Hello everyone,

I was wondering if anyone had any experience with using flex ducting in a high rodent area.  I live in the upper Midwest next to a bunch of soy beans and corn.  The mice and rats are everywhere even though we do keep their populations relatively low due to our three cats.

My geothermal contractor said the rodents are not a problem with the flex duct since they use insulated commercial grade.  I would go nuts if I had to tear down my ceilings and rip out the flex duct if the rodents start eating and nesting in it.  If I choose to go with rigid metal ducts that would mean more or the ceiling would initially have to get ripped out to put in the necessary supports for the sections of ducting. As the contractor is planning it now all supply and return runs will be flex duct.  Any help will be greatly appreciated.

                                                                                                                                    Thanks,
                                                                                                                                            Matt    

I have replaced flexible ducting from rats and mice chewing through it, especially possums in my area that get into a crawl space. If you have a big problem i would put in metal ducting to be safe. I don't know of any commercial grade flex duct that would stop the teeth of a mice. They usually like to nest in the insulation so i would also make sure to get your ductwork sealed since if they get into the insulation you could get a smell from it through the gaps in ductwork unless they are sealed with mastic.

I don't see why you would need to rip out the ceiling initially with metal duct but don't with flexible. Each duct is going to take the same amount of space, but the metal ducting will probably cost a bit more. Metal ducting also gives better airflow than flexible when installed properly.

Rodents love flex duct especially the fiberglass .First you should eliminate the rodent problem from within your structure. Galvanized steel duct if installed correctly would eliminate rodents from getting inside the ductwork.They will still chew or nest in the outer fiberglass insulation.Other than eliminating the pest, the best bet would be to line all galvanized ductwork.Hang ductwork so it not laying on ceiling. Yes as SkyHeating pointed out, better airflow,less fan horse power needed resulting in a higher efficiency system.

Almost nobody runs sheet metal down here (Jax, Fla) owing to the cost. Rodents will tear up flex and ductboard. An even bigger worry is that they also gnaw electrical cable. I pulled down some paneling awhile back and they'd gnawed romex down to bare copper.

Regardless of type of ductwork, be as certain as possible home is rodent proof.

If rodents can get to the duct work, the rodents will tear up that flex duct, that I guarantee. I've seen rodents gnaw through 2x6 wood framing and squeeze through openings the size of a dime. Once inside of the walls and ceiling/attic, they will cause a lot of damage. Romex is just another thing for them to gnaw on.

Unless it is made of the steel, glass or concrete, rodents will gnaw on it.

I agree, I have seen them be very destructive to plastic for no apparent reason. Now I use more steel and concrete and put poison and traps around.

Thanks for all the great information. It was a big help in making my decision.