Method of installing a floor heating apparatus

A method of installing piping of a floor heating apparatus according to the present invention relates to a method of installing a floor heating apparatus in which pipes for circulating heat medium liquid are located on a floor base structure and they are covered with a flowable floor substrate material. After an adhesive is applied on a surface of the floor base structure, a tube assembly is positioned on said adhesive so that the lower face of a base plate of the tube assembly is bonded to said floor base structure by means of said adhesive, the tube assembly having a plurality of tubes made of an elastic material and said base plate made of the elastic material which integrally carries said tubes. A self-leveling material is poured and extended on the tube assembly. According to such a construction method, a number of floor heating pipes can be quickly and simply installed on a floor surface and a density of installation of floor heating pipes can be relatively readily increased. Further, a lifting or offsetting of the pipelines can be prevented so that the pipelines are allowed to be uniformly embedded, the thickness of the self-leveling material can be reduced down to approximately 2 cm and a temperature distribution of the floor finish surface can be made even.

TECHNICAL FIELD 
This invention relates generally to a construction method of installing a 
floor heating apparatus, and more particularly, such a method in which 
pipes for circulating heat medium liquid are positioned on a floor 
substrate and are covered with a flowable floor substrate material. 
BACKGROUND OF THE INVENTION 
Generally, a floor heating system is provided with metallic pipes embedded 
in a floor structure for circulating heat medium liquid theretrhough, and 
is arranged to raise a floor surface temperature by means of circulation 
of the heat medium in its circuit, such as hot water heated to a desired 
temperature. Such pipes made of a metal are covered with a flowable 
material, such as concrete or mortar so as to ensure a durability of pipes 
against a load or impact imposed on the floor, and are embedded in the 
floor structure by setting or cure of the floor substrate material or 
floor base material. Further, one type of floor heating system is proposed 
in Japanese Utility-Model Laid-Open Publication No.63-184834 (Japanese 
Utility-Model Application No.62-73917 filed by the present inventor) 
wherein hot water pipes made of elastic material are embedded within a 
floor substrate material. This type of floor heating system comprises a 
sheet, such as a heat insulation sheet or a waterproofing sheet provided 
on a floor slab, e.g., a concrete slab, and elastic pipes for circulating 
hot water, i,e., heat medium liquid. The elastic pipes are arranged on the 
aforementioned sheet and a floor self-leveling material is deposited and 
extended on the sheet and pipes. 
In such a conventional floor heating system, however, a buoyancy acts on 
the floor heating pipes so as to lift or unseat the pipes or cause a 
deviation of the pipe positions, and therefore, this results in 
difficulties of construction work for the floor structure. Thus, overwork 
and complicated steps are required in a construction work, and the 
thickness of the self-leveling material has to be unnecessarily increased. 
Especially, since an increment of the thickness of self-leveling material 
limits an effectively usable room volume or space in a building, any 
improvement of construction method allowing a reduction of the thickness 
of self-leveling material has been desired. 
Further, a surface of floor structure made in accordance with a 
conventional construction method may present an unacceptable irregularity 
or deviation of a temperature distribution owing to an uneven installation 
of the embedded floor heating pipes. Therefore, an improvement of 
construction method for relatively easily effecting uniformity in a 
temperature distribution has been desired. 
Still further, a concrete surface or the like, on which floor heating pipes 
are to be installed, practically has a slight inclination or irregularity. 
The floor heating pipes on such an inclination or irregularity may present 
vertical ups and downs, offsetting or slight twist, and for that reason, 
it is difficult to ensure a uniform covering depth of the self-leveling 
material covering the pipes. Such an unevenness of the covering depth 
results in the aforementioned irregularity or deviation of a temperature 
distribution, and further, it leads to development of cracking or crazing 
on a floor surface in relation to the temperature variation of the floor 
structure. 
For overcoming those disadvantages, it is an object of the present 
invention to provide a construction method for installing a floor heating 
system which can improve the efficiency of construction work and which can 
reduce the thickness of self-leveling material, and further, which can 
ensure a uniformity of temperature distribution of the floor surface and 
prevent cracks or crazes from being developed. 
