Good understanding of heat transfer methods is necessary to choose the perfect roof insulation







The roof is one of the essential components of home construction because it protects homes from the weather elements and provides a comfortable living environment inside. From the beginning, the protective quality of roofs has been a dominant factor in its selection. As the environment changes drastically and temperatures have become extreme in many places. With summer temperatures rising alarmingly, the roof is once again in focus for improving home insulation that can drastically bring down living costs. The roof is the most crucial element in home construction because poor insulation can severely increase your utility bills, which can go up by 15%. To keep energy costs under control and use utilities lesser so that it contributes to environmental betterment, it becomes imperative to insulate your home, especially the roof correctly, to make your home more energy-efficient.

As the climate across the world is changing fast and becoming worse, homeowners face the challenge of making homes more energy-efficient. They can do so by upgrading existing homes or constructing new ones with advanced insulation. The focus must be on plugging the gaps through which unwanted heat transfer takes place so that it reduces the load on heating and cooling equipment. It does lots of good for the environment besides saving money on utility bills.  The roof is most prone to heat losses because of the vast area that remains exposed to the environment, and losses can be as high as 30%. Paying attention to roof insulation alone can contribute to considerable energy saving provided the wall insulation is in order and complements the efforts in overall insulation improvement.

How the roof insulation impacts operational costs, and building performance is what we will discuss in this article. Typically, the roof insulation of commercial buildings that have low-slope roofs remain attached to the roof deck and plays a vital role in providing thermal barrier as well as facilitating drainage and providing a working platform.  According to the experts at Storm Pros Roofing & Construction, for the best return on investment, homeowners must pay enough attention to roof insulation. 

The role of thermal barrier

Heat transfer through the roof happens in three different ways – conduction consists of heat transfer between objects which are in touch with one another, convection is the method of heat transfer in which heat travels through air or liquid media, and radiation is heat transfer through the air. Regardless of how the heat transfer happens, it affects the building performance, but there are ways of controlling it.

How to control heat transfer by conduction

Conduction is most prevalent when heat passes from one solid material to another, and it travels through the particles that constitute the objects. The process of heat transfer is intuitive, and to keep it under check, you must focus on the property of the insulation materials that enable it to control the rate of heat transfer.

R-value, which is the factor that denotes the heat transfer capability of the insulation material, should be high to achieve better insulation. In the next step, the target must be to increase the overall R-value of the roof system.  R-value denotes the insulation level, and higher R-value means better insulation. Since the R-value of different materials varies, the choice of insulating materials influences the heat transfer rate. Extruded polystyrene or XPS and polyiso have the highest thermal value per inch, and wood fiber is the poorest in this regard. Carefully considering the individual R-value of the components used in insulation contributes to the overall R-value.

Bridging across the components of the roof assembly and eliminating thermal shorts are some ways of controlling heat transfer. The bridging effect happens from the mechanical fasteners that aggravate the problem of heat transfer. Using adhesives instead of fasteners or using fasteners that possess non-thermal bridging properties are some ways to take care of the problem.

Convection heat transfer control techniques

Convection is the method of heat transfer through the air or gaseous media. Controlling air movement across the roof surface that takes place between the gaps in insulation and due to membrane upliftment by strong winds should help to control the heat transfer rate. To address the problem of heat transfer, you must install air barriers made from cement and gypsum boards, plywood foil-faced polyiso, fully adhered single-ply, and OSB.

The problem of heat loss by convection does not happen only in hot climates. It is also prevalent in cold climates too. It occurs when moisture moves from the warm interiors towards the dry exterior. As a result, no condensation takes place under the membrane. At places where the climate is hot, the movement of moisture happens in the reverse direction from the humid and warm exterior towards the dry interior that leads to condensation above the deck. To resolve the problem, you must use a vapor retarder made from a material of high permeability like polyethylene films, XPS, single ply, expanded polystyrene or EP, and asphalt felt.

Roofing insulation impacts drainage

The primary task of roof insulation is to improve the insulation quality of the roofing system that affects the overall insulation of the house. There is another role that it plays, which often many people fail to note. The insulation system impacts the roof drainage system that helps roofs last longer. By using tapered insulation boards, it is possible to create a slope to divert away from the water from the curbs and walls and channelize it towards the roofing outlets such as drains and gutters. It is easy to implement the technique for buildings under construction. It is also possible to retrofit it in old buildings by maintaining a gradient of a quarter-inch to a foot for creating the most appropriate slope that drains the water efficiently. However, maintaining higher slopes might be necessary depending on the complexities of roof geometry. 

Since the roof insulation experiences some good amount of foot traffic, and sometimes it serves as a platform for people to stand upon, adequate protection of the insulation is most necessary.  Covering it with boards and installing walkways are some ways of protecting the insulation.

Leave a Reply

Your email address will not be published. Required fields are marked *