is it a code to use ridgid metal to vent a bathroom exhaust fan

Question

I live in NY and the building insp. said I have to remove the plastic flex on the bathroom exhausts and replace with ridgid steel pipe. I know it is good practice to use insulated pipe but this is a seasonable building with no heat.

Answer 1

 

 

Hi,

 

The only thing I was able to find which unfortunately doesn’t specify the material type that has to be used for the bathroom exhaust is here (Residential Code of NY State) - http://publicecodes.citation.com/st/ny/st/b400v07/st_ny_st_b400v07_16_section.htm?bu=NY-P-2007-000013

 

The idea behind the rigid bathroom fan duct is that the flexible type tends to collect condensation which results in duct sagging and accumulation of condensate in the low spots. There are also BPI Standards that require air ducts running through unconditioned spaces to be insulated.

 

There are also exhaust fan manufacturers recommendations (the following is from Broan):

What type of duct is recommended, rigid or flexible?

It is recommended, where possible, to use rigid duct. It has less resistance to air flow and allows the fan to operate much more efficiently. If flexible duct is used, be sure the duct is as straight as possible.

You may need to call your local building department for advice or convince the inspector that there will be no condensation since this property has no heating system and it is only used on seasonal basis / during warm months.

Comments

I understand the reason behind ridgid isulated duct or i have even used insulated flex in homes but this is a bunk house used only for summer and the building inspector is a real ass and says I have to change it out because it is a building code. He has not submitted me with any building code section yet . I think he is full of it. This is the same guy who told me to connect my flex to the plumbing roof vent pipe.

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Why don't you call or visit local building department and describe this situation. Ask for the paragraph from the building code that he based his request on.