top of page
  • jordantulkki

What Causes Roof Waterproofing Failure?

Updated: Sep 29, 2021

Residential and commercial roofs are exposed to the elements for their entire lifespan. Reputable roofing contractors install sturdy and reliable roofing, but not even the best materials can last forever. One of the most common and prevalent problems has to do with waterproofing.

What Causes Roof Waterproofing Failure?

Waterproofing failure can affect your home or your business, so providing a solution to the problem is a matter of urgency, and it typically takes time and a considerable amount of money to complete the repair or replacement. That said, however, it might help if you understand the common causes of waterproofing issues that can plague a roof. If you know enough about the problem, you might be able to prevent it.

Here is a list of the most common reasons behind roofing waterproofing issues.

Improper Preparation and Installation

Did you know that most waterproofing issues can be traced back to poor workmanship? This is true for up to 90% of all waterproofing failures. It’s not just the roofing material that should be prepared. A contractor should know how to prepare the surface on which the material is to be installed.

Roofing material manufacturers have specific instructions regarding surface conditions and how the roofer can prepare both the material and the surface before application. Roofing materials, especially roofing membranes, require optimum surface conditions before their application.

Some of the factors to consider are:

  • Drainage provisions for the surface

  • Smoothness and cleanliness of the surface (scrapped and vacuumed)

  • No debris, residues, protrusions, voids or any formwork distortions on the surface

Before the workers install the membrane or any other roofing material, there should be sufficient time allotted for waterproofing and preparation. The waterproofing activity should not be an afterthought. It should be part of the roofing installation schedule.

Poor workmanship often leads to incorrect installation, or the use of methods or products that do not fit the roof requirements. When this happens, your roof is likely to require frequent roof repair until the leaking is completely addressed or you are left with no choice but to replace the roof.

Adhesive Failure

Roofing systems depend largely on effective adhesion to be waterproof. When the surface is not completely devoid of moisture, the roofing membrane adhesive is very likely to fail. Roofers that install such roofs are trained in checking for surface dryness.

Roofing contractors should know what specific material is suitable for the surface they’ll be working on to ensure complete adhesion and waterproof performance.

Using the Wrong Materials

It doesn’t matter how dry or how clean the surface is or how good the materials are. If it’s the wrong material for the job, you can expect waterproofing problems - and soon. Using the wrong materials invariably leads to rapid deterioration and premature failure because it doesn’t match the structure. In some cases, the material might last for a while, but the energy efficiency would be questionable at best.

If your building ends up with the wrong roofing materials, it’s probably the fault of the person in charge of sourcing the materials. If the contractors did not understand the requirements or failed to look at the details of the requirements, they might choose a material that they think is best for the application, but is actually wrong. The result is often waterproofing failure.

Unless your contractor follows the exact specifications of the manufacturer for the material in question, you could end up with an expensive fix or a premature roof replacement, both of which will take time and money.

Sometimes, the right material is chosen and installed, but the owner of the building decides to apply a change to the roofing system that is not compatible with the material. For example, if your roof is not intended to hold equipment like air conditioning units or if the roof is not adjusted to that it can accommodate the equipment, penetrations can become a cause for concern. The same is true for roofs that are not intended to hold rooftop greenery or a garden, which also requires a special drainage system.

Hiring the Wrong Contractor

Another area of concern when it comes to waterproofing is the expertise of the contractor that you hire. It makes sense to choose a contractor that specializes in the type of roofing system that you need for your building. Roofing contractors who are certified by the manufacturer of the material are the best option as they receive specialized training and have to pass exams to keep their certification. You can also ask them about the subcontractors they hire and how long they’ve worked with them, just to be sure that they are applying the correct methods in installing the right roofing material.


Of course, even if you hired the right contractors, and they used the right material, the weather still has a lot to do with the success or failure of the waterproofing. As there is nothing you can do about the weather, you can simply prepare your roofing system for extreme weather events like storms.

Working with a reputable roofing contractor and applying the proper maintenance methods can prolong the life of your roof and make it less likely to be damaged by a storm. After the storm, it’s important to have your roofing system inspected for waterproofing problems and given the correct roof repair wherever it’s needed. Some people believe that modern roofing systems do not require as much maintenance as old ones do, or they require no maintenance at all. This is simply a myth. Whatever type of roof you have and whatever the kind of weather in your area, it’s important to give your roofing system a thorough inspection and regular maintenance.

Get in touch with A1 Quality Roofing, Inc. We can help you install, maintain and replace your roof, and we always check thoroughly for waterproofing. Call us at (951) 877-4406, or fill out our form here.

106 views0 comments


bottom of page