Basements and cellars should ideally be waterproofed on the positive side of the walls during the construction phase. However, either this does not happen or at some stage the waterproofing fails.
Under these circumstances it is necessary to waterproof the insides of the walls (negative side) in a process called “tanking”.
Surprisingly, national building regulations have no specific reference to the waterproofing of basements, cellars and other sub-terranean structures. There is, however, in SANS 10021:2006 a reference to “dry” and “wet” sites inferring that there needs to be additional measures undertaken in “wet” sites or wherever water tables are likely to be affected by seasonal rains.
For “dry” sites it is usual to apply one layer of 4mm APP torch-on membrane to the walls or a suitable liquid-based polyurethane waterproofing. The success of torch-on membrane is based on full adhesion of the membrane to the underlying substrate and the careful sealing of all overlaps. Due to the weight of the rolls, it is common for lengths of membrane to be cut from the roll, increasing the number of overlaps that have to be sealed.
Polyurethane waterproofing products are more than capable of handling the additional pressure of “wet” sites, but when using torch-on membrane it is advisable to use 2 layers, with the second layer positioned in such a way as to protect the underlying laps.
Once this initial waterproofing fails, it is almost taken for granted that there can be no remedial action on the positive side. In many cases there are adjacent roads or walkways or simply backfill that has been applied all around the building. The only way of treating moisture ingress is, therefore, from the negative side of the walls.
There are few waterproofing products that can handle negative water pressure. Torch-on membrane, cold bitumen and polyurethanes are all prone to separation from the substrate under such conditions. The most common alternative is the use of a cementitious product in a process called “tanking”.
Depending upon the depth underground and the degree of water pressure, this can normally be achieved using a cementitious slurry such as our SWS Slurry. 2-3 coats of slurry will need to be applied to the walls once plaster has been removed. NEVER apply slurry over plaster especially if this plaster is already contaminated with salts. This is inviting failure. Always pay particular attention to the wall/floor joint which is the weakest point in the structure, and preferably re-inforce this using Fillet Seal. Cut a “V” joint into the wall at the base and pack this area with the Fillet Seal mixed with water or diluted Bondaid Plus. You may also need to apply several coats of slurry to the floor if this too is leaking. It is absolutely vital that each layer of product fully cures before application of an additional coat.
There will be occasions, however, when normal waterproofing products are either inappropriate or inadequate to deal with the presence of subterranean moisture.
In these circumstances it is necessary to seek an alternate solution which accept the presence of moisture and merely channels it to a means of extraction.
One such product is Cavity Drainage Membrane (CDM).
The underground vaults in the Roman Baths in Bath, England were the subject of a major project run by Safeguard Europe. These vaults were some considerable distance underground and were constantly under water as a result of the high water table and lack of waterproofing.
Since there was considerable water pressure on the existing walls, it was decided to address the problem by installing a Cavity Drainage Membrane system. The CDM allowed water to be channelled to a self-actuating pump which then evacuated the moisture as long as it was present. By fitting the CDM system, it was possible to provide new walls and floor which gave a totally dry appearance, even though beneath the surface water penetrating the original walls and floor was being effectively drained.
Rolls of CDM are joined together with a special waterproof double-sided tape. Plugs attaching the CDM to the wall are waterproofed using a further waterproof sealing rope around the head of the plug.
When joining two sections of CDM, apply the lower section over the upper section to ensure a watertight seal.
The finishing touch is the fitting of a pump in a sump dug into the floor and to which all moisture drains. From this self-actuating pump water is evacuated to the outside by means of piping. Remember that such pumps always require battery back-up or some other power source, particularly in South Africa!
Waterproofing of roofs, basements, etc. shall be laid under appropriate manufacturer guarantees supplemented
by a contractor workmanship guarantee. Waterproofing to flat roofs shall be laid with a minimum fall to outlets of
1:80 and include all outlets, etc.Waterproof of external basment walls shall take into account the definition of dry and wet sides as per SANS 10021: 2006 6.15.2 and 6.1.5.3 and provide one or two layer membrane systems as
appropriate descriptions of sheets or membrane waterproofing shall be deemed to include all labour costs.
Apply Safeguard SG720″ primer to prepared surfaces, followed by two coats of “Safeguard SG280” waterproofing polyurethane and one coat of SG PU440 with SG PU Fabric on horizontal and vertical joints.
Apply Safeguard SG720″ primer to prepared surfaces, followed by two coats of “Safeguard SG280” waterproofing polyurethane and one coat of SG PU450 with SG PU Fabric on horizontal and vertical joints.
