technical_library

AS 3740-2004

Waterproofing of Wet Areas in Residential Buildings

SCOPE

This Standard sets out requirements for materials and minimum design and
installation criteria for of the waterproofing of wet areas within residential buildings.
It includes typical details of construction materials and methods. It does not cover situations where flooding of the wet areas occurs through overflowing of vessels and showers or plumbing failures.

NOTES:
1 Appendix A - provides guidance on means for compliance with this Standard.
2 Appendix B - provides design considerations for wet area waterproofing.

APPLICATION

This Standard applies to all residential buildings and is intended for use by building
regulators, designers, builders, waterproofing contractors and associated trades.

NOTE: This Standard may also apply to other buildings where the use of wet areas is similar to that in residential buildings.

AS 4654-2009

Part 2: Design and Installation

Waterproofing membrane systems for exterior use

SCOPE

This Standard sets out the performance criteria and provides deemed-to-comply solutions for the design and installation of external waterproofing membrane systems for all buildings, including planter boxes and landscaped areas, that can affect the waterproof integrity of the building or cause deterioration and damage to adjoining finishes or structural elements.
Where the waterproofing system is likely to be in contact to root systems of vegetation, it shall be root resistant.

This Standard is not intended for use in applications such as swimming pools and spas and excludes concrete admixtures or penetrating sealers or similar and decorative coatings.

In addition to providing performance criteria and design considerations, examples of deemed-to-comply design and installation solutions are given. These do not include options for concrete admixtures, penetrating sealers or decorative coatings.
Where specific details and installation techniques are not covered by this Standard, manufacturer’s instructions should be followed.

APPLICATION

This Standard applies to all parts of Australia, and it is intended for use by designers, manufacturers, specifiers and installers of external waterproofing membrane systems.
It may also be used as a reference for new and remedial building work.

AS/NZS 4858:2004 Wet Area Membranes

SCOPE

This Standard sets out the performance and general test requirements for waterproof
membranes as defined in AS 3740.
The Standard does not apply to metal shower trays, preformed shower bases or
exposed membranes.
The Standard may also be applied to waterproof membranes used in non-residential
buildings.

APPLICATION

This Standard applies to buildings throughout Australia and New Zealand and is
intended for use by manufacturers, suppliers and specifiers of waterproofing
membranes, and appraisal bodies.
The Standard may also serve as a useful reference document for residential property
owners and managers.

REFERENCED DOCUMENTS

The following documents are referred to in this Standard:

AS
1145 Determination of tensile properties of plastics materials

1145.3 Part 3: Test conditions for films and sheets
3558 Methods of testing plastics and composite materials sanitary plumbing and
Fixtures

3558.1 Part 1: Determination of water absorption characteristics
3740 Waterproofing of wet areas within residential buildings

ASTM
E 96 Standard test methods for water vapour transmission of materials

Standars for balconis and decks

CHECKLIST

References: : AS 4654: 2009 Part 1 & 2; AS 4858:2004: and the BCA;
What material is substrate? (Compressed Cement Sheet; Waterproof Ply; Concrete, etc)
Has a min. 50mm set down from finished surfaces at thresholds been allowed?
Does substrate have fall (min. 1:100) to drainage point ?
Are sheets screw fixed, not nailed ?
Are screws countersunk below surface level?
Are screw heads to be sealed over with PU Sealant?
Gaps between sheets of 8 –10mm? Sheets must not be butt joined.
Does decking sheet abut any walls? – should be a 8-10mm gap.
Are all gaps sealed with low modulus polyurethane and treated in accordance with the Class of membrane being used?
Will the membrane be tiled over? If not – What UV protection is to be provided?
N.B: Manufacturers do not recommend “Particle Board” for external application.

PREPARATION:

Clean:
All areas to be coated must be clean and free of all dirt, dust, contaminants, etc.

