200 mm concrete block with 2 layers of gypsium STC

hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 2:38 am

what is the aproximately STC of 200 mm block with 2 layers of gypsium of 13 mm and 18 mm on each side of the block?

is adviceble one 13mm on one side and 18 mm on the other side?? or both of them on both sides??

bert Stoltenborg · Post by **bert Stoltenborg** » Sun Jan 09, 2005 2:48 am

It's better to put all the gypsum on one side of the blocks. Avoid triple leafing.
And try to make the gap as big as possible, put mineral wool in the gap and don't attach the gypsum construction to the blocks.

I don't know the STC. What kind of noise are you trying to isolate?
If it is music, STC is not the proper spectral weighting. STC overestimates the sound isolation for music sound.

Bert

z60611 · Post by **z60611** » Sun Jan 09, 2005 3:55 am

bert Stoltenborg

It's better to put all the gypsum on one side of the blocks.

Why?

hugo_inside:
Are the blocks filled or hollow?

hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 4:51 am

And try to make the gap as big as possible

what gap? I don't wanna gaps, only gypsium panels, without rockwool.

What kind of noise are you trying to isolate?

A music band. Drums, bass, guitars... But not spending all my money.
With floating floor and rocksheet on walls.

Are the blocks filled or hollow?

In principle, blocks are hollow. I ask about this before but I had got not clear ideas. What's your advice?

bert Stoltenborg · Post by **bert Stoltenborg** » Sun Jan 09, 2005 5:16 am

I thought you were trying to increase the isolation of a wall by adding sheets of gypsum in front of it.
Just adding mass to the wall won't work as well as putting the gypsum on an airgap in front of it.

z60611 · Post by **z60611** » Sun Jan 09, 2005 5:52 am

I thought I'd give some numbers to illustrate what Bert is saying.

Given a solid filled concrete block ~200mm thick, let's assume it's STC-44. (this may be way invalid, probably low, because I just used gypsum density)

Sticking a 13mm sheet of gypsum onto it (with glue) would boost it to STC-45.

Sticking two 13mm sheet of gypsum onto the concrete (with glue) would boost it to STC-46.

A {concrete block wall ~200mm thick, 1/2" wood furring strips screwed to the concrete, a bit of insulation between the furring strips, and a 13mm sheet of gypsum screwed to the furring strips) would also be around STC-46

But a {concrete block wall ~200mm thick, 2x4 wood studs screwed to the concrete, a bit of insulation between the studs, and a 13mm sheet of gypsum screwed to the 2x4's) would be around STC-53

And a {concrete block wall ~200mm thick, a one inch air gap, 2x4 wood studs, a bit of insulation between the studs, and a 13mm sheet of gypsum screwed to the 2x4's) would be around STC-65

And a {concrete block wall ~200mm thick, a one inch air gap, 2x4 wood studs, a bit of insulation between the studs, and two 16mm sheet of gypsum screwed to the 2x4's) would be around STC-73

(these are all insul predictive software - i.e. theoretical guesses)
These statements completely ignore flanking losses, and ignore the LF isolation effects (STC hides these)

z60611 · Post by **z60611** » Sun Jan 09, 2005 6:47 am

Here's some better numbers from "Noise Control In Buildings" by Cyril M. Harris, page 5.52, who in turn quotes the test lab NRCC

Paint, 8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], STC-53 (125hz 37db)

8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], 5/8" (16mm) gypsum board, STC-50 (yes it's lower! amazing what a bit of paint on concrete will do) (125hz 35db)

8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], 1.5" (38mm) wood studs with fiberglass bats, 5/8" (16mm) gypsum board, STC-55 (125hz 37db)

Paint, 8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], resilient channels, 5/8" (16mm) gypsum board, STC-59 (125hz 40db)

5/8" (16mm) gypsum board, 8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], 2.5" (65mm) steel studs with fiberglass bats, 5/8" (16mm) gypsum board, STC-61 (125hz 40db)

5/8" (16mm) gypsum board, 2.5" (65mm) steel studs with fiberglass bats, 8" (190mm) concrete block [48 lb/ft^2 (235 kg/m^2)], 2.5" (65mm) steel studs with fiberglass bats, 5/8" (16mm) gypsum board, STC-72 (125hz 49db)

hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 7:05 am

but wich price do you pay for each way??

hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 9:35 am

So, it's better and cheaper to build concrete block with paint walls, than concrete with 16 mm sheetrock?

thanks for you information!!

knightfly · Post by **knightfly** » Sun Jan 09, 2005 4:31 pm

Hugo, before you start on this can you re-post the price info (for materials) you had on another thread?

Also, since you will be having several bands in several practice rooms, all thumping away on their drums/bass and NOT wanting to hear the OTHER bands drums and bass, we should discuss this some more - and you should FORGET about STC, because it means NOTHING in your application... Steve

hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 8:04 pm

Before I post the new price list, I must say that all the other places with practicing rooms for renting have : Paint + Concrete Block ( 15 mm to 20 mm ) + carpet in the inner side of the room. Perhaps blocks are filled with sand. On the floor , 3 mm of rubber, and some places 3 - 4 mm of carpet. On CEILINGS 2 mm gypsium and 20 mm fiberglass or rockwool panels and more rock wool over there.

but I want to do diferent but not so much expensive... Later, I'll put the new price list.

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hugo_inside · Post by **hugo_inside** » Sun Jan 09, 2005 11:38 pm

Price list:

44 mm x 93 mm x 3000 mm fir stud ------ 14 €

1 concrete block 200 mm x 200 mm x 400 mm ---- 1.20 €

13 mm x 1200 mm x 2500 mm sheetrock --- 7.10 €

rock wool panel 1350 x 600 x 40 mm --- 2.37€

rock wool roll 7000 x 1200 x 70 mm ---- 17 €

steel studs :

800 x 30 mm ---- 2.5 €
U form stud 349 x 310 x 340 x 24 mm --- 3'5€

knightfly · Post by **knightfly** » Tue Jan 11, 2005 7:16 am

Hugo, I'm really behind for the forseeable future; I posted this on your other thread, if you can check that; if you can, I'd prefer that you figure out for yourself how many blocks, studs, etc, it will take to build the walls I recommended in your other thread so you can see which will cost less.

I would forget about carpet, other than maybe on floors, for the practice rooms; the sound will be CRAPPY doing that. Better you set up something like simple frames and rockwool across the corners, then random chunks of rockwool on walls and ceiling, just to kill the flutter and still keep the rooms a bit live.

See your other thread for more... Steve

hugo_inside · Post by **hugo_inside** » Tue Jan 11, 2005 9:07 am

but, you're talking about the sound in the room... the soundproofing is not the problem. Isolation is the problem. But, after some posts, I realize that there's no cheap total isolation... but I learn some concepts about this...

knightfly · Post by **knightfly** » Thu Jan 13, 2005 3:06 am

Soundproofing is just another word for isolation - they both mean "not hearing the sound on the other side of the wall" -

The other aspect is "acoustic treatment" - this means that, once the room is isolated (or soundproofed) you then need to make the room "sound good" inside - this has almost NOTHING to do with isolation, except that some types of treatment can WEAKEN the isolation of a wall.

Sound PROOFING is what we accomplish with mass-air-mass construction, proper caulking of all joints, painting of blocks, etc - (Bert, Hugo was talking earlier about HOLLOW concrete blocks; unless they are filled, you would NOT want to put another AIR gap or it would be triple leaf...)

acoustic treatment is the traps, absorbers, etc, you want to build for the inside of the rooms; it is this part that makes the room either nice or not so nice to play music inside.

Hope that helps... Steve