How Do You Stop a Flat Roof From Leaking? (Updated for 2022)

flat roof with water ponding

Can a flat roof be repaired?

Commercial structures are typically large, spanning as long as football field, or longer, and much wider. They are often manufacturing or warehouse facilities (think Amazon) and with those business types means there is machinery and merchandise inside. Because flat roofing is common, there are special considerations for the materials used for the roofing, the maintenance, and repairs. When one gets a leak in their flat roofing, it generates concern and worry like finding the flat roof leak causes and getting the flat roof leak fix done promptly. 

If a facility manager or owner of a commercial structure with flat roofing chooses to replace the roof, they find that the cost is significant and could lead to interruption to business. Instead of replacing the flat roofing, repairs are possible, usually with a silicone coating. This will make it waterproof and extend the lifespan of the original flat roofing material. Commercial flat roofing repair provides an inexpensive, quick, and true solution to roof leaks. 

How do you find a leak in a flat roof?

Locating a leak on flat roofing will depend on what type of flat roofing material is present. A built-up flat roofing material that is covered with gravel will give you a  challenge while a singly-ply flat roofing membrane makes it easier.  Here are steps to follow in finding a leak on flat roofing surfaces: 

  • CLEAR DEBRIS FROM FLAT ROOFING SURFACE: Removing any debris is key in finding damage that is causing the leak. This will require walking the roof surface, so wearing appropriate footwear and following all safety precautions is recommended. After clearing debris, check for blisters, bubbles, cracks, punctures, splits, and tears. For a gravel-covered flat roofing surface, any missing gravel is a strong indication of possible leaking. 
  • CHECK COLLARS, FLASHING, AND SEAMS: Checking the collars and flashing are necessary because of the protection they provide a roof. If they are bent, loose, or missing, the roof leak could be around the edges or penetrations. You may need to sweep gravel away from these areas to check for the collars and flashings. Single-ply roofing materials are seamed and can come loose, allowing water seepage. These are areas where flat roofing leaks are possible. If there is any gaps or separations, you have found the problem. 
  • EXAMINE THE PATCHING: If there has been previous patches on flat roofing, there is always possibility of it leaking again.  After there has been several patches, are large patches, new flat roofing replacement is the best option. 
  • LOW SPOTS: Flat roofing is not completely flat, there is always some slope to the surface. When a leak is discovered, an inspection of the roof may find a low spot where water is pooling and that can begin degrading the roofing material, thus a leak starts.

What causes flat roof leaks? and Do flat roofs always leak?

Commercial flat roofing allows more interior space and convenient area for installing the HVAC units. However, flat roofing has its problem, with leaks being one.

  • Drainage: Poor drainage is a  common cause of flat roofing leaks. There is a slope to flat roofing, but it is slight and proper drainage is important.  
  • Flashing and Membrane: Maintenance of flat roofing structures is important.  Monthly inspections can catch a potential problem before it becomes a major disaster. 
  • Age: Regardless of your diligent efforts of inspections and maintenance, a flat roofing will age and with age, leaking can begin. 

No, flat roofing does not always leak. If it is installed properly and regular inspections and maintenance are kept on routine as recommended, there should never be a leak.  When flat roof leaks in heavy rain, it is usually poor workmanship with the installation, the inspections did not find issues and have repairs made, or maintenance has not been performed.

roof drainage on flat roof

How do you waterproof a flat roof?

Commercial structures, waterproof flat roofing isn’t a one-size-fits-all method. Most of these roofs are custom-installed and unique characteristics. If you have the need to waterproof your commercial structure flat roofing, we recommend using a commercial roofing contractor with experience in working with the type of roofing material on your building. 

Based on the type of material, embedded gravel, EPDM, BUR, metal, or modified bitumen one of the following will be recommended by the contractor:

  • Reinforced polyurethane liquid that is cold when applied by either roller or sprayed 
  • APP or SBS or bitumen sheets applied by torch-down method
  • Rolled or sprayed on cold rubberized liquid 
  • Single-ply PVC or TPO, fully-adhered membrane sheets

Okay, you are in charges of a commercial structure with flat roofing.  The flat roof is leaking, “what do I do?”, you’re asking. In America, the common materials for flat roofing are one of the following: 

  • EPDM
  • Modified bitumen 
  • BUR 
  • TPO 
  • PVC 

A small leak or temporary repair can be done by your building management or maintenance team with a plastic tarp, 2×4 boards, screws, and roofing tar.  Stretch the tarp over the leak on the rooftop. Spread roofing tar over the edges of the tarp and then screw the 2×4 boards on each edge. 

From the inside of the building, place a container under the leak with a tarp under it. If you can reach the ceiling, poke a hole in any bubble so that the water can drain out. Call 214-295-5500 today for your flat roofing needs in Dallas, TX.