Thoroughly clean and prepare the surface, as per Safeguard Method Statement for Surface Preparation.
Apply one coat of Safeguard solvent-based Bitumen Primer to the surface ensuring full coverage without any “ponding” of primer on the surface.
Allow to dry and heat-fuse one layer of Safeguard Euro Gecko 4mm APP single re-inforced Bitumen Membrane to the primed surface, lapping all side walls and dressing into and around outlets and upstands.
Provide 100mm side laps and 150mm end laps to adjoining rolls of membrane, ensuring that laps are properly “bled”.
Suitable performance-related products are acceptable.
5-7 days after application of the Bitumen Membrane, thoroughly clean the surface of the membrane and apply 2 coats of Safeguard Bitumen Aluminium paint to the membrane using a brush, roller or spray.
Equivalent products are acceptable.
Thoroughly clean and prepare the surface, removing all laitance, dust, dirt, grime and grease.
Apply one coat of solvent-based Bitumen Primer to the surface ensuring full coverage without any “ponding” of primer on the surface.
Allow to dry and heat-fuse one layer of 4mm APP single re-inforced Bitumen Membrane to the primed surface, lapping all side walls and dressing into and around outlets and upstands.
Provide 100mm side laps and 150mm end laps to adjoining rolls of membrane, ensuring that laps are properly “bled”.
5-7 days after application of the Bitumen Membrane, thoroughly clean the surface of the membrane and apply 2 coats of Bitumen Aluminium paint to the membrane using a brush, roller or spray
Thoroughly clean and prepare all external walls from foundation to 2 brick courses above finished ground level as per Safeguard Method Statement for Surface Preparation.
Apply one coat of Safeguard SG 720 Primer to the walls by spray, roller or brush and allow to dry.
Apply two coats of Safeguard SG PU 610 by spray, roller or brush. If applying by spray, dilute with 5% MEK. Allow the first coat to dry overnight. A third coat should be applied where “Wet” sites are encountered as per SANS 10021:2006 6.1.5.3
Protect membrane with soft board or dimpled membrane prior to backfill.
Equivalent performance-related products may be supplied.
Thoroughly clean and prepare all external walls from foundation to 2 brick courses above finished ground level, removing all dirt, dust, grime grease and any unnecessary mortar,
Apply one coat of Polyurethane Primer to the walls and allow to dry.
Apply two coats of Polyurethane waterproofing membrane to a DFT of 1-2mm. The membrane should accommodate temperatures from -30? to +90?C and have a minimum elasticity of 600% with a Shore A hardness of 60 or greater and a Tensile strength of 4N/mm? or greater. Allow the first coat to dry overnight. A third coat should be applied where “Wet” sites are encountered as per SANS 10021:2006 6.1.5.3
Protect membrane with soft board or dimpled membrane prior to backfill.
Thoroughly clean shower walls and floor, removing all loose dirt, mortar, grime and grease. Walls should not be plastered.
Apply a coat of Safeguard Latseal Slurry mixed with Bondaid to the walls and floor, embedding a non-woven polypropylene membrane into the slurry at all joints.
Allow to cure overnight and apply a further coat of Safeguard slurry to the entire area.
At the joint with the outlet, an expandable polyurethane sealant should be applied to cover both surfaces. This should be allowed to cure, together with the slurry before application of any tiles/mosaics.
Equivalent products are acceptable.
Thoroughly clean shower walls and floor, removing all loose dirt, mortar, grime and grease. Walls should not be plastered.
Apply a coat of cementitious waterproof slurry mixed with bonding liquid to the walls and floor, embedding a non-woven polypropylene membrane into the slurry at all joints.
Allow to cure overnight and apply a further coat of slurry to the entire area.
At the joint with the outlet, an expandable polyurethane sealant should be applied to cover both surfaces. This should be allowed to cure, together with the slurry before application of any tiles/mosaics.
PRODUCT GUARANTEE
Polyurethane Roofing – SG PU280
Polyurethane Foundation – SG PU610
Joint Sealant – SG Flex20
Bitumen Roofing – 4mm Torch-on membrane
Polyurethane Undertile Showers / Balconies – SG PU610
Cementitious Undertile Showers/Balconies – Latseal Slurry
SG PU 280 Flat Roof
SG PU 610 Garden Roof
SG 4mm Bitumen Roof
SG PU 610 Foundation
SG PU 280 Car parking
Waterproofing of roofs, basements, etc. shall be laid under appropriate manufacturer guarantees supplemented
by a contractor workmanship guarantee. Waterproofing to flat roofs shall be laid with a minimum fall to outlets of
1:80 and include all outlets, etc.Waterproof of external basment walls shall take into account the definition of dry and wet sides as per SANS 10021: 2006 6.15.2 and 6.1.5.3 and provide one or two layer membrane systems as
appropriate descriptions of sheets or membrane waterproofing shall be deemed to include all labour costs.
