GB2527491A

GB2527491A - Complete flood protection

Info

Publication number: GB2527491A
Application number: GB1407079.1A
Authority: GB
Inventors: David William Beddoes
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-04-22
Filing date: 2014-04-22
Publication date: 2015-12-30
Also published as: GB201407079D0

Abstract

A method of flood protection of buildings with three key components: hydrophobising impregnation 18 of the external walls 1using a water resistant chemical which retains the permeability of the substrate to which it is applied, without altering the appearance of the treated walls; installing a cavity drainage membrane 13 on the floor and internal walls of the building; installing a perimeter floor drainage system 4 with adjustable pivotally connected corners and T-pieces, and a deflector to aid water flow along channels. Additionally, the drain may be ventilated either by a mechanical fan or passive stack ventilation, to evaporate moisture and to aid in the removal of harmful gases such as radon. The extract ventilation may be linked to the sump pump.

Description

Complete Flood Protection

Background

The Stem Report bought together scientific evidence to show that global warming is responsible for climate change and emphasised the importance that humans must act now to prevent catastrophic future results (Stem, 2006). Climate change has introduced a new volatility to precipitation, drought, heightened storm intensities and has contributed to a catalogue of disasters across the globe (Goulder, 2006). Evidence shows that climate change is happening now and hydrological modelling predicts an increase in both magnitude and frequency of flood events across the United Kingdom (UK) (Prudhomme et al., 2002). The new UK strategic government policy to address flood and coastal risk management is Making space for water' which in effect has informed the owners of flooded homes that it is now their own problem that they themselves must manage. The government strategy is to accept that large scale engineering projects to protect communities is no longer sustainable and homeowners must install resistance andtor resilience measures at property level (Treby et at, 2006). The homeowner is urgently in need of an effective holistic solution that can be installed with limited finds as government funding over 2012-20 16 is to be reduced by 10% compared with the previous four years budget and this is in the face of increased risk of flooding due to climate change. The limited government funds should not be used to subsidise measures such as door guards and airbrick covers which will not on theft own prevent floodwater getting into houses, they must be allocated to a suite of measures to provide a complete solution that satisfies all the routes of water ingress as identified by research (Balaam, 2009). In general, the fabric of a building is permeable to water and even with well fitted extemal aperture guards in place the floodwater finds its way into the building. Normal standard specification brick walls are in most cases not watertight when they are subjected to hydrostatic flood pressure (USACE, t998). Measures that are designed to accept controlled water ingress and allow the rapid collection of water, removal of water and subsequent drying of the building are thought to be potentially viable (ODPM, 2005).

An extensive study commissioned by the Department for Communities and local Government (DCLG) and Environment AgencyiDEFRA was aimed at obtaining some understanding of how a building behaves when subjected to floodwater. A comprehensive series of tests were undertaken on common building materials and a selection of wall types. The published results of this study in Report WP5C (DCLG) showed that it was not possible to predict the water a permeability of a wall by virtue of its components and often the water leakage rates through a wall exceeded the maximum leakage rate associated with that of the weakest wall component.

Striking inconsistencies such as a masonry wall constructed under laboratory conditions with virtually impervious components that can leak water at an alarming rate of up to 400 litres/minute were never adequately explained. In the established field of basement waterproofing technology the perimeter floor drain (PFD) is linked to a sump/pump unit and used to keep basements thy. In a basement waterproofing installation the water ingress must first percolate through the soil surrounding the basement which slows the rate of water movement and subsequent ingress. The rate of water ingress in a typical basement is slowed and controlled to such an extent that an average basement can use a 0.6HP pump that handles litres per minute, maintaining a minimum safety factor of 3, and still easily pump out all water ingress collected by the PFD system. In a flood event the floodwater stands directly outside the building wall, there is no slowing by water percolation through soil, and therefore there is a much greater rate of water ingress. As shown by the results of WP5C (DCLG) a measured rate of water ingress of 400 litres/hour/metre through the walls of an average building of 40 metres perimeter would result in 16,000 litres/hour water ingress which is far in excess of a standard sump/pump unit. As a safety factor of at least 3 is required when designing pumping capacity a capability to pump 48,000 litres/hour is needed which would require at least four sump/pumps for an average building. Also such very high rates of water ingress and extraction from within a building can lead to piping' of fines' within the soil and subsequent subsidence and structural damage to the walls and floors of the building.

