Published on October 31, 2022 by Jason Reisman

How to Waterproof a Flat Roof: Steps from the Pros

Want to stop roof leaks for good? Call Eustis Roofing at 352-343-4240.

Most homeowners don’t worry about their roof until it leaks. While overall maintenance is vital to ensure maximum roof performance, waterproofing is the most crucial part of maintaining a flat roof. Unfortunately, not many people know how to waterproof a flat roof.

Sloped roofs allow water to slide off easily into the gutters. Flat roofs have a shallow slope that directs water, but when leaves, sticks, and other debris collect on them, the water often has nowhere to go.

Read on to learn how to waterproof a flat roof and why it’s important.

Choosing a Waterproofing Method

Industry professionals use multiple flat roof waterproofing solutions. The main factors to consider for flat roof waterproofing are:

  • Environment: Think about the temperatures and air quality in your area.
  • Structure and roof size: Different methods work better for residential and commercial roofs.
  • Budget: Some waterproofing solutions are more costly than others.

While someone may recommend a waterproofing technique that worked for them, it may not be the best option for you. As such, consider these factors carefully before making a decision.

How to Waterproof a Flat Roof

The three most common flat roof waterproofing options are:

Reinforced Bitumen Membranes (RBM)

This process begins by laying two or three membrane layers on the roof surface and bonding them with hot bitumen. Once combined with a polyester carrier, it creates a waterproof material. This layer covers the insulation for warm flat roofs and covers the structural deck for cold ones.

You can attach the roof membrane using several methods, such as:

  • Rolling the membrane over hot bitumen
  • Cold adhesive
  • Gas torch
  • Self-adhesive

Liquid Waterproofing

This option uses a coating to seal the roof and effectively weatherproof it. It works for all types of roofs but is most commonly used for flat roofs. Additionally, the coating lasts between 20 and 40 years, depending on the quality of the product, maintenance, and installation.

The most popular liquid waterproofing options include the following:

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

Single-Ply Membranes

If you want to know how to waterproof a flat roof that is larger than others, single-ply membranes are best for commercial buildings and large residential roofs. The membrane sheets can cover the entire roof, and you can attach them to your roof in numerous ways, including

  • Adhesion: Polyurethane adhesives secure the membrane and insulation.
  • Fastening: This attaches the membrane to the roof deck with plastic screws.
  • Ballasting: This gravel top coat protects the membrane from UV rays while holding it in place.

Call Eustis Roofing Today!

If you’re looking for a company that knows how to waterproof a flat roof, you’ve come to the right place. At Eustis Roofing Mclntosh, FL we have an excellent team of trained and experienced roofers who can handle flat roof leaks and any other roofing needs. Click here to learn about roof trends that won’t go out of style, and call us at 352-343-4240 for any questions or concerns.

Jason Reisman

About The Author: Jason Reisman

Jason Reisman, ERC’s General Manager is a problem solver! Jason is hands-on with finding solutions to difficult problems as well as constantly researching, exploring new concepts, discovering new inventive ways and is passionate about being the most experienced, most knowledgeable and most dependable in the roofing trade. He’s hands-on with training and instruction ensuring every job have the up to date and state of the art equipment to perform with precision to be in and out without delays. Jason loves competing with his Dad on the golf course!