Flat Roof Problems

Flat Roof Problems

This page deals with what flat roofs are and gives examples of various types of problems they can experience.

I personally own a house with a flat cool coated roof, and my office building in my back yard also has a flat roof on it. So not only do I work on them I also live with them. According to some people this is a great thing and others think its terrible. More on that later.

First of all, the term “flat roof” is somewhat misleading. Many people think of “flat” as being the same thing as level.

What is a Flat Roof?

A flat roof should ALWAYS have a little bit of slant to allow for water-drain off. Think of a flat pool table where the balls always roll to one end because the table is not level. At first glance many flat roofs will appear to be level, but upon closer inspection it can be seen they are built with a slight rise for drainage. This is important to avoid the confusion I often see with regards to clients who don’t know what to call their style of roof.  Understanding this is important to avoid the confusion clients often experience in trying to describe their style of roof.

What is a Pitched Roof?

A pitched roof is typically considered to be a shingle or tile roof. The easiest way to communicate what your roof type is to call it one of the three: “Flat, Shingle or Tile”. The types of problems presented below might give some the impression that flat roofs are not desirable. In the Southwest and other arid climates, flat roofs are extremely desirable for several reasons which are illustrated below.

Why would I want a Flat Roof?

I grew up in the Midwest. As such I lived in an area with lots of snow and cold winters. Shingle roofs were common and due to the weather the roofs needed to be replaced every 15 years or so. It was commonly known and expected. Every few years or so the region would experience severe storms or even small tornadoes. It was normal for people to replace a few missing or damaged shingles. In general the roofs held up well and drained off the water like they were supposed to.

Fast forward twenty years. I, Robert Anderson am now living in Arizona!  There are not many houses with shingle roofs.  Why?  Shingle roofs soak up a TREMENDOUS amount of heat and turn a Tucson attic into an oven in the summer time. This is NOT energy efficient and people living in the southwest figured this out a long time ago.

A reflective roof coating was the answer THEN and NOW. Back then the reflective coating was silver.  The logic was to have the roof act like a mirror and reflect the heat.  This was superior to shingles, however not by much. The silver coating reflected some of the visible light but the UV light was still soaked up in the coating and the roof heated up significantly.  The heat  then shortened the life of the roofing materials.

As technology and knowledge grew, white-cool coating became the solution. This coating reflected a great deal more of the UV and when clean would stay within a few degrees of the air temperature. If it was 115 degrees outside the clean white roof would be 115 degrees. NOW people were excited! I have measured this (the heat not the excitement) personally. So the figures I use above are not based on theory but my actual experience. A shingle roof  easily reaches 150 degrees under hot the summer sun. An old style silver roof would frequently hit 140 degrees whereas a cool-coated white roof would be more like 115 degrees. When the roof on a 2,000 square foot house is reduced in temperature by 25 degrees for months at a time there is going to be significant savings on the air conditioner electric bill.

From a maintenance point of view there are many advantages to owning a cool-coated roof. First of all finding a leak on a shingle or tile roof can be troublesome and time consuming. Tile roof leak problems are typically dealt with on a larger scale. If the corner is leaking it is common for forty square feet of tile to be removed to identify the problem. Shingle roofs typically leak at the edges or where two roof sections come together and water drains in a “V” shaped section. When the shingles are replaced they typically do not match and the roof looks patched. The choice is easy. Live in a house with a white cool coated flat roof. If there is an issue I can almost always see where it is and how to fix it. Annual inspections are also simple and quick.  It is much more cost effective and easy to repair.

What is the advantage of White Cool Coated Roofs?

Now we have reviewed the positive aspects of flat roofs, but you are probably not viewing this page because your roof is in great shape but because you have a problem. Shown below various problems associated with flat roofs.