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Flat & Low Slope Roofs 

It really depends on your structure and the architectural design elements built into the design.  Sloped roofs are better than flat roofs since gravity drains away water to avoid any standing water.  The truth is, most flat roofs are not totally flat.  Almost all flat roofs are built with very slight slopes that drain away water to avoid standing water.  If water is a roof's biggest enemy, consider standing water to be the leader of that enemy.  But flat roofs are common in Hawaii and to protect your flat or very low sloped roof, we recommend a 100% silicone seamless rolled on membrane coating that is 100% waterproof and very highly resistant to UV deterioration.

Knowing if your roof is flat or sloped or a combination of both helps Maui Roofs & Repairs categorize your roof and roofing options right away.  These are the two main distinctions in the roof industry with different materials and methods of construction for each type.  Flat roofs on Maui are typical for commercial and industrial roofs for large buildings and warehouses.  Hotels commonly have flat roofs and even some homes do too.  

Common materials and systems that work great for flat roofs on Maui are the self adhered membranes also known as peel and stick membranes which are torch welded together for reliable seems that are reliable depending on the expected weather exposure.  All overlapping membranes installed as rolls come with limitations and their own set of issues.  The older flat roofing systems applied with the hot tar kettle pot and hot mopped onto roofs and are becoming a thing of the past.

Flat roofs installations and repairs on Maui are very common as many hotels, large commercial buildings, and condominiums have flat roofs.  Maui Roofs & Repairs installs a flat roofing system that has proven to be the only flat roof waterproofing system that consistently holds up to Maui’s year round tropical climate.  We like 100% silicone coatings for flat to low sloped roofs and acrylic coatings for sloped roofs.

PROS to solid roof coatings: 
  • 100% silicone

  • Seamless

  • Stays flexible 

  • Long warranties

  • 100% waterproof

  • Adheres to virtually any surface

  • Reflects sunlight and solar energy

  • Apply directly on top of existing flat roof

CONS to solid roof coatings:
  • Holds dirt

  • Low resistance to tearing​

As flat roofing technology has evolved over the years we are currently in the exciting era of 100% silicone coatings.  100% silicone coatings are exactly that, a top coat that is applied on top of a new or existing base layer.  No matter which kind of flat roof you currently have or if you’re installing a new flat roof, we always recommend coating your flat roof with a 100% silicone coating to guarantee a true waterproof flat roof that lasts longer than any other option available in today’s market.


A flat roof is generally totally flat or almost flat with a very slight pitch.  Flat roofs usually have a means for water to drain off the roof through scuppers, roof drains, or gutters.  For roofs that do not slope and drain, the issue of ponding water must be addressed.  Flat roofs are common in Maui due to the tropical climate where the threat of ice damage and snow loads are non-existent and because of the useful space available on flat roofs which can be utilized for air conditioning units, solar panels, and sky lights.

The latest and greatest innovation in the flat roofing industry is the development of cold applied liquid membranes commonly referred to as liquid roofing.  Think of liquid roofing as the most super incredibly advanced special paint used to paint and coat your roof to provide a 100% waterproof and seamless barrier on your roof with many more additional features and benefits.  Compared to older flat roof systems that involved boiling hot stinky asphalt kettles that are dangerous and only last a few years in Maui’s year round sun, cold applied liquid roofs require no open flames or heat sources and the coatings provide a seamless waterproofing barrier around any protrusions and equipment located on the roof.

There are numerous liquid roof coatings available, but our favorite is GacoRoof 100% Silicone.  Here are the main reasons why Maui Roofs & Repairs recommends GacoRoof 100% Silicone for your new flat roof installation or repair:

It works - Roof after roof, year after year when properly installed by Maui Roofs & Repairs a liquid roof using GacoRoof 100% silicone provides the best flat roof waterproofing and protection we currently know of.  We’ve never had a major issue with a flat roof after we’ve installed GacoRoof 100% silicone per the manufacturer’s instructions.

​100% silicone - 100% Silicone is the best flat roof coating on the market today outperforming and outlasting any and all acrylic, urethane, and asphalt coatings.  Unlike other roof coatings, GacoRoof 100% silicone in unaffected by UV light and will not deteriorate even after years of constant UV exposure.

