CA2143393A1 - Drainage system - Google Patents

Abstract

A drainage system which assists in water-proofing basements and the like by providing channels for ground water flow comprises a sheet of rigid material with a backing surface and a front surface separated by partitions. Filter material on the front surface will separate ground water from solids and a series of perforations on the front film will permit ground water to flow into the channels between the films and be conducted in the space between the films to the drainage system.

Description

2This invention relates to an improved ground water 3drainage system. In particular, it relates to an improved 4means for draining and water-proofing inground installations 5such as basements and the like.

6In many countries it is common to build residential, 7as well as commercial properties, with one or more levels of 8occupied space below ground level. Commercial and highrise 9residential buildings often include underground parking, and 10single family dwellings commonly have a basement which is used 11to contain heating, lighting, plumbing and laundry facilities, 12storage space, or additional living quarters.

13Traditionally, these basement facilities have been 14dug into the ground and provide a foundation for the main part 15of the building. Since they need to be buried deep enough to 16avoid damage by frost, it becomes logical and economically 17 advisable to create occupiable space. These basement -1 foundations have traditionally been made of concrete blocks 2 grouted with mortar or occasionally by solid poured, 3 reinforced concrete walls and floors.

4 Because such basement walls are buried in the S ground, they are exposed to ground water and natural porosity 6 or eventual cracks result in leakage or moisture penetration 7 so that basements are commonly damp. However, in modern times 8 efforts have been made to construct a more rigid and water-g proof foundation so that the space which is created in the foundation structure is more usable. Apart from making a 11 better quality basement wall, the most effective way to keep 12 a basement dry is to provide effective drainage and this is 13 often done by surrounding the basement at the floor level with 14 drainage tiles which is then generally covered with crushed lS stone or sand so that ground water in the area of the basement 16 wall will easily drain away without having the time or the 17 pressure to find access through the walls of the basement.

21~3393 1 To aid in this water-proofing technique it has 2 become customary to coat the outside surface of basement walls 3 with a layer of water-proofing material such as tar, pitch or 4 asphalt. More recently it has become customary to place a S layer of hollow material against the water-proof coating so as 6 to provide a channel enabling any ground water to pass 7 downward to the drainage tile.

8 The most common water drainage system now in use 9 consists of a semi-rigid sheet of impermeable plastic having a series of indentations on the side adjacent to the basement 11 wall (or water-proof layer), and conversely, a series of bumps 12 on the outward surface over which is adhesively fastened a 13 matting of water permeable fabric, usually synthetic.

14 This drainage layer provides a protective coating so that dirt backfilled around the basement wall does not damage 16 the integrity of the water-proof coating, and it provides a 17 means whereby ground water can penetrate the fabric and 1 trickle down through the spaces between the fabric and the 2 plastic sheet to the drainage tile at the bottom of the 3 basement where it is carried away.

4 The problem with the existing system is that the irregular surface against the pitch or asphalt provides 6 pressure points and allows the pitch to migrate into the 7 indentations creating zones of thinness surrounding that area.

8 On the other side the spaced protrusions provide a poor g support for the very flexible synthetic fabric and the pressure of the water and soil around it tends to push the 11 fabric into the spaces between the lugs rendering them less 12 open to the flow of ground water as a drainage system.

13 It is therefore the purpose of this invention to 14 provide a drainage system which overcomes the aforementioned disadvantages and provides a more effective, less costly, and 16 advantageous drainage material.

17 These objectives and other advantages are sought to 214~393 1 be employed by means of the present invention which comprises 2 a sheet of semi-rigid material having a flat planar backing 3 surface film and a flat planar front surface film with a 4 series of partitions disposed between said films to hold them apart and in spaced parallel relationship to each other. A

6 series of perforations on the front surface will permit water 7 to pass into the spaces between the films and a filtered cloth 8 covering the front surface film will serve to permit water to g pass through while providing a barrier to exclude solids or soil material. The filter material may be made of a matting 11 of synthetic fibres and the perforations in the front film of 12 the semi-rigid sheet material may be a series of horizontal 13 scores or cuts or a pattern of holes.