Moisture Barrier:
If substrate is damp, then a suitable moisture barrier should be used to prevent rising moisture causing blistering and/or delamination of the membrane.

Sealant:
It is recommended that a low modulus polyurethane sealant be used to seal all gaps/joints.

Primer:
All surface areas to be sealed and coated should be primed with a suitable primer in accordance with manufacturer’s recommendations.

Bond Breaker:
All gaps/joints that have been sealed with PU shall have a bond breaker placed over in accordance with the membrane manufacturers recommendations and the Class of membrane.

Perimeter:
Wherever the horizontal substrate abuts a vertical structure, a light gauge right-angle (min.50x50) shall be installed. This angle shall be fixed and sealed to the horizontal substrate only, ensuring any corners/laps are properly joined and sealed.

Detail Treatment:
To all internal corners, joints, penetrations, outlets, cracks, wastes, and high stress areas - Treat in accordance with the membrane manufacturer’s and the Class of membrane recommendation.

APPLICATION:

Apply the selected/recommended liquid membrane coating by brush, roller, squeegee, or sheet membrane in accordance with the manufacturer’s instructions for number of coats, etc. and required Dry Film Thickness (DFT).

At the transition of horizontal to vertical, the membrane shall be continued up the vertical to a minimum height above the finished horizontal surface in accordance with AS 4654:2009 Part 2.

PRECAUTIONS:

To avoid potential delamination or blistering of the cured membrane system, ensure that each application coat is completely and fully dry prior to further over coating as advised by the manufacturer of the product being used. Cure times will be longer in cooler or humid conditions. Avoid excessive “heavy” over coating layers and hot or windy conditions as premature surface skinning of the membrane may occur resulting in improper curing and possible surface blistering of the product.

Ultra Violet Resistance:
Some membranes have little or no UV resistance and require covering with tiles or some form of liquid coating if to be left exposed.

Adhesive Compatibility:
Most liquid membranes are compatible with two part cementitious adhesives manufactured for use with non-porous tiles for external use. Check with the manufacturers for further details.

Trafficable Membranes:
If no tiling is to be placed over the membrane, and the area is subject to light foot traffic, then a non-slip coating must be applied over the membrane to protect the surface.

Hypalon Tape

Standars for internal wet area

CHECKLIST:

What material is the substrate? (Compressed Cement Sheet; Waterproof Ply; Concrete.) Timber floors must be totally waterproofed (Ref. AS 3740)
Does substrate have fall to drainage point?
Are sheets screw fixed, not nailed?
Are screws countersunk below surface level?
Are screw heads sealed over with PU Sealant?
Gaps between sheets of 5 –10mm? Sheets must not be butt joined.
Are all gaps sealed with low modulus polyurethane?
Will the membrane be tiled over?

NOTE: Timber floors (ply included) should have F.C sheeting layered over the top prior to membrane application.

PREPARATION:

Clean:
All areas to be coated must be clean and free of all dirt, dust, contaminants, etc.

Moisture Barrier:
Not all water based membranes will adhere to a damp surface, this will delay the curing time. Depending on Positive or Negative side from the water source.
If the substrate is damp, and a solvent based urethane is to be used, then a suitable moisture barrier should be used.

Sealant:
It is recommended that a low modulus polyurethane sealant be used to seal all gaps/joints.

Primer:
All surface areas to be sealed and coated should be primed with a suitable primer in accordance with manufacturers recommendations.

Bond Breaker:
All gaps/joints that have been sealed with PU shall have a bond breaker tape (40mm width) placed over in accordance with the Class of Membrane (Ref: AS/NZ4858:2004)

Detail Treatment:
To all internal corners, joints, penetrations, outlets, cracks, wastes, and high stress areas, apply one heavy coat of liquid membrane to approximately 150-200mm width. While still wet embed a 125mm wide strip of reinforcing fabric (Polyester or Fibreglass) until completely wet through and saturated. Reinforcing fabric shall be centred equally to bridge corners, joints, cracks, or differential surfaces. Another coat of liquid membrane (wet on wet) is then applied over the strip area ensuring the cloth is totally embedded and saturated into the wet membrane. This application shall be allowed to fully dry through.