DISCLOSURE OF THE INVENTION 
The present invention provides a method of installing a floor heating 
apparatus, said apparatus including pipes for circulating heat medium 
liquid, said pipes being located on a floor base structure and covered 
with a flowable floor substrate material, comprising: 
applying an adhesive on a surface of said floor base structure; 
positioning a tube assembly on said adhesive so that the lower face of a 
base plate of the tube assembly is bonded to said floor base structure by 
means of said adhesive, said tube assembly having a plurality of tubes 
made of an elastic material and said base plate made of an elastic 
material which integrally carries said tubes; and 
pouring and extending a self-leveling material on said tube assembly. 
According to such a construction method, a number of pipes can be quickly 
and simply positioned on a floor surface by positioning on the floor 
surface the tube assembly including a plurality of tubes. Further, since a 
spaced distance between the respective tubes on the tube assembly can be 
set to be a relatively short distance, a density of installation of floor 
heating pipes can be relatively readily increased. 
Still further, according to the above arrangement of the present invention, 
a plurality of pipelines can be simultaneously installed quickly and 
simply, and each of the pipelines are kept in position against a buoyancy 
acting on the pipelines because the base plate is adhered on the floor 
base structure by means of the adhesive to secure the pipelines on the 
surface of the floor base structure. Therefore, a lifting or unseating 
movement of the pipelines and offsetting thereof during a pouring work of 
the floor self-leveling material can be prevented. Since prevention of 
unseating or offsetting of pipelines allows the pipelines to be uniformly 
embedded, the thickness of the self-leveling material can be reduced to 
approximately 2 cm and a temperature distribution of the floor finish 
surface can be made even. In addition, as the pipelines are installed by 
means of its substrate plate which is bonded to the floor base structure 
through the adhesive, the position and the depth of the embedded pipes can 
be appropriately adjusted, the covering depth of the self-leveling 
material can be uniformed and cracking or crazing can be prevented from 
occurring. 
According to a preferred embodiment of the present invention, said adhesive 
is a cationic adhesive or cation type adhesive, in which dirt or dusts 
present on concrete surface are contained to be mixed together. Thereby, 
an exfoliation of the adhesive layer is prevented from being caused and 
the adhesive strength of the pipe assembly is generally enhanced. 
Preferably, the adhesive is further applied on the tube assembly so that 
the tube assembly is wholly covered by the adhesive. As such a cationic 
adhesive, "ARON CATIOCRETE"(trade name) (acrylic cation type polymer 
cement mortar) manufactured by TOAGOSEI CO., LTD. can be preferably used. 
"ARON CATIOCRETE" is obtained by blending an cationic acrylate emulsion 
"ARON CATIOCRETE BASE" with "ARON CATIOCRETE FILLER". The following 
adhesives are exemplified as preferred adhesives: 
Acrylic resin type adhesive: "PETLOCK"(Asahi Chemical Industry Co., Ltd.), 
"ARON WATER SHUT"(Toagosei Co., Ltd), "ARON SUPER GROUT"(Toagosei Co., 
Ltd), 
"ARON WET TIGHT"(Toagosei Co., Ltd), 
Polyester resin type adhesive: "POLYMORTAR"(Kowa Chemical Industry Co., 
Ltd.) 
Inorganic type adhesive: "CATION FILER K"(Sankei Chemical Co., Ltd.) 
Methacrylate resin type adhesive: "BAMITIGHT"(Tomen Co.) 
Polyvinyl acetate/ethylene copolymer emulsion type adhesive: "U-PRIMER"(Ube 
Industries. ltd.), "UB. CATION-R"(Ube Industries. Itd.), "REOBOND VP"(Reo 
Chemical Co., Ltd.) 
Epoxy resin type adhesive: "EMS-20"(Konishi Co., Ltd.), "MARINBOND M-102" 
(Epoxy Industries. Ltd.), "S. DYNE"(Sekisui Chemical Industry Co., Ltd.) 
