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Floor Bracing Anyone?

knotscott

knotscott

Super Member
I've been a proponent of stiffening speaker boxes and damping panels to reduce their overall contribution to the sound since I first learned about box resonance over 40 years ago.

Today I stiffened my room by bracing the suspended floor. (sorry no pics!) Our living room is a 20' x 24' space with 2 x 10 joist construction suspended above a 37" high crawl space. There's a beam splitting the 20' span, which left two 10' sections that resonated in certain places when I stomp on them, and I suspected when I played loud bass heavy passages. I installed a couple of 7' 2x4 braces supported underneath in the middle of those two 10' spans, starting a few feet in front of where the speakers are. The stomp test reveals much less noticeable resonance now. Sonically, there's a bit less bass output, which was anticipated and points to the floor resonance contributing to the bass, but now bass is more detailed, tighter, and more musical....I've actually adjusted the bass output up just a bit for now to compensate for the perceived loss, but I'll definitely be experimenting with the balance more over the next couple of weeks.

The corners and ceiling are still "unaddressed", but this was a good step in the right direction. Anyone else brace their floors?
 
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No need here, my house is concrete block on a concrete slab. With a poured concrete roof.

But that sounds like a cool project. I never considered looking into the floor in my old house -typical wood with a basement.
You often hear about how important the room can be to overall sound but I think this is the first time I have seen something like this. Its almost always about wall treatments and such.
 
My front room is also on a slab, but my bedroom upstairs is typical 1950s bouncy house. Never had any sort of deep bass up there, just lots of boom and it was very much felt in the flooring so I'm not surprised that stiffening the floor had the results posted.

One thing I regret not doing during construction in my front room is bracing the walls better. The whole structure is concrete block with stud walls set inside the block to allow insulation and wiring. The footer is nailed to the concrete, header goes into the wood ceiling beams but the middle just floats. Had I been planning better I probably would have tied the center of the wall to the concrete block behind it at regular intervals to tighten things up more.
 
RVT1K said:
No need here, my house is concrete block on a concrete slab. With a poured concrete roof.

But that sounds like a cool project. I never considered looking into the floor in my old house -typical wood with a basement.
You often hear about how important the room can be to overall sound but I think this is the first time I have seen something like this. Its almost always about wall treatments and such.
Click to expand...

Our former house had a concrete slab at ground level and it made for a pretty solid listening floor...the wall panels, corners and ceilings were still an issue, but such is life with a box in a box! I had some corner bass traps at the other house that my wife hated.

Room treatment isn't much of an option now, but she can't see the floor bracing!
 
gadget73 said:
My front room is also on a slab, but my bedroom upstairs is typical 1950s bouncy house. Never had any sort of deep bass up there, just lots of boom and it was very much felt in the flooring so I'm not surprised that stiffening the floor had the results posted.

One thing I regret not doing during construction in my front room is bracing the walls better. The whole structure is concrete block with stud walls set inside the block to allow insulation and wiring. The footer is nailed to the concrete, header goes into the wood ceiling beams but the middle just floats. Had I been planning better I probably would have tied the center of the wall to the concrete block behind it at regular intervals to tighten things up more.
Click to expand...

Next time! ;):biggrin: (at least you have the slab working for you)
 
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It was a retrofit sort of deal. The block walls were pre-existing, the walls within the walls were done for convenience. Project had been partially completed by someone else with a different purpose too so compromises were made. Oh well, I still ended up with a not-terrible space that is isolated from the rest of the house so I can listen at whatever volume I want and not affect anyone else. On the other side of that wall is an unfinished space I use as a workshop area, then another block wall with a false wall set inside it to the living room of the house. Between two block walls and two layers of insulation there is pretty good isolation. More of it leaks through the door than anything else.
 
gadget73 said:
It was a retrofit sort of deal. The block walls were pre-existing, the walls within the walls were done for convenience. Project had been partially completed by someone else with a different purpose too so compromises were made. Oh well, I still ended up with a not-terrible space that is isolated from the rest of the house so I can listen at whatever volume I want and not affect anyone else. On the other side of that wall is an unfinished space I use as a workshop area, then another block wall with a false wall set inside it to the living room of the house. Between two block walls and two layers of insulation there is pretty good isolation. More of it leaks through the door than anything else.
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Nice situation to have! My space is the main living room, and it opens significantly into the dining room and kitchen, and gets heard all over the first floor.
 
