GB2030203A

GB2030203A - Forming drainage passages

Info

Publication number: GB2030203A
Application number: GB7837410A
Authority: GB
Original assignee: Rdl Eng Services & Sales Co Lt
Current assignee: Rdl Eng Services & Sales Co Lt
Priority date: 1978-09-20
Filing date: 1978-09-20
Publication date: 1980-04-02

Abstract

The provision of a drainage outlet in a concrete floor or roof is simplified by casting the floor or roof with a core 6 located on the surface on to which the concrete is poured, the core being removed after the concrete has set. The core is at least as high as the required thickness of the concrete. A shaped plastics outlet member, to which a downpipe can be attached and whose external shape corresponds generally to that of the core, is then located in the hole left by the core. The core can be formed of metal or plastics materials, or it can be of expanded polystyrene or other easily destroyed material which is chipped or burnt out or otherwise extracted from the hole. <IMAGE>

Description

SPECIFICATION Forming drainage passages This invention relates to a method of forming a drainage passage in a concrete roof or floor.

When concrete roofs or floors requiring drainage outlets are cast in situ, it is common practice to leave a section around the location of the drainage outlet free of concrete in the form of a boxed hole by providing shuttering around the location, and then to instal the outlet separately within the opening when the concrete has set. The outlet will typically take the form of a funnel-shaped fitting, formed from a plastics material, to which a downpipe is connected. The outlet is installed separately because a plumber is required to instal the necessary pipework, e.g. the downpipe and drainage, and it is generally not practical to arrange for the plumber to be present when the casting is carried out.

According to the present invention, there is provided a method of forming a drainage passage in a concrete roof or floor, which comprises locating a core on the surface upon which the floor or roof is to be cast, the core having a height at least equal to the thickness of the roof or floor required, casting the concrete around the core and allowing the concrete to set, removing the core from the concrete to leave a hole therethrough, and locating in the hole an outlet member which closely conforms with the hole and which has means for securing a pipe thereto.

The core and the outlet member are suitably funnel-shaped in elevation, i.e. having an inverted frusto-conical section joining a cylindrical or tubular section. The means for securing a pipe may comprise an elongate tubular section projecting beneath the concrete roof or floor, the pipe coupling with this section in conventional mannerforjoining pipes.

The core may be formed of a durable plastics material such as polypropylene or of a light-weight mild steel, so as to be re-usable, or a glass-fibre reinforced plastics material may be used. Alternatively, the core may be formed of a material which can be readily destroyed in situ to remove the core from the concrete, for example expanded polystyrene, which can be burnt out or chipped out.

Where an insulating layer formed, for example, of expanded vermiculite in asphalt or lightweight concrete, is to be laid on top of the concrete roof or floor, an additional core may be used above the first core, or an extension of the first core. This additional core or extension may be cylindrical, the outlet resting inside the hole formed thereby.

The outlet may have a flange therearound, and if desired screws may be passed through the flange to secure the outlet to the roof or floor.

Reference is made to the accompanying drawing, in which: Figure 1 shows a small portion of a roof member being cast; and Figure 2 shows an outlet suitable for use in the method of the invention.

Although Figure 1 shows, for convenience, a very small area being cast, the area to be cast would normally be large relative to the size of the outlet.

Four wooden shuttering members 1 are secure together to define the area 2 in which the concrete is cast, on a temporary supporting surface 3. A steel wire reinforcing mesh 4 is located within the area 2 and spaced from the surface 3 by a plurality of spacing members 5 which engage cross-members of the mesh 4.

An expanded polystyrene core 6 has an inverted frusto-conical portion 6a and a cylindrical portion 6b which is placed upon the surface 3. The core 6 is supported by wire rods 7 inserted into the expanded polystyrene and resting on the surface 3 at a distance from the base of the core 6.

Concrete is then poured into the area 2 to the required depth and allowed to harden. The core 6 may then be removed by burning and the exposed rods 7 cut off flush with the surface of the concrete within the hole formed by the core 6. The shuttering 1 is also removed.

Referring to Figure 2, the outlet 8 is formed of a plastics material and has a tubular portion 8a of the same external diameter as the cylindrical portion 6b of the core, a hollowfrusto-conical portion Sb of the same external shape and dimensions as that 6a of the core 6, and a flange Sc around the upper rim of the frusto-conical portion Sb. A protective grid 9 has a flange 9a arranged to locate on the outlet 8 and a plurality of fins 9b defining a plurality of small apertures 9through which water may flow but leaves and other debris are prevented from passing.

The outlet 8 is located in the hole left in the concrete roof by the core 6 and covered by the grid 9, which is attached to the outlet 8. A rainwater pipe may then be connected to the tubular portion 8a.

The method of the invention permits drainage passages to be formed in a concrete roof or floor during casting ofthewhole roof orfloor, allowing simple installation of the drainage pipes at a later date. The method also provides temporary sealing of rainwater penetration into openings cast in roof slab.

