In today's building industry and economy, we all want to get the most value out of what we purchase. Therefore, when you make a large investment like building a house, it becomes critically important to protect the investment through proper product specification and maintenance to ensure you will get the longest possible life out of your roof system.
Water can cause major structural damages to a home, which can add up to million of Naira. Poor maintenance and damage due to leakages can cause a substantial drop in property value. By choosing and specifying the right waterproofing systems in and around your client building or home, you can prevent or minimize the damaging effects of water.
More often than not, waterproofing is not given critical consideration during the design and specification stage of the project and when it is considered at all it is merely given flirting attention. In today's building industry and economy, Engineers, Architects and Quantity Surveyors want to deliver the most value to their client.
To achieve this there is a need to be innovative and leverage on the benefits of technological advancement that has made hitherto impossible construction feats possible today. Ideally waterproofing cost is usually less than 0.1 % of the total cost of constructing a structure however; this minute cost is often ignored for cheap substandard products in order to save cost a consequence which is often aesthetics, structural and property damages.
Researching and learning about the different waterproofing materials for your clients might not be the most exciting way to spend your time but sooner or later you'll see the benefits and advantages that this offers to both you and your client.
Prerequisite for choosing waterproofing systems
I shall be limiting my discussion in the first part of this article to Above grade waterproofing. With so many different types of products and systems available in the Nigerian construction Market today, it is good to understand how each of this available material benefits your client; it is important to select the most appropriate product based on your environment and needs. Some important roof conditions to consider when selecting a restoration coating include:
Criteria for Selecting the Right Roof Coating
- Ponding water
- Chemical exposure
- High heat exposure
- UV exposure
What you basically need to know is that there are a range of roofing choices available to you, each with their own attributes. The important point here is that these options allow you to tailor your choice based on what factors are most important to you, be it budget, longevity, style or a combination of all three.
Above all, good and professional installation is key in all form of waterproofing jobs.
Selecting the Right Roof Coating
Subjecting a roof or restoration coating to any or all of these conditions will greatly affect its performance and life expectancy. Therefore, when selecting from the variety of roof coatings available in the market today, it is important to consider the features and benefits of each coating type, as well as its drawbacks. This section provides information about the different types of waterproofing systems, the advantages offered and the drawbacks. Below are the different options available:
Polyurethane Roof Coatings
Polyurethane coatings are the most advanced form of waterproofing system in the market today because they provide a highly durable surface that protects the roofing system from a wide variety of conditions for the longest period of time. Urethanes typically have higher tensile strength when compared to most other coatings, allowing the coating to resist expansion and contraction of the roof system. This can be very important in high stress areas, around penetrations, or on wall flashings where your building endures the most abuse.
Good roof practice recommends no Ponding water. However, small bird baths are typical on most low slope roofs. Urethanes will provide better protection in bird bath areas. Since roofs tend to fail first in areas prone to ponding water, selecting a urethane coating (in addition to creating positive drainage) is a good choice when you want to have a long lasting waterproofed roof systems. Typically polyurethanes unlike traditional membranes can last for upward of 25 years without maintenance.
Conclusion: Polyurethane coatings offer the best, most resilient and effective protection against weather, water attack, UV exposure for your structures. They also offer the longest value for money. They are also often warranted by manufacturers. The downside of polyurethane system is that it is expensive in the short term, however, the client can always enjoy water tight structure for a longer time than any other products.
Acrylic Roof Coatings
Acrylic coatings are very common in the roofing market today because they are typically water-based products and are cost effective. Water-based acrylic roof coatings are both easy to use and environmentally friendly. Acrylic coatings are most often used for reflectivity, and they are designed to cool the roof down. The net effect is reduced energy costs as well as protecting the roof surface from UV exposure. Acrylic coatings are also typically very "elastomeric," allowing for fluctuations in temperature without affecting the actual coating. However, they typically do not have a high tensile strength, and this can affect the coating's ability to resist wear and tear, making the roof restoration or coating more susceptible to damage from ponding water. In general, acrylic coatings help reduce cooling costs at a more economical value, while at the same time increasing the service life of your roof surface by protecting it from UV exposure.
Conclusion: Acrylic coatings are very easy to use, typically cost effective and they have the added advantage of flexibility. However, they are known not to be durable because they cannot sustain Ponding water for a long time. Except for the fact that they are economical clients have to be careful in area where they are used as their failure can cause significant damages and they are often not warranted by the manufacturers.
Bituminous membrane sheets (Felt)
Bituminous membrane sheets are the oldest and most widely known form of roof waterproofing system. They have been around for time immemorial and have been the longest form of waterproofing system known to modern man. There are different types and qualities of the bituminous membrane systems in Nigeria market, For instance, the Italian Scodoplast, Egyptian membrane, tropical, reinforced are the different characteristics of the membranes in the market today. There also different classes of thickness such as the 2MM, 3MM, 4MM etc. all this factor play a part in determining the longevity and durability of the felt membrane
Conclusion: The bituminous felt membrane is the most popular and widely known roof waterproofing system and it does the job. However, technology has provided us with many alternative and better systems that address the limitation of bituminous membranes. Bituminous membranes are not UV stable, they lose their quality faster ones water start ponding on it and the joints are always potential leaking points
Silane based nano technology penetrants, crystalline, and acrylic coatings
Silane based nano technology products, crystalline and cementitous coating are other means of waterproofing roof systems. This methods are however not reliable for the following reasons. Nano technology and other penetrants cannot cover cracks that occur after installation, which are often inevitable especially with the construction practice in this part of the world, the also cannot accommodate movements since they are integrated into the concretes
While some companies such as Kryton and Zypex have attempted to design crystalline systems for roof waterproofing they have not been entirely successful .Crystalline is only suitable for sub grade structures because they do not have ability to accommodate movements and cannot successfully be used for roofs with cracks larger than 1MM.
Conclusion: 3rd generation crystalline systems permanently waterproof concrete. However, they are only suitable for below grade applications as they cannot accommodate movements and cracks which may often be difficult to rule of because of our workmanship and climatic conditions.
Know Your Roof Coatings
As you can see, there are many different types of coatings you can select from for your roof protection and restoration. When selecting a coating to protect your roof, make sure that you consider what you want to achieve: Are you more concerned about long time protection, cost, aesthetics or durability. Each of these coatings has its own strengths and specific advantages that make it suitable for certain roof conditions. Selecting the right coating will ensure long-term protection to your roof system.
Balogun Collins is the head of Technical for Advanced Concrete Technologies Ltd, He has over 12 years experience in the waterproofing and construction industry.