In accordance with a further preferred embodiment, said base plate is 
formed to be a continuously extending strip-like plate, and lower wall 
portions of said pipelines are integrally connected to each other by means 
of the base plate. Said base plate and pipelines are an integral mold 
integrally molded from a rubber material, and preferably, reinforcements 
of short fibers are mixed thereinto. 
In a preferred embodiment, the tubes are integrally molded in a form of 
elongated continuous strip-like sheet, and delivered to a construction 
site as a rubber roll which is defined by a wound sheet in a formation of 
roll. 
In one embodiment of the present invention, the floor base structure on 
which the tube assembly is installed comprises an upper layer of a 
waterproofing sheet and a reflection sheet underlying the waterproofing 
sheet. In use of the waterproofing sheet and the reflection sheet, the 
heat dissipation or heat loss in a lower direction can be blocked by 
reflection effect of the reflective sheet, and the reflection sheet is 
covered by the waterproof sheet so that deterioration of the reflection 
sheet is prevented. As a floor substrate component, plywood boards can be 
used, and the plywood boards may be alternately stacked in an offsetting 
formation of two-layered structure. A panel of three-layered structure 
comprising an insulation board interposed between veneer boards can be 
used as the plywood board. In a case where such a panel of three-layered 
construction is used, heat dissipation in a lower direction is blocked by 
its heat insulation function. 
In an another embodiment, the floor substrate constituting a floor base 
structure is supported adjustably in height by a plurality of adjusters. 
Adjustable support of the floor substrate by a number of adjusters allows 
the floor substrate to be adjusted in its inclination or irregularity, so 
that a flatness of the floor substrate surface can be ensured and a space 
is defined below the substrate to be used as soundproof or insulation 
buffer or a space for containing building mechanical piping or electrical 
wiring network of OA devices. 
In the present invention, the way of applying the adhesive includes various 
kinds of application method., e.g., application of the adhesive by means 
of a brush, trowel, roller or the like, spraying of the adhesive, or 
pouring and spreading thereof. However, the present invention is not 
limited in a specific way of applying the adhesive.

BEST MODE FOR CARRYING OUT THE INVENTION 
Preferred embodiments of the present invention will now be described in 
detail with reference to the attached drawings. 
The constructional structure of a floor heating apparatus according to the 
first embodiment of the present invention will be described with reference 
to FIGS. 1 and 2. 
The floor structure shown in FIG. 1 comprises a floor slab 10 and a thermal 
insulation material 11 disposed thereon. The floor slab 10 constitutes a 
main structural part, such as a reinforced concrete slab, ALC panel, or PC 
panel containing required reinforcing bar or reinforcements. A reflective 
sheet or reflection sheet 7 is disposed on the thermal insulation material 
11, and further, a waterproof barrier sheet 6 is disposed on the 
reflective sheet 7. 
A cationic adhesive 5 is applied or sprayed on the predetermined areas of 
the waterproof sheet 6 so that a hot water pipe assembly 2 adheres thereto 
by the adhesive. If the substrate to which the adhesive is to be applied 
is a surface of the concrete, the cationic adhesive functions to prevent 
the exfoliation of the adhesive layer and enhances the adhesive strength 
obtained thereby. This is because the dirt or dusts present on the 
substrate are mixed with the adhesive. 
