John Sayers' Recording Studio Design Forum Archive

I have to say that this place is an awesome resource for anyone that is trying to put his or her own room together. I'm old enough to remember when personal computers and the internet didn't exist, and I'd hate to think of what I would have to go through to find out the stuff that is readily available on this board!

Anyway, I'm doing a 22 X 22 foot garage conversion, and the existing structure has block walls that are 7'9" high. The roof truss pretty much sits on top of this, and before I do any construction I wanted to ask if I should fill the cavities in the block. My friend did that with his commercial studio for more mass, filling in the courses of block with sand.

What do you guys think?

This is a construction question so I've moved it to that forum.

cheers
john

beautyfish

Assuming all else is done right, then filling the block with sand or mortar is a good thing. By doubling the mass you get a few extra db in isolation.

Given the cost and outlay of time, is it worth doing, in your opinion?

Given the cost and outlay of time, is it worth doing, in your opinion

Only you can answer that. How much isolation do you want? If was doing it and planned to ne there for a while, I would, just to know that the best that could be done in that part was done. Of course afer walls, you have the roof and the openings, doors, windows, ventilation etc.

Andre

More important - if you intend to add stud frames and an inner leaf of 1-2 layers of drywall, then NOT filling the blocks will cause them to act as a double leaf partition all by themselves, and adding your inner drywall and frame will cause you to LOSE isolation in lower frequencies. So, if you intend to add an inner wall leaf you NEED to fill the blocks, either with sand or with concrete/grout... Steve

The answer is "Yes it is worth they effort to fill them"........ equally important in either case.

Rod

Damn, the rooms I was planning on converting into my new studio are built using those blocks... Does this mean I need to fill them if I am to create a room within a room? I do need isolation... is there any other way to gain the required isolation, or am I stuck...

Pretty much stuck, unless you'll be happy with a little better midrange isolation and quite a bit worse LF isolation, sorry - if your new ceiling for the inner room is lower than the total wall height, you might get good results by drilling holes in the top blocks and filling thru those, as long as the new wall/ceiling joint ends up below where you drilled the holes (you'd still need to patch the holes after filling, of course) -

I'm not absolutely positive this would be acceptable, but think it would be much better than leaving the blocks hollow and adding another leaf to the equation... Steve

nah, I'll need low frequency isolation, tracking lots of live drums etc... I have been operating in a single (untreated) room setup with the same external walls (concrete blocks) for some time and have had no problems tracking drums etc (touch wood), but i want to give my ears somewhere to hide from the noise

I am new with this acoustic design stuff, but I've been scouring this site for a while... forgive me a stupid question, and I think I know the answer, but adding an extra leaf will actually reduce the isolation?

Looks like I'm going to need to treat my existing room and run with that for a while, can't justify the expense of building a proper studio at the moment if i have to fill all the wall cavities to do it properly...

Ok..so the consensus is to fill the blocks. Now, at the risk of sounding stupid.....what is the best way to get the sand UP there? I figured on using something like a highway cone as a funnel, but I'm assuming that I would probably buy sand by the yard and have a truck deliver it. Do I build a scaffold and just use muscle power to pack bags, haul the sand up and pour it down, or are there tricks? Am I better off pumping concrete down the voids instead, given how much time and effort it will be to wrestle all that sand around? What do you guys think?

Guys, I'm draggin' my ass to bed after a fun 12 hours on 4 hrs. sleep; I've not yet had time to read all this, but there's quite a bit on block -

http://irc.nrc-cnrc.gc.ca/practice/noi1_E.html

Also, check the top and bottom of this page -

http://www.domesticsoundproofing.co.uk/tloss.htm

if you consider the 50 dB example as just adding a third leaf to the 36 dB wall, you'll see that the STC does indeed improve with the extra leaf - just not as much as taking up the same amount of space with only TWO leaves.

However, STC doesn't tell the whole story - I've read that an extra leaf improves mid range TL (where STC is calculated for all practical purposes) but that it HURTS the LOW frequency performance. I don't have a way yet to calculate anything but a double leaf wall, and that only marginally -

Figuring this another way, though - starting with the 57 dB wall, if you add leaves BETWEEN the two you get either the 40 dB or the 47 dB wall; so in essence, adding a leaf between two leaves (narrowing the air gaps) will lose you anywhere from 7 to 17 dB.

So, if you add a third leaf to the inside or outside of an existing partition, you will improve it somewhat - but if you want optimum TL in a given wall thickness TOTAL, then forget the inner leaves. Again, I'm not totally sure what happens to LOW frequency but I know it isn't good... Steve

Filling - haven't done this yet. Rod Gervais is the man to ask on this, but he's really busy right now - if you need an answer, you can email him direct - he posted his email here -

http://www.johnlsayers.com/phpBB2/viewt ... c&start=15

you can send him a link to this thread, and ask his advice - he'll get to you as soon as he can...