The home I purchased has a crawlspace below an addition that was put on to the original structure. The HVAC contractor that did the work ran 2 long runs of flex-duct to the 2 registers in the room of the the crawl space.

Is this acceptable? Do I need to be concerned about the elements or possibly animals getting into the crawl space and chewing holes in the flex duct?

2 Answers 2


I would not use flexible duct in a crawl space. It is like a 4 lane freeway for animals and bugs. Rigid duct is very easy to piece together. Even long runs might take you an extra few minutes.


Flex duct is commonly used in crawl spaces. That said it is vulnerable to punctures, animals and other hazards. Animals have no particular reason the chew the ducts, but sometimes they will anyway. Flex duct is cheaper to install than hard duct, and (at least initially) it is easier to make it not leak.

Put in some rat traps and be happy I'd say.

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