14 The invention may be better understood by the following description of one embodiment thereof with reference 16 to the accompanying drawings in which:

17 Figure 1 is a perspective view of a portion of a 2143~93 -1 drainage system which is part of the existing 2 prior art;

3 Figure 2 is a perspective view of a piece of a 4 drainage system in accordance with the present invention;

6 Figure 3 is a cross-sectional view of an 7 installation using an embodiment of the 8 present invention.

9 In the views of Figure 1 and Figure 2 the structure is formed in a right angle for better illustration.

11 In the prior art illustrated in Figure 1 a sheet of 12 semi-rigid material such as polyethylene or polyvinylchloride 13 2 has a back surface 4 with a series of indentations 6 which 14 on the front side appear as a series of projections 8.

Overlying the projections and adhesively attached to the outer 16 surface or "top" of the projections is a layer of woven 17 synthetic material 10. In use, the back surface 4 is placed ~193393 1 against the foundation wall (or most commonly against the 2 water-proof asphalt coating) where it is adhesively held in 3 place. Afterwards the foundation is backfilled and the soil 4 rests against the woven fabric lo. This is intended to (a) protect the asphalt from damage by stones and other material 6 during the backfilling process, and (b) provide a permeable 7 filter (the fabric 10) through which water may pass but solid 8 particles of soil will be filtered outward. The ground water g then travels vertically down past and between the projections 8 in the space between the fabric layer 10 and the semi-rigid 11 sheet 2 so that it easily runs vertically down to the drainage 12 tile or whatever system is designed to carry away excess 13 ground water.

14 The problem presented by the prior art is that the back surface of sheet 4 has recesses 6 into which the asphalt 16 water-proofing tends to migrate under pressure. This tends to 17 thin the layer of water-proofing material in and around the -1 area of these recesses and minimizes its effectiveness.

2 Furthermore, the pressure of water and soil against the fabric 3 10 tends to push it into the spaces between the projections 8 4 so that eventually it will tend to plug these water courses.

s In some cases it may rupture under pressure and allow fine 6 soil or other material into the space so that it plugs up and 7 becomes ineffective.

8 The embodiment of the invention illustrated in 9 Figure 2 comprises instead a sheet 12 of semi-rigid material, such as polyethylene or polyvinylchloride, constructed of two 11 films 14 and 16 which are spaced apart and held in parallel 12 relationship by vertically extending and perpendicularly 13 disposed webs 18 forming a series of spacers or partitions 14 holding the surface films 24 and 26 apart so as to create vertical hollow tunnels bounded by adjacent webs 18 and the 16 opposing films 14 and 16. On the outer front face of the film 17 16 is an adhesively attached layer of matted synthetic fibre 1 material 20, which provides a water-permeable filter capable 2 of removing most solids from ground water.

3 In the illustrated embodiments in Figure 2 part of 4 the water-permeable synthetic fabric is cutaway to show the outer surface of the film 16 which is perforated by horizontal 6 cuts or slits 22. A portion of the outer film 16 is cut away 7 to illustrate the structure of the webs 18 which create the 8 vertical water courses in the illustrated embodiment.

9 Figure 3 illustrates the installation of a drainage system of the present invention as illustrated in Figure 2 on 11 a foundation wall having been backfilled. In this 12 illustration the basement wall 30 and basement floor 32 are 13 surrounded by drainage tile 34 which is buried in crushed 14 stone 36 in the conventional way. The exterior surface of the basement wall has a layer of asphalt water-proofing 38 against 16 which is installed in a drainage system of the present 17 invention as illustrated in Figure 2.

1The inner surface of backing film 14 which is flat 2and smooth without indentations lies against the pitch 38 3without creating any pressure spots or areas for migration.

