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Help! Rasing sunken living room and it’s SO LOUD.

Meghini's picture


First time post and I’m in a bit of a panic.


I have a contractor rasing my ~4” sunken living room. He usually does really good work. We decided to raise it with wooden sleepers, partly because I’m in grad school for architecture and we’d talked about it in a constrution methods class and concrete is prohibitively expensive. 

Except it’s really, really noisy to walk on . And I was planning to use this as a dance paractice space, among other things. (Including my home workspace for school projects, so time is of the essence) I understand it will obviously be nosier than flooring on concrete, I just didn’t expect orders of magnitude more noise.
I got home to find that he’d run pressure treated 2x4s in contact with the slab 4’ apart (as far apart as the 19/32 osb allows). And he has cut 2x4s to be 16” on center at 90 degrees to the sleepers but turned with the 4” side up and attached to the wood that touches the concrete with a 2” gap underneath.
My understanding was that this should be done with 4x4s at 16” on center with all pieces in contact with the concrete slab. Everything I’ve seen online is 2x4s but they all seem to be in contact with the slab. My current plan is to make him pull up the OSB he has down and run sleepers in contact with the slab at 16” on center and have any other wood in contact with the slab as well. 
Im also considering some kind of insulation or sound dampening in the spaces. I have a friend who works in theater who says they use sand- is there something designed to reduce echo? This obviously isn’t impact or transmission class noise. We’re in Phoenix Az so water and cold are not issues. 
It’s also my understanding that to achieve as little noise as possible you need a rigid surface. So having the wood touch the slab creates a more rigid surface. My contractor is saying we can put a 1/4” layer of concrete on top of the osb  to get the same effect. I don’t think that keeps the 4’ OSB from not being aduquately supported. Am I incorrect? Is one of the mistakes using 19/32 osb rather than thicker sub floor? 
The flooring that will go on top is floating cork with one of the highest quality sound absorbing underlayments. We have that in all our bed rooms and the associated hall. He says this raised floor currently sounds like the hall. I think what he’s built is a large wooden drum. Is it possible that it really sounds better once I get the floor and underlayment on? 
Or have I just lost $600 for all this wood and I should just have him take it all out and cope with a 4” sunken living room? Because if I can’t use it for one of its primary purposes, it’s pointless. (Edit: got photos to post) 
I was supposed to be able to work i there by the end of the week and that seems increasingly unlikely.
Any help you can give is greatly appreciated.

Use a hole saw to cut through (post #216435, reply #1 of 17)

Use a hole saw to cut through and fill the cavity with spray foam.

Is there a particular kind of (post #216435, reply #2 of 17)

Is there a particular kind of spray foam you recommend? or specific qualities I should be looking for?

thank you!

hmmm.... (post #216435, reply #3 of 17)

1) his method seems like way more work than doing it properly

2) 2x4s on the flat have little structural integrity, esp. to span a 4'

3) Assuming this is slab on grade, I would think a vapor barrier should go down first (30# felt), which would also provide some cushion for any expansion/contraction of the wood. Can't assume there is a vapor barrier underneath the concrete. Also, are you in an area with radon? Might be a good opportunity to remediate that while you have this exposed.

4) seems like he could remove the 2x4s on the flat and turn them 90 degrees and rest them on the concrete. A bit of work but you don't lose the money of buying more wood.

Seems just an odd way to approach this.

I thought so too. Everything (post #216435, reply #6 of 17)

I thought so too. Everything I've learned/seen doesnt have any thing except the 2x4s spanning the whole room at 16" on center. I went in least night to find this. Which actually uses more wood? I think he just doesnt wnat to scribe the 2x4's. 

He was just here and (after a bunch of arguing) aggreed to get more of the wood in contact with the slab. I *think* that mens turning the 2x4's that are on the flat to be correctly upright, but he says he needs more wood so maybe hes just planning to slide pieces underneath as you can see in some of them now. 

