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by Joe Salmon
Marketing Director, Australian Building Adhesives

Waterproofing is the formation of an impervious barrier which is designed to prevent water
entering or escaping from various sections of building structures. Internal areas that are
waterproofed include bathrooms, shower recesses, laundries and toilets. Whilst external areas
waterproofed extends to roofs, planter boxes, podiums, balconies, retaining walls and
swimming pools.

Waterproofing can be applied to various substrates and backgrounds such as: concrete,
cement render, fibre cement sheets, gypsum boards, and timber. We will examine the
importance, and role of waterproofing in greater detail during the course of this presentation.


The first real need for waterproofing dates back to the days of Noahs Ark. The 40 days of
incessant rain inspired people to take some course of action to prevent water from entering
their habitat. In the early days people relied upon thatch, such as straw, reed, leaves and other
dried vegetable matter as a barrier against water entering their home.

Over time more sophisticated waterproofing materials were adopted. These included: animal
skins, timber shingles, and natural stones like slate. The architectural designs of the day such
as high pitched roofs helped overcome some of the shortfalls and limitations of the materials
that were used. Over the centuries other waterproofing materials were used such as metals eg.
copper, lead, zinc, and tin.

Waterproofing has come a long way since Noah's day. The discovery of oil, coupled with the
advances of chemistry saw the arrival of numerous petroleum derived waterproofing products
such as bituminous, butyl rubber, neoprene rubber, hypalon etc.

Technological improvements and breakthroughs are occurring on a da ily basis. Over time
today's waterproofing membranes such as polyurethanes, acrylics and polyesters will become
as antiquated as leaves and animal skins are today.

If we refer back to the definition of waterproofing as an impervious barrier designed to prevent
water entering or escaping from building structures, then the importance of waterproofing is
reflected in the consequences of not waterproofing.

Water which enters or escapes from buildings can have immediate and long term undesired
effects. Apart from damage to the buildings contents, structural damage is unavoidable if the
problem persists.

Water damage is second only to fire as a cause of building decay and deterioration.
Furthermore, the Australian building systems appraisal council, ABSAC, a division of the
CSIRO state that the majority of building materials have a considerable shorter life span when
subjected to moisture or emersion over a prolonged period of time.

The casualties of water damage include:

· Rotting of timber structures and finishes such as floor joints, beams, floors, studs, skirting,
architraves and frames.

· Corrosion of metals such as steel reinforcement in concrete, steel beams, lintels, metal door
frames etc.

· Swelling of plasterboards and the subsequent debonding of ceramic tiles.

· Electrical hazards causing the possible short circuit of lighting and power points.

· The blistering of paint.

· Unsightly deterioration of the building facade.

· Health problems due to dampness, which may lead to respiratory problems.

· Rotting carpet.

(Refer to overheads)

The importance of waterproofing can not be overstated. The damage caused to the building's
structure, coupled with the high cost of rectification warrants the careful design and application
of waterproofing.

The role of waterproofing is to protect a building's visual and structural integrity. It achieves this
by forming an impervious membrane that prevents water entering or escaping from wet areas
to dry areas.

In order to effectively fulfil this role a memb rane must possess the following qualities:

· The membrane mus t be impermeable to prevent the passage of water.

· Flexibility - membranes need to accommodate any normal movement that may occur in
building structures.

· The membrane mus t be durable, it must be able to retain it's integrity over a long period of

· The membrane mus t lend itself to design details in a building. It must be suitable for each
specific application. The membrane is useless if it cannot be applied where needed because of
structural details.

· The membrane mus t be able to breathe permitting the escape of moisture vapours from
building interior and substrates.

· The membrane mus t be compatible with adhesives to ensure long term adhesion where tiles
are directly fixed over the membrane.

· User friendly, the membrane must be easy to apply, relatively lightweight, non hazardous , and
environmentally safe.

· In exposed areas such as rooftops, the membrane should require little maintenance, and in
the event of damage must be easily repairable.

· It should provide a continuous film, without areas of weakness such as overlaps, which could
prove to be a potential source of water entry.

· The membrane mus t be suitable to withstand environmental and climatic conditions.

There are generally two types of waterproofing membranes - sheet membranes and liquid
membranes. The nature of the problem to be addressed determines which type of membrane
to be used.

1. Sheet Membranes

The purpose of sheeting membrane is to completely cover any imperfections in the substrate or
background. They are numerous and include:

· Metal sheets in the form of lead, copper or stainless steel flashing o r trays.

· Multilayer bituminous paper system with gravel topping for protection.

· Butyl rubber sheeting

· Semi-rigid asbestos asphalt sheeting

· Bitumen/polyethylene sheets

· E.P.D.M. Ethylene propylene Diene Monomer

· Chlorosulphanated rubber (Hypalon)

· PVC Polyvinylchloride

· Neoprene rubber

· Torch-on sheeting consist of layers of polypropylene bitumen modified.

The sheeting membranes can be applied as fully bonded to the substrate or unbonded. In both
cases sheets must be overlapped about 100mm wide and bonded to each other by adhesive or
by heat welding. The seams are the weakest point in the system.

Sheeting membranes in general suffer from poor exposure resistance, temperature stability
and little recovery from deformation.

All sheet membranes require venting if the substrate is water logged, or severe bubbling will
occur developing stresses onto the adhesive leading to eventual adhesion fracture.

