Type of double concrete wall and isolation for best soundproofing effect?

[Dag Ekeberg]

I’ve been browsing threads all day but can’t quite find the answer…

I’m putting in a ground floor room underneath our Thai Style stilted house. I have 25 cm (10”) wide beams, so the thickness of the wall is given (namely 10”…)

Meaning, I’ll be putting in a double concrete wall. The cheapest is a double cinderblock (breeze block) wall. That leaves a 5 cm (2”) air gap which I’ve been told can be filled with those heat insulation mats (Chang brand) they use for roof insulation, since they also kill sound.

Questions:

1. Will a double red brick (those tiny bricks) wall have a noticably better sound isolation effect (those walls are 2-3 times more expensive including the cement), or will the difference be meaningless when the sound through the (double glazed) windows are added?

2. How about q-block outer wall and cinderblock (or red brick) inner wall?

3. Any suggestion for isolation material in the air gap? Remember, the issue is sound, foremost (village radio comes on at 6am).

[bankruatsteve]

I suggest "Superblock" which is commonly available at 7.5cm width - leaving a gap if you do a double wall. Personally, I don't like gaps unless filled with some insulated material - but I don't think we need to start that one again. If you go with q-block and something else, I would put the q-block on the outside - just b/c it will be the better insulator. A double wall of anything will probably be OK - although I just think the Superblock should be the standard choice. Noise will come through your windows - and that's another recent topic.

[Dag Ekeberg]

I suggest "Superblock" which is commonly available at 7.5cm width - leaving a gap if you do a double wall. Personally, I don't like gaps unless filled with some insulated material - but I don't think we need to start that one again. If you go with q-block and something else, I would put the q-block on the outside - just b/c it will be the better insulator. A double wall of anything will probably be OK - although I just think the Superblock should be the standard choice. Noise will come through your windows - and that's another recent topic.

Thanks, I was quoted 33 baht pr q-block. That makes q-block four times more expensive than cinderblock (5.5 baht), taking into account the difference in size. You say a double wall of anything will probably be OK. Then I'm temped to go for cost saving...

[bankruatsteve]

I "think" the going price for 7.5cm Superblock from Global House is around 20 baht. (?)

[Dag Ekeberg]

I "think" the going price for 7.5cm Superblock from Global House is around 20 baht. (?)

This is out in the wilderness of Isan, probably some transport involved... I tried to tell the guy that the price should be around 20, but he said the price had increased like crazy after the flooding in 2011 (!?)

[passingas]

Not sure of pricing of ACC block, but I used it as the exterior wall with a red brick interior wall with nothing in between and am totally, totally amazed at how sound proof it turned out to be. That combo is as sound-proof as it is a thermally insulated one. If heat is of no concern, then probably just go with a double wall of anything if all you want is sound proofing. I used to build recording studios in another life time and then it was total vibration isolation concerns. That meant nothing connected....floors, walls or ceilings....everything had to "float". Lots of special rubber mounted isolators were used and the real challenge was the HVAC stuff. Good luck. pg

[Dag Ekeberg]

Thanks, passingas, that sounds really encouraging. It’s tempting for cost reasons to go for the cinderblocks as inner wall, but you chose red brick. Any reason?

Got an interesting email from a pal who builds condos here. He said they use those smart q-blocks in their double walls, but important not to use same thickness on both inner and outer wall - has to do with the physics of sound waves apparantly. They have just air inside the walls, no insulation.

[passingas]

We used the red bricks as they were way better made than the cinderblocks. The closest outfit making those cinder blocks used the bare minimum of cement and then really didn't cure them at all....their idea of curing was to stack them out in the sun. You looked at them wrong and they would crumble. The red bricks were very solid. They were delivered in a dump truck and very few broke upon dumping. I was going for the thermal aspects of it, not necessarily the sound proofing...I found this out after the fact! it was a very nice extra, indeed.

Physics of sound waves...that hits a harmonic, indeed. We had to make bass traps to keep standing waves from ringing in certain areas of a studio. Most of the control rooms had them, but a few big rooms needed them as well....so that same thickness could play a role in cutting down on sound transmission...however...the idea of isolating the vibration is really what kills the sounds from bleeding into the environment you are trying to quieten.

If heat inside is not an issue....go with a double wall of those cinderblocks....or cinderblocks and ACC...or even red brick. Good luck. pg

[klikster]

Thanks, passingas, that sounds really encouraging. It’s tempting for cost reasons to go for the cinderblocks as inner wall, but you chose red brick. Any reason?

Got an interesting email from a pal who builds condos here. He said they use those smart q-blocks in their double walls, but important not to use same thickness on both inner and outer wall - has to do with the physics of sound waves apparantly. They have just air inside the walls, no insulation.

I think you will find that the spacing of the wall elements rather than the thickness of them will be what contributes to a standing wave. If you are anticipating a standing wave problem, fiberglass will help.

[cdmtdm]

use the large concrete blocks and fill the centers with concrete , the dimensions are 40cm length x 18cm height x 14cm thick , they have two large hollow cores to fill with concrete ... i buy them in isaan for 13 baht each , machine pressed and strong as hell ...