​Adheres to virtually everything - GacoRoof will bond to and provide a waterproof coating to most surfaces without a primer including existing roofing systems like built up roofs, cap sheets, metal roofs, modified bitumen membranes, polyurethane foam roofs, asphalt, tar & gravel, concrete, asphalt shingle, tiles, low pitched roofs, and flat roofs.

Stays flexible - Even under extended exposure to ponding water, GacoRoof 100% silicone will remain flexible and maintain adhesion while other coatings become brittle and degrade after just a few years.

Ideal for ponding water - Ponding water is a flat roofs biggest problem and GacoRoof 100% silicone is the solution.  GacoRoof will not change, soften, bubble, loose adhesion, swell, or degrade under permanent standing water.

Saves time & money - GacoRoof 100% silicone is commonly applied to old weathered roofs that would normally require a complete re-roof.  Apply GacoRoof 100% silicone to your old flat roof and you’ll virtually have a new and rejuvenated roof with the added benefit of avoiding the cost to completely re-roof your existing roof.  This product can be applied with your building occupied and virtually eliminates any downtime or loss of production.

Saves more money - GacoRoof 100% comes in several colors including money saving white.  By eliminating traditional black and dark colored flat roofs, a white roof will reflect the sun’s heat energy and can be as much as 70 degrees cooler than your old black asphalt roof.  This results in a tremendous reduction in electricity used to cool your building.

50 year material warranty - All GacoFlex coatings offer an outstanding 50 year limited material warranty to stand behind their product’s famous claims.

Other less recommended and traditional flat roofing options.

Maui Roofs & Repairs is recommending and installing more and more peel and stick membrane style roofing systems roofing systems followed by a 100% silicone top coat for owners that want the best flat roof waterproof protection that Maui roofing contractors can offer.  We are seeing the flat roofing materials and technology evolve from the very old, dangerous, and toxic method of the hot tar kettle asphalt roof, to the less dangerous torch welded membranes, to what is now becoming the new standard in roofing membranes known as “peel and stick”.

Modified Asphalt Bitumen.

This started out with the traditional old and very dangerous and toxic method of boiling the tar in a kettle and hot mopping the liquid asphalt onto your roof.  The industry’s next solution to the danger and toxicity of a boiling kettle of molten asphalt were single ply asphalt sheets that were rolled onto the surface.  These still required a propane torch to change the asphalt from a solid to a liquid and caused a new issue of creating seams.  The solution to the heat source was the development of “peel and stick” modified bitumen sheets which is where we are at today.  The peel and stick method alone can be effective, but there are 4 negatives:

 

  • Modified bitumen asphalts deteriorate after exposure to UV light from the sun.

  • Seams fail over time.

  • The sub-surface receiving the sheets must be impeccably clean and dry.

  • Single-ply does not offer much durability.


Polyvinyl Chloride (PVC)

The answer to modified bitumen asphalt roofs were PVC roofs.  PVC roofs made significant improvements to bitumen asphalt roofing systems and quickly became a popular flat roofing choice.  PVC roofs do not contain asphalt which address the need for a heat source to apply and are considered much safer to install and maintain.  PVC is white which has incredible reflective properties to reflect the sun’s heat and keeps the roof surface and building significantly cooler.  PVC roofs come in multi-ply options and are significantly stronger and more durable than modified bitumen asphalt roofs.  While a significant improvement over a modified bitumen asphalt roof, PVC roofs still have their negatives:

 

  • Comes in rolls and seams must be field taped or glued together.

  • Seams still fail over time.

  • Seams require frequent maintenance.


Ethylene Propylene Diene Monomer (EPDM)

EPDM’s are a very popular flat roofing choice because of its durability, low installation cost, and is quick to install.  EPDM is a synthetic rubber membrane that is derived from oil and natural gas which usually comes from recycled materials such as rubber tires.  EPDM roof coatings offer a long life expectancy.  As good as an EPDM roof sounds it suffers the same fate as all the other membrane sheet applied roofing systems that rely on seams.  The disadvantages of EPDM roofs are:

 

  • System relies on seams.

  • Seams breakdown over time under sun exposure.

  • Seams leak and require maintenance to maintain watertight bond.​

Maui Roofs & Repairs  808-219-0300

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