4The webs 18 hold the front film 16 at a spaced interval and 5create vertical channels for water flow to the drainage tile 634 at the base. A series of slits 22 running horizontally or 7at some angle to the horizontal along the outer film 16 8provide means whereby water may pass into the water course 9created by the webs 18. On the outer front surface of the 10system a flexible woven water-permeable fabric material 20 11provides a barrier which prevents the inflow of solid material 12but will allow water to pass through. To the outside of the 13woven material the soil 40 is backfilled in the usual way.

14Because of the advantage of this system, material which has 15been excavated may be used and need not be specially designed 16or highly permeable material such as crushed rock or sand.

17It will be readily seen that any ground water which _, 1 accumulates in the backfill or soil surrounding the basement 2 can migrate to the woven fabric and pass through it while any 3 fine solid particles are filtered out. The water will then 4 pass through the slits or perforations 22 into the water courses 18 so that they can migrate vertically down to the 6 drainage tile and be carried away.

7 It will be additionally appreciated that the present 8 system provides two layers of semi-rigid plastic material 14 9 and 16 to protect the asphalt water-proofing against any stones which may be thrown against the basement wall during 11 backfilling (as will the spacing provided by the webs 18).

12 Because the back surface 14 is flat and planar, it 13 does not create pressure spots or cause migration of the 14 asphalt water-proofing. In addition, because the front film 16 is also flat and planar, it resists the pressure of the 16 surrounding water or backfilled material and prevents the 17 woven fabric from sagging or penetrating into the water 21 i3393 1courses as it does in the illustrated prior art.

2For this reason the woven filter material may be 3lighter, thinner, and less expensive.

4Material such as that illustrated in the preferred Sembodiment may be made in large flat sheets with relative ease 6and the perforations 22 may be created in any number of ways 7including a pattern of slits or a pattern of holes.

8The woven fabric may have varying characteristics gbut should be permeable to water, relatively impermeable to 10fine soil particles, and have acceptable strength and 11resistance to deterioration in underground conditions. Some 12materials of this nature are currently available including 13one sold under the Trade Mark "~ A.l~E", made of synthetic 14 fibres.

15Although Figure 1 and Figure 2 show material bent at 16right angles, this is merely for illustrative purposes, and 17flat planar sheets are considered easier to make, transport 1 and use.

2 It should also be realized that although the present 3 invention is described for its usefulness in water-proofing 4 basements, it may also be used in horizontal or low slope roofing provided proper structural criterion are adhered to.

6 In such use it would, of course, be advisable to have the 7 water courses directed towards the low point or drainage 8 system.

9 As presently conceived, the semi-rigid sheet material could be made by extruding a synthetic polymer such 11 as polyethylene or PVC. If so, the partitions 18 would 12 logically be continuous but it is not necessary that they form 13 a complete barrier between various chambers so long as they 14 provide the necessary strength to space the front and back films apart.

16 It will, of course, be realized that numerous 17 variations and modifications of the illustrated embodiment may 1 be employed without departing from the inventive concept 2 herein.

Claims (5)

1. A drainage system comprising:
- a sheet of semi-rigid material having a flat planar backing surface film;
- a flat planar front surface film;
- a series of partitions disposed between said front and back films to hold said films apart and parallel to each other;
- a series of perforations in said front surface film to permit water to enter the space between said films;
- a filter material covering said front surface film adapted to permit water to flow therethrough and providing a barrier to fine solids.

2. A drainage system as claimed in claim 1 in which said filter material is a matting of synthetic fibres.

3. A drainage system as claimed in claim 1 or 2 in which said perforations consist of a series of slits extending at an angle to the longitudinal extension of said partitions.

4. A drainage system as claimed in claim 1 or 2 in which said perforations are a pattern of small holes.

5. A drainage system as claimed in claim 1 or 2 in which said semi-rigid sheet is an extruded synthetic polymer.