Floating Floor Question

Eric_Desart · Post by **Eric_Desart** » Wed Aug 13, 2003 5:46 am

Just a thought,

Looks as a nice construction.

Why not building the inner walls on the floating floor?
Make the floating floor in concrete as well.

With the right material (Kinetics thing that Steve often menten, E.A.R. foam, CDM materials or SYLOMER) this can perfectly be done.

Weight is no problem.

I do not think it becomes more expensive (in Western terms).

Eric.
PS: I once worked for ca 1.5 year in Indonesia (Bandung in 1976)

knightfly · Post by **knightfly** » Wed Aug 13, 2003 3:27 pm

"I do not think it becomes more expensive (in Western terms). " -

Exactly my concern, Eric - Ari posted early on in this thread that a floated concrete floor was too expensive - now I'm trying to get him to clue me in as to what is expensive and what is cheap in Indonesia - it seems to me that having the existing floor slab-sawn to isolate from outer walls would be about as costly as doing a real floated concrete floor, but then I'm still reeling from the discovery that London charges over 5 TIMES as much for gypsum wallboard as I pay for it here, so, as the wife said to her drunk husband, "What a WINO..." (What do I know?)

Hopefully, with enough input from Ari, we can get him set up with all the isolation his old and crotchety neighbors need... Steve

Post by **John Sayers** » Wed Aug 13, 2003 3:51 pm

I must say I find it interesting that timber is more expensive than brick in Indonesia. Isn't timber one of your biggest exports??

cheers
john

knightfly · Post by **knightfly** » Wed Aug 13, 2003 4:14 pm

Maybe that's the problem John - they exported it all...

Seriously, lumber seems to be going up here as well, gotta be at least partly because we (not me, I know better) have been selling all the GOOD logs to the Japanese, they go out of the ports here by the million board feet.

Pretty soon, all you'll be able to buy are fiberglas or steel "2x4's"...

Here's a list of Indonesia's exports, BTW - oil and gas, electrical appliances, plywood, textiles, rubber

from this site

http://www.odci.gov/cia/publications/fa ... os/id.html

Now we know everything about Indonesia except which part Ari's from, and how expensive materials really are... Steve

bolehnggak · Post by **bolehnggak** » Fri Aug 15, 2003 2:50 pm

Thanks for the answers, everyone. You guys even checked the list of Indonesia's exports. Wow!

Steve, about the answers you gave me about the re-bar, inner and outer footing etc, is it something like this? (See picture below)
I think the inner footing is still having hard contact with the outer footing through the cement floor. Is it okay? Or did I misintepret your explanation?

As for ceiling construction, the inner ceiling would be built over the inner wall, so no contact with the existing structure, it would be gypsum board on a frame, with rockwool insulation.

About budget, yes, US$600. Actually for Indonesians nowadays, it's quite expensive, since Indonesia suffers from economy crisis. Rupiah lost its value from Rp.2500/US$ to Rp.8500/US$. At the peak of the crisis few years ago, it even reach Rp.15000/US$.

I don't really know about economy, but maybe because the timber price has to follow the current world market price, because they are export goods, and bricks are made for local market, so the price pretty much unchanged.

A brick is Rp.200, the price is the same now and ten years ago. 18mm plywood soared from Rp.30000/item to Rp.120000/item. What confuses me is that the price of gypsum board has never really go up, the 12mm gypsum board costs Rp. 30000/item.
The price of concrete and timber had extremely soared, but the brick isn't. So I hope that my studio would be more bricks than woods or concrete.

Eric, can you give details on building inner wall on a floated slab, maybe in drawings? Sorry, lack of construction skill.

Ari

P.S. Eric, I live in Bandung! Where did you work? I'm not even born at that time.

knightfly · Post by **knightfly** » Fri Aug 15, 2003 6:55 pm

"I think the inner footing is still having hard contact with the outer footing through the cement floor. Is it okay? Or did I misintepret your explanation?" -

You're not too far off what I was referring to Ari - only you would need to cut completely through the existing slab just inside the outer wall , then again about 400 mm inside, then dig out the concrete between those two cuts, drill the horizontal holes into the inner, remaining slab, and finally pour a new footing around the added re-bar. Doing this, you would need to insert something soft, like sound board or possibly foam insulation board, against the outer, remaining part of the floor slab so that you don't bridge the inner remaining slab to the outer.