NOTE: If using fibreglass to reinforce joints consider the movement capabilities because fibreglass reduces flexibility.

Hobless Showers:
Provision must be made for the placement of a WATERSTOP on the floor to prevent capillary action or water creep into adjoining rooms. This is achieved by placing a non-ferrous angle (aluminium or brass) on the floor at the doorway, AND ALSO placed to contain the actual shower area.

APPLICATION:

Apply the selected/recommended liquid membrane coating by brush, roller, or squeegee in accordance with the manufacturers instructions.
At the transition of horizontal to vertical, the membrane shall be continued up the vertical for a minimum of 25mm above the retained water level of the shower or for at least 150mm.

PRECAUTIONS:

To avoid potential delamination or blistering of the cured membrane system, ensure that each application coat is completely and fully dry prior to further overcoating (as a guide a minimum of 24 hours should be allowed between coats). Cure times will be longer in cooler or humid conditions.

Adhesive Compatability:
Most liquid membranes are compatible with two part cementitious adhesives manufactured for use with non-porous tiles for wet areas. Check with the manufacturer for further details.

Panerating surface sealers for concrete

CHECKLIST:

Have there been problems with previous coatings?
Has the surface been previously sealed?
Is the surface porous?
Are there any contaminants which would prevent penetration?
Is the surface thoroughly dry?

Acid wash then rinse thoroughly.
Apply liberally but remove excess. Keep coats thin.

DO NOT

Acid wash Calcium Carbonate or Terracotta substrate.
Expect SEALER to provide a high gloss surface on porous surfaces.
Use for a glaze coat.
Use for high traffic areas.
Apply in thick coats.

ALWAYS
Do a sample to assess the suitability and expectation.

TROUBLE SHOOTING

Milky white appearance:
Associated with moisture and/or applied too thickly.
Strip or remove excess with Xylene or Acetone.

Small Blisters:
Surface not primed or material too thick causing bubbles when rolled.

Peeling surface:
SEALER has not penetrated the concrete as it should due to oil contamination, moisture or previous coatings.
Reassess the preparation.

standards for planter boxes

CHECKLIST

Have there been problems with previous coatings. If so, do you know the reasons
Is moisture penetrating through the surface being coated?
Are there any contaminants which would prevent bonding?
Is the surface dry?
What temperatures will be experienced during the curing period? Curing progresses slowly when the temperature drops below 14oC and progresses too quickly above 30oC.
Is the surface to be coated exposed to constant UV Rays?

Apply a primer
Allow finish coats to cure for a minimum of 10 days before backfilling. Longer in cooler conditions.
Protect from rain for 24 hours – longer where ponding occurs.
Reinforce with fabric especially over cracks and joints.
Place protection board over all membrane surface area.
Ensure proper drainage allowance has been made.

DO NOT

Allow water to pond before the product has fully cured.
Attempt applications when rain is imminent.
Allow material to come in contact with solvents.

TROUBLE SHOOTING

Membrane breaking down and going pale:
Membrane has not fully cured caused by water and/or cold temperatures.
Remove water and damaged material. Re-coat and improve the environment for drying. Thin coats dry quicker. Consider a cement based accelerator.

The floor is still soft, but the walls have cured:
Moisture is present, not allowing for proper curing.
Provide adequate drying conditions, and prevent water entry. Remove damaged material and recoat.

Precaution with planter boxes:
Ensure membrane is inert and will not have any adverse effect on plant life. After the initial curing period of 10 days, wash down the surface with water prior to backfilling. Check the Ph levels. Allow the soil to settle for 24 hours before adding plants

Potential risks for wet area

The Australian Standard AS3740 – 2004 ‘Waterproofing of wet areas within residential buildings’ has classified them into three levels as follows:

High          Shower recess
Medium     Rest of bathroom outside of the shower area and laundries
Low           Water Closet (WC) room and the immediate area around a sink in a kitchen, bar or a water vessel of similar usage.