As shown in FIG. 2 , the hot water pipe assembly 2 comprises a 
longitudinally extending elastic carrier plate 21 and a plurality of 
elastic hot water pipes 22 which are disposed in parallel on the carrier 
plate 21 and spaced a predetermined distance from each other. A lower part 
of the wall of each hot water pipe 22 is embedded in the carrier plate 21 
and formed integrally therewith. The carrier plate 21 and hot water pipes 
22 are integrally formed as a continuous elongated strip-like sheet by 
means of a predetermined rubber forming or molding method, and the pipes 
22 carried by the carrier plate 21 in an equal spaced distance from each 
other. The carrier plate 21 and hot water pipes 22 constituting the hot 
water pipe assembly 2 are wound up in a formation of a roll, which is 
so-called "rubber roll", and such a rubber roll is delivered to a 
construction site. A strip-like continuous sheet, i.e., the hot water pipe 
assembly 2 unrolled from the rubber roll forms a continuous strip-like 
zone of the hot water pipes on the waterproof sheet 6. A strip-like 
continuous sheet, which contains reinforcements such as short fibers in a 
raw rubber material so as to be improved in its pressure resistance, may 
be preferably used as the hot pipe assembly 2, and said rubber roll may be 
supplied to a construction site in a form of the pressure-resistant rubber 
roll comprising such a continuous strip-like sheet rolled up. One of the 
preferred materials for forming such pressure-resistant rubber roll is, 
for example, a rubbery composite material comprising a continuous phase of 
rubber component and finely-divided nylon components dispersed within the 
continuous phase. Such a material is exemplified by "UBEPOL-HE"(trade 
name) manufactured by Ube Industries, Ltd. Alternatively, short fiber 
reinforcements may be blended with said raw rubber material so as to form 
a short-fiber reinforced elastomer, which elastomer can be used as a 
material for the pressure-resistant rubber roll. Such short fiber 
reinforcements can be obtained by carbonizing the surface of the short 
fibers which have been placed under a high temperature inert gas 
atmosphere, or which have been subject to blowing of small amount of 
oxygen or oxidizing agent under a high temperature vacuum condition. 
Natural rubber or synthetic rubber, or a mixture of synthetic resinous 
material and natural or synthetic rubber can be used as the raw rubber 
material. Further, instead of the above rubber roll, a roll of a formed 
resilient sheet made of synthetic resinous material may be employed. 
In the installation steps after laying work of the waterproof sheet 6, 
cationic adhesive 5 is further applied or sprayed on the hot water pipe 
assembly 2, and thereafter, a self-leveling material 4 is poured and flows 
to extend on the surface of the floor so as to cover the hot water pipe 
assembly 2. Further, a floor finishing material, such as flooring 
material, tatami-mat applicable to a floor heating system, or carpet, are 
laid or installed on the self-leveling material 4. 
The thickness H of the self-leveling material 4 may be set to be 
approximately 2 centimeters (cm). As regards the self-leveling material 4, 
a self-leveling material containing a gypsum material should not be 
employed because such a gypsum material is apt to aid a cracking or 
crazing to grow. On the other hand, a self-leveling material containing 
ceramic or cement material can be preferably employed as the self-leveling 
material 4. An example of such a material is the quick-setting type of 
self-leveling material containing cement as prescribed in JASS 15, M103, 
such as "Quick Ceramic Flow (QCF) " manufactured by Ube Industries, Ltd. 
Further, the self-leveling material 4 may be mixed with additional 
materials or additives depending on its purposes of use. For example, a 
waterproofing agent may be added to the self-leveling material 4, when 
waterproofing is required in the construction site or the constructed 
portion in which the hot water pipe assembly 2 is to be installed. When 
the self-leveling material 4 is used in the construction site or the 
constructed portion requiring a relatively high strength or rigidity, 
reinforcements, e.g., finely-divided short steel fibers or synthetic 
fibers, a metallic net or mesh, may be blended or embedded in the 
self-leveling material 4 in dependence on the environmental condition or 
construction condition. Further, a liquid adhesive such as an acrylic 
aqueous solution may be added to the self-leveling material 4 to enhance 
the strength of the self-leveling material 4, or a hardening accelerator 
for appropriately accelerating a setting time of the self-leveling 
material 4 may be added thereto so as to adjust the setting time thereof. 
Still further, the self-leveling material 4 can be poured to the 
construction area, after a liquid metal, a heat transferable material or 
the like, such as an aqueous solution including aluminum for increasing 
the heat-transferable coefficient is appropriately mixed therein. 
A method for installing the floor heating apparatus 1 shown in FIG. 1 will 
now be described. 
