Soundproofing and Shared Heating Vents
4/16/2013 at 1:30:54 AM
I am planning to soundproof the ceiling of a downstairs suite bedroom that has our guest bedroom above it. I understand what needs to be done to decouple the ceiling with hat channel and clips, and add mass with insulation between the joists prior to hanging 5/8 drywall or sound drywall. I am just struggling with whether or not to eliminate the shared heating register on the ceiling or keep it.
The upstairs and downstairs registers appear to be quite similar oriented off of the main duct. The downstairs bedroom has its own electric baseboard on the outside wall if needed, but of course I would like the keep the heat pump efficiency of the air duct for financial heating costs over time.
If I am only looking for a ~50% reduction in noise to be comfortable I have considered the following options:
1. Keep the register and move it on the ceiling by adding additional length to duct with duct board that has a few turns to reduce noise transfer.
2. Same as above with acoustical flex tubing instead.
I understand that this cold reduce air flow - but if the register was removed and just ended there would be no air flow at all. Isn't some warm air flow through the register better than using 100% baseboard electric?
Any thoughts or experiences with this?
Thanks in advance for any responses.
4/16/2013 at 11:25:29 AM
Those two options will help.
Keep in mind that acoustical flex tube and even standard 26-32 gauge galvanized steel ducts, sealed well, will only baffle higher frequencies. Insulating around these further reduces the sound transmission. Ideally the rooms downstairs would have an independent HVAC system. Removing the vent entirely, is illegal - occupied spaces require fresh, conditioned air based on square footage, occupancy, and use.
One (thorough and expensive) option would be installing electric baseboards and an air exchanger for those rooms. On the cost effective side of options - maximize the space between vent openings and insulate between them well.
Hope this helps! Let me know if you have any questions.
Tj Winter
4/16/2013 at 5:16:51 PM
If your messing with the ceiling you may have many more options than you think. Re-designing the duct work using sheet metal fittings may allow ducting to the basement floor level.
If bulkheads and air flow are not problematic re-locate the basement "take-off "fitting and run your duct to a more suitable location. In a corner/closet to floor level would be easy to hide.
4/17/2013 at 8:26:16 AM
What you have proposed will all work as additive measures to reduce sound transfer. The insulated flexible duct is also a good idea, however when adding flex duct you should use the next size up to maintain the flow. Bringing the duct straight from the plenum (main duct) will ensure that the air is not "shared" between the two rooms and thus reduce sound leakage.
Also a note of caution, when running flexible ducts, keep them free of kinks as much as possible and opt for gentle bends instead. This will maintain flow and reduce turbulence, ie.(noise). I would also keep the duct to the lower room, near the floor as opposed to the ceiling, (basically a duct is a hole in the wall surface). Why spend considerable cash on that ceiling only to put more holes in it? Same goes for lighting fixtures, use care in your selection.
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