These different levels of risks for water damage is based on how often water flows across the surface and the likely damage caused by not controlling the spread of water into the structure of the building.

High risk means that there is a high probability that the structure of the building could be damaged if the water used within the risk area is not confined within the area and drained to the drainage outlet. This area required full floor waterproofing that is drained into a drainage outlet connected to an approved waste drain.

Medium risk is where accidental spillage needs to be confined to the room where the spillage occurs and not allowed to flow through into concealed spaces in adjoining rooms or damage the floor substrate within the wet area room. Prevention of entry into concealed spaces of adjoining rooms is a requirement of the Building Code of Australia (BCA) together with the requirement to prevent damage to the structural integrity of the floor of the room. These areas need periphery flashings to prevent accidental flooding under walls into concealed spaces in adjoining rooms. They may or may not be fitted with a floor drain. If a floor drain is fitted in some states it is allowed to drain them to the perimeter of the building and not connect it to drainage system. It must be realized that these floor drains are only there to drain accidental flooding. If they are connected to a sewerage drain then it’s essential their water trap is maintained. This usually done by draining a regularly used fixture into the floor waste trap.

Low risk is where the risk of accidental spillage is low and the only area needing waterproofing treatment is directly around the vessel concerned. For example the bench-top wall junction if the rim of the vessel is within 75 mm of the wall at the back or side of the vessel. In the case of a WC room it requires that the junction between the wall and the floor needs to be treated in such a way that it will prevent water leakage through to adjoining rooms.

Waterproofing pounds and water features

For full and detailed information and application specification on product/s selected, the manufacturers data sheets should be consulted or contact the local representative prior to application.

Surface Preparation:
All surfaces to be coated are to be clean and free from any loose materials and contaminants.
Make good all defects and depressions using a modified mortar.
Fill any gaps, expansion joints, etc. with a compatible low modulus Polyurethane sealant and allow to fully cure.

Additionally seal high stress areas such as structural cracks, joints, penetrations, and wastes with reinforcing mesh (fibreglass or polyester), embedded between two heavy wet on wet coats of a Class III Membrane and allow to fully cure before proceeding. The finishing can be a two part cementitious membrane coloured with oxide or acrylic tint.

Moisture Barrier
Experience has shown that in many instances where water features, ponds, etc. are set into the ground, hydrostatic pressure from the external side of the feature may have a detrimental effect on the membrane installation. The effect is blistering and/or delamination of the membrane, which may result in failure of the membrane and loss of water.

To overcome this problem we recommend the application of a moisture barrier to prevent any ingress of moisture from the outside.
This can be achieved in either of two ways:
External - tanking membrane; or
Internal - moisture barrier prior to membrane application.

Waterproof Membrane:
The selection of which membrane to use is dependant on a number of conditions and generally there is no one membrane to suit all applications. Before commencement consideration needs to be given to the following;

SUBSTRATE:
Type of substrate. E.g: concrete, blockwork, brickwork, etc.
Degree of movement anticipated in structure;
Is structure above or below ground level;
Is substrate cured, wet, damp, or dry;

MEMBRANE CURING/PROTECTION:
Ponds and/or water features are usually structures that are box or dish type in their design and as such do not allow for good air flow to assist in the drying and curing of the membrane.
Before water is placed into these structures manufacturers of membranes recommend that their product should be fully cured. As a guide we believe this timeframe of curing should be 14 days from installation of the final coat of membrane, however manufacturers recommendations must be followed.

