More problems with EPDM rubber...

[hugo_inside]

I have new problems with EPDM rubber:

I found a company who made this kind of rubber with durometer 60 but price is very very high!!! 161€ + VAT sq/meter. aprox 225$ sq/ meter.(21$ sq feet).

But another company offers me EMPD shore 30-35 at 65€ sq meter. Three times down the price of EPDM shore 60.

I don't have much money now for spending 21$ sq feet on EMPD for REHEARSAL ROOMS FLOOR.

I think of doing floating floors without any rubber. Or EMPD shore 35 will do anything on sound profing??

What can I do???

[knightfly]

There is a BIG difference in load support between 35 duro and 60 duro; so, depending on your floor design and materials, the more expensive might actually be cheaper (less pieces, smaller pieces needed) - do you have a drawing of how you intend to make the floated floors? Steve

[Sword9]

Also, keep in mind that you're not going to be laying the EDPM down like a flooring surface, so you don't need hundreds of sq. feet of it.

[hugo_inside]

Thanks Steve and Sword9,

I know, Sword9, I don't need to go laying EPDM on all the floor surface. But in spite of this, I need EPDM rubber for 150 sq meters of floating floor.

I have 5 rehearsal rooms with 3 x 5 meters size. One room 6,50 x 3,10, another rehearsal room 5,50 x 3,10 and a REcording Studio 8,90 x 4'50 meters.

Joist are 100 x 50 x 6000 mm

This is my idea for 5 x 3 meters rooms:

[knightfly]

Have you calculated the total weight that will be supported by the EPDM for one of these floors? Steve

[hugo_inside]

I don't know exactly ...

- 3 or 4 or 5 or 6 musicians: wide weigh range
- Drums
- 1 or 2 guitar amps: wide range too...
- 1 bass amps: from 30 to 50 kg
- Voice amp: form 30 to 150 kg


But I'm thinking... people usually put their amps close to the walls and the center of the floor is where they place the mic stands or efects pedals... Maybe this thing could help...

[hugo_inside]

If I put 150 kg/m3 rockwool under the joists, this will do anything?

I'm thinking of put this rockwool between floating floor and walls...but under the joist perhaps it doesn't work

[Julián Fernández]

I´m not sure, so wait for KF to answer you, but the density of your wool has NOTHING to do with the weight that you´re going to put over the floor... Putting rockwool under the floor with help with insolation...
I mean... you have to calculate how many weight are you gonna have inside the room so you can determinate how many pads you may need... (that´s why under the walls you need more rubber than in the center of the room).
Hope this help...

[hugo_inside]

Gracias por contestar Julian , a ver si coincidimos un dia y charlamos.

I'm so desperate because of floors. My construction is so delayed (over 2 months) and I haven't got much money. And I still don't started the studio room.

If puting this rockwool (150 kg/m3) doesnt work anything, I float the floors only to level the floor to door...maybe in future I put rubber pads under joists.

Because I don't wanna spend the same money in 1 sq meter of EPDM than in all the joist I need for 150 sq meters.

[Dan Fitzpatrick]

I think you need to figure out how much the ROOM weighs, that is your biggest weight on the rubber ... good to remember what is going IN the room too though, that's the one i tend to forget.

see this post, 3/4 down for some weight estimates

then see this thread to find out more about using EPDM under your floor

If my math is correct, Sharward (second link above) is using about 1.8 square feet of EPDM for a 15,000 pound room 9 feet by 17 feet. (50 pieces at 3.5" x 1.5")

granted, you have over 4 times the square footage. but Sharward's floor is solid brick (heavy) if you have a lighter room you need fewer pieces of EPDM for optimal compression, that is why knowing the weight is so important. plus, Sharward is putting about 300 lbs per epdm unit and you can go higher i believe ...

disclaimer: this is based on my own reading of this site. do your own research on this, i am NOT an expert!!

dan

[sharward]

Nice post, Dan -- I was going to write something similar this morning but I was (am) very short on time.

Sharward is putting about 300 lbs per epdm unit and you can go higher i believe . . .

Dan, I think you mean lower because I think he's going to be using a lower durometer rubber, which can hold less weight per square foot. However, the fact that his floor is lighter (no bricks) might mitigate that.

Bottom line, I agree that this is something that can't be "eyeballed." It needs to be carefully calculated. The risk of not doing so is, at best, overweighted and prematurely worn out rubber, and at worst, severely overweighted or severely underweighted rubber that is completely useless resulting in a lot of sound leakage!

[Dan Fitzpatrick]

Hi Sharward! .... what I meant to say was he can have MORE weight per puck if he was using the 60 durometer material.

Because, if i understand correctly (referring to the chart contained in your thread linked above), at 300 lbs per "puck" you are at the "light" end of the spectrum of how much weight you can safely put on them and still be in the "zone" (actually if you don't use teflon it looks like you are around 5-6% compression).

i think you noted that 25% compression occurs at between 1100 and 1800 lbs, and as i look at the test data chart i see that if you double your weight per puck one is closer to 10% compression (dry, no teflon) ...

so that means that the cost conscious hugo_inside can cut his EPDM expenditure in HALF to more like $80 ... again, depending on the weight of his room, and assuming he isn't stuck with a minimum purchase.

it starts to become a question of, how small can the pucks be and how few can you use and still have it be structurally ok. especially with a "light" room. for example to double the weight on *your* pucks you'd have to remove half of them, or cut them in all in half. would that be stable? a 1 1/2" x 1 3/4" wide puck?

the amount of pucks people are using in photos i've seen seem to be a lot based on the data you've gathered. it almost makes me think i'm completely reading the chart wrong or missing something major.

Again, not based on any experience, just my own reading of this site.

Dan

[sharward]

. . . the amount of pucks people are using in photos i've seen seem to be a lot based on the data you've gathered. it almost makes me think i'm completely reading the chart wrong or missing something major.

That's been my take as well, Dan. I figure, I've got one chance to put the pucks in and no chance to fix them later (well, virtually no chance).
As for the rest, I'm sure Steve has some thoughts on all of this, so we just have to get out of his way and be a little patient until he gets a chance to post them.

[knightfly]

Smaller pucks are actually better in most cases, as long as you don't go TOO small; the Mason industries bridge pads that were linked earlier on use WAFFLE technique so as to allow DEFORMATION, which is more the way elastomers work. IF you make the pucks TOO large, there is no place for them to "deform" to, and they act differently.

Hugo, other than that you need to follow the links Dan and Keith have given in the last 4-5 posts, and understand that it's the ENTIRE weight of your ROOM and EVERYTHING that will be suspended on the rubber that you need to calculate; it doesn't have to be perfect, but it should be CLOSE. EXceeding 10% deformation of your pucks by very much will shorten their working life by several years, so this is fairly important.

Please read Dan's links above, and see if that answers your questions... Steve