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Greetings! This is my first post to this forum, and I am so stoked to have found the forum (hopefully) just in time as my basement remodeling project is underway, en route to becoming a multi-purpose family room / home theater. House is up on supports, the foundation has been ripped out, 5-foot deep trenches are dug around the location where the new foundation will be poured, and the rebar + forms are getting put in place as I type.
I have done a ton of online research, including reviewing many posts on this forum in order to learn as much as I can about how to properly build the main family room from a soundproofing perspective, as directly above the room are my daughters' bedrooms with the master bedroom not too far away above the garage that will be next to this room. I have depicted this in one of the attached diagrams of the upper floors. But I would love any/all input on other matters like lighting, HVAC, etc. I have attached a diagram that I will reference throughout this post. Many thanks in advance for whatever advice you can provide, confirmation (or refutation) of my assumptions, etc.
General Context
Here is how I plan to tackle the various aspects of the room, mainly focused on soundproofing...
Ceiling
Walls
Soffits / HVAC
Floor
Windows / Sliding Glass Patio Doors
Interior Doors
Lighting / Electrical
General
Again, thank you for whatever advice you can provide - may the Force be with you!

I have done a ton of online research, including reviewing many posts on this forum in order to learn as much as I can about how to properly build the main family room from a soundproofing perspective, as directly above the room are my daughters' bedrooms with the master bedroom not too far away above the garage that will be next to this room. I have depicted this in one of the attached diagrams of the upper floors. But I would love any/all input on other matters like lighting, HVAC, etc. I have attached a diagram that I will reference throughout this post. Many thanks in advance for whatever advice you can provide, confirmation (or refutation) of my assumptions, etc.
General Context
- House is in Burlingame, CA which is situated on the peninsula of the San Francisco Bay Area near the airport and built in 1925
- Split level, so new room being build underneath the upper part of the back of the existing house - which are all bedrooms, of course
- My primary goal is to keep sounds of TV, movies, video games, entertaining, etc. from waking up / disturbing anyone sleeping in rooms upstairs
- Weakest links seem to be windows and sliding glass patio door on Northeast wall. Also concerned with sufficient sealing and isolation to mitigate flanking into upstairs.
Here is how I plan to tackle the various aspects of the room, mainly focused on soundproofing...
Ceiling
- Double Drywall + Green Glue following guidance
- Interleaved, caulked, backer rods with Double Drywall of walls at intersections per this post
- Second layer installed perpendicularly to first
- Acoustic caulk seams and intersections
- Hat Channels per specifications in this article and Sound Isolation Clips
- Spacing: every 48" (will this be strong enough?) ***
- Additional ones for supporting soffits
- Are these RSIC-V's OK?
- Use RSIC-1's (like these) that can attach to the side of the joists in order to minimize the amount of drop to ~1/4" and thereby maximizing ceiling height and reducing amount of excavation required
- Spacing: every 48" (will this be strong enough?) ***
- R19 Insulation
Walls
- Double Drywall + Green Glue
- Same techniques described above for ceiling
- Acoustic Caulk + Sill Gasket under bottom wall plates per bottom of this article and this post
- R13 Insulation
- Northwest + Northeast Walls
- These will both be false walls
- Based on some of the weaknesses I'm dealing with, are DC-04's or the like worth it? If not, any advice on how to support them?
- Southwest Wall
- Am assuming the laundry room / bathroom provide an "air pocket" for upstairs. They are also beyond the sleeping areas above. Did not plan to DD + GG the walls or ceiling - cool?
- Toward the South corner of the wall, it runs along the other side of the stairway to the upstairs living area. I assume that in this case consideration definitely needs to be given to either staggered stud wall or use of hat channel + clips - is one better / preferable to the other?
- Also wondering about best way to secure the wall as it extends to the bathroom - I am more worried about how to isolate it from the ceiling - looks like RSIC-U's would work, but am again wondering if the door and window frames make this wasted effort
- Southeast Wall
- Wall will be connected to the stem wall off the foundation
- Plan to DD + GG one side of stud wall, but I was not going to do staggered studs or otherwise isolate - is that a problem? Believe the wall will attach to a beam, which brings up the question of using RSIC-U's or the like - or not
- I should mention that the master bedroom is above the garage, and will not have a ceiling - just insulation at this point
- Stairs up to door will be plywood framed platform - is there anything that would be necessary to do to keep sound from going through them into landing and hallway beyond? is this a concern or not?
- Duct to Soffit - still working out how to get to the soffit on the Southeast wall. Currently, as shown in the light green on the diagram, we may figure out a way to go under the stairs into the wall at the other end, then up through in-wall metal duct to the soffit and out through the wall into the soffit - if we just stagger studded that little section of the wall, would it help or no?
Soffits / HVAC
- Plywood + Drywall + Green Glue (Example post)
- Depicted as purple entering crawl space at #6 and #8, while #4 is the more creative approach I previously described.
- Acoustic flex duct
- What kind of insulation?
- Any recommendations for sizing the soffit? Can I go really tight, or should there be a certain amount of room for insulation?
- Grills positioned in the middle on the side facing each other and blowing toward center of ceiling (#11 and #3)
- Use of appropriately sized PVC when traversing walls
- At #10 is where I plan to have all the home entertainment components. I will need to run conduit into the soffit and out into the crawl space in order to route Cat5, and such. I can probably route it directly into the built-in home entertainment shelves and cabinets that will be right there - and recommendations on soundproofing this, if at all?
- Similarly, I will also need to bring in speaker wiring through the wall - any special boxes, and techniques for minimizing leakage?
- Do I need to consider Dead vents (thread and specific comment)? Inline duct Silencers? Currently, the ducts aren't right-angling when they come out into the crawl space.
- Furnace will be in the #12 location
Floor
- Concrete slab
- Pergo with some tile near wet bar and in front of Patio door
Windows / Sliding Glass Patio Doors
- These seem to be the biggest weakness. I have read some posts that talk about potentially using neoprene to isolate the sliding patio door and windows from the structure; however, I am also concerned about the fact that the opening for the door and windows will connect the outside structure and inside floating wall. Any ideas?
- I am less concerned with noise reaching the neighbors as noise reaching occupants above
Interior Doors
- Solid Core for stairway as well as laundry room access points
- Automatically closing door bottoms (like these)
- Any other tips/tricks?
Lighting / Electrical
- Plan on using wall sconces all around the main room.
- With the windows and patio door issue, is stuff like using putty pads on outlet boxes worth the added expense and effort? Figured I would just concentrate on acoustical caulking of regular boxes
General
- Speaker isolation necessary? Currently, I plan to have a built-in entertainment center against the Northwest wall.
- Would have the LCR speakers sitting on it
- Subwoofer on the floor underneath it - do I need to try to isolate that from the Pergo floor?
- Would wall-mounting the surrounds be ok, or defeat the purpose?
Again, thank you for whatever advice you can provide - may the Force be with you!