An equally significant problem for flooded buildings is drying out after a flood event in both the short and long term. The occurrence of secondary flooding is frequently experienced on buildings that have been reinstated after a flood event. Most recently, in Hull UK where flood victims have found themselves still not able to reoccupy their homes after eighteen months due to secondary flooding, many victims have moved back into their homes only to be forced out again by secondary flooding (Wainwright, 2008). In essence, as a result of a flood event, moisture can get locked into damp materials for many years causing chronic problems of reoccurring dampness e.g. an accumulation of moisture below a solid floor cannot evaporate through the solid concrete/damp proof membrane and will pass to the sides of the room and into the base of the walls and walls which appear thy will harbour moisture which then evaporates via the internal room to ruin internal finishes. As part of the reinstatement work the measurement of dampness by moisture meters would indicate that walls were dry but the locked in moisture eventually has to find a way to escape. This occurrence of locked in moisture has been experienced before in buildings where there has been a problem with rising dampness, plumbing leaks and drain defects. In these situations the accumulation of moisture reservoirs in foundations is exactly the same as found in a flood event. The moisture trapped below floors and within foundations is forced to the sides of the rooms and into the base of walls to cause problems of damp and decay: * Moisture content rises to allow the growth of decay organisms * Materials loose their structural strength * Mould growth becomes a significant health hazard * Movement of soluble salts in pores. of materials causes aesthetic and structural damage.

This is one of the reasons why the companies that inject new damp proof courses into walls have always insisted on the re-plastering of internal walls with a salt-proof and waterproof rendering. It is in order to cover up the problems that will surface over time due to moisture reservoirs under floors and in foundation walls. There has never been an effective solution to this problem and the rendering cover up is not always successful. A method is needed to reduce floodwater ingress through any type of external wall down to levels that are then manageable by maintainable ventilated perimeter floor drainage systems. In many areas of the UK there are very permeable soils which due to recent extreme concentrated rainfall are now introducing a new problem of saturated ground resulting in groundwater rising from beneath floors to enter buildings which must also be addressed.

Statement of Invention

To overcome these problems the present invention proposes a method of increasing the external water resistance of masonry walls, subsequently handling the remaining floodwater ingress by the use of an accessible perimeter floor drain system with a cavity membrane and latter possible drying and ventilating of the building structure.

Advantages The method does not rely on external resistance alone which will always eventually fail, instead a combination of increased external resistance reduces water ingress to manageable levels whereby internal resilience measures handle the inevitable water ingress.

The method provides protection against not only external floodwater but also groundwater which can rise up through the floors of a building.

Treatment of the external face of a masonry wall can be carried out from outside the property.

Treatment of the external wall greatly reduces the rate of water ingress through the wall.

Treatment of external walls can be combined with an energy saving impregnation to both increase water resistance and reduce heat loss by as much as 30% through treated walls.

Less water ingress means the building can be dried out faster.

Less water ingress leads to smaller moisture reservoirs below floors and within foundation walls.

Reduced rates of floodwater ingress mean no risk of structural damage due to pumping out large volumes of water from the building.

Reduced rates of water ingress can be handled by the already proven perimeter floor drain systems and sump/pumps as tried/tested and currently used in basement waterproofing technology.

The perimeter floor drain collects not only water from walls but also the vulnerable floor/wall join when groundwater rises from below floors and foundations.

Extraction of floodwater from the bottom of the wall cavity keeps cavity insulation dry and maintains its insulating properties.

Extraction of floodwater from the bottom of the wall cavity ensures that internal wall finishes are not damaged by water.

The use of perimeter floor drains to collect water allows low profile cavity membranes and laminate floor finishes to be used which reduces loss of ceiling height in rooms.

S

Wall membranes are not always needed when functional external resistance is applied to external walls and wall cavities are drained of floodwater.

Perimeter floor drains can be flood tested and sump/pumps tested at any time.

The new T piece with internal water deflector plate now enables access into the perimeter floor drain system via the sump. A drain inspection camera or hose can be inserted via the sump chamber access lid and be pushed along the link drain to then pass around the corner into the length of the perimeter floor drain. By means of pushing along different sides of the link drain both lengths of perimeter floor drain on either side of the T piece can now be accessed. The internal water deflector plate provides a constant radius for the bend in the inspection camera or hose and prevents kinking as they are fed through the T piece and along the perimeter floor drain.

