Heat Transfer

Introduction
One of the most important aspects of a house and one that is not usually paid much attention to is the roof. The roof is responsible for maintaining the harsh elements of nature out such as rain, snow, wind, and sun. It helps to create a safe and hospitable environment where everyone can feel comfortable no matter the conditions on the outside. Yet achieving this goal is no easytask. Lots of study and design must be taken into account before one begins construction. A roof can be made using a number of material including cement, metals, woods, plastics and glass just to name a few. For the construction of a house in Puerto Rico, the most commonly used material is cement. However, a roof made of cement alone is continuously exposed to sunlight and rain causing a great dealof damaged. From exposure to sunlight the surface gets oxidized leading to chemical humiliation, weakening the roof. And due to the moisture caused by the rain, the roof experiences additional corrosion and contraction forces. In order to prevent further damage from occurring, a roof coating can be applied. A roof coating is a monolithic and fully adhered fluid applied on the roof surface. Itpossess elastic properties that allow it to stretch and return to their original shape without damage. In addition, the benefits of applying a roof coating is that it eliminates leaks while keeping the roof surface cool maintaining lower temperature on the inside and reducing energy cost.
Currently, a variety of products can be found in the market designed for the application of roof coatings. Someof the most common brands available in Puerto Rico are Lanco, Crossco, Gardner and Superior Product Coating. Each product contains its own special type of formula which can include polymer modified acrylic elastomers and polyureas, asphalt cutbacks and emulsions, silicones, SPF and high-performance urethanes. However, the right choice of coating depends on the surface on which it is to be appliedand the purpose. For example, white roof coatings, tinted roof coatings, elastomeric, aluminum and metal roof coatings are some of the most commonly employed roof coatings yet they all contain different features and uses. White roof coatings, for instance, are chosen because of its opaque and reflective ability due the transparent polymeric materials such as acrylic and white pigments liketitanium dioxide. These coatings typically reflect 70 to 80 % of the sun’s energy and are good for areas that have high heat and high humidity. Another well used coating is the elastomeric roof coating which is very versatile and can be applied on a large variety of roofs such as single-ply, metal, asphalt, polyurethane foam or concrete roofs. An elastomeric roof coating creates a uniform, seamlesssurface that remains flexible even at low temperatures. It is also elastic and reflective in nature.

For the purpose of this project the selected roof coating was Master-Seal, which was designed and produced for Puerto Rico. The Master-Seal surface applied waterproofing system is the result of more than 20 years of investigation and field testing. Manufactured with the best synthetic rubberemulsions available in the industry it is specially designed for tropical climates, horizontal roofs with minimum slope and drainage where water ponding is prevalent. It is also resistant to foot traffic and reduces interior temperatures. Master-Seal is comprised of three specialized products reinforced with a fiberglass or polyester mesh. The first is the Master-Seal Roof Primer: a thin liquidformulated to penetrate porous surfaces to seal and provide a strong surface bond. After drying it becomes a tough and flexible film, clear in appearance. The second is the Master-Seal Roof Sealer: a heavy, thick liquid used to seal cracks and crevices. It is designed to become, after drying, a tough and flexible waterproofing film of semi-transparent red color. And last is the Master-Seal Roof Coating:...