Air ducts under house

[cmv73]

I have a 35 year old house that is raised about 1 foot off the ground. Over the years my air ducts have come loose and are touching the ground in some spots. I know this cant be good with the moisture that can stay under there. I am interested in changing all the ducts under the house. Could anyone tell me the best kind of duct for this situation. Please feel free to add any other advice.

[HayZee518]

What I'm thinking is a flexi duct. It is fiberglass with an aluminized outer coating and is flexible. Since you're so close to the soil, galvanized will over time rust out again.

[lonestarheir]

I usually don't disagree with HayZee, but I have to on this one. I would go back with metal, insulated with foil back insulation. If properly maintained it will last you much longer than flex duct. Ususally what happens is ducts are broken or damaged by the various people that have to access the crawl space. So the best thing to do is visually check each time someone leaves the space to make sure that no damage was done. Flex duct will make access to the area a bit better, but will have to be replaced about every five years or so. The other problem with flex is the ability for vermin and such to get into it. If properly sealed the metal will not. Flex should be cheaper, but metal will pay for itself in the end.