Attic ventilation is an often overlooked feature of roof construction, but it is important to both the house’s construction and the material on the roof. Though it would seem logical to seal attic and roof areas tightly against moisture and cold air, this method is not the best way to protect materials. Ventilation for hip roofs, in particular, requires special methods to allow for proper air flow.
Importance of Ventilation
Good ventilation is advantageous for lowering heating and cooling costs, preventing damage to roofing materials, reducing deterioration to floorboards and lessening the incidence of ice dams on the roof. Insulation and ventilation should get equal attention, according to the American Society of Home Inspectors website. Soffit vents, can vents, ridge vents, attic turbines and power vents are common types of attic ventilation equipment. The rule of thumb for attic ventilation is 1 free square foot of ventilation for every 150 square feet of attic space.
Hip Roof Construction
The hip roof is a type of design that has all of its surfaces sloped down to meet the walls on all four sides, generally in a gentle slope. This design is different than the gable roof that is commonly found on homes in that it is shaped like a pyramid. Hip roofs have a more complicated structure of trusses, though the walls are easier to build because they are all the same size. Gable roofs have two shorter wall surfaces and two tall surfaces. Roof space is more limited in the hip roof design, which can make ventilation more difficult. Hip roofs are more resistant to high winds, however. Hip roofs come in a number of adaptations, including simple hipped roofs, pyramid-shaped hip roofs, cross-hipped roofs which puts two hipped roof areas together, half-hipped roofs which create an eave on the roof edge and Dutch gable which is a hybrid between gabled roof and hipped roof designs.
Ventilation for Hip Roofs
Hip roofs may not get sufficient ventilation because they create a large volume of space that requires a more complex system of air flow. Also, commonly used ridge vents do not provide a sufficient amount of air flow on their ridges, according to the VentMASTER Attic Ventilation website. This design can cause problems with overheating and moisture condensation on roofing materials as well as in attic areas.
Other Hip Roof Ventilation Options
Static/passive roof louvers can also be installed to assist in the ventilation in attic roofs. Special vents as well as ventilation fans may be necessary to provide good airflow for hip roof areas. Attic fans with automatic thermostat and humidistat features are the solution for this roof problem in hip roofs.
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