M1502.4.1 Material and size. Exhaust ducts shall have a smooth interior finish and be constructed of metal having a minimum thickness of 0.0157 inches (0.3950 mm) (No. 28gage).

(a) can I use metal spiral pipe (not sure if it meets the "smooth" definition) ? e.g.,: https://www.homedepot.com/p/Master-Flow-4-in-x-5-ft-26-Gauge-Spiral-Pipe-26SP4X60/205330690 (b) does it need to be 4" or can it be a larger diameter


According to your pic yes. The smoother the pipe less chance of lint build up.Stay with the 4 inch.They make brushes to clean out easy.And fits the vent caps made for dryer.

  • Thank you for your reponse. Just to clarify It is ok to use the spiral pipe and no its not ok to use larger diameter – firefiend Jun 8 '19 at 0:54
  • Yes to the pics you sent. My real feeling is get smoother pipe. Your choice – user101687 Jun 8 '19 at 0:58
  • that pipe is pretty smooth on the inside .... i wonder if the air flow is less turbulent in one of the two directions – jsotola Jun 8 '19 at 1:13
  • Aim it to air flow ,if you want, – user101687 Jun 8 '19 at 1:22
  • smaller pipe has stronger wind, you need wind to prevent lint build up. so say with 4" – Jasen Jun 8 '19 at 10:37

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