Surface waterproofing vs Concrete Additives

Waterproofing is one of the most problematic issues when it comes to the building industry in Australia. There is a statistic often quoted in the building industry. Waterproofing and water ingress issues is 2.8% of total construction cost but accounts for 83% of building defect complaints.

Basically there are two systems namely additives to concrete and surface treatments (waterproofing or tanking). Both have advantages over the other as well as unique situations where the other will not be a suitable application.

Concrete Additives:

The capillary crystalline waterproofing reacts in the presence of moisture to form a permanent, non-soluble crystalline structure that grows deep within a concrete mass filling its pores, hairline or micro cracks and capillary tracts to make it waterproof. In the absence of moisture, the crystalline components will lie dormant indefinitely. Should moisture become present at any time, the chemical reaction or healing process starts and will repeats itself automatically and advances even more deeply into the concrete and to the source of the water ingress. It also saves time and labour as backfilling can begin immediately eliminating the wait time and additional excavation associated with traditional Surface “waterproofing” products.

Crystalline additives can be applied as a surface treatment as a remedial fix if there are leaks which cannot be accessed from the leaks origin. This has proven to be extremely cost effective and successful.

The biggest architectural advantage is that it is now easy to create architectural off shutter concrete elements such as thin floating slabs or polished roofs and decks and balconies, suspended pools, giving you that industrial look. But keep in mind if the concrete cracks more than 2mm the crystalline products wont bridge the gap.

Surface waterproofing

Polyurethane waterproofing membrane system
These include bituminous (bitumen based) sheet membrane, butynol (rubber) sheet membrane, modified acrylic urethane membranes, polyurethane and Bitumen liquid membrane systems, and cementitious (cement based) products and they all have specific uses where they perform best.

Bituminous (bitumen based) (or more commonly call torch on) sheet membrane applications are best for external tanking, roof tops, garden beds “green roofs, planter boxes and with a mineral cap sheet are UV stable and are suitable for high traffic areas, but they do soften slightly on very hot days. They can be mechanically fixed down allowing the under lying surface to breathe or they can be torch applied directly into the surface. Note: When directly applying torch on into the surface in lager areas its wise to install a vent to allow the surface under the membrane to breathe this stops the membrane from delaminating.

Modified acrylic urethane membranes are best for internal bathrooms and concrete roof or deck coverings as most of them on the market are UV stable, I would still recommend a top coat or wear coat for heavy trafficable areas. Also I recommend a good primer on top of the concrete or compressed cement sheet. we use a full blown epoxy as a primer this eliminates bubbling if there’s any moisture in the concrete it gives us a better chance of adhesion, all ways reinforce any cold or movement joint.

Butynol sheet membrane is one of the best membranes on the Australian market, one of the main reasons I like it is because you have to get qualified to install it prior to the manufacturer selling it to you. 95% of waterproofers don’t know how to install this product. At Australian waterproofing we install it in bathrooms, rooftops, balconies because it is such a specialised product it will cost you a little bit more but the results are incredible.

Liquid Bitumen is not regarded as a green building product since it is derived from crude oil and the fumes produced whilst it is being applied are harmful to the environment. Most are not UV stable; there most common use is on below ground basements, retaining walls and planter boxes.

Cementitious membrane applications are ideal for areas where there no movement expected between building materials which need to be waterproofed. Cementitious based waterproofing is very easy to apply and polymer additives can be mixed in to add to its waterproofing capabilities. This system is widely used by tilers as it is part of a complete tiling system (screed, self-levelling compounds, membrane, tile adhesive) manufactures push for these systems in specifications as it means more sales, An acrylic additive is usually used as a primer to achieve better adhesion or bonding. The main disadvantage is that because it is cement based it does not have any degree of stretch so it may crack over time.

The design and installation of any waterproofing systems for your project is one of the most important things to consider when starting any project. You must use a membrane fit for purpose followed by expert application and consider protection of the membrane system and long term maintenance, using these membrane systems its usually easy to maintain and leaks if they ever happen are easy to repair but a bit more difficult to find. Most leaks are caused by mechanical damage or different degrees of movement and sometimes the age of the membranes as all membranes have a lifespan.

You decide for yourself witch system is better but at Australian waterproofing company I would nearly always choose Surface “waterproofing” over Concrete Additives 98% of the time.

If you need anything relating to the design, installation of waterproofing for your project contact Australian Waterproofing Company, we give you the best advice, best product, competitive pricing and fantastic customer service that will best suit your project.