Are there disadvantages to a flat roof?

flat roof on a row of colorful buildings

Keeping Your Flat Roof in Shape

With winter hitting the United States, owners of commercial structures are realizing their buildings need flat roof repair. Here in Indiana, the spring and summer likely did some unknown damage. With even a little bit of rain and even some sleet and snow, some leaks have been discovered! That leads us to some big questions surrounding these kinds of roofs.

How do you stop a flat roof from leaking?

Flat or low-sloped roofs are popular among commercial structures because of construction costs. It also makes a convenient space to have HVAC systems installed, saving the actual real estate for parking. Flat roof repairs and maintenance are also easier and less expensive than a sloped roof. 

However, flat roofs do tend to leak when they aren’t maintained correctly, causing immediate needs for flat roof repairs. When this happens, the best thing the owner or maintenance crew can do is call a professional commercial roofing contractor to inspect and make the needed repairs. They may use one of several types of flat roof coatings for the flat roof repair job. 

An experienced commercial roofing contractor will know that not all flat roof surfaces can use the same type of coating for a flat roof repair job. For example: 

Flat Roof Materials That Can’t Use a Flat Roof Repair Coating: 

  • Gravel: This rough surface is inconsistent, making it extremely difficult to coat because the material moves around while the coating is being applied. 
  • EPDM (ethylene propylene diene monomer): A flat roof repair of this material can be coated, but with a limited number of products. Some choices for a flat roof repair coating would include acrylic polymers and urethanes.
  • PVC (Polyvinyl Chloride):  This type of roofing material has an integrated solar protection and reflectivity that can be damaged by a flat roof repair coating.

Flat Roof Materials that are Good Candidates for Flat Roof Repair Coating:

  • Bituminous roofing: This is an excellent for candidate for flat roof repair coating once the surface is smoothed. 
  • Concrete roof decking: This type of flat roof material is generally adapted for heavy foot traffic, making an ideal surface for flat roof repair coating with a waterproof coatings. Popular choices are epoxy and polymers, or for more cost effectiveness, a urethane coating. 
  •  are the most cost-effective method for waterproofing traffic areas.

Can a flat roof be repaired?

Depending on the amount and severity of the damage that has caused a need for a flat roof repair job, yes. But prevention is the best flat roof repair! A commercial structure roof should be inspected by qualified professionals once a year and after significant weather events. With these inspections, they can identify issues that may become a problem in the future. Once these issues are addressed, it has minimized the need for flat roof repairs. 

The types of coating materials that can be used for flat roof repairs are: 

  • ASPHALT: A bituminous product with added solvent for thinning will aid in applying the material. Aluminum pigments are added by the manufacturer for reflectivity, some manufacturers add modifiers that enhance the longevity, strength, and thickness. For additional reinforcement, fiberglass strands may be added. 
  • ACRYLIC ELASTOMERS: A newer type of flat roof repair coating that is highly reflective, exceeds the SRI scale. This white coating is installed over existing bituminous or non-bituminous for flat roof repairs at 12 mils thick or 20 mils thick.
  • POLYUREAS: A fairly new product in the industry, this polymer-modified product is specified at a similar application rate of acrylic elastomers. Some are thicker when dry, up to 60 mils, more like a urethane flat roof repair coatings. 
  • URETHANES: This polymer-modified product is ideal for a flat roof repair of concrete substrates, like a parking deck and comes in a one- or two-component formulation. Not recommended to apply over other flat roofing products.
  • SPF: A spray-applied flat roof repair foam that is insulating, not considered a coating, but the formation and penetration it provides makes for a good insulating value and waterproofing.

How do I stop my flat roof from ponding?

Pooling and ponding of water is a common issue with a flat roof; repair is needed immediately to prevent further damage to the roofing material. Several things can cause this to happen, like the slight pitch to the roof being insufficient or the drainage being clogged. 

For pooling or ponding flat roof repair, adding a layer of insulation, tapering it off to the edges will fix the problem. With clogged drains, these need to be cleared so the water can flow on through from the gutters. 

How do you waterproof a flat roof?

There are three waterproofing methods for a flat roof: 

  • Liquid waterproofing: This particular type of roof coating includes liquid fleece membranes and fiberglass liquid. Good for use on most roofing surfaces and will last up to 40 years if installed correctly.. 
  • Single-ply membrane: This flat roofing repair to waterproof comes in 1 to 2mm wide, and 1 to 2mm thick, by 20m long. Performs best when coupled with a warm flat roof, so the roofing contractor will add an extra layer of the material before the insulation, then fasten to the membrane. 
  • Reinforced bitumen membranes: Two to three layers of membranes are placed on the flat roof; repair is done with the application of hot bitumen applied, which bonds the layers. Combined with a polyester carrier, it is then positioned across the insulation and attached to the membrane. 

What is the best material for a flat roof?

Roofing experts recommend PVC for commercial structures with flat roofing. The membrane is moisture resistant, durable, and the white surface makes for an excellent heat-reflective roofing surface without any additional coating.

How can I make my flat roof look better?

Keeping a flat roof repaired and clean is the first step to a better looking flat roof. Choose a roof coating that works with the architecture of the structure while providing the structure the protective layer it needs. 

Having a vegetative roof installed is not only a good way to make your flat roof look better but it also helps the environment around the building. A green roof can be designed for clients and employees can enjoy it with seating. It could also become a community garden with vegetables for all to work and enjoy. The possibilities are endless.

How much does it cost to replace a flat roof?

As you probably expect, it is based on the size of the roof and the type of flat roofing material you choose. The typical cost for built-up bituminous commercial flat roof replacement will be between $11.50 and $14.50 per square foot.

What is the life expectancy of a flat roof?

A flat roof on a commercial structure that is properly maintained can last up to 20 years. The type of material used along with maintenance, repairs, and upkeep can lengthen that time frame and lack of those things can shorten the lifespan. 

In Closing – Curiosity? 

Have you wondered “Just how is a flat roof constructed?” The basics of flat roof construction will include the ceiling on the interior. This is nailed to support joists with decking material. A vapor barrier is installed next with insulation and a roof board to follow. Last, is the roofing material you choose for your structure.