24 CFR § 3280.708 - Exhaust duct system and provisions for the future installation of a clothes dryer.
(a) Clothes dryers.
(1) All gas and electric clothes dryers must be exhausted to the outside by a moisture/lint exhaust duct and termination fitting. When the manufacturer supplies the clothes dryer, the exhaust duct and termination fittings must be completely installed by the manufacturer. If the exhaust duct system is subject to damage during transportation, or a field connection between transportable sections is required, complete factory installation of the exhaust duct system is not required when the following apply:
(i) The exhaust duct system is connected to the clothes dryer, and
(ii) A moisture lint exhaust duct system is roughed in and installation instructions are provided in accordance with paragraph (b)(3) or (c) of this section.
(2) A clothes dryer moisture-lint exhaust duct shall not be connected to any other duct, vent or chimney.
(3) The exhaust duct shall not terminate beneath the manufactured home.
(4) Moisture-lint exhaust ducts shall not be connected with sheet metal screws or other fastening devices which extend into the interior of the duct.
(5) Moisture-lint exhaust duct and termination fittings shall be installed in accordance with the appliance manufacturer's printed instructions.
(b) Provisions for future installation of a gas clothes dryer. A manufactured home may be provided with “stubbed in” equipment at the factory to supply a gas clothes dryer for future installation by the owner provided it complies with the following provisions:
(1) The “stubbed in” gas outlet shall be provided with a shutoff valve, the outlet of which is closed by threaded pipe plug or cap;
(2) The “stubbed in” gas outlet shall be permanently labeled to identify it for use only as the supply connection for a gas clothes dryer;
(3) A moisture lint duct system consisting of a complete access space (hole) through the wall or floor cavity with a cap or cover on the interior and exterior of the cavity secured in such a manner that they can be removed by a common household tool shall be provided. The cap or cover in place shall limit air infiltration and be designed to resist the entry of water or rodents. The manufacturer is not required to provide the moisture-lint exhaust duct or the termination fitting. The manufacturer shall provide written instructions to the owner on how to complete the exhaust duct installation in accordance with provisions of § 3280.708(a)(1) through (5).
(c) Provisions for future installation of electric clothes dryers. When wiring is installed to supply an electric clothes dryer for future installation by the owner, the manufacturer shall:
(1) Provide a roughed in moisture-lint exhaust duct system consisting of a complete access space (hole) through the wall or floor cavity with a cap or cover on the interior and exterior of the cavity which are secured in such a manner that they can be removed by the use of common household tools. The cap or cover in place shall limit air filtration and be designed to resist the entry of water or rodents into the home. The manufacturer is not required to provide the moisture-lint exhaust duct or the termination fitting;
(2) Install a receptacle for future connection of the dryer;
(3) Provide written instructions on how to complete the exhaust duct installation in accordance with the provisions of paragraphs (a)(1) through (5) of this section.