After constructing a floor slab 10, such as a reinforced concrete slab, a 
thermal insulation material 11 is laid on the floor slab 10. Preferably, a 
formed insulation plate having a high heat resistance and a low 
thermal-expansion coefficient may be employed as the thermal insulation 
material 11. The floor slab 10 is, e.g., a concrete slab-on-grade or a 
floor concrete slab defining each floor level. The thermal insulation 
material 11 may be adhered to the floor slab 10 by an adhesive. Although 
the thermal insulation material 11 is located on the floor slab 10 in FIG. 
1, the thermal insulation material 11 can be positioned on an underside of 
the floor slab 10; otherwise, the installation of the thermal insulation 
material 11 may be omitted. 
In the embodiment as shown in FIG. 1, a reflective sheet 7 for blocking 
radiation heat, such as an aluminum sheet, is laid on the thermal 
insulation material 11, and then, a waterproof sheet 6 is laid on the 
reflective sheet 7. These sheets 7 and 6 define a floor substrate material 
3. The reflective sheet 7 and the waterproof sheet 6 can be bonded on the 
thermal insulation material 11 by means of an adhesive. A waterproof sheet 
made from a material having a high heat resistance and low 
thermal-expansion coefficient may be employed as the waterproof sheet 6. 
The reflective sheet 7 is covered with the waterproof sheet 6 so that the 
protection of the waterproof sheet 6 prevents the reflective sheet 7 from 
being deteriorated. The installation of the reflective sheet 7 and the 
waterproof sheet 6 can be omitted depending on the design condition or the 
construction condition. 
The cationic adhesive 5 is applied or sprayed on the waterproof sheet 6 so 
as to form a first adhesive layer 51 thereon. The first adhesive layer 51 
is merely applied or sprayed on the region on which the hot water pipe 
assemblies 2 are to be positioned, so that the first adhesive layer 51 is 
provided in a formation of discrete strip-like adhesive layers spaced a 
predetermined distance from each other. Alternatively, the adhesive 5 may 
be applied or sprayed on the entire surface of the floor substrate 
material so as to form the first adhesive layer 51 extending throughout 
the entire surface of the floor substrate material. 
The strip-like hot water pipe assembly 2 is unrolled from the 
aforementioned rubber-roll, and positioned on the first adhesive layer 51 
so as to be spaced apart a predetermined distance, preferably an equal 
distance from each other. The carrier plate 21 of the hot water pipe 
assembly 2 is fixedly secured on the water proof sheet 6 by the first 
adhesive layer 51 and the pipelines defined by a plurality of hot water 
pipes 22 are raised from the carrier plate 21 and exposed thereon. Then, 
the adhesive 5 is further applied or sprayed on the hot water pipe 
assembly 2 to provide a second adhesive layer 52, which covers the hot 
water pipe assembly 2 and extends over the surface of waterproof sheet 6. 
Thus, the hot water pipe assemblies 2 are entirely covered with the 
adhesive 5 as shown in an enlarged scale in FIG. 2. 
After the step of applying or spraying the adhesive 5 on the hot water pipe 
assembly 2, a self-leveling material 4 is poured and extended over the 
floor surface and a leveled even upper surface of the floor substrate 
material is formed in accordance with the self-leveling action of the 
self-leveling material 4, and thereafter, the aforementioned floor 
finishing material 12 is to be installed thereon. 
In such a construction method, after installation of the hot water pipe 
assembly 2 unrolled from the rubber-roll and adhesion of the assembly 2 to 
the waterproof sheet 6 by means of the adhesive 5, the self-leveling 
material 4 is poured thereon so as to form an even floor substrate surface 
for the floor finishing material 12. The hot water pipe assembly 2 
comprising the carrier plate 21 and the hot water pipes 22 is a 
strip-shaped sheet, the elevation and thickness of which are flat and 
thin, so that it can be embedded surely in position within the relatively 
thin self-leveling material 4. 
In accordance with such a construction method, a number of floor heating 
pipelines can be simply and rapidly installed on the floor surface through 
the steps of laying on the floor surface the hot water pipe assemblies 2 
including a plurality of hot water pipes 22. Also, the density of the 
floor heating pipelines on the floor surface can be increased relatively 
easily, because the spacing distance between the adjacent pipes on the hot 
water pipe assembly 2 can be set to be relatively small. 
