Floor to Floor Impact Vibration
Folks, I’m considering starting a blog called Flipped Frustrations that is all about the perils of buying a flipped townhouse in Brooklyn and the corners cut (@cate, maybe I’ll write an anonymous article for brownstoner) I knew there would be “stuff” but had I gone deeper into this forum first I may have been dissuaded. The attraction of something “turnkey” is real though and when information disadvantage of renovating your own (architects! GCs! engineers! subs!) exist too + cash budget are so much higher it can feel even more perilous. IDK maybe I’d have just as many frustrations if I was doing this myself and making all the mistakes. Or, in realizing that some of these “problems” are just par for the course when owning a 120+ year old structure. Don’t get me wrong, it can be fun and gratifying at times but I’m very much on a downswing at the moment.
My new frustration: when my upstairs tenants are walking around I can feel their footsteps in my parlor floor and at times event on my basement floor. When someone is walking around the basement, I can feel their footst eps in my parlor floor. My theory is that in renovating the parlor to an open floor plan they didn’t cross beam any of the parlor ceiling joists, add a LVL, or structurally support the new wood stud walls that were built (vestibule, utility closet, bathroom, exterior). As a result, footsteps are transferring through those new wood stud walls right into the parlor floor joists. Same thing for the basement floors.
1. Does my theory of what’s going on hold water for people here? I’m a missing culprits?
2. What would have been the ‘right’ way to have done this when it was gutted? Or, said differently, do townhouses done right have this issue?
3. Who is the right person to find to diagnose the issue? Structural engineer? Architect? An experienced contractor? I’m so tired of hunting for good tradespeople so recommendations welcome.
4. Where would you think they’d start with remedying? I can see this being an expensive problem to fix so trying to absorb what I’m looking at as far as pain. Or, if it’s even even worth doing.
Thanks in advance for the support.
Guest User | 4 years and 4 months ago
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dorkofwindsor | 4 years and 4 months ago
hellobedstuy, I wouldn’t necessarily put the onus on flippers only – knowledge of acoustics is not at the forefront of most contractors. Some know a little, many know nothing, and plenty know only the fallacies. Architects and structural engineers know more, but it still seems like a joke to me that STC rules the building codes. The frequencies involved in your situation – “feeling” footfalls – is so low (7-10hz?) none of that would apply. But its really been the open floorpan that has brought this to the forefront. I’m not sure even the science has definitive answers yet. For example, in an open floorpan like yours would beefing up the nonstructural partition walls as if they were load bearing reduce the flanking? It depends, maybe, maybe not. It is the result of a complete acoustical system – just as those old beefy partition walls cured all of this. You could isolate all partition walls like a recording studio build ($$$ to re-do) – but then you still have a resonant floor (more resonant now?) and you see where that could go after all the expense.
So de spite my running at the mouth (I know enough to be dangerous, but more than most), I would start at the source (floor) as you recommended as it would address flanking both up and down. I personally would add vibration damping between each layer – one on top of the actual joists (strips of material), between subfloor sheets and below hardwood. I’ve posted my thoughts on that somewhere in this forum – some think its complete overkill but I would bet none have lived in an open floorpan of a reno’d townhouse like us. One open floorpan house that I lived in built with a contractor from chinatown was literally like living inside a drum – it was unlivable. Ask a random contractor and they will say put in some insulation lol.
After that, as for noise traveling through the air, that could further be addressed with common solutions through the floating of beefed up ceilings if necessary.
Guest User | 4 years and 4 months ago
@dorkofwindsor, agree with everything you said about sound and also makes sense that an open floor plan makes for a more resonant space. Your words of warning to anyone considering a flipped house are spot on. They’re a mess behind the walls.
Again though, the sound isn’t the real question I’m looking to answer here. My problem isn’t that I can hear their footsteps, it’s that I can *feel* them in _my_ floor. That seems like a framing and support issue and not a drywall thickness issue.
My thoughts on solving it would be 1. remove their floor and add layering to dissipate the impact at its source 2. identify which areas the framing is carrying too much load and add additional supports (to joists, to studs) to dissipate it before it reaches my floor joists.
I can have theories but would much prefer a plan and finding the right person to create/execute it.
dorkofwindsor | 4 years and 4 months ago
hellobedstuy, when you remove all the plaster in a flip and replace with single sheet drywall, and remove walls all bets are off. You need modern soundproofing techniques, which you will rarely get with a flipper. Also, when people walk with their bare heels they are like rubber sledgehammers. Somehow all that plaster makes most of that stuff go away since mass stops sound. But pretty much everything you said makes sense. “Opening up” the floorpan also makes the floor far more resonant, basically a giant drum. All those old tiny rooms everywhere were compensating for a lot – mass, resonance, etc. When you remove all that mass, the flaws come alive.
Guest User | 4 years and 4 months ago
@Bob, I’m open to that possibility. Kind of goes back to the question — who can help me identify whether it’s a structural thing and the right mitigation?
RobertGMarvin
in General Discussion 4 years and 4 months ago
Keep in mind that some of the movement (and noise) to which you refer is something that occurs in old row houses and might have nothing to do with corners the flippers might have cut.
xtinaillustration | 4 years and 4 months ago
Oh I see – well it’s a similar problem I believe. You want their floor (the framing) to move less; perhaps the joists could have been beefed up (stiffened) to deflect less, but isolating your wall framing from the floor framing above (decoupling the top stud from joists) would help keep the vibrations from transferring to your floor.
Guest User | 4 years and 4 months ago
Ha, I thought about adding a disclaimer that I’m not referring to noise but my initial post was already verbose. I’m specifically focused on the movement. Noise and movement can occur together but don’t necessarily need to. One can hear footsteps above but not feel them. One can feel certain vibrations but not hear them. I understand why that’s where ones mind goes but The noise is not my concern at the moment. Now, making structural improvements may also help the noise too but I want to be very clear that sound mitigation not the goal nor the annoyance. I don’t think it’s typical to be sitting on your parlor couch and feel the footsteps of the person above you.
As an aside, I already have isolated the ceiling to help with the noise (which makes this more frustrating because I could have fixed structural issues at the same time and didn’t realize they existed)
xtinaillustration | 4 years and 4 months ago
Also one can use special acoustical clips to isolate wall framing from ceiling framing, so that vibrations like impact noises don’t transfer to the wall framing.
xtinaillustration | 4 years and 4 months ago
Your theory sounds reasonable – impact noises (like footsteps) travel through structure. I believe the most effective way to prevent this is to install a resilient underlayment (mat) under the wood floor (separating the wood floor from the subfloor). It’s expensive to fix at this point since you have to pull up the finished floor. Simpler fixes include rugs with rug pads, if you can convince the upstairs tenants to put some down!