When flushing the system the T piece deflector stops water and/or sediment being washed back and forth across the end of the link drain and due to its shape directs water flow into the link drain. Subsequently, sediment can be removed by way of the sump/pump chamber lid.

For maintenance purposes one side of the new T piece can be used to introduce a hose into the perimeter floor drain and the flushing water will then travel around the perimeter floor drain to carry sediment back to the new T piece where the deflector plate will direct it into the link drain and then onto the sump for removal.

Accessibility into the new system of perimeter floor drains now allows regular maintenance of the perimeter floor drain installations and provides for repairs if necessary.

Ventilation of the perimeter floor drain will facilitate drying out immediately after a flood event.

Continued long tenn ventilation of the perimeter floor drain will evaporate the moisture reservoirs from under floors, within foundations and within the structure to prevent the occurrence of secondary flooding.

Ventilation of the perimeter floor drain collects moisture from walls and the vulnerable floor/wall join.

Extract ventilation of the perimeter floor drain can collect and dispose of harmful ground gases that enter a building from the surrounding soil e.g. Radon.

Extra costs and disturbance due to internal re-plastering of walls with salt-proof and waterproof renders in attempts to cover up the effects of the evaporation of moisture reservoirs is not required.

The method is functional, cost effective, easy to install and can be installed with government grant aid which is available to flooded homes.

The method can be used in combination with a Dado Wallboard system when floodwater heights exceed the structurally safe limits of 600mm.

Drawings The method will now be explained and examples of the invention described by referring to the accompanying drawings: Figure 1 a plan view to show installation to a building.

Figure 2 a cross-sectional drawing to show installation to an external cavity wall.

Figure 3 is a line thawing that shows an end elevation of (a) one part perimeter floor drain and (b) two part snap together perimeter floor drain.

Figure 4 is a plan view to show a typical installation in a single room of the new system having perimeter floor drains combined with the pivotally connected elbow bends and T piece.

Figure 5 is a line drawing to show the pivotally connected elbow bend.

Figure 6 is a line drawing to show the pivotally connected T piece.

Figure 7 Shows plan views of the perimeter flood drain, T-piece, link drain and sump chamber to illustrate the accessibility provided by the new pivotally connected T-piece with water deflector plate.

Figure 8 is a plan view of the T-piece and sump chamber to show water and/or sediment flowing into the sumpipump chamber.

Figure 9 is a line thawing of the new T-piece to show the internal water deflector plate that also acts as a support for the T-piece soffit.

Detailed Description

Floodwater penetration through the completed wall is not affected by the permeability of brick or mortar but occurs as a direct result of conditions at the interface between brick and mortar which is dependent on a little known quality of the brick known as initial rate of absorption together with mortar mix and the skill of the mason when laying. The permeability of a wall is due to the extent of bond' and is directly affected by the compatibility of materials used and also any unidentifiable flaw in construction such as a repositioned brick may cause an otherwise watertight wall to leak large amounts of water, such a leak can cause a tenfold increase in rate of water ingress. The water permeability of masonry walls is dependent on cement hydration at the interface between masonry unit (brick) and mortar at the time that the masonry unit is laid onto the mortar bed. The interface join is the intimate contact area between the masonry unit and the mortar and it is important to realize that it is not the mortar joint itself The interface join and resultant extent of bond' that resist water penetration occur immediately after the brick is laid onto the mortar bed and incompatibility of brick and mortar, delay in laying the brick and subsequent disturbance of the brick will damage the interface join. The mechanical attachment between brick and mortar is not the same as the extent of bond' at the interface join. It can be very difficult to pull or dislodge a brick from a mortar bed but if the initial rate of absorption (IRA) of the brick and mortar mix are incompatible or delay and disturbance have occurred then there will be little or no interface join, no extent of bond' and the resultant wall will be highly permeable to water.

The physical brick adhesion to the mortar bed and water permeability are each due to different properties of the brick and mortar, The majority of masonry walls must therefore be regarded as prone to large rates of water ingress due to incompatibility and/or defects introduced during the laying of the bricks. In order to be absolutely certain that the resistance of a masonry wall is raised to an acceptable level the extent of bond' at the interface between brick and mortar must be addressed in areas where standing floodwater will come to bear against the masonry wall. The interface could be sealed by the application of a complete external rendering as seen in WPSC (DCLG) or waterproof coating, however renders have many disadvantages e.g.: To apply rendering/coatings down to external ground level and protect the lower courses of the brickwork where hydrostatic pressure is the greatest involves bridging across the damp proof course and as such will allow rising damp within the wall (DCLQ, 2006).

