Cinder Block

[Jeazii]

I am starting new construction soon in my backyard. The building will be free standing. Issolation is very important because of my neighbors, I wanted to see what everyone thinks about using cinder block filled with sand or foam as opposed to more traditional construction. Let me know if anyone has experience with cinder block and its issolation qualities. Thanks.

[Rod Gervais]

Originally Posted by Jeazii

I am starting new construction soon in my backyard. The building will be free standing. Issolation is very important because of my neighbors, I wanted to see what everyone thinks about using cinder block filled with sand or foam as opposed to more traditional construction. Let me know if anyone has experience with cinder block and its issolation qualities. Thanks.

Jeazii,

Forget the foam - it will not help - in fact it will hinder.

The sand (however) is a different matter - it is an excellent product for block walls in it's ability to damp the wall from an isolation point of view - and is exactly whatI used for POWER STATION NEW ENGLAND in the outer most wall construction.

Rod

[Dani Pace]

Another material for filling block walls is vermiculite, it is a mineral which is lighter in weight than sand yet has similar sound reduction properties and better insulating properties. A good building supply store should either stock it or be able to order it for you easily. It will cost you a bit more than sand but it has double the benefit, it isolates and insulated at the same time in the same amount of space. It's definitely worth checking into before deciding.

[Rod Gervais]

Originally Posted by Dani Pace

Another material for filling block walls is vermiculite, it is a mineral which is lighter in weight than sand yet has similar sound reduction properties and better insulating properties. A good building supply store should either stock it or be able to order it for you easily. It will cost you a bit more than sand but it has double the benefit, it isolates and insulated at the same time in the same amount of space. It's definitely worth checking into before deciding.

Dani,

On the insulation part you are correct - on the isolation part - you are mistaken.

what you are creating with sand (at roughly 100 PCF in weight) is an extremely massive single leaf as one part of your 2 leaf MSM Isolation system.

Vermiculite (on the other hand) is a lightweight mineral (50 to 90 pcf) - but before commercial use it is heated - and does one of the things it does best - which is to expand to 10 or more times it's original size - and thus ends up in application only weighing about 5 -10 pcf.

Aside from the dampening effect of sand - the sheer addition in mass adds tremendously to LF isolation - and we all know that's the problem area - Mid and HF transmissions are eaiily handled through the use of an isolated inner wall with even a few layers of gyp board on it's face.

Sincerely,

Rod

[Dani Pace]

Rod, thanks for the additional info about vermiculite. I agree that it does not have the density of sand so it has less mass, but it is still some pretty neat stuff. I live in an area where vermiculite is minned so I am used to seeing unprocessed vermiculite used fairly often for this purpose. One thing I think we will all agree on is that a cinder block wall needs to be filled with something, the hollow space inside the blocks is an invitation for problems where sound transmission is a concern.

[Rod Gervais]

Originally Posted by Dani Pace

Rod, thanks for the additional info about vermiculite. I agree that it does not have the density of sand so it has less mass, but it is still some pretty neat stuff. I live in an area where vermiculite is minned so I am used to seeing unprocessed vermiculite used fairly often for this purpose. One thing I think we will all agree on is that a cinder block wall needs to be filled with something, the hollow space inside the blocks is an invitation for problems where sound transmission is a concern.

Dani,

reality is probably about a 6 to 8 dB gain with sand - plus it's value to damp the block itself.......

Raw vermiculite will add almost nothing from an insulation point of view (It's just too dense for that purpose) and will be anywhere from a low of about 3dB (50pcf) to a high of just about 7dB

BUT - due to the loss of super fine particles like sand - it will not dampen the same as sand.

Rod

[Jeazii]

Thanks for all the input guys! I think i will go with the sand, LF is the biggest concearn. On the inside I am planning on two layers of sheetrock with a 1" air gap, sound good?

[Rod Gervais]

Originally Posted by Jeazii

Thanks for all the input guys! I think i will go with the sand, LF is the biggest concearn. On the inside I am planning on two layers of sheetrock with a 1" air gap, sound good?

Nope - that doesn't sound all that good.........

For good isolation you need a wall framed inside - which (if 2x6 @ 2' o.c. (which will add more LF iso versus 2x6 @ 16": o.c.) if placed 1" from block - would be a 6 1/2" air space - and then 2 layers of gyp -

THEN you have something worthwhile........

Sincerely,

Rod

[Rod Gervais]

BTW - one last thing -

Make very certain that you install sleeves for any penetrations you will need to make as construction goes on - before sand placement.

It is impossible to sneak things ouside (such as electrical outlets - lights - exhaust vents, etc., etc. ) without loosing the sand in the cavities - and once the walls are complete it is just as impossible to fil them up properly.

So take your time and make sure you have thought through everything that has to pass through those walls.

AND MAKE SURE TO KEEP THAT SAND BONE DRY.......... wet sand is a bad thing - never settles right - and makes for damp block work - which is a baaaaddddd thing.

Rod

[john1192]

rod,

did you ever build this cinder block building ... i am interested in doing the same thing ... was wondering about cost ... can you send me an email with a general figure of what it cost you to do this ... am having a hard time finding a good resource for cinder block construction costs for a building on the web ...

thank you cheers

john

john.hartmann@ca.rr.com

[Rod Gervais]

Originally Posted by john1192

rod,

did you ever build this cinder block building ... i am interested in doing the same thing ... was wondering about cost ... can you send me an email with a general figure of what it cost you to do this ... am having a hard time finding a good resource for cinder block construction costs for a building on the web ...

thank you cheers

john

john.hartmann@ca.rr.com

John,

Yes I did - build it that is - but that was back in 1994 and the costs wouldn't mean anything today........ BUT - tell me where you are (means all the difference in the world believe it or not) and I might be able to give you a ball park idea.........

Rod

[john1192]

thank you rod,

i am in los angeles ... near culver city ...

i understand the 1994 vs. 2008 thing ...

yes, any ballpark will be helpful

cheers ...

john

[Rod Gervais]

8x8x16 std weight 7.75 per sf of wall
bond beam - 9.34 pr sf bond beam
door lintels 8.28 per sf of lintel
core & beam filling
grout 2.35 per sf of wall (this is 1 #4 bar @ 16"centers w/ structural grout.
sand 1.3 per s.f. of wall

That should pretty much cover it and be somewhere in the ball park

Rod