He also says we could just pour concrete around the wood. And then we wouldnt need the rebar and mesh that previous contractors had said would cost so much. But he would charge a lot more becayse he hates concrete. (im not going to lie. He;s done pretty good work on other stuff at amazing prices. I've done most of this myslef in he last so I kinda have an idea what good looks like. And we need him to do other stuff so I dont want to piss him off. but that seems like a bad reason to have something done incorrectly.)

I'm also worried that we flip all this wood and put in sound absobing insulation and it will be *better* but for a couple hundred more we could have concrete.


Is piuring concrete in/around the wood a good idea? I've done it for forms but never for something permamanaet?


concrete expensive? who told (post #216435, reply #4 of 17)

concrete expensive? who told you that ?


Looks like about a 16 ft by 12 ft room, 4" thick concrete over existing slab needs just a bit over 2 cubic yards.

Even 80# bags from big box is only about $250. 

You dropped $600 for PT lumber and osb, how is concrete expensive ? 

Labor?  Pheonix located?  Most places here there will be a dozen or so illegals standing outside the big box very happy to mix and pour 4" slabs, you migh even find one or 2 fairly proficient at it..

Probaly 20 or 50 folks outside big box stores in Phoenix.

re:  current plan 'pull up the osb':  Ouch. 

A layer of 3/4" ply over exsiting osb GLUED down.  the underlayment and cork flooring WIll reduce sound considerbly.

concrete (post #216435, reply #5 of 17)

I was told by at least 6 contractors, some licenced some non licenced, that because its 12.5'x20.5 ft it needs mesh, if not rebar and the lowest quote I got for that was $2500, highest was $5000.

The illegals out side the big box stores have laregly evaporaed in the last few years. 

The current guy says he can pour concrete around the wood, thus elimating the need for mesh...bu he hates pouring conctrete so he'd charge us more money. 

You got all kinds of bad (post #216435, reply #11 of 17)

You got all kinds of bad information. Concrete would have been fast and inexpensive and last forever. Whatever wood floor you put down is going to sound like a drum so close to the concrete floor. A 1/4" concrete overlay on plywood? Was he serious?  Before you waste any more time and money pull it all up and hire a concrete crew.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

The contractor has said he (post #216435, reply #7 of 17)

The contractor has said he could pour concrete around the existing wood (the ply/osb would come off ovbiously). Hes un hapy about it and it would cost more than trying to make the wood work and putting in insulation, but he says he wouldnt need mesh or rebar because of the wood. I've poured concrete in wooden forms but never anything permananet. Is it a good idea? 


I was leaning toward making the wood work with insulation, but the forum has me thining maybe the concrete is better. 

update:  Contarctor was (post #216435, reply #8 of 17)


Contarctor was just here and is mad at me, whatever.

After much arguing hes willing to get more of the cross pieces to touch the slab. I think that means taking off the flat 2x4's and scribing them to fit properly. He did  say I'd need to get more wood. (It might mean shoving 2x4s under existiing 2x4's as you can see in parts of the photo. I'm really not happy with that.) But he wont charge me extra for the labour. If we go that route I found Safe n' Sound sound insulation that I think wed put in the gaps before the osb goes back on. It has the best NRC I can find at a reasnable price. 

He kept saying that the only way to have a totally quiet floor was concrete (I never expected this to be totally quiet). He's willing to pour concrete in/around the wood thats down. He says that means it wouldnt need the rebar/ mesh that made just doing concrete so expensive. But he hates concrete, and will charge more, so with materials it ends up being about $300 more. Is pouring concrete around wood like that a good idea? I've used wood as a concrete form but never on a permanent basis. $300 isnt the end of the world but $300 to do something really diffacult to take out if the wood causes it to do weird [JOBSITE WORD] seems like a horrible idea.

I like the idea of concrete because theres no chance that we spend the moeny and do the work and its still really noisy. We got some of the flooring out and walked on it- it was fine even a foot from a support. Where the "supports" are floating is was NOT fine. I worry that well buy the insualtion and such and it will still be bad.

I also dont want to totally piss this guy off. He's done excellent work on other parts of our house for amazing prices (and I like him). And I've done lots of this myself so I know what I'm looking at, mostly. I have a bunch of other projects that need to get done and if he wont work here anymore I'm screwed. I'm in architectire grad school so i have neither time nor money. 