It is difficult to achieve adequate adhesion of the rendering to brickwork without extensive chasing out of joints (mm. 15mm) and/or spatterdash coats even then salts within the bricks themselves may dislodge areas of rendering due to the force of crystalisation pressure within the pores (Crook and Day, 2005).

* Rendering is labour intensive and expensive because it is a multi layered construction with an undercoat and subsequent thinner top coats (Monks, 2000).

* Heat expansion reduces adhesion and promotes cracks in the rendering that let in water.

* Lengths of rendered plinth in excess of six metres will require some form of expansion joint that may let in water (Crook and Day, 2005).

* A rendered plinth sits at the base of a wall where the likelyhood is that excess water that runs do'm the wall from concentrated rainfall can most easily penetrate the wall to rendering joint.

* Once water gets behind a rendered plinth and into the bricks it is extremely difficult to dry out and subsequent frost action can dislodge the rendering (BRE, 1983).

* Changing the external appearance of a property with rendering may not be allowed by the planning department, particularly in conservation areas.

* Some owners would not agree to their home being covered with a rendered plinth as, for them, it would serve as a constant reminder of the risk of a flood event.

* Many waterproof surface coatings as applied to masonry are not vapour permeable and do not allow the masonry to breathe resulting in moisture being trapped within the wall and trapped moisture will cause actual damage to the wall itself * Impregnating the masomy will only seal the smallest of cracks and line the pores of the masonry and cannot ensure to adequately seal all the interfaces between bricks and mortar where floodwater enters.

The use of a colourless impregnating hydrophobation is proposed to address the problems of interface joins and so reduce initial rates of water ingress through masonry walls without the disadvantages of rendering/coatings. The impregnating chemical is water resistant, highly frost resistant and retains the water vapour permeability of the substrate to which it is applied.

The impregnating chemical is colourless and as such does not alter the appearance of treated walls.. The external face of the wall is impregnated with a hydrophobising liquid. The joints and bricks become uniformly water repelling, even narrow joints and cracks are filled and the wall remains highly water vapour permeable. An added advantage for the homeowner is that the hydrophobising impregnation is energy saving and also serves to reduce heat loss by as much as 30% through the treated walls. Where the construction of the external wall is very poor the walls can be repointed before the application of the hydrophobising liquid. The hydrophobising impregnation seals the interfacial cracks and coats the capillaries without blocking the pores and so the wall is still able to breathe whilst benefiting from a significant reduction in water permeability. The hydrophobising treatment can be cream based (more suitable for DV!) which makes it easier to apply a uniform coat or solvent based and sprayed in coats for professional application, the impregnation lasting from 15 years upwards. Initial tests on water flow through single skin London Fletton brick walls at about 600mm head and after treatment to joints and impregnation of wall as detailed above show a reduction in rate of water ingress down to lower than the levels measured for rendered walls in WP5C (DCLG). The rendered walls of WP5C let in 3% of the corresponding leakage rate through a typical masonry wall, whereas the walls treated as (b) above let in a mere 0.25% of the corresponding rate. The significant reduction in the rate of water ingress allows the use of a perimeter floor drain system to handle the remaining water that enters the building.

Figure 1 is a plan view to show installation to a building. The external face of the outer masonry skin (1) is treated to seal the interface joins and so reduce the rate of water ingress through the wall. The cavity (2) is formed between outer skin (1) and inner skin (3) and collects floodwater that passes through outer skin (1). For some installations, dependent on floodwater heights and type of external wall the holes (5) may preferably be drilled through the bottom of the inner skin (3) allow all water from the cavity (2) to pass into the ventilated perimeter floor drain (4). Arrows (6) show the passage of the floodwater from the wall cavity (2) through the holes (5) and into the ventilated perimeter floor drain (4). If the holes (5) are not drilled the floodwater will pass through both skins of the wall and into the perimeter floor drain. The entire floor surface is covered with a cavity membrane which collects groundwater that rises through the building floor and transfers it to the perimeter floor drain. If necessary in areas of very high groundwater levels multiple holes can be drilled in the top surface of the perimeter floor drain to aid rising groundwater trapped under the cavity membrane to enter the perimeter floor drain more easily. The water collected in the perimeter floor drain (4) will come from the catty, pass through both skins of the wall (1 & 3), from the floor to wall join and from groundwater that rises up from the soil beneath the floor and is trapped under the cavity membrane. The water ingress is transferred (as shown by arrows 6) by the perimeter floor drain to the sump/pump unit (7) for removal from the building (pumped to outside). The single skin internal wall (8) has a perimeter floor drain (4) on one side only and is cross-drilled to collect water in the ventilated perimeter floor drain from both sides of the wall.

