trusses spaced 16 inches apart on center. The assembly was hoisted above a work station and was supported on a jig while reinforcing and spraying of the assembly were on performed, joint compound mud was prepared by mixing Durabond 45 joint compound powder with water and a polyvinyl acetate latex (55% solids;
sold under the trademark Elves JC~I by Reich hold Chemicals in the proportion: 25 pounds of the powder, 1.4 gallons of water, and one quart of the latex. The joints between the plasterboards were taped with a I
2.5 inch wide, adhesive-backed glass fiber mesh tape and the Joint compound mud was applied to a thickness just ~tfEicient to Jill the voids in the tape. Staples and screws in the field of the plasterboards were covered with the mud.
A dry plaster having the formulation (in percentage by weight):
Beta-hemihydrate 73.72 "Valpro 59D" (TAM.) foaming Agent 0.04 Oakfeild Rewarder ** 0.27 Casey ZH2 0.02 Puerility 25.95 * to give a setting time of 9-12 hours ** a protons material derived from skin, hooves, bone and the like manufactured and marketed by United States Gypsum Company was mixed with one quart of the above identified latex per hundred pounds of the dry plaster and sufficient water (about 10.3 gallons per hundred pounds of dry plaster) to produce a 5" to 6" diameter slump patty when released from a 2" x 4" brass cylinder. Mixing was done in the twin hoppers of a plaster spray pump sold under the trademark Carousel by Quick spray, Inc. A solution of aluminum sulfate (23% by weight in water) was placed in a catalyst ICM/mls , - I
tank attached to the Carousel pump cart and the plaster was sprayed onto the plasterboards while the joint compound was still wet. pole gun with an atomizing nozzle was used to spray the plaster. The catalyst solution was entrained in an atomizing air stream pumped into the nozzle at 28 to 30 psi. The plaster feed setting on the pump was 6 (about 8~8 to 9 liters per minute) and the catalyst injection setting was 50 (about 175 mls per minute). A
first coat of plaster was applied to about 2l3 of the ceiling before a second coat was applied over the still wet first coat to build up a veneer having a total thickness of about one-eighth of an inch. The remaining 1/3 of the ceiling unit was plastered in a similar fashion. An esthetically pleasing, monolithic looking textured surface had been applied to the ceiling assembly. The elapsed time between the commencement of taping the completion of the plaster spraying operation was LCM/ml~
g 45 minutes. The spraying of a coat of latex-based white paint was started while the final 1/3 of the ceiling was being plastered. The reinforce-mint, application of the veneer and painting were completed in 55 minutes.
The ceiling was hoisted into place atop the upright partitions of a mobile hone on the assembly line after a 15 minute delay for the install-ton of a ridge plate along the trusses.
Mobile home units having monolithic ceilings fabricated by the method of this invention have been transported hundreds of miles from the factory to dealer's lots without causing cracks in the ceilings.
While a detailed description of the invention has been set forth, it will be appreciated that many variations in the details may be made by those skilled in the art without departing from the spirit and scope of the invention.
A dry plaster having the formulation (in percentage by weight):
Beta-hemihydrate 73.72 "Valpro 59D" (TAM.) foaming Agent 0.04 Oakfeild Rewarder ** 0.27 Casey ZH2 0.02 Puerility 25.95 * to give a setting time of 9-12 hours ** a protons material derived from skin, hooves, bone and the like manufactured and marketed by United States Gypsum Company was mixed with one quart of the above identified latex per hundred pounds of the dry plaster and sufficient water (about 10.3 gallons per hundred pounds of dry plaster) to produce a 5" to 6" diameter slump patty when released from a 2" x 4" brass cylinder. Mixing was done in the twin hoppers of a plaster spray pump sold under the trademark Carousel by Quick spray, Inc. A solution of aluminum sulfate (23% by weight in water) was placed in a catalyst ICM/mls , - I
tank attached to the Carousel pump cart and the plaster was sprayed onto the plasterboards while the joint compound was still wet. pole gun with an atomizing nozzle was used to spray the plaster. The catalyst solution was entrained in an atomizing air stream pumped into the nozzle at 28 to 30 psi. The plaster feed setting on the pump was 6 (about 8~8 to 9 liters per minute) and the catalyst injection setting was 50 (about 175 mls per minute). A
first coat of plaster was applied to about 2l3 of the ceiling before a second coat was applied over the still wet first coat to build up a veneer having a total thickness of about one-eighth of an inch. The remaining 1/3 of the ceiling unit was plastered in a similar fashion. An esthetically pleasing, monolithic looking textured surface had been applied to the ceiling assembly. The elapsed time between the commencement of taping the completion of the plaster spraying operation was LCM/ml~
g 45 minutes. The spraying of a coat of latex-based white paint was started while the final 1/3 of the ceiling was being plastered. The reinforce-mint, application of the veneer and painting were completed in 55 minutes.
The ceiling was hoisted into place atop the upright partitions of a mobile hone on the assembly line after a 15 minute delay for the install-ton of a ridge plate along the trusses.
Mobile home units having monolithic ceilings fabricated by the method of this invention have been transported hundreds of miles from the factory to dealer's lots without causing cracks in the ceilings.