Further, in accordance with the aforementioned construction method, the hot 
water pipe assembly 2 is prevented from lifting or unseating, and it does 
not cause their positional deflection during the casting step of the 
self-leveling material, nor irregularity and unevenness of the surface of 
the floor substrate material. Therefore, the hot water pipe assembly 2 can 
be securely embedded in position within the self-leveling material as 
relatively thinly cast, and thus, a relatively thin and even covering 
layer of the self-leveling material 4 can be formed on the hot water pipes 
22. As the result, an irregular temperature profile does not occur when 
circulating heated water through the hot water pipe assembly 2, and 
therefore, a uniform temperature distribution profile can be presented on 
the floor heating surface. As regards the constructed portion having a 
difficulty in installation of the hot water pipe assembly 2, a ring of 
strip-like or linear member or the like is attached to the curved portion 
of the hot water pipe assembly 2, and it is secured by the double-coated 
adhesive tape, so that an unseating or reversing motion of the hot water 
pipe assembly 2 can be restricted. In the above-mentioned embodiment, the 
heat dissipation or heat loss in the lower direction can be blocked by 
reflection of the reflective sheet 7, and the heat efficiency or 
insulation effect is improved by the formation of the first and second 
adhesive layers 51 and 52 covering the hot water pipe assembly 2. 
Further, in accordance with the above-mentioned arrangement, the thickness 
of the self-leveling material 4 can be substantially reduced, as the hot 
water pipe assembly 2 comprising the resilient carrier plate 21 and the 
resilient hot water pipes 22 is bonded on the floor surface (on the 
waterproof sheet 6) by means of the cationic adhesive 5. The hot water 
pipe assembly 2 comprising a plurality of elastic hot water pipes 22 on 
the upper surface of the elastic carrier plate 21 tends to restrict the 
generation or development of clacking or crazing of the overlying 
self-leveling material 4, so that the thickness of the self-leveling 
material 4 can be reduced down to 20 mm, and therefore, the thickness of 
the floor substrate for the floor finishing material 12 can be extensively 
reduced. This advantage derived from the pipe assembly 2 cannot be 
obtained from the conventional metallic piping. 
A method for installing the floor heating apparatus according to the second 
embodiment of the present invention will be described with reference to 
FIG. 3. 
The second embodiment of the present invention relates to the floor 
structure for multistory buildings, such as condominium buildings or 
hotels, in which soundproof or sound damping abilities against footsteps 
or noises are considered to be important. 
The second embodiment differs from the first embodiment in the following 
points: 
In the first embodiment, the floor substrate material 3 (the reflective 
sheet 7 and waterproof sheet 6) and the thermal insulation material 11 are 
interposed between the floor slab 10 and the hot water pipe assembly 2, 
whereas in the second embodiment, laminates 8 of plywood are used as the 
floor substrate material 3, which are adjustably supported by means of a 
number of adjusters 9a, 9b, 9c, . . . . In the illustrated embodiment, the 
adjusters 9a, 9b, 9c, . . . adjustable in height are provided to stand 
substantially vertically on the floor slab 10. Square shaped laminates 13, 
each side of which is about 1 meter, are disposed successively on the 
adjusters 9a, 9b, 9c, . . . and supported at each corner of the respective 
laminates 13 by the adjusters 9a, 9b, 9c, . . . . After installation of 
the laminates 13, the laminates 8 are disposed thereon. The laminate 8 may 
be a sandwich panel of three-layered structure comprising an insulation 
panel 8a of 3-4 mm thickness interposed between the veneers 8b and 8c. The 
total thickness of the panel may be ranged from 12 mm to 28 mm. A plywood 
panel generally used in the building construction can also be used as the 
laminate 8. A preferred insulation material for the insulation panel 8a 
is, e.g., a molded polyolefine foam such as "Toray PEF" (registered 
trademark) commercially available from Toray Industries. Inc. This kind of 
insulation material can also be used as an insulation material in the 
other embodiment. 