Arrow (6) shows water from ventilated perimeter floor drain (4) entering the link-drain to sump/pump (7) for extraction from the building. The perimeter floor drain system uses corner pieces and a T-piece at the link drain connection that all feature internal deflector plates to facilitate access and maintenance of the perimeter floor drain system see Patent Pending GB1117089.l, GB1102662.2 and GB1102661.4. The perimeter floor drain may also be ventilated. The ventilation for the ventilated perimeter floor drain (4) is provided by mechanical fan or passive stack as shown (21). Extract ventilation (22) can also be linked to the surnp pump (7). The ventilation (21 and/or 22) can be used to dry out immediately after a flood event and also the use of continued long term ventilation can serve to evaporate and dispose of the moisture present in moisture reservoirs that is responsible for secondary flooding. Ventilation can also be used to remove dangerous ground gases such as Radon, the use of extract ventilation being far more effective that simply trying to seal out the entry routes of the gases. The ventilated perimeter floor drain (4) is situated at the floor/wall join where the dangerous gases enter the building.

Figure 2 is a cross-sectional drawing of the installation to an external cavity wall. The outer skin of masonry (1) has the external face treated with impregnating hydrophobising chemical to seal the interface joins (18) and so reduce the rate of water ingress through the wall. New research shows that even for the most permeable of bricks and walls that have the highest rates of water leakage that interface join treatment reduces the rate of water ingress to around 0.25% of the highest rate as measured in WP5C (DCLO). Therefore the leakage of 400 litres/hour would be reduced to 1 litre/hour or 40 litres/hour for an average building with a 40 metre perimeter. This reduced rate of water ingress combined with floodwater/groundwater that rises from beneath a flooded building can now be handled by a standard 0.6HP sump/pump unit (7). Treatment of interface joins (18) provides an acceptable extent of bond' to make the outer skin virtually impermeable, even if the bricks and mortar used were not compatible, delayed in laying or were disturbed after the bricklaying process. The outer skin (1) external face interface joins (18) must be treated from ground level up to the expected/acceptable floodwater level which is 600mm maximum differential height. With a differential height in excess of 600mm there is a possibility of structural damage and floodwater must be let into a building, but a combination of the above method and a Dado Wallboard' patent pending (1B1021254.6 forms a solution for excessive differential flood heights. The reduced quantity of floodwater that manages to pass through the outer skin (1) after it has been treated will enter the wall cavity (2) and will sit on top of the concrete cavity fill (19). A conventional cavity wall has weep holes in the bottom of the outer skin in order to let water collected by the cavity drain out into the soil, however in this installation the weep holes would let in floodwater and so they are sealed. The build up of water in the cavity (2) passes through the inner skin of the wall and into the perimeter floor drain (4). If holes (5) are drilled in the inner skin (3) the water will also pass through the holes and into the perimeter floor drain (4). The holes, if drilled, (5) are set at a level to prevent water rising up into the inner skin (3) and causing damage to internal finishes and also at a level so that the cavity insulation (17) is kept thy. This installation can be used for cavity or solid walls. The ventilated perimeter floor drain (4) is positioned around the edge of the solid floor (14). The damp proof membrane (15) and hardcore (16) are shown below the solid floor. The ventilated perimeter floor drain (4) stands away from the internal face of the inner skin by small spacers or a strip of cavity membrane (20) to allow any water that drips down the face of the inner skin to drain down to the bottom channel section of the ventilated perimeter floor drain. In some installations a cavity membrane may also be attached against the inside face of the wall to expected flood height and underneath the plaster finish to collect water ingress and transfer this down to the perimeter floor drain (4). The ventilated perimeter floor drain (4) is fixed to the inner skin (3) along its length to prevent any tendency to lift when water enters. A cavity membrane (13) with floor finish (12) may be fitted above the solid floor (14) and ventilated perimeter floor drain (4). The floor cavity membrane (13) can be sealed around the edges to the ventilated perimeter floor drain or surface of building wall with waterproof self adhesive tape (23). Floor membrane (13) can collect groundwater/floodwater ingress through cracks and water which rises from below the floor through joints in solid floors. The ventilated perimeter floor drain (4) can collect water from the cavity (2) via holes (5), water rising under the floor (14) and passing through floor to inner skin (3) joint together with water collected by the floor membrane (13). Various types of floor finish can be laid onto a floor membrane (13) e.g. laminates, chipboard, cement/sand screeds. In areas where dangerous ground gases are present the extract ventilation by the ventilated perimeter floor drain (4) can remove the gases from the building as they mostly enter through the cavity and vulnerable floor/wall joints. Access points are available to provide accessibility to the ventilated perimeter floor drain for testing and maintenance. The wall plaster finish (9) is shown with typical skirting board (10) fitted over, plastic skirting is the most suitable material in flood prone buildings.