The advantages of sheeting membranes provide highly trafficable surfaces and have insulating
2. Liquid membranes

The liquid applied membrane provides a fully bonded, continuous seam-free, homogenous
layer with no laps or joins which is a major advantage over sheeting membranes.

Some of the liquid membranes available are:

· Mastic asphalt

· Two components polyurethane tar modified

· Two components tar epoxies modified

· Single pack moisture curing polyurethane

· Water based epoxy two part for hydrostatic pressure situations

· Polyester resin two parts reinforced wit fibreglass matt

· Flexible epoxy resin two parts

· Bitumen latex modified single pack

· Acrylic co-polymer water based single part

· Acrylic co-polymer cement modified two components

In general liquid applied membranes are easy to apply, seamless, semi-flexible or
elastrometric, ease of detailing, ease of maintenance and repair, UV resistant and economical.

One of the important characteristics of liquid membranes is it's ability to breathe.

Regardless of which class of membrane is used, waterproofing membranes are only as good
as the applicator. Manufacturers and distributors expect their product to be applied as
specified. Failure to adhere to their recommendations can retard the performance of the

Thus far in our presentation we have primarily discussed waterproofing in a contemporary
context. So what does the future hold for waterproofing? Will the membranes differ? Will further
standards on Waterproofing be introduced? Will formal training cou rses be established? Our
crystal ball reveals the following:

· Waterproofing membranes will have more than one role. Not only will they be impervious to
water they will also incorporate sound proofing, thermal insulation and ceram ic tile adhesive

· Currently there is an Australian Standard that applies to waterproofing, however the standard
relates only to waterproofing in internal wet areas. Over time we envisage waterproofing
standards to embrace other fields of application such as roofs, balconies and podiums etc.

· There is no TAFE trade course exclusively for the waterproofing industry. Waterproofing is a
subject within the tiling and building courses. In the future waterproofing will be a stand alone
trade course. The standard of waterproofing will be higher as the next generation of
waterproofing applicators become more skilled through greater training.

· As the importance and role of waterproofing increase applicators may become regulated, and
manufacturers may become more discerning to whom they supply.
· Waterproofing membranes will be more robust to keep abreast of changes that occur in
building designs, building materials, systems, and techniques.

· Waterproofing membranes will be environmentally friendly, free from harmful carcinogenic
substances. Governments will have a greater input in the contents, handling and application of

Many people in the waterproofing industry are genuinely excited about the Industry's future, the
advent of new products, wider fields of application, and a growing recognition of it's importance
augurs some encouraging signs for the future.


The problem of leaking showers is one of the most common, costly and disruptive failures
currently occurring in domestic buildings. A research project was undertaken by the Building
Research Centre, to determine measures to minimise the likelihood of such waterproofing

The research team set out to find reasons for and solutions to the problem. A search for
information was undertaken and included a survey of current building practices, literature
review, a survey of local municipal councils on reported and documented failures of bathrooms
and shower compartments, surveys and interviews with general contractors, specialist
contractors, banks, lending bodies and government and non-government organisations.
Inspections of new and defective shower installations were also investigated.

The research was divided into four main stages:

(i) current building practice

(ii) testing full-scale shower modules

(iii) further testing and determ ining effective construction systems.

(iv) communicating recommendations throughout the industry.

The consequence of the research project led to the establishment of Australian Standard AS
3740-1989, which is "Waterproofing of Wet areas within Residential buildings". Since 1989 the
standard has been reviewed, and has been superseded. The current edition of this standard is
the 1994 edition.

The standard has been helpful to specifiers, builders and applicators in creating awareness
and drawing attention to the importance and role of waterproofing. Over time we expect this
standard will lead to a reduction in the number of failures in wet areas within residential
Unfortunately there is no current standard that covers any other field of application such as
laundries, roofs and balconies. In order to further enhance the credibility of waterproofing and
restrict the damage that water causes, standards for all areas of applications need to be

Standards Australia welcome suggestions for improvements to Australian Standards.
Australian Building Adhesives is in the process of preparing a submission to Standards
Australia which outlines the need to establish waterproofing standards in all areas of
applications. We hope our submission will arouse further interest in waterproofing, encourage
discussion and lead to research.


The awareness and understanding of waterproofing has grown significantly over the last
decade. More and more people are recognising the important role that waterproofing plays in
today's building industry. Ten years ago a similar type of presentation on waterproofing would
have drawn few attendees. Even as recent as five years ago there were no industry
associations. Today, industry bodies such as Waterproofing Industry Council Of Australia
(W.I.C.A.) have emerged as waterproofing grows in prominence as a building material.

Let me conclude by saying that waterproofing is a critical component of any building structure.
The four keys to successful waterproofing are:

· proper consideration at the design stage

· choosing the right product for the job

· adequate preparation

· the correct application.

The ramifications of failing to waterproof, or waterproofing ina dequately can be horrendous.


1. Cannon, R.Waterproofing - An EnigmaAustralian Building News

2. Hartog, H.Concrete Repair and Waterproo fing Suspended Slab

Australian Building News

3.Keeping Water Out of Buildings Is A Refined Business

Australian Building Construction & Housing
4.The Bathroom BookAustralian Building Construction & Housing

5. Uher, T. E. and Wollaston, B. V.Wet Area Construction in Dwelling

Building Research Centre, School of Building, The University of NSW

Speech 1 - DAY 1 - 5 June 1995

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