Everyone in my neighborhood complains endlessly about new construction, but our flat is just 10 years old and a podium + 3 configuration. We're on the first floor, which is x-braced TJI's on steel beams, with the driveway to our parking area beneath us, so no neighbors to annoy with bass! Our floors have an inch and a half of gypcrete between the subfloor and engineered white oak floor boards- it feels like concrete using the stomp test. Even better, there is a stairwell on either side of our living room, with an demising wall, sandwiching gypsum/glass board sheathing and another insulated demising wall between our unit and the stairs on the front wall, with another insulated wall on the other side of the stairs to the unit next door and the same in reverse on our back wall. With occupied units on above and beside us, our only exposure to the outside is just 2 exterior walls, insulated with a/b foam and insulated windows- our gas & electric bills are about a third of what I used to pay, living in a 150 year-old row house. We rent, but I'm in no hurry to move, as this place has been great for the hifi hobby!
 
I put sister joists on every single one of my floor joists upstairs and down during the renovation process of my old (1912) house years ago. In the basement I also installed 3 girders which helped take the "moment" off the joists and flooring. I also believe properly braced and rock solid floors are very important.
 
DesertRatt said:
That's a new concept to me. Is this a custom house? Is concrete roof common? Where in the world is this?
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The house is custom and it was my wife and I who came up with the floorplan. It was new to me as well but it was an option that the builder offered along with trusses/sheet metal.
We live in Belize - retired here 4 years ago now - and this type of construction is common. You can get a wood house made here and many do because it is less expensive. But wood here requires constant maintenance due to the weather and, most importantly, all the wood eating/boring insects that are not limited to termites. If you know what to look for, there are termite nests in the trees all over.

I'm sure you have a cement mixer and pump in mind but this is Belize and that equipment is rare if available at all. My roof and slab were poured by hand via an army of workers and a bucket brigade of 5 gallon paint or spackle buckets.
There were several guys who just kept the portable mixer going with buckets of sand, gravel, water, and bags of cement. There was a bunch of guys carrying the filled buckets (on their heads with a folded up, empty cement as a cushion) up a ladder. And some guys spreading the concrete out. They started early in the morning and didn't stop until it was done late in the afternoon. It was amazing to watch.
 
Concrete slab, block house, here, built on the coast of Florida. Here they pour concrete down the open blocks with rebar or metal straps. The concrete down the empty blocks tie into rebar that is protruding up from the poured slab, so the walls are reinforced to the slab and then they use the straps extending out of the block on top to fasten to the rafters to tie them to the walls. You basically have a strap from under your slab, thru a poured block wall all the way up and then fastened to the rafters. The older houses only had a few nails to fasten them to the rafters so to pass a wind mitigation inspection you have to add a few more nails thru the straps into the rafters. And those are every 18 inchs or `24 inches apart down the wall. They need this to keep the roofs from lifting when a hurricane beats on your house for 24 hours before it passes thru. It makes for a good solid foundation and with carpet or rugs on the floor it is pretty good.
 
RVT1K said:
I'm sure you have a cement mixer and pump in mind but this is Belize and that equipment is rare if available at all. My roof and slab were poured by hand via an army of workers and a bucket brigade of 5 gallon paint or spackle buckets.
Click to expand...
The front part of my house was done this way. Its a flat roof, originally done in 3"x12" dimensional lumber on 24" spacing with tongue and groove boards on top of that. On top of the wood is about 2" of concrete. On top of THAT is rubber so it actually seals. It was done in the 50s, and I fully expect it was done using buckets to lift it.
 
My house has a crawl space and I'm having the floors reinforced and encapsulated by a company called DFX (Dynamic Foundation Experts) out of Memphis, TN.

They gave me a good quote and offered 5 year interest-free financing.
 
Little speakers wont resonate much if at all on concrete. My 15" Vegas are on concrete and at a certain volume the cabinets will resonate, along with everything else around me. But I put the cabinets on some rubber domes that I got from Amazon and that took away almost all of the resonance at that particular volume level. Now I have my subs on them too, and their cabinets are much stiffer than the cheap Vegas, but it also helps tame the house resonance.
 
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