In the second embodiment, the inclination, irregularity or uneven condition 
of the floor substrate material 3 can be appropriately corrected by means 
of the adjusters 9a, 9b, 9c, . . . , so that the horizontal level or 
flatness of the floor substrate surface for the floor finishing material 
12 can be adjusted. Further, the space defined below the floor substrate 
material 3 improves the soundproofness or the sound damping ability of the 
floor structure against footsteps or noises, and provides a piping or 
wiring zone for containing a building mechanical piping or electrical 
wiring network. 
In the second embodiment, the cationic adhesive 5 is applied or sprayed on 
the floor substrate material 3 (laminate 8) in the same manner as the 
first embodiment described with reference to FIG. 1, and then, the hot 
water pipe assembly 2 unrolled from the rubber roll (not shown) is laid on 
the adhesive 5, whereby it is fixed on the floor substrate material 3. 
The third embodiment of the floor heating apparatus 1 of the present 
invention will now be described with reference to FIG. 4. This third 
embodiment relates especially an installation of the floor heating 
apparatus 1 on the floor of wooden structure. 
In the floor structure of this embodiment, a plurality of floor joists 15a, 
15b, . . . spaced a predetermined distance are joined to sleepers 14, and 
laminates 8 (see FIG. 5) of the type explained in the second embodiment 
are laid on the floor joists 15a, 15b, . . . . The floor structure 
including the sleepers 14 and floor joists 15a, 15b, . . . support the 
floor substrate material 3 defined by the laminates 8. 
Nets and wooden pieces 16 are installed on the sleepers 14 in a region 
between adjacent floor joists 15a, 15b . . . and the space defined between 
the layer 16 and the laminates 8 may be filled with an insulation material 
17 of approximately 5 cm thickness. 
The cationic adhesive 5 is applied (or sprayed) on the floor substrate 
material 3 (laminate 8) in the same manner as described with reference to 
the first and second embodiments, and then, the hot water pipe assembly 2 
unrolled from the rubber roll (not shown) is secured on the floor 
substrate material 3 by means of the adhesive 5. The adhesive 5 is further 
applied or sprayed on the hot water pipe assembly 2, and a casting 0step 
of the self-leveling material 4 of 2 cm thickness on the hot water pipe 
assembly 2 is performed. The floor finishing material 12 is further 
installed on the smooth and horizontal floor substrate surface formed by 
the self-leveling ability of the self-leveling material 4. In FIG. 4, a 
tatami-mat for floor heating 12a, CF (cushion floor) sheet or P-tile 
(vinyl tile) 12b, carpet 12c, and wooden flooring for floor heating 12d 
are illustrated respectively as examples of typical floor finishing 
materials 12. 
Although the preferred embodiments of the present invention have been 
described in detail, the present invention is not limited to those 
embodiments. For example, the details, shapes, materials, or numbers of 
components or the structural element forming the floor structure can be 
altered or changed without departing from the scope and spirit of the 
present invention. These can be selectively designed or incorporated 
depending on the specified purposes and appropriate or optional materials 
can be selectively used in view of the constructed portion or part. For 
example, a panel comprising a stiff glass wool layer interposed between 
sheets of synthetic resinous material can be used as a floor substrate 
material. Further, in a wooden floor structure, a floor substrate 
structure constructed by alternately stacked two plywood plates can be 
employed for dispersing a relatively larger partial load or local load. 
Still further, in lamination of two plywood plates, an insulation material 
or a heat reflective panel (sheet) may be interposed between the upper 
laminate and the lower laminate for energy-saving. Many other types of 
boards for architectural construction, such as a sizing board can be 
substituted for the laminates. 
INDUSTRIAL APPLICABILITY 
In accordance with the construction method of the present invention, the 
efficiency of piping work for installing the floor heating system can be 
improved, the thickness of the self-leveling material can be decreased, 
the uniformity of the temperature profile on the floor surface can be 
ensured, and cracking or crazing of the floor surface can be avoided.