PLANTS, FISH, etc:
It is our experience that most water based membranes are compatible with most species of both fish and plant life. However, due to variations in water delivery and health of plants and fish at time of placement, we emphasise that the water should be tested prior to placing plants and/or fish to ascertain compliance and compatibility with their supplier’s recommendations

Waterproofing pounds and water features

For full and detailed information and application specification on product/s selected, the manufacturers data sheets should be consulted or contact the local representative prior to application.

SUBSTRATE:
Type of substrate. E.g: concrete, blockwork, brickwork, etc.
Degree of movement anticipated in structure;
Is structure above or below ground level;
Is substrate cured, wet, damp, or dry;

Waterproofing standards for internal wet areas

Waterproofing Standards Change (HIA Building News – July 2004)
The way you will need to waterproof certain bathrooms within residential buildings has changed. New requirements have been listed under Australian Standard AS 3740-2004.
The old Standard AS3740-1994 has now been superseded. As noted in the previous edition of Building News, the acceptable construction practice has been removed from BCA 2004 for Wet Areas leaving the acceptable construction manual (AS 3740) as the only means of compliance, unless an alternative solution can be sought.

Here is an outline of some of the minimum requirements for waterproofing wet areas under AS 3740-2004.

TIMBER FLOORS:
Bathrooms with timber floors, including particleboard and plywood will need to be waterproofed over their entire surface area, excluding the area under a preformed shower base and a built-in bath. It will be a requirement to waterproof the entire timber floor whether the shower is enclosed or unenclosed.

WALL/FLOOR JUNCTIONS:
The bath/floor and wall/floor junctions must be waterproofed to a height of 25mm above the finished floor level (not structural floor level), with a horizontal leg of 50mm.

WATERSTOP ANGLE:
A “waterstop” angle will be required at doorways, the angle must finish flush with the top of the finished floor level with a horizontal leg of 50mm adhered to the floor.

FLOOR WASTE:
Note that it is not a requirement to provide a floor waste in a bathroom of a Class 1 building. A floor waste however needs to be provided for Class 2 buildings where the floor of the bathroom is located above another sole occupancy unit.

VANITY UNITS/FIXTURES:
There is no specific requirement for a vanity unit that sits on a floor of bathroom that requires full waterproofing of the floor, but as a precaution you should consider installing the vanity on top of the finished floor so as not to compromise the waterproofing requirements of the floor. You would then seal between the floor and the base of the unit to prevent moisture ingress into the panel material of the vanity unit.

Alternatively, if fitted before the tiling, the membrane should be returned up the vertical surface of the vanity to the top of the finished floor level.

DOOR JAMBS/ARCHITRAVES:
Door jambs and architraves that are installed prior to the installation of floor tiling should be waterproofed to the finished floor level to provide continuous seal between the perimeter flashing and the “waterstop”. The Standard recommends that door jambs and architraves be installed above floor tiling where possible.

FLOOR – CONCRETE OR COMPRESSED SHEET:
If the bathroom floor is either concrete or compressed fibre cement sheet flooring then there is no requirement for full waterproofing of the floor and the extent of floor waterproofing will depend on whether it has a bath with a shower over it or the shower recess is enclosed with a shower screen.

BOND BREAKERS:
The new Standard also nominates appropriate bond breakers for a certain class of membrane used. Bond breakers are required at wall/floor and hob/wall junctions to prevent the membrane bonding to these junctions so that movement of the building can take place without breaking the membrane. You must ensure that the correct class of membrane is used with the appropriate bond breaker to comply with the standard.

MEMBRANE STANDARD AS/NZS 4858:
Note that the new Standard refers to AS/NZS 4858 “Wet Area Membranes” where the old Standard did not, so you will need to ensure that the membrane used complies.
FLASHING MATERIALS:
Flashing materials must be a material that is deemed waterproof under the Standard. These include Stainless Steel, copper, waterproof flexible sheet flooring materials with sealed joints, or membranes meeting the requirements of AS/NZ 4858. Zincalume could only be used as a backing material behind sheeting or substrates and then the corner or junction waterproofed as per the Standard.