Hi all,

I am currently working with an HVAC contractor to help us finish our unfinished basement. I would like to reduce noise transfer between ducts in the rooms in the basement but also between the basement and the main floor of our house. Basically I’d like the basement space to be somewhere where people can be fairly loud with things like movies or music and hear as little as possible between rooms and also between the basement and the main floor and visa versa. (I already know the basement ceiling insulation and such is important and I’ll be addressing that separately)

I’m wondering, when they go to install the new duct runs in our basement and a new return air in the basement, what should I do in order to prevent a lot of noise going throughout the HVAC system?

I’m not sure how much detail to give here, and obviously without you seeing it we are limited here. But here’s something to maybe work with:

• There will only be one single return in the basement. It will be located somewhat near a return air duct on the main floor. But in order to get to the main floor return, the basement return will go about 5 feet South to the main return trunk, then immediately bend around to go 12 feet the opposite direction (North) and then 3 feet up into the main floor return.
• As far as supply ducts go perhaps I could describe it this way. Of all supply lines, the closest distance between a main floor duct and a basement duct would be the following. The basement supply register duct goes about 15 feet to the East and connects to the main supply trunk. It then immediately bends the opposite direction (West) and goes 5 feet and then connects to the main floor supply register.

The HVAC installation company that I’m likely going to go with has essentially said the following:

• They pretty much always do hard ducting instead of flexible for all of their installations.
• For the return air they would have a 12x12x4” box with 1” thick board insulation for the first 3 feet of the return air duct and they said that this should eliminate 99% of noise for this return (I'm assuming this is both ways, into and out of this return). They said they would use the following product for that 3 foot section: “Quiet Barrier (TM) Specialty Composite”
• For the supplies they said they didn’t think that noise transfer would really be an issue. But if I was concerned about it, they could maybe do something where the last couple of feet of supply ducting is a little bit bigger than normal but some kind of insulation would go inside (?) the duct which would bring its cross-sectional area back to “normal”.

A family member also told me when they built their basement that they did flexible ducting on the last few feet of their supply lines in order to produce a few bends in the line to reduce sound transfer.

What would you all recommend I do? Should I go with the HVAC company’s recommendations? Would you suggest I do something else? I’m quite a bit more sensitive to noise than others and so I want something that will work well. I’m not terribly concerned about cost, though I don’t want to go too crazy.

Thanks!