Frequently Asked Questions about Roofs, free information

FAQ's about Roofs
by Mike Conley Q. Why do shingle roofs last about ten years when they are warranted for twenty to twenty-five years?
A. The manufacturer warrants the material and workmanship of the shingle for twenty to thirty years, depending on the quality of the shingle, not the installation, or the age. (There are even forty and fifty year warrantees, in some parts of the country) That does not mean the roof cover will last twenty years. The average in this area is twelve to fifteen years, for a shingle roof. Many factors affect the longevity of a shingle roof cover. In Florida the wet, hot climate affects the materials that make up the shingle. The granules give the shingles color and are washed away by repeated wind and rains. The hot sun affects the asphalt by breaking it down and drying up the essential oils in the asphalt. That's why shingles will cup, curl and become brittle. In addition, the attic ventilation will affect shingle longevity. A hot attic will age the shingle quicker than sun alone. Generally, the highest quality shingles last the longest, if properly installed and on an adequate surface.

Q. I'm seeing more and more radiant barrier installed in new homes. If this barrier is reflecting 95% of the radiant heat from the sun, as advertised by the manufacturer, how does it affect the shingles on the roof?
A. Radiant barrier is very effective in maintaining lower attic temperatures and, a significantly better comfort zone in the home. Tests have shown that using it does not impact the life span of the roof shingles in any noticeable way.

Q. How does radiant barrier work?
A. Radiant barrier is reflective sheeting that is stapled between the roof rafters or trusses. It is sometimes draped, loosely, over the rafters prior to the roof sheeting being installed. It is now available attached to plywood sheeting. The radiant side faces down or towards the attic.
The majority of heat gain in any attic is from the sun. This is known as radiant heat, as it is radiating from the sun. As sunlight beats down on a roof, the energy (radiant energy) that penetrates the roof covering and decking converts to heat. Exactly like sunlight coming through your window. The one difference is that some of that sun energy coming through your window is actually light because the window is clear. Your roof does not allow light to pass because it is opaque. Therefore, there is a much larger amount of heat generated in your attic than in your house. Radiant barrier is very effective in reflecting that heat back through the roof before it heats up your attic. The end result is a cooler attic, more life span of your roof cover, an A/C system that cycles less. More energy savings all around.

Q. Is any one-roof style better than another?
A. The worst kind of roof style is the Spanish style flat roof with a raised wall around its perimeter. It is swimming pool waiting for the next rain to fill it. It works well in the southwestern states where the climate is dry, but not in Florida. We have a lot to them in this area. This kind of roof is designed with drains to allow for run off. Often times they are not maintained and they become clogged. Generally, basic, simple roofs are the best. The fewer breaks and protrusions through the roof deck the better. In addition, a steep roof does better than a low slope roof. Steep roofs shed water more quickly and dry out much faster. A rule of thumb for low maintenance roofing is, stay away from flat or very low sloped roofs, (0/12 to 3/12) minimize breaks in the roof; dormers, multi-level roof lines all require detailing, flashing and are opportunities for moisture to enter eventually, keep it simple.

Q. Why is attic ventilation so important?
A. Attic's act as an air space between the sun and our living area. Attic's afford us a buffer so that we have some control over the amount of energy we need to live or work in a comfortable environment. In a multi-story building, each floor serves to accomplish the same thing. Most existing housing in this area is single story. Allowing the attic to "breath" so to speak creates a buffer space between the suns heat and the A/C setting in our homes. There are various materials on the market that contribute to this end. Fiberglass insulation slows the penetration of heat through our ceilings. The way it does that is by creating stagnate air within the fiberglass. Air is a fairly good insulator against heat when not moving. (Just the opposite is true when the temperature is too cold) Radiant barrier helps prevent heat from entering the attic. Tile roofs have an air space between the tile and the underlayment. This adds yet another air barrier. Mostly allowing attic air to vent is the best possible method of preventing attic heat gain during the day.

Q. What is roof flashing and why is it used?
A. Flashing, usually metal, is a bridge between dissimilar building materials. It is usually found at the drip edge of a roof, around a chimney or between the roof cover and a wall. Flashing is used because of its flexibility and it can be shaped to fit most corners and angles. Areas that are flashed usually have a lot of moisture and wear and tear. Metal flashing wears well and takes a lot of abuse.