A Guide to Waterproofing Concrete House Roofs



Concrete roofs have been an integral part of modern architecture for decades. Although they are typically seen as rooftops for commercial buildings, with changes to styles and architecture for residential buildings, homes are now also being constructed using this roofing method, with concrete shingles also starting to become popular in residential home structures. Even though concrete has been chosen as a superior material for both housing and commercial structures, it doesn’t mean that it is able to avoid the elements like other materials do.

Waterproofing is one way you can help avoid damage from occurring earlier than anticipated and will inevitably help your concrete roof to last a lot longer. Adding waterproofing to your roof is a great way to protect your building and is well worth the investment.

Concrete flat roof construction and issues

We have all seen the types of roofs where you will see the design incorporate a flat roof in order to make it look both appealing and elegant in style. However, proper design of such a roof style is required in order to ensure rainwater is drained away from the roof as soon as possible. ‘Water-ponding’, or the stagnation of water due to rainfall on such roofs, is the leading cause of deterioration of concrete materials in roofing.

Variations in both temperature and moisture levels can lead to differential thermal movement. Combined with the potential acids left by rain that has evaporated, this can lead to the serious deterioration of what should be a stable, concrete roof.


Roof membrane systems

When looking at ways to waterproof a concrete roof, a waterproofing membrane is considered to be the most important aspect of a roofing system, as it is the key to keeping water out of the building. There are varying types of roof membrane systems on the market, so it’s important to understand the differences in order to choose the right system for you and your construction needs.


Liquid-applied membranes

Used on site in liquid form, liquid-applied membranes are rolled, brushed or sprayed in place, then cure to create a water impermeable membrane coating. These membranes are manufactured from a variety of products including coal tar, bitumen, polyurethane & acrylics. Using this type of membrane makes for a seamless, easy-to-apply project that gives you a result that is relatively easy to maintain and repair, if needed. One of the key factors about liquid-applied membranes is that proper supervision is required during application, as the recommended thickness of the product must be installed correctly to achieve its waterproofing properties. Without proper application, the solution may be installed incorrectly resulting in a failed leaking substrate.


Pre-formed sheet membranes

Pre-formed sheet membranes are another excellent choice for waterproofing your roof and there are two versions available in the market. These membranes are supplied as a waterproof sheet  & require them to be welded/joined together to form a watertight membrane.

Firstly there are bitumen torch-ons, this is where a  fabric is blended with polyester or fibreglass to create a polymer-modified bitumen membrane, these are installed using a flame from a propane torch.You may also find Polyvinyl Chloride (PVC) pre-formed sheet membranes on the market. Hot air welded at overlaps & junctions they can be bonded with an adhesive, and are well designed to deal with the pressures of high winds, excessive rainfall and other weather-related stresses including being UV Stable.  Some products are also modified to be fire retardant, so they can also provide a good fire rating to help protect your building in case of an emergency.


Wolfin Waterproofing Systems

One such polymeric PVC waterproofing system is the Wolfin sheet membrane system. Wolfin can be laid loosely on the surface or bonded (Wolfin GWSK) and due to its high quality composition, has outstanding properties to enable greater longevity & service against all climates and conditions and are used in new & remedial applications. Wolfin is used on most substrates and areas and is compatible for a number of installations including over failed bitumen, asphalt, sheet and liquid membranes and is used in critical areas (Over Habitable Spaces) where waterproofing  is of the highest importance. This German-manufactured product also has a high tear and puncture resistance, making it one of the most trusted and reliable products on the market to date.


Cosmofin Waterproofing Systems

Cosmofin is known in the industry as being a reliable and long-term product that provides great performance in a number of applications. This product is a PVC waterproof membrane that includes a central glass non-woven inlay. Cosmofin is often used for a wide variety of building structures such as residential, commercial, civil and marine construction projects. It is also used for many applications , not exclusive to rooftops, such as balconies, terraces, retaining walls and planter boxes. With its clean application with any waste being recyclable, Cosmofin waterproofing systems are also extremely high tear and puncture resistant.

Both Cosmofin and Wolfin products are versatile enough to be used on a number of materials. Not limited to concrete roofs, these products can be utilised to waterproof other building materials including steel, timber, CFC, masonry etc.

Designed to withstand chemicals in domestic and industrial constructions, they’re highly durable, UV stable and in the event it is required, easy to repair.


Waterproofing a concrete roof for safety and longevity

Whether it’s a concrete rooftop that you’re concerned about, or perhaps there are other construction materials you want to ensure are stable and waterproof for years to come, there’s no doubt that investing in superior waterproofing systems is the best way to protect your assets. Not only can you protect your roof from the extreme climates Australia can often bring, you can also have the peace of mind that you are doing the best that you can to protect your building and constructions from unnecessary damage.

And remember, if you’re having any other water problems in the home it’s best to consult with a plumber before taking action.