How to Waterproof a Flat Roof: Guide from the Pros

Published: August 18, 2023 by Steven Griffin

Stay ahead of flat roof leaks. Call Sugar Land Roofing at 832-944-7663 for roof waterproofing and repairs.

Flat roofs provide a number of advantages for modern commercial buildings and even homes. Cost-effective and easy to maintain, flat roofs work well in applications demanding coverage for significant square footage, such as hospitals, schools, and high-rise buildings. 

At Sugar Land Roofing, we help our clients protect their flat roof investments with flat roofing services in Missouri City, TX.

In this blog, we talk about how to waterproof a flat roof the professional way. To extend the lifespan of your roof, learn more about this expert roofing service and why it matters.

What Is Roof Waterproofing? 

Many people assume roofs have natural waterproofing thanks to shingles. However, flat roofs don’t have shingles, and roofs with missing shingles do not always leak. So how does your roof keep the inside of your home dry when it rains?

In truth, without professionals taking specific steps to waterproof a roof, these structures would leak and damage a home or business. For most homes, roof waterproofing comes in the form of a rubberized asphalt underlayment, on top of which experts install shingles or tiles. For flat commercial roofs, however, waterproofing requires protective top layers. 

Why Professional Flat Roof Waterproofing Outlasts DIY Jobs

Commercial property owners frequently assume waterproofing a flat roof is an easy DIY project. Beyond the often surprising expense of equipment and materials, safety and skill factor heavily into the equation. 

Attempting DIY flat roof waterproofing can put property owners, their buildings, and other people at risk for injury or other damage. Experienced roofing experts like those at Sugar Land Roofing not only have the right tools for the job, they have the training and knowledge necessary to use them and complete any job safely and effectively.

Now that you know why professional flat roof waterproofing solutions can save you time, money, and stress, learn how to waterproof a flat roof the professional way below. 

How to Waterproof a Flat Roof: The Professional Way 

The standard of service a roofing company provides reflects the quality of its results. Choose to work with a roofing company that keeps you involved and informed every step of the way, starting with a detailed roof inspection. 

Roof Inspection

To provide accurate project estimates and check for any repair needs, a dependable roofing company will inspect your flat roof surface and other structures. This step in the process allows professionals to get accurate square footage measurements, check for any existing damage, and recommend a waterproof material that best suits your roof surface. 

For large buildings and extensive commercial campuses, thorough roof inspections may require time. When planning roof maintenance needs, keep initial inspection needs in mind. 

Estimates and Project Parameters

Next, your chosen roofing company should provide detailed pricing estimates. Look for transparency in this process, and request details as necessary. A trusted service provider will provide an itemized quote for any expenses you may incur during the course of the project. 

During this stage, your roofing contractor should also discuss how long the project should take, appropriate working times for your building’s schedule, and other parameters. 

Roof Waterproofing Options

Depending on your roof, budget, and other factors, a seasoned roofing expert may recommend one or more flat roof waterproofing options. If given multiple choices, remember that your choice of waterproof material could impact the project’s overall price. 

Liquid Waterproofing

When using liquid waterproofing, contractors apply a specialized hydrophobic fluid as a whole-roof coating. While most commonly used on commercial flat roofs, liquid waterproofing also works well when applied to pitched or domed rooftops. 

The type of liquid varies depending on the application and other factors, but options include:

  • Liquid fleece
  • Fiberglass liquid
  • Glass-reinforced liquid plastic 

Liquid waterproofing coatings last between 20 and 40 years, depending on upkeep and other conditions. Learn more about how to waterproof a flat roof using liquid coatings by speaking with a roofing expert in your area. 

Reinforced Bitumen Membranes

Many residential and commercial property owners choose reinforced bitumen membranes as a waterproofing material for their rooftops. 

Reinforced bitumen membranes bond together up to three layers of bitumen, applied to the flat roof surface. Experts then apply a polyester carrier to seal and complete the waterproofing process. 

Installation methods include hot and cold applications, with both methods resulting in a finished product that lasts up to 30 years. Reinforced bitumen membrane roofs require very little maintenance and can last longer than their expected lifespan with proper maintenance. 

Single-Ply Membranes

Most common with larger commercial properties such as hospitals and college campuses, single-ply membranes come in rolled sheets. 

Roofing experts use a variety of methods to attach single-ply sheet membranes to existing roof structures, including fastening, adhesives, and ballasting. Fasteners may be plastic or metal, and ballast typically comes in the form of gravel or stone. Adhesives include polyurethane blends to stick the membrane to the roof.

Single-play membrane flat roof waterproofing typically lasts around 25 to 40 years, depending on conditions like upkeep and weather.

Signs Its Time for Flat Roof Waterproofing and Repair

Many property owners put off maintenance like flat roof waterproofing until it’s too late. You may already need roofing repair if you notice signs such as: 

  • Blistering in the waterproofing layers
  • Pools of water forming on the roof and lasting for more than two days
  • Cracking in the membrane or waterproofing layer’s surface
  • Visible water damage inside the building
  • Electrical issues in the ceiling of the top floor
  • Any sagging of ceiling material in the building

Covering a damaged roof with additional waterproofing material can lead to further damage and safety hazards. Experienced roofing contractors will recommend appropriate repairs to prepare the roof for safe and effective waterproofing. 

Dependable Roofing Services in Missouri City, TX

Now that you know how to waterproof a flat roof, learn more about flat roof coating and other roofing services by exploring our blog. 

To get started protecting your roof and property today, reach out to our Sugar Land Roofing team in Missouri City, TX, at 832-944-7663 today. 

About Steven Griffin

Steven Griffin has been in the roofing industry for over 30 years. He has worked with a host of roofing companies throughout Florida and Texas. He started Sugar Land Roofing with a vision of bringing quality roofing services at an affordable price to those living in the Greater Houston, Texas area.