Figure 3 is a line thawing that shows an end elevation of one part perimeter floor drain and two part snap together perimeter floor drain. Figure 3 (a) shows a one part perimeter floor drain with an upstand (A), a perimeter floor drain can be installed with or without this upstand. The upstand is sometimes used against the inside wall of a building to hold the lower edge of a waterproofing structure in place and hence is not always needed. The one piece perimeter floor drain has holes (B) in the channel sidewall in order to collect water that has passed though the external building structure. Figure 3 (b) shows a two part perimeter floor drain that consists of upper flat soffit section (C) and lower channel section (D). The two part perimeter floor drain may also feature an upstand (A) where needed and has the holes (B) to collect water ingress into channel section (D). The two separate parts, upper flat soffit section (C) and lower channel section (D) securely snap together as shown at (B). When the cavity membrane (item 13 in Figure 2) is placed on the floor of the building to prevent the ingress of rising groundwater the cavity membrane sits on top of the upper flat soffit section (C) and extra holes may be drilled in (C) where necessary to allow groundwater trapped beneath the cavity membrane to enter the perimeter floor drain more readily. Perimeter floor drains without an upstand (A) may be used to collect excessive rising groundwater by having them across the floor surface and linking into the perimeter floor drain at their ends using a T-piece.

Figure 4 is a plan view to show a typical installation of the new system in a single room having perimeter floor drains combined with the pivotally connected elbow bends and T piece and the entire floor then covered with a cavity membrane. The external solid wall structure of the building that serves to filter the water ingress as it enters the building is treated with the hydrophobising impregnation as shown (F). Inside the building the straight lengths of perimeter floor drain (as figure 3) are shown as (0) and the link drain (H) transfers the water to the sump/pump (J) or gravity exit point. The pivotally connected T piece (K) transfers water from perimeter floor drain into the link drain (H). The pivotally connected elbow bends (L) are situated at each internal corner of the building and can be adjusted to suite each corner to ensure axial alignment of perimeter floor drains. An access point or jetting point (N) can be used to introduce flushing water into the system which, provided there are no obstructions, will then make its way around the perimeter floor drain as shown by arrows (M). The new pivotally connected elbow bends (L) and the new pivotally connected T piece (K) will ensure that the inverts are level across every joint and that axial alignment of channels across joints is achieved. Hence without any obstructions the collected water will flow under gravity along the level channels to the T piece (K) where it will transfer into the link drain (H) and into the sump (J) for removal from the building. The concrete slab or floor of the room can be covered by a cavity membrane (see item 13 in Figure 2) which will collect any groundwater that rises from under the floor of the building. The rising groundwater will not enter the habitable room but will be kept below the cavity membrane and transferred to the perimeter floor drain for removal from the building. In areas where there is excessive rising groundwater extra floor drains can be installed across the central area of the floor of the room below the cavity membrane in order to move the excess water into the perimeter floor drain system. These extra floor drains are basically as shown in Figure 3 but without the single upright section (A) which normally sits against the internal wall and these extra drains are connected into the perimeter floor drains using T-pieces at each of their ends.

Figure 5 is a line drawing to show the pivotally connected elbow bend. The bend has two top flat soffit sections (P) which are mitred and then a pivotal connection is made across the mitred join using a connecting piece (R) and connectors (Q). The connecting piece (R) can be a separate item or part of one of the top sections that is pivotally connected to the other top section. The design uses at least one pivotal connection (Q) between the two top sections (P).

