A few days ago an old prospect called me on a Sunday Morning, He happens to be the MD of one of the flourishing architectural firms in Lagos. The news was that the roof of his house was leaking, can my company send somebody down that same Sunday to inspect the building and recommend which of our range of products could be used to address the situation right away.
Calls like this reminds one that it’s raining season again and many home owners, Civil engineers, construction companies and architects nightmare. Its nightmare when your client calls you in the middle of the night to rant that the building you just handed over less than a year is leaking profusely and the home interiors have been damaged by rain water. Let’s face it: no one enjoys running around the house with buckets every time its rains. Its terrible experience that has both psychological and health implication for the whole family.
There are 3 most common causes of roof leakages especially in this part of the world. Below is a brief discussion on these causes and how to prevent them during and after the construction process.
- Roof Flashings
Flashing is any metal usually aluminum or galvanized steel that are installed on the joints of your roofs in order to create water resistant barrier. Flashings are often coated with bitumen and tar to block any point of water entry.
How it happens
Leakages occur through the flashing as result of hot weather activities such as Utra -Violet rays, resulting in high temperature melting the bitumen coating and degrading it. The frustrating thing about this is that most times the client does not even know where the leakages are coming from. This is because often times when there is roof leakage the first place our mind goes is the membrane or coatings on the roof whereas the roof flashing maybe the culprit.
The first step is locating the source of the leakage. Once you locate the source of the leak, remove the nails used to fasten the flashing, repair or replace the old flashing and apply a coat of bitumen or other roofing sealants.
- Damaged Roofing Sheets or Shingles
Damaged roofing sheet is also another common cause of leakage. However, this culprit is often easier to diagnose. The simplest method for investigating this, is after discovering the leakage, you will have to visit the roof. If your visit to the roof showed that the leakages are coming from the roofing sheet areas and not the concrete areas, you may then need to bring in the roofing contractors to investigate properly.
How It Happens
More often than not the damages are caused by human activities on the roof, bad workmanship, especially when they roofs are installed during the dry season and sometimes because of the gradual degradation of the nails and flash band used during installation.
Depending on the type of roof, the solution is often easy, the first thing to do in this instance will be to call in the roofing experts. If it’s broken shingles, the will need to be replaced, if it is aluminum there may be need to use flash bands to cover the exposed nails, coating with bitumen and sometimes replacement of the roofing sheets.
- Expired Felt Membranes or damaged waterproofing Coatings
By far the most common cause of leakages in many instances is expired, substandard or Felt damaged membranes. Of course, on most occasions, it could be a combination of all three factors. The truth is that most Architects, Consultant Structural engineers and construction companies in this part of the world are only familiar with the bituminous felt membrane, even though it is fast becoming obsolete in Europe, America and many developed countries
The practice most often is to specify felt membranes because the Engineer is not aware of the new and improved systems like Polyurethane systems, EPDM. The resultant effect is to observe in many instances that roof terraces waterproofed begin to leak in less than a year. In this article we will address the bituminous membrane and two of the most advanced and best performing waterproofing product class.
Bitumen Felt Membrane
Bitumen felt membrane sheet is the oldest form of waterproofing system in Nigeria and most part of the world and infact, still the most widely used. When installed properly the waterproof membrane system.
The most important thing to know about bitumen whether in sheet or liquid coating is that, they come in different grades, class and quality. For instance a 4.5 MM Italian Scodoplast will give you a different longevity and performance as against an equally 4.5MM of an unbranded product.
Weakness and Limitation
The major weakness with the Bitumen system be it Sheet or Liquid is that they are not very UV resistant, they are heavily subject to weather damage. Especially in our environment where we experience high temperature swings. The heating and cooling results in the expansion and contraction which eventually damage the bitumen felt.
Polyurethane and EPDM Systems
We live in a twenty first century world, and this century has offered us many improved and revolutionary products and services that has made life easier for us today. Polyurethane and EPDM waterproofing falls in this class. The advantage of this two products is that they have been specifically engineered to have greater capacity to withstand and resist weather and UV attack. A good polyurethane and EPDM membranes will each last three times the typical life of a bitumen membrane or coatings .I repeat myself again , Three times ! The PU system works on all the disadvantages of the felting system and turned them to advantages.
A good example of the polyurethane system is the Maricoat systems, Marithan systems and the Mariseal systems.
How it happens
The challenge with the felt membrane sheets is that once water comes in through any of the seams, and moisture is trapped the whole felt will need to be eventually removed and replaced because it will lose it bondability.
Whereas in Polyurethane coatings damages can be localized because the materials often have very high adhesion to the substrate, so a particular area can be cut off repaired if need be without affecting the integrity of the whole area.
Whether you have a new roof, an old roof or you are specifying for a new project, wear and tear is unavoidable. There will always be raining season and the sun will never stop releasing ultra violet rays. The smart thing therefore is to ensure that you have chosen a system that will give you long term protection from the elements. The decision here, is balancing budgetary constraint with durability and longevity. This is also a difficult decision to make given the budgetary constraint that often occur in a project and because more often than not the client does not appreciate the value of quality waterproofing until the roofs start leaking and the interiors are damaged.
If you need more information or would require us to advise you on any of your projects please visit our office or call us on
Tel: 234-818-243-5430 or Tel: 234-818-243-5381