HVAC Ducting: Rigid Metal vs. Flex
My company does about half our work in new construction and half in whole house remodels. If you were to blindfold me and take me into a house that has the drywall removed, I could tell you the decade it was built just by seeing the ductwork. Here in Austin houses built in the 50’s & 60’s have just about 100% rigid metal ductwork. Then, starting at the 70’s flexable duct starting on the scene and rigid metal has almost totally disappeared from residential construction. I’ve only been building since 1995 so I can’t say for certain why we left the sheet metal guys behind but I suspect it was manly for cost reasons. In this video I’ll make a case for going back to rigid metal ducts for your trunk lines and keeping your flexable ducts to the last 10′ or less of a duct run. There are many reasons to opt for Rigid Metal Ducts but here’s a few highlights.
-smoother interiors mean better air flow
-rigid metal is more likely to be installed without constrictions whereas flex duct can easily be pinched down
-rigid metal is installed then mastic is applied to air seal THEN insulation is applied on the outside so there is less chance of fibers getting into your air stream
-rigid metal is straight and smooth walled, you have to work to crush or kink rigid metal
-rigid metal is not easily damaged by rodents and UV light
I find there to be few HVAC companies who utilize this strategy so be sure to ask around before evaluating bids on an HVAC system that are entirely consisted of flex ducting.
-Matt Risinger, Principle of Risinger Homes an Austin TX based Architect’s building company