1. A method of providing a drainage passage in a concrete roof or floor, which comprises locating a core for moulding the drainage passage on the surface upon which the floor or roof is to be cast, the core having a height at least equal to the thickness of the roof or floor required, casting the concrete around the core and allowing the concrete to set, removing the core from the concrete to leave a hole therethrough, and locating in the hole an outlet member which closely conforms with the hole and which has means for securing a pipe thereto.

2. A method according to Claim 1, wherein the core used has an inverted frusto-conical section joining a cylindrical or tubular section.

3. A method according to Claim 1 or 2, wherein the pipe is secured to a tubular extension to the outlet member projecting beneath the concrete floor or roof.

4. A method according to Claim 1,2 or 3, wherein a core formed of expanded polystyrene is used.

5. A method according to Claim 4, wherein the core is removed from the set concrete by burning.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Forming drainage passages This invention relates to a method of forming a drainage passage in a concrete roof or floor. When concrete roofs or floors requiring drainage outlets are cast in situ, it is common practice to leave a section around the location of the drainage outlet free of concrete in the form of a boxed hole by providing shuttering around the location, and then to instal the outlet separately within the opening when the concrete has set. The outlet will typically take the form of a funnel-shaped fitting, formed from a plastics material, to which a downpipe is connected. The outlet is installed separately because a plumber is required to instal the necessary pipework, e.g. the downpipe and drainage, and it is generally not practical to arrange for the plumber to be present when the casting is carried out. According to the present invention, there is provided a method of forming a drainage passage in a concrete roof or floor, which comprises locating a core on the surface upon which the floor or roof is to be cast, the core having a height at least equal to the thickness of the roof or floor required, casting the concrete around the core and allowing the concrete to set, removing the core from the concrete to leave a hole therethrough, and locating in the hole an outlet member which closely conforms with the hole and which has means for securing a pipe thereto. The core and the outlet member are suitably funnel-shaped in elevation, i.e. having an inverted frusto-conical section joining a cylindrical or tubular section. The means for securing a pipe may comprise an elongate tubular section projecting beneath the concrete roof or floor, the pipe coupling with this section in conventional mannerforjoining pipes. The core may be formed of a durable plastics material such as polypropylene or of a light-weight mild steel, so as to be re-usable, or a glass-fibre reinforced plastics material may be used. Alternatively, the core may be formed of a material which can be readily destroyed in situ to remove the core from the concrete, for example expanded polystyrene, which can be burnt out or chipped out. Where an insulating layer formed, for example, of expanded vermiculite in asphalt or lightweight concrete, is to be laid on top of the concrete roof or floor, an additional core may be used above the first core, or an extension of the first core. This additional core or extension may be cylindrical, the outlet resting inside the hole formed thereby. The outlet may have a flange therearound, and if desired screws may be passed through the flange to secure the outlet to the roof or floor. Reference is made to the accompanying drawing, in which: Figure 1 shows a small portion of a roof member being cast; and Figure 2 shows an outlet suitable for use in the method of the invention. Although Figure 1 shows, for convenience, a very small area being cast, the area to be cast would normally be large relative to the size of the outlet. Four wooden shuttering members 1 are secure together to define the area 2 in which the concrete is cast, on a temporary supporting surface 3. A steel wire reinforcing mesh 4 is located within the area 2 and spaced from the surface 3 by a plurality of spacing members 5 which engage cross-members of the mesh 4. An expanded polystyrene core 6 has an inverted frusto-conical portion 6a and a cylindrical portion 6b which is placed upon the surface 3. The core 6 is supported by wire rods 7 inserted into the expanded polystyrene and resting on the surface 3 at a distance from the base of the core 6. Concrete is then poured into the area 2 to the required depth and allowed to harden. The core 6 may then be removed by burning and the exposed rods 7 cut off flush with the surface of the concrete within the hole formed by the core 6. The shuttering 1 is also removed. Referring to Figure 2, the outlet 8 is formed of a plastics material and has a tubular portion 8a of the same external diameter as the cylindrical portion 6b of the core, a hollowfrusto-conical portion Sb of the same external shape and dimensions as that 6a of the core 6, and a flange Sc around the upper rim of the frusto-conical portion Sb. A protective grid 9 has a flange 9a arranged to locate on the outlet 8 and a plurality of fins 9b defining a plurality of small apertures 9through which water may flow but leaves and other debris are prevented from passing. The outlet 8 is located in the hole left in the concrete roof by the core 6 and covered by the grid 9, which is attached to the outlet 8. A rainwater pipe may then be connected to the tubular portion 8a. The method of the invention permits drainage passages to be formed in a concrete roof or floor during casting ofthewhole roof orfloor, allowing simple installation of the drainage pipes at a later date. The method also provides temporary sealing of rainwater penetration into openings cast in roof slab. CLAIMS

6. A method according to any preceding Claim, wherein a layer of insulating material is located on the upper surface of the concrete, and the core is selected to extend upwardly to the surface of the material.

7. A method according to any preceding Claim, wherein the outlet member has a flange around the upper end thereof, the flange being secured to floor or roof.

8. A method according to Claim 7, wherein the flange is secured by means of screws driven therethrough.

9. A method of providing a drainage passage in a concrete roof or floor, substantially as described with reference to the drawings.