External tanking is the application of a waterproof membrane to the outside of a basement or substructure in accordance with BS8102:2009 (Type A form of construction). Generally, waterproof membranes are installed horizontally onto a concrete blinding layer and vertically onto reinforced concrete or masonry sub-structures.
When selecting a suitable external tanking system, consideration should be given to the form of construction, ground water level, ground drainage, soil type and ground contamination. Boundary line construction applications, including secant piling, contiguous piling and sheet piling, create challenging substrates due to factors such as the need for excessive surface preparation, so selection of the correct waterproofing system is crucial. Externally applied membranes should be protected against damage during backfilling. Sub-soil drainage systems should be incorporated in to the design where required.
In areas where the water table is classed as "High", please consult the RIW Technical Department.
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Internal tanking is the application of a waterproof membrane to the inside of a basement or substructure in accordance with BS8102:2009 (Type A form of construction).
When selecting a suitable internal tanking system, consideration should be given to the form of construction, ground water level, ground drainage, soil type and ground contamination. When tanking internally with applied membranes, hydrostatic water pressure acting upon the membrane must be resisted by loading the horizontal membrane with a 65mm (min) screed. The vertical membrane should be loaded with an internal skin of masonry, 20-40mm from the membrane, incorporating mortar packing directly against the membrane. External sub-soil drainage should always be incorporated into the design where required.
In areas where the water table is classed as "High", please consult the RIW Technical Department.
Find out more about the RIW internal tanking range of products.
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A damp proof membrane is a continuous and impervious membrane applied above or below ground floor slabs to prevent water ingress into a structure. The membrane should be linked to the DPC. A damp proof membrane can be applied either to the top of the slab or beneath on to a concrete blinding. Moisture sensitive internal finishes are protected from any residual moisture in the concrete when the membrane is applied to the top of the slab.
Consideration should be given to selecting highly flexible or preformed membranes for modular or suspended floor constructions such as block and beam. Liquid applied coatings based on epoxy resins are suitable as a surface membrane beneath levelling compounds or floor finishes.
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A tough waterproof membrane should be applied directly under a raised access floor to act as a water containment system, preventing the passage of water through to other areas. Modern hi-tech buildings can contain a great deal of sensitive electrical equipment which needs to be protected from water intentionally introduced into the building, such as through automatic sprinkler systems and via core areas incorporating toilets and showers.
Consideration should be given to its compatibilities with epoxy adhesives used to fix the pedestal to the sub floor, eliminating the necessity to puncture the containment membrane. The membrane will also act as a good quality dust sealer and provide an impact resistant floor finish with a Class 1 spread of flame rating under a raised access floor.
Find out more about the RIW raised access floor waterproofing range of products.
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Plant room floors are generally bunded and/or waterproofed to contain any leaks or spillages from faulty tanks, plant or pipe work. The consequences of leaks into critical areas adjacent to, or below can be costly and disruptive. Plant rooms in basement areas also need a containment system to prevent contamination of the ground and provide damp proofing to separate electrical plant from other areas.
Consideration should be given to the waterproofing system's resistance to chemicals and abrasion, allowing it to be applied as an exposed system to concrete and masonry bunds. A slip retardant finish with a Class 1 spread of flame rating is also achievable.
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Many contemporary buildings today incorporate landscaped basement roofs, commonly known as plazas or podia. The basement can vary from habitable space to car parking, so it is vital the correct waterproofing system is selected when waterproofing the podium deck.
Consideration should be given to deck movement, drainage, waterproofing continuity at expansion joints, drainage outlets, landscaping and most importantly what is below the deck. The same influences should be considered when waterproofing other elevated concrete decks such as balconies and terraced areas. A drainage board laid over the membrane will enhance its performance by channelling water to designated drainage points, whilst also protecting the membrane. Hand applied systems that can also be sprayed generally offer the best solution.
Find out more about the RIW podium deck waterproofing range of products.