The connecting piece can also incorporate a deflector to aid water flow around the elbow bend. The gap (W) between the two top section mitred edges allows the two top sections to rotate relative to each other so that the elbow bend can be fitted into building corners that are not exactly 90 degrees, this is an important feature in maintaining both axial and invert alignment and it allows secure joints to be made between straight lengths of perimeter floor drain and the elbow bend fittings. The connecting piece (R) is rotationally and securely connected so that the two top sections (P) are held together on a level plane. Two lengths of perimeter floor drain lower channel section (S) are mitred and fixed to the pivotally connected top sections (P). The gap (W) is maintained across the join of top sections (P) and lower sections (S) so that the elbow bend when fully assembled as show in figure 5 can pivotally rotate to fit into corners that are not exactly 90 degrees. The lower channel sections (S) extend out past the top sections (P) and are a feature of the new elbow bend as they are used to form a secure joint with the straight lengths of perimeter floor drain. If the two part perimeter floor drain (as figure 3b) is being used on an installation the straight channel of the perimeter floor drain is placed against the end of the extended elbow bend channel (S) and then the top section of the perimeter floor drain is snapped into place, spanning across the channel joint to create a secure staggered joint. There is no longer a straight butt joint that passes directly through both top and channel sections of the perimeter floor drain which is the major disadvantage associated with current rigid bends. If a one part perimeter floor drain is being used for the straight lengths of perimeter floor drain then the protruding channel section (S) will slide inside any of the one part perimeter floor drain channels currently available to form a secure joint. The pivotally connected elbow bend is universal and can therefore be used in installations of two part and one part perimeter floor drains and in both cases will provide a secure joint to the straight lengths of perimeter floor drain and the pivotal connection will ensure that soffits and inverts are kept at the same level across the bend to prevent obstructions to water flow.

Figure 6 is a line drawing to show the pivotally connected T piece. The top section (U) of a length of two part perimeter floor drain is pivotally connected (Q) to the link drain top section (V). This pivotal connection allows adjustment of the angle of intersection at the T piece and ensures that on a construction site installation the link drain is axially aligned into the T piece in order to prevent obstructions to water flow and also achieve a secure joint. The link drain top section (V) is set under the top section (U) so that the invert in the link drain is lower than that of the perimeter floor drain to encourage water to flow from the level perimeter floor drain invert into the link drain invert. A length of two part lower channel section has the side wall cut away and is fixed into the top section (U), similarly a lower channel section is cut and fixed into the link drain top section (V). In both cases the channel sections are longer than their respective top sections and protrude out as shown (5). As previously described above for the elbow bend (see figure 5) the protruding channels provide secure joints to both one part and two part perimeter floor drain straight lengths to ensure axial and invert alignment and hence no obstructions to flow. The lower channel section at the point of intersection must have the sidewall removed to allow water to pass into the link drain and removal of the sidewall weakens the construction of the T piece and reduces the capacity of the flat top soffit section to handle floor loadings. A support can be fitted that spans between invert and flat soffit top section at the point of intersection. The support sits inside the T piece in the channel section and serves to both support the weak flat top section and due to its shape also deflects water into the link drain passageway.

The pivotally connected elbow bend and T piece need gaps such as (W) shown in figure 5 so that they can be adjusted on a construction site during installation. Such gaps would not be acceptable in any form of conventional drainage as the gaps would allow the entry of sand, minerals and impurities that would soon lead to a blockage in the drain. In this invention the pivotally connected elbow bends and T pieces are installed as part of a perimeter floor drain that only collects water that has already been filtered by the structure of the building in which it is fitted. In these circumstances the gaps (W) can only serve to introduce filtered water into the perimeter floor drain and the most important issue is to keep axial and invert alignment across secure joints so that the water can flow under hydraulic head alone to the sump.

The pre-made elbow bends and T piece make installation much easier and quicker on site.

The pre-made bends can be fitted to the exact corner angle and then the secure joints hold the system together during assembly. The T piece link drain connection can be accurately aligned to meet the sump location. The whole installation process needs less skill to complete, as the operatives no longer have to try and mitre odd shaped plastic mouldings with woodsaws.

With pre-made items the system is simply snapped together. There is no longer any need to try and tape together misaligned joints in wet conditions, and these joints which are so crucial to the proper functioning of a perimeter floor drain can be secure, correctly aligned and look professional for the client.

