Roofs, Roofs, Roofs (part 1)

December 2, 2015

Roofs, roofs, roofs. It’s a key factor in any home, yet it can be overlooked so easily. They just sit there with no moving parts. They are usually a bland or dark color. And they're actually at their best when we don't notice them. If your roof is grabbing your attention, it probably means you have a leak. Then, you realize no building component is more important or works harder.

For this month we will concentrate on what is called 3-tab shingle asphalt. By far the largest type of roof used in the Midwest. Asphalt shingles come in two varieties: fiberglass and organic.

Fiberglass shingles are made of a woven fiberglass base mat, covered with a waterproof asphalt coating, and topped with ceramic granules that shield the product from harmful UV rays. Due to the composition of the fiberglass mat, less asphalt is needed to give the shingles their durability and strength. The result is a lighter weight and thinner roofing material. Fiberglass shingles also have a higher fire rating than organic varieties and generally carry a longer warranty. Fiberglass shingles were developed in the 1980s, but have quickly become the roofing material of choice for most homeowners and contractors today.

The traditional organic mat-based shingles are made from a recycled layer of felt paper, asphalt-saturated for waterproofing, and coated with adhesive asphalt into which the ceramic granules are embedded. With 40 percent more asphalt than their fiberglass counterparts, the traditional organic mat-based shingles are heavier, thicker and more costly. While organic shingles are considered more rugged and more flexible, they are also more absorbent and can warp over time. The additional asphalt content also makes them less environmentally friendly. All Three-tab shingles are distinguished by cutouts—tabs—made along their long lower edge. The result is that “each shingle looks like three separate pieces when installed, but it’s only one.” Architectural asphalt shingles contain no cutouts, but their lower portions are laminated with an additional asphalt layer. This creates the contoured, dimensional look that gives them their name. Asphalt sealant bonds the layers, reinforcing the shingles’ waterproof capability. Though durable, architectural shingles are not recommended for low-sloping roofs, which are more vulnerable to wind-driven rain.

 


We experience a lot of double layering and some times triple layering of shingles on one roof. This happens when the homeowner does not opt to take off the older layer and adds a second or third. Add several inches of snow throughout the winter. The excess weight created adds stress to the trusts and frame, causing the roof to sag. Spend the extra dollar and have the professionals remove the old layer. In these instances double layering is no good in the winter.

Proper Ventilation is also important. Without it, heat and moisture build up in an attic area and combine to cause rafters and sheathing to rot, shingles to buckle, and insulation to lose its effectiveness.

Therefore, it is important never to block off sources of roof ventilation, such as louvers, ridge vents or soffit vents, even in winter. Proper attic ventilation will help prevent structural damage caused by moisture, increase roofing material life, reduce energy consumption and enhance the comfort level of the rooms below the attic.

In addition to the free flow of air, insulation plays a key role in proper attic ventilation. An ideal attic has:
•    A gap-free layer of insulation on the attic floor to protect the house below from heat gain or loss.
 
•    A vapor retarder under the insulation and next to the ceiling to stop moisture from rising into the attic.
 
•    Enough open, vented spaces to allow air to pass in and out freely.
 
•    A minimum of 1 inch between the insulation and roof sheathing.
The requirements for proper attic ventilation may vary greatly, depending on the part of the United States in which a home or building is located, as well as the structure's conditions, such as exposure to the sun, shade and atmospheric humidity. Nevertheless, the general ventilation formula is based on the length and width of the attic. NRCA recommends a minimum of 1 square foot of free vent area for each 150 square feet of attic floor—with vents placed proportionately at the eaves (e.g., soffits) and at or near the ridge.

 

 

 

 

 

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