Roofing Shingles: The Good, the Bad, and the Ugly

What you need to know about roofing shingles

If you’re buying a tract-built house, the chances are close to 100 per cent that the roof will be asphalt shingles, the most cost efficient roofing material currently available.

The builder will ask you to pick one from a selection of colors and grades displayed on sample boards. But if you’re like most people, you’ll find it hard to imagine what a few pieces of asphalt encrusted shingles will look like 15 to 30 feet from the ground and replicated 1,600 to 2,000 times.

It’s much easier if you start with the big picture. When you pull back for that big pan shot, you’ll see that the slope of the roof is its defining characteristic.

If the slope of the roof on your new house will be shallow, 15 degrees or less, the roof will not be a strong visual element. Looking at it from the ground, you’ll see the leading edges of the shingles and their overall color more than the shingles themselves or their pattern. Picking a good quality shingle that keeps out the elements without going overboard on looks is a reasonable strategy.

But given the housing styles that are popular today, it’s more likely that the roof on your new house will have a much steeper slope and be a prominent architectural feature.

If you’re considering that perennial favorite, the Cape Cod, half the front elevation will be the roof. In both theses cases, the shingle pattern will be very visible, and the roof itself will be the first thing those resale buyers will see as they drive down the street towards your house.

For resale, looks count.

In the world of asphalt shingles, there are two types, “3 tab” and “dimensional,” also called “architectural” and “laminate.” A 3-tab shingle has two notches cut into the lower edge so that when it’s laid on a roof it looks like three smaller shingles. Seen from below, 3-tab shingles have a very distinguishable repetitive pattern.

This type of shingle costs less than a dimensional type, but its precise pattern requires more time to install. Thus, it is less favored by roofing crews who are usually paid by the number of shingles they install, not by the hour.

For a shallow pitch roof, however, the three tabs is a reasonable choice.

A “dimensional” or “laminate” shingle has extra pieces of shingle laminated to it that give the appearance of thickness and texture when seen from below.

There is no discernible shingle pattern so that it can be installed more quickly than the 3-tab type. Besides the real shadow line created by the added thickness of the extra pieces, most manufacturers embellish this with artificial shadow lines created by the artful placement of colored granules.

The thickest and most expensive dimensional shingles, which usually carry the designation “40-year shingles,” often have two artificial shadow lines plus an overall subtle texturing of the shingle.

The “30 years” dimensional shingle has only one fake shadow line, less subtle blending of the granule colors, and the shingle is not as thick.

The least expensive, “25 years” dimensional shingle, which many tract builders offer as standard, has a less pronounced shadow line, and its thinner shingle creates less of a three-dimensional effect.

To give consumers more choices, some shingle manufacturers also sell a less expensive 3-tab textured shingle with a fake shadow line.

When viewed up close on a sample board, only the shingle manufacturer’s artifice will be apparent. To get an idea of what the shingles will look like when viewed from afar, you need to find a finished house with a roof that has a similar size and slope.

The other consideration when choosing an asphalt shingle is longevity–how many years can it shed water and keep the rest of your house dry? Assuming that the roof has an adequate slope and is installed correctly, this will depend on the local climate and how much asphalt, the key waterproofing ingredient, is on the shingle.

Shingles were once differentiated by weight, which indicated the amount of asphalt in the shingle. Then, about 20 years ago, as more and more manufacturers switched to making shingles with fiberglass cores that did not require as much “black gold,” they began to categorize shingles by their projected years of useful life.

Since there is no industry-wide standard for what constitutes “40 years,” “30 years” and so forth, this designation has been left to individual manufacturers to determine.

In the absence of manufacturing precision, some explanation of asphalt shingle mechanics may be helpful.

• The key factors are time and temperature.
• The hotter asphalt becomes on your roof and the longer it stays hot, the shorter its useful life will be.
• Even seemingly benign weather will heat up a roof.
• When the air temperature is a mere 75 degrees, the roof surface can easily reach 140 to 160 degrees.
• The heat causes the asphalt to expand; the hotter it gets and the longer it stays warm, the longer it will be in a “stretched” position. When the sun goes down, the asphalt contracts back into its original position.

The UV rays of the sun are problematic as well, attacking the asphalt and causing it to become brittle and cracked. The granules–those pulverized stones or glazed ceramic pieces that give a shingle its color–function as a “UV umbrella” to shield the asphalt from the sun.

Eventually after several thousand heating and cooling cycles, the asphalt loses its ability to contract back into its original shape, and the granules start to fall out, exposing the asphalt underneath to the sun.

How many years does it take for a roof to look bad? Climate clearly affects low long a given manufacturer’s “25-year” shingle will last; so will its color.

Since the staying power of the granules is a critical factor, a quick, but telling test no matter where you live is to run a quarter across the granules on a builder’s sample. If a lot come off, it’s not a great shingle, and you should question the quality of the other materials the builder is using.

The core material in the shingle can affect its longevity. In the northern areas, which experience extreme freeze-thaw conditions, some roofers prefer an older style asphalt shingle with an organic mat core instead of a fiberglass one.

Before you pick one of the shingles that your builders offers, consult with several local roofers and building supply stores.

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