If your existing slab is thick, for example 200mm or more, then depending on how expensive it is in your area to have concrete slabs cut (they do this with a diamond grit blade and a special, water-cooled saw - it's pretty costly here in the US) - you might be better off just doing a 75-100 mm floated slab and then building your brick walls on top of that.

Here is Kinetics version of floated concrete floor using their rolls of pads separated by soft fiberglas - I'm linking to it mainly for illustration purposes. Note that they show a perimeter isolation board - this can be just soft "sound board", such as Homosote or Celotex, the main thing is that the floated slab NOT touch the wall (in your case, the existing wall) - please check out ALL the material they show on floated floors, so you can get an idea of what's involved.

http://www.kineticsnoise.com/architectu ... nstall.pdf

In order to build a new brick wall on top of a floated slab, you would need to increase the number of pads under the portion of the slab where the wall will go. The floated slab itself should have extra re-inforcing steel around its perimeter where the brick wall will sit.

Depending on the cost to cut through the existing slab floor and its thickness, it may be cheaper to just add a floated slab. If cutting through the existing slab in just one place would be cheaper, and if the slab is thick enough NOT to need an additional footing under it where the brick wall would go, you may be able to cut along the existing wall, clear through the concrete floor, then fill that cut with caulking, and build your new inner brick wall just inside the caulked floor cut-through.

That method wouldn't give quite as good isolation as a true floated floor, but would be pretty good provided the slab is COMPLETELY severed by the perimeter cut, and you don't accidentally bridge the cut when building the inner wall.

If none of this made sense, post back and I'll draw a picture or two... Steve

bolehnggak · Post by **bolehnggak** » Sat Aug 16, 2003 1:24 am

Today I just inspecting the space with the builder, and here's what I found, the floor is just a cement floor, maybe only 5cm thick. Below that is just soil. Here's the picture.
If this is the condition, what should I do?

Ari

knightfly · Post by **knightfly** » Sat Aug 16, 2003 4:11 am

Ari, in that case here is what I would do - I've edited your drawing (on one side only, you would do this all around the perimeter)

Note that in many parts of the world you can't just build a wall on top of a straight, same thickness footing - that's why I drew the footing as I did. Your local codes should cover this, there's nothing magical about this part. Only the NON-rigid separation from outer walls and INNER floor.

BTW, your inner brick wall, if your bricks are about 100mm thick, will weigh about 350 pounds (160 kg) per lineal foot, so your footing needs to be able to support that weight without settling. Codes usually call for the footing to be resting on "undisturbed earth", meaning you dig down, remove all loose material, set your forms, pour the concrete, pull the forms, cure the concrete, insulate with foam (see drawing) then build the wall, render the inside (bricks are porous enough that this is necessary for good isolation) then add whatever wall covering you intend. Don't forget to render the outer wall, dry it, glue the insulation on BEFORE you build the inner wall...

Doing JUST THIS should improve isolation tremendously - if it were me, I'd do JUST THIS MUCH and not float the inner floor right away. Once you finish the new wall and do your ceilings as you mentioned, with NOTHING in the inner part solidly attached to the outer part, I would put a drum kit and drummer, bass player and huge amplifier in the room, close the doors (You ARE planning a sound lock (double door with a few feet between, absorption on all surfaces), right?

Have the drummer and bass player play as loud as they know how, and check the level while standing next to the wall inside your neighhbor's building (be sure and ask permission, and explain that you're trying to NOT disturb them EVER, even a little bit) -

If you (or more importantly, your NEIGHBOR) can't hear ANYTHING, just move the rest of your stuff into your new studio (after whatever acoustic treatment you need to do) and enjoy.

If your neighbors are not quite happy, THEN you can invest in a floated floor. Whatever acoustic treatment you do inside the inner walls will have almost ZERO effect on sound proofing, especially with double brick walls, so you won't have to tear anything out in order to find out if this treatment is enough. Yes, the room will sound crappy for this test, but that's to be expected with no acoustic treatment inside.

It wouldn't hurt at this point if you were to provide more details of your intended ceiling construction - remember, the weakest link will define the performance of the entire structure... Steve