A Guide To Attic Insulation Types And Installation
OLIVER OLINGER, WRITER
Ohio-based contractor Corey Thrush was doing an inspection one day when he noticed something odd.
The roof, though fairly new, had a lot of nail pops – and nails that stick up can break or damage the shingles.
Thrush, co-owner of Thrush & Son Complete Home Improvement in Dayton, OH, was puzzled. Everything looked fine from the outside. So he asked the homeowner if he could look in the attic.
What he saw was astonishing: the attic was full of insulation – more than 3½ feet of it (after settling).
Recommendations for that area of Ohio call for only 16 to 20 inches of insulation. Plus, no baffles had been installed near the eaves, so the soffit vents were completely blocked.
During the hot summer months, heat trapped in the attic had caused the shingles to buckle severely and the nails to pop.
Using the correct amount of insulation is crucial to a balanced and efficient roof system.
The Immense Importance Of Insulation
Attic insulation is an integral part of a roof system. Too much insulation can cause ventilation problems while too little can contribute to heating/cooling issues for the living spaces below.
Proper attic ventilation can prolong the life of a roof by keeping attic temperatures more evenly controlled throughout the year.
High attic temperatures during the hot summer months can cause roof shingles to distort, deteriorate and buckle over time. Spray foam on the underside of the roof deck magnifies the effects of the heat. Properly installed insulation, however, will protect the home’s living areas from attic heat and save money on cooling costs. Together with balanced ventilation, insulation will help keep attic temperatures and humidity levels low enough in the summer to prevent roof problems.
Poor ventilation in the winter can lead to ice dams and condensation. Proper insulation in cold weather keeps the heated air inside the house and out of the attic where it can create condensation on the roof deck and cause water damage to the wood. Warm air escaping into the attic can also cause snow to slowly melt on the roof. The resulting water then drips down toward the eaves, freezes again and becomes an ice dam, which will damage the roof even more.
R-Value and Climate
Insulation’s resistance to the flow of heat is referred to as “R-value.” However, other factors, such as insulation type and thickness, should be considered when choosing insulation because R-value only rates heat flow by conduction. R-value does not measure convection, radiation or air filtration. The Department of Energy recommends R-values between 30 and 60 depending on climate zones, although almost every zone allows for R-values up to R-60.
When installing a roof system, more is not necessarily better. Less is not better either. A roof system works effectively when all of the components function together properly.
Installing the proper amount of insulation in an attic requires that a contractor know the recommended R-value for a particular climate and correctly install right amount of insulation to meet that R-value. Contractors also should be aware of the following:
Make sure that space between joists and studs is filled. No exposed ceiling drywall should be visible anywhere.
Do not cover attic vents. Soffit vents may require baffles to allow for air flow past the insulation.
Do not compress insulation to make it fit into awkward places. Compressing insulation reduces its ability to insulate against heat or cold.
Too much insulation can result in moisture buildup in the attic, which can rot wood, facilitate mold growth, leak down into the living areas and damage the roof. Stay within the recommendations.
In areas where moisture is inevitable (such as around pipes or ducts), use an insulation that will not react negatively to getting wet. Fiberglass and cotton batts and loose-fill cellulose absorb water and condense when exposed to moisture. Contractors can use a moisture-resistant insulation such as polystyrene or polyisocyanurate insulation sheets.
A Few Words of Caution
Foam insulation is the topic of an ongoing debate. Electric companies and many homebuilders believe that spray foam’s high R-value makes it more energy efficient. They advocate using it on the entire roof deck, including between the rafters, to insulate the whole attic instead of just the attic floor.
Foam’s insulating properties can indeed make for a cooler (in the summer) or warmer (in the winter) living space, cutting down on heating and air conditioning costs.
Roofers, however, often see the dangerous (and expensive) side of spray foam. In fact, most manufacturers will not warranty asphalt shingles on a roof lined with spray foam.
Using spray foam to insulate the entire attic can seal off attic ventilation so air doesn’t flow properly. It can also make thorough roof inspections difficult or impossible.
If water infiltrates through the shingles, a roof deck can rot without any visible signs. Closed-cell spray foam won’t even allow moisture to penetrate, so any moisture above the foam will be trapped between the foam and shingles.
Roof System Done The Atlas Way
Proper attic insulation and ventilation are critical to maximizing the life expectancy and efficiency of a roof. Combined with the components of an Atlas Signature Select® Roofing System – Atlas shingles, underlayment, hip and ridge shingles and starter shingles – the roof is designed to help protect the home for many years. Contact Atlas today to learn more.