Apply Safeguard SG720″ primer to prepared surfaces, followed by two coats of “Safeguard SG280” waterproofing
polyurethane and one coat of SG PU440 with SG PU Fabric on horizontal and vertical joints.
Apply Safeguard SG720″ primer to prepared surfaces, followed by two coats of “Safeguard SG280” waterproofing
polyurethane and one coat of SG PU450 with SG PU Fabric on horizontal and vertical joints.
Thoroughly clean and prepare all external walls from foundation to 2 brick courses above finished ground level as per Safeguard Method Statement for Surface Preparation.
Apply one coat of Safeguard SG 720 Primer to the walls by spray, roller or brush and allow to dry.
Apply two coats of Safeguard SG PU 610 by spray, roller or brush. If applying by spray, dilute with 5% MEK. Allow the first coat to dry overnight. A third coat should be applied where “Wet” sites are encountered as per SANS 10021:2006 6.1.5.3
Protect membrane with soft board or dimpled membrane prior to backfill.
Equivalent performance-related products may be supplied.
Thoroughly clean and prepare all external walls from foundation to 2 brick courses above finished ground level, removing all dirt, dust, grime grease and any unnecessary mortar,
Apply one coat of Polyurethane Primer to the walls and allow to dry.
Apply two coats of Polyurethane waterproofing membrane to a DFT of 1-2mm. The membrane should accommodate temperatures from -30? to +90?C and have a minimum elasticity of 600% with a Shore A hardness of 60 or greater and a Tensile strength of 4N/mm? or greater. Allow the first coat to dry overnight. A third coat should be applied where “Wet” sites are encountered as per SANS 10021:2006 6.1.5.3
Protect membrane with soft board or dimpled membrane prior to backfill.
Thoroughly clean and prepare the surface, as per Safeguard Method Statement for Surface Preparation.
Apply one coat of Safeguard solvent-based Bitumen Primer to the surface ensuring full coverage without any “ponding” of primer on the surface.
Allow to dry and heat-fuse one layer of Safeguard Euro Gecko 4mm APP single re-inforced Bitumen Membrane to the primed surface, lapping all side walls and dressing into and around outlets and upstands.
Provide 100mm side laps and 150mm end laps to adjoining rolls of membrane, ensuring that laps are properly “bled”.
Suitable performance-related products are acceptable.
5-7 days after application of the Bitumen Membrane, thoroughly clean the surface of the membrane and apply 2 coats of Safeguard Bitumen Aluminium paint to the membrane using a brush, roller or spray.
Equivalent products are acceptable.
Thoroughly clean and prepare the surface, removing all laitance, dust, dirt, grime and grease.
Apply one coat of solvent-based Bitumen Primer to the surface ensuring full coverage without any “ponding” of primer on the surface.
Allow to dry and heat-fuse one layer of 4mm APP single re-inforced Bitumen Membrane to the primed surface, lapping all side walls and dressing into and around outlets and upstands.
Provide 100mm side laps and 150mm end laps to adjoining rolls of membrane, ensuring that laps are properly “bled”.
5-7 days after application of the Bitumen Membrane, thoroughly clean the surface of the membrane and apply 2 coats of Bitumen Aluminium paint to the membrane using a brush, roller or spray.
Thoroughly clean shower walls and floor, removing all loose dirt, mortar, grime and grease. Walls should not be plastered.
Apply a coat of Safeguard Latseal Slurry mixed with Bondaid to the walls and floor, embedding a non-woven polypropylene membrane into the slurry at all joints.
Allow to cure overnight and apply a further coat of Safeguard slurry to the entire area.
At the joint with the outlet, an expandable polyurethane sealant should be applied to cover both surfaces. This should be allowed to cure, together with the slurry before application of any tiles/mosaics.
Equivalent products are acceptable.
Thoroughly clean shower walls and floor, removing all loose dirt, mortar, grime and grease. Walls should not be plastered.
Apply a coat of cementitious waterproof slurry mixed with bonding liquid to the walls and floor, embedding a non-woven polypropylene membrane into the slurry at all joints.
Allow to cure overnight and apply a further coat of slurry to the entire area.
At the joint with the outlet, an expandable polyurethane sealant should be applied to cover both surfaces. This should be allowed to cure, together with the slurry before application of any tiles/mosaics.
