What is the HUD-code requirement for whole-house ventilation in a mobile home?
Thursday, January 31, 2019
HUD requires that a manufactured home have a whole-house ventilation system with a minimum capacity of 0.035 cubic feet per minute per square foot of floor area. So 1200 square foot home would require 0.035 x 1200 = 42 cfm fan capacity. But the code further states that it cannot be less than 50 cfm or more than 90cfm, so a 1200 square foot would need 50 cfm of mechanical ventilation.
The system must have a manual control that is labeled “WHOLE-HOUSE VENTILATION,” and cannot draw or exhaust air from the crawl space, floor, wall, or ceiling/roof assemblies. The ventilation system can be part of the home’s heating and cooling system, but must be capable of being operated separately.
The whole-houe ventilation requirements are typically met by manufacturers with a small, low volume fan behind a grille in the ceiling of a hallway that exhausts out the roof or a fresh-air intake duct from the roof that connects to the return air plenum of the furnace or air handler. The requirement that it be be able to be operated separately is fulfilled by setting the air handler fan at “ON” at the thermostat if the heating/cooling system is off.
Here’s the full text of the HUD whole-house ventilation requirements at 24 CFR 3280:
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