MNM Exam 2 Questions With Answers

MNM Exam 2 Questions With Answers What are the primary functions of enclosures? - ANSWER- keep water out Prevent Air Leakage Control Light Control the Radiation of Heat Control the Conduction of Heat Control Sound What are the secondary functions of enclosures? - ANSWER- Resist Wind Forces Control Water Vapor Accommodate Movement Thermal Expansion/Contraction Moisture Expansion/Contraction Structural Movements Resist Fire - sometimes a primary function, depending on context Address Installation Requirements for the Exterior Wall Allow for Maintenance Weather Gracefully Where should glass be used at? - ANSWER- -Glass should be used where it can supply daylighting and provide views, but also limited to prevent overheating, glare, or excessive heat loss through the envelope. -Windows that can be opened and closed by the occupants can help reduce energy costs, in some cases What areas of the envelope should be air-tight? - ANSWER- The entire envelope should be detailed for air-tightness. Fresh air to be provided by building ventilation system, not by air leakage through ext. wall How can you maximize heat in the winter? - ANSWER- south-facing walls to let in heat and sunlight What 3 conditions must be satisfied for water to penetrate a wall? - ANSWER- -There must be water present at the outer face of the wall. -There must be an opening through which the water can move. -There must be a force to move the water through the opening. -If any one of these conditions is not satisfied, the wall will not leak How can you prevent water leakage? - ANSWER- -Keep water away from the wall, if possible via overhangs or projections. -Try to seal every opening. This "barrier wall" typically proves unreliable. -Eliminate or neutralize the forces that move water through a wall. -Provide strategies for internal drainage or secondary defense, via cavities within the wall assembly that allow for drainage (pressure equalized design and rainscreen design What are the 5 forces that move water through a wall? - ANSWER- gravity momentum surface tension capillary action air currents/pressure differentials How does water get into the building through gravity? - ANSWER- Is a factor in pulling water through a wall only if the wall includes an inclined plane that slopes into—rather than out of—the building -Sometimes a loose gasket or errant bead of sealant can create this condition even if components are designed correctly How does water get into the building through momentum? - ANSWER- -Momentum of falling raindrops can drive water through a wall only if there is a suitably oriented slot or hole that goes completely through the wall. -Neutralized by applying a cover to each joint in the wall or by designing each joint as a simple labyrinth How does water get into the building through surface tension? - ANSWER- -Causes water to adhere to the underside of a cladding component. -Allows water to be drawn into the building. -Provision of a drip on any underside surface to which water might adhere will eliminate the problem. How does water get into the building through capillary action? - ANSWER- -This is the surface tension effect that pulls water through any opening that can be bridged by a water drop. -Primary force that draws transports water through the pores of a masonry wall. -Can be eliminated by making each of the openings larger than a drop of water can bridge. -Can also/alternatively provide a concealed capillary break somewhere inside the opening What is pressure-equalized wall design? - ANSWER- Allows wind pressure differences between inside and outside of exterior wall to neutralize themselves How does pressure-equalized wall design work? - ANSWER- -Create an airtight plane, called the air barrier, behind the outer face of the wall. -Air barrier is protected from direct exposure to the outdoors by an unsealed, labyrinthjointed layer known as the rainscreen.