The T-piece can also be used to connect the ends of floor drains into the perimeter floor drainage system. A floor drain is a perimeter floor drain as shown in Figure 3 but without the upstand (A) so it is installed across the floor to collect excessive groundwater which rises up through the central area of the floor and is trapped beneath the cavity membrane which is laid on the floor surface. These extra floor drains are needed where very permeable soils allow large volumes of groundwater to rise through internal floors as all water ingress must be managed because cavity membranes will not handle water which is under high pressure.

Cavity membrane systems are designed to manage water ingress and do not resist its passage to cause stress on the structure like cement renders.

Figure 7 is a plan view of perimeter floor drain, T-piece, link drain and sump chamber to show the accessibility provided by the new pivotally connected T-piece with water deflector plate and support (b) and an existing standard T-piece in (a). The left hand side (a) shows perimeter floor drain A with a standard T-pieee W that joins the perimeter floor drain to the link drain Cf. Link drain 0 runs to the sump/pulnp chamber H. The drain inspection camera or hose R can enter through the sump/pump chamber lid and be pushed along the link drain G. When R reaches the T-piece it cannot negotiate the corner into the perimeter floor drain and hits against the channel wall, there is no way to direct the camera or hose around the corner and along the perimeter floor drain. In Figure 7 the right hand side (b) the new T-piece has the internal water deflector plate and support D attached. The drain inspection camera or hose R can now pass around the corner into the length of the perimeter floor drain. By means of pushing R along different sides of the link drain both lengths of perimeter floor drain on either side of the T-piece can now be accessed. The internal water deflector plate and support 1) provides a constant radius for the bend in the inspection camera or hose and prevents kinking as they are fed through the T-piece W along the perimeter floor drain A. Figure 8 is a plan view to show water and/or sediment flowing into the sumpipunip chamber during normal operation or during flushing out of the system. The flushing water has been introduced through jetting points set into the perimeter floor drain. In this plan the perimeter floor drain A is connected to the link drain 0 with a T-piece W. The T-piece W has an internal support D attached. This plan shows the drainage system in use. The arrows C show the flow of water through the system. The perimeter floor drain collects water though pre-drilled holes in the channel sides, this water runs to the T-piece where it is passed into the link drain 0 and hence on to sump/pump chamber H. The arrows C show flow of water and/or flow of sediment when the drainage system is being cleaned by flushing out. The support D stops water and/or sediment being washed back and forth across the end of the link drain and flows into the link drain G. Subsequently, sediment can be removed by way of the sump/pump chamber lid. As shown in Figure 7 one side of the new T-piece can be used to introduce a hose into the perimeter floor drain and the flushing water will then travel around the perimeter floor drain to cariy sediment back to the new T-piece where the deflector plate will direct it into the link drain and then onto the sump for removal. The new T piece with internal water deflector plate now enables access into the perimeter floor drain system via the sump. A drain inspection camera or hose can be inserted via the sump chamber access lid and be pushed along the link drain to then pass around the corner into the length of the perimeter floor drain. By means of pushing along different sides of the link drain both lengths of perimeter floor drain on either side of the T piece can now be accessed. The internal water deflector plate provides a constant radius for the bend in the inspection camera or hose and prevents kinking as they are fed through the T piece and along the perimeter floor drain.

When flushing the system the T piece deflector stops water and/or sediment being washed back and forth across the end of the link drain and due to its shape directs water flow into the link drain. Subsequently, sediment can be removed by way of the sumpipump chamber lid.

Figure 9 is a line thawing of the new T-piece to show the internal water deflector plate that also acts as a support for the T-piece soffit. For illustration purposes this thawing shows a rigid connection at the T-piece join, whereas in practice the new T-piece also features an adjustable joint and an invert level slightly lower in the link drain connection to aid water movement from perimeter floor drain to link drain and sump.

Claims

Claims 1. A method for complete flood protection of buildings comprising: hydrophobising impregnation of the external walls; installing a system of perimeter floor drainage using adjustable corners and T-pieces that feature deflector plates; installing a cavity membrane.
2. The method of claim 1, further comprising installing floor and/or wall membranes.
3. The method of previous claims, wherein the perimeter floor drain is ventilated by mechanical means.
4. The method of previous claims, wherein the ventilating is accomplished by passive stack.
5. The method in any of the previous claims that uses extraction by ventilating of perimeter floor drains to remove harmful ground gases that enter a building from surrounding soil.
6. A method substantially as described herein with reference to the accompanying drawings.