Whats the best way forward that isnt ripping out everything and pouring concrete. That woudl be awesome in a perfect world, but isnt helpful here. If everything gets ripped out I'm just stuck witha sunken living room forevere and cant even get my floor laid down becaue I dont have the right trasition pieces for the step. 


I reallly, really need to be able to have  my work space set up in there no later than new years. i'm having a hard time holding on in school as is.



Thanks again for your help


Just did a walk around in (post #216435, reply #9 of 17)

Just did a walk around in this place to make sure.  We just moved into this 20-year-old 2-level condo with about 800 sq ft per floor.  The upper floor is wood I-beam joists.  There is a barely-perceptable squeek when you walk by the stairway -- otherwise it's completely silent.

The place we moved from was a slightly larger house built in 1976, with 2x8 joists.  It had a lot of squeeks at one time, but over the years (mainly when the flooring was replaced) I silenced most of them.  Mostly a matter of screwing down the subfloor.

It IS possible to have a quiet floor without resorting to concrete.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

thank you thats good to (post #216435, reply #13 of 17)

thank you thats good to know 

FWIW, I have a barn shop (post #216435, reply #10 of 17)

FWIW, I have a barn shop floor made with 4x4 PT DFir 4 ft OC sitting on 2 to 4" thick concrete just underthe 4x4 right on the  bare dirt.  Ground is wet year around.(PNW). .  1-1/4" plywood on the 4x4s with vapor barrier (probably no need for vapor barrier in phoenix)

 19 YO this year, nary a problem. Quiet.  The concrete inamong and under the PT wood isno problem, your osb in contact will be a problem  if there is any moisture -- for folks reading this that are NOT in phoenix or arid SW. 

yeah, one thing I know for (post #216435, reply #15 of 17)

yeah, one thing I know for sure is pt wood needs no vapor barrier here. I had several profs in my architeture masters who are in the trades confirm this with me. 


If we did the concrete the plywood/osb would be gone. it would just be around the pt wood. I'm just not sure if thats a good idea or a horrible idea. 



The floor should have been (post #216435, reply #12 of 17)

The floor should have been framed 16" on centers over a layer of 30 pound felt with the 2X4's on edge and screwed to the concrete so they can't move. I would have filled the spaces with mineral wool and glued the plywood down.  Any movement will cause the entire floor to drum.

FYI, concrete would not need rebar or mesh as it wouldn't be structural. You'd be placing it over the existing structural concrete floor.  Pouring concrete around wood is always a bad idea.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

Would screwing the wooden "frame" to the concrete help? (post #216435, reply #14 of 17)

Aside from the felt this is what I thought was happening. The ship has sailed on the felt for 5 of the 2x4's. would it make sense to get it for under new wood I'm going to make him put down. He has a wooden frame around the room that everything is attached to, would it help to make him screw that to the concrete (whcih is only on one side) and maybe studs on the other? I'm serioulsy considering drawiing apicture of just the 2x4's 16" on center and saying DO THIS. 

I'm going to get mineral wool insulation, now. My reasrch before indicated it was a maybe you need it maybe you dont thing, I think I need it. And he did glue the plywood/osb down (theres both becuase home depot ran out. not kidding) I think the long 2x4's are also glued down. 

Movement is not your friend (post #216435, reply #16 of 17)

Movement is not your friend so screwwing the wood down is good, the more the better. The minerlal wool would be just to stop  the noise and viberations from walking on the plywood from bouncing off the concrete.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

I realize that this, as we (post #216435, reply #17 of 17)

I realize that this, as we used to say at work, is probably OBE (Overtaken by Events), and that you are probably locked into the option of pouring the concrete as in your other thread, but there is an option that I haven't seen mentioned.

To get a really stiff floor, since the solid concrete option was so expensive, what should have been done, IMO, is to size the sleepers to allow for extra layers of floor sheathing. I would have used at two, maybe three layers of 3/4" Advantech, heavily glued and screwed together. With a extremely stiff subloor & mineral wool between the sleepers, there'd be no vibrations or noise at all.