While a detailed description of the invention has been set forth, it will be appreciated that many variations in the details may be made by those skilled in the art without departing from the spirit and scope of the invention.
Claims (11)
- The subject matter claimed is:
l. In a factory built housing unit ready for transport from the assembly line over the road, a crack resistant ceiling having a monolithic surface which comprises a series of spaced-apart, parallel trusses, a plurality of plasterboards fastened to the trusses in edge-to-edge relationship, glass fiber mesh tape spanning the gaps between adjoining plasterboards, a single layer of latex-modified, setting-type joint compound filling the tape and having a thickness substantially equal to that of the tape, and a seamless veneer of latex-modified plaster. - 2. In a manufactured housing unit ready for transport from the assembly line over the road, the ceiling of claim 1 and a crack resistant wall having a monolithic appearance, said wall comprising a framework of studs, runners and plates, a plurality of plasterboards fastened to the framework in edge-to-edge array, glass fiber mesh tape spanning the joints between the plasterboards, a single skim coat of latex-modified, setting type joint compound substantially flush with the tape, and a seam-less veneer of latex-modified plaster over all.
- 3. The ceiling of claim 1 wherein the filled tape is from about 0.008 to about 0.015 inch thick.
- 4. The ceiling and wall of claim 2 wherein the skim coated tape is from about 0.008 to about 0.015 inch thick.
- 5. A factory built, monolithic looking, crack-free ceiling in a manufactured housing unit, said ceiling comprising a row of spaced-apart roof trusses, a plurality of plasterboards fastened to the lower chords of the trusses in edge-to-edge array, glass fiber mesh tape spanning the joints between the plasterboards, a single skim coat of latex-modified, setting type joint compound substantially flush with the tape, and a seam-less veneer of latex-modified plaster over all.
- 6. A method for the assembly line fabrication of a ceiling having a monolithic surface for factory built, transportable housing units, said method comprising:
(a) fastening a plurality of plasterboards in edge-to-edge array to a row of ceiling trusses to form a substantially flat ceiling substrate;
(b) taping the joints between adjacent boards with a glass fiber mesh tape;
(c) pressing a single layer of latex-modified, setting-type joint compound into the voids of the tape so that the thickness of the layer is substantially equal to that of the tape; and (d) spraying a set-accelerated, latex-modified slurry of calcined gypsum and water onto the array of plasterboards to form a veneer over the entire ceiling substrate;
wherein the elapsed time from the commencement of the taping to the completion of the spraying is from about 45 to about 55 minutes per thousand square feet of ceiling area. - 7. The method of claim 6 wherein the layer of point compound is wet while the veneer is being sprayed.
- 8. The method of claim 6 further comprising the spraying of a coat of latex-based paint over the still wet veneer and wherein the elapsed time from the commencement of the taping to the completion of painting one thousand square feet of ceiling is from about 55 to about 60 minutes.
- 9. The method of claim 8 further comprising hoisting the finished ceiling structure into place on the upright framework of the housing unit and wherein the elapsed time from the commencement of the taping of a one-thousand square foot ceiling to such placement is from about 60 to about 75 minutes.
- 10. A method for the assembly line fabrication of a structural panel assembly having a monolithic surface for factory built, transportable housing units, said method comprising:
(a) fastening a plurality of plasterboards in edge-to-edge array to the framework of the structural panel assembly to form a substan-tially flat substrate;
(b) taping the joints between adjacent plasterboards with a glass fiber mesh tape;
(c) pressing a single layer of a latex-modified, setting-type joint compound into the voids of the tape so that the thickness of the filled tape is substantially equal to that of the unfilled tape;
and (d) spraying a set-accelerated latex modified slurry of calcined gypsum and water onto the array of plasterboards to form a veneer over the entire substrate. - 11. The method of claim 10 wherein steps (b), (c) and (d) serially overlap.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61726384A | 1984-06-04 | 1984-06-04 | |
| US617,263 | 1984-06-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1229462A true CA1229462A (en) | 1987-11-24 |
Family
ID=24472924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000478460A Expired CA1229462A (en) | 1984-06-04 | 1985-04-04 | Monolithic ceiling for manufactured housing |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1229462A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9938717B2 (en) | 2015-03-18 | 2018-04-10 | Awi Licensing Llc | Faced ceiling system |
| US10267039B2 (en) | 2012-09-04 | 2019-04-23 | Awi Licensing Llc | Ceiling systems |
| US11293178B2 (en) | 2012-09-04 | 2022-04-05 | Awi Licensing Llc | Ceiling systems |
-
1985
- 1985-04-04 CA CA000478460A patent/CA1229462A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10267039B2 (en) | 2012-09-04 | 2019-04-23 | Awi Licensing Llc | Ceiling systems |
| US10711461B2 (en) | 2012-09-04 | 2020-07-14 | Awi Licensing Llc | Ceiling systems |
| US11293178B2 (en) | 2012-09-04 | 2022-04-05 | Awi Licensing Llc | Ceiling systems |
| US9938717B2 (en) | 2015-03-18 | 2018-04-10 | Awi Licensing Llc | Faced ceiling system |
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