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RIW liquid membranes can be applied onto superstructures as an effective vapour barrier prior to the installation of rainscreen and other forms of cladding systems. The membrane is designed to protect superstructure (reinforced concrete, steel or masonry) against attack and prevent moisture ingress from water vapour that may become trapped within the cavity.
If the waterproof membrane is to be left exposed for a period greater than 28 days prior to the installation of the cladding, consideration should be given to the UV stability of the selected membrane.
Find out more about the RIW superstructure waterproofing range of products.
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Cavity drainage systems within the basement or substructure form a continuous pre-formed cavity, which intercepts and drains away incoming water in accordance with BS8102:2009 (Type C construction). They also provide a vapour barrier to enable this low risk form of construction to be used for the highest grade of basement usage without ventilating the cavity. The membrane is usually installed inside the basement structure and on to the structural slab. Facilities for draining ground water ingress must be incorporated into the design.
When selecting a suitable cavity drainage system the external basement structure must provide enough resistance to water ingress to ensure the cavity only accepts a controlled amount of water. Consideration should also be given to the form of construction, ground water levels, external ground drainage and soil type.
Find out more about the RIW cavity drainage systems available.
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Retaining walls can be external walls forming part of the landscape design or walls that form part of a property. Landscape walls, possibly with weep holes incorporated to alleviate hydrostatic pressure, are much less critical but often require a membrane to prevent dampness from the ground spoiling the aesthetic nature of the design. Walls that protect habitable areas must be considered as high risk and tanked accordingly. A profiled drainage board will enhance the performance of the membrane.
Find out more about the RIW retaining wall waterproofing range of products.
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Designs incorporating wet rooms require a watertight containment system to be installed behind the ceramic tiles and finishes, to prevent water penetration through the tile due to commissioning leaks, substrate movement and grout failure. A flexible system should be considered on modular construction products such as plywood and plasterboard. Systems that incorporate membranes that can be applied quickly and allow immediate tiling help minimise construction delays.
Find out more about the RIW wet room waterproofing range of products.
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Often situated below the floor slab, lift pits can be subject to hydrostatic pressure. They are usually small and externally tanked in difficult, wet and confined working conditions making the installation of a waterproofing system challenging. Consideration should be given to using an easily applied high performance waterproofing system and incorporating a small sump or low point in the base of the pit from which water can be pumped from in the event of extreme weather conditions.
Find out more about the RIW lift pit waterproofing range of products.
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Waterproofing a planter is no less critical than other areas, leaks can be damaging and costly, planters also require a membrane to prevent dampness spoiling the aesthetic nature of the design. If irrigation pipes are required consideration should be given to waterproofing around these. The membrane in a planter should be protected against damage during backfilling and garden maintenance.
Find out more about the RIW planter waterproofing range of products.
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Movement joints within a reinforced concrete structure below ground are perhaps the weakest part of the structure and should be protected from ground water ingress with the installation of a bentonite hydrophillic waterstop. This forms a permanent pressure seal to exclude water ingress through the joint.
Find out more about the RIW range of products for waterproofing movement joints.
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Ground contaminants and gases such as radon, methane and carbon dioxide must be considered when deciding upon a waterproofing design. Gases can enter the building via cracks and joints that form within the structure, so a flexible membrane should be selected that is capable of accommodating movements in the structure without fracturing.
Find out more about the RIW range of gas and radon resistant barriers.
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Damp proof courses are used to prevent moisture from the ground rising into the internal fabric of the structure. They should be installed 150 mm minimum above external ground level and linked to the DPM protecting the floor slab. Cavity trays are designed to divert water within cavity wall construction through to the outside. It is especially important to ensure cavity trays above basements are carefully installed with fully taped and sealed joints to prevent water bypassing the tanking membrane.
Find out more about the RIW damp proof course and cavity tray products.
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Multi-phased construction of new buildings and additions to existing structures may require temporary protection against water ingress to individual floors or walls as the project progresses. Consideration should be given to the ease of installation, UV stability, impact resistance and durability of the membrane. Where necessary, suitable drainage discharge points should also be incorporated.
Find out more about the RIW range of products for temporary waterproofing.
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