concrete block confusion & other oddities

Joey-T · Post by **Joey-T** » Wed Aug 18, 2004 4:35 pm

Hello, all.

I'm new here (was directed to this site by a poster at tweekheadz). After quite a while spent trying to piece together studio tips from various places online, I thought I had some kind of generalized gameplan. After reading a bit in this section of the site, now I'm not so sure. I have enough carpentry experience to build, coming from the construction and HVAC fields, but I'm no acoustics scientist.

A little background on what I hope to accomplish... I am planning a room addition on my house or a seperate stucture for a studio and practice space. I am currently using a 16x24 detatched garage with no insulation (imagine my neighbors' joy). I am still weighing the pros/cons of addition vs. new structure. My property is a triangle shape with roads on all three sides, one of which is moderately busy. The space will be large enough to house a double bass drum set and a baby grand, along with space enough for a small control room and room enough for a few other musicians. In short, enough room for a typical rock band to practice and record comfortably. Diminsions and layout are still in the making. My goal, of course, is to keep outside noise (traffic) out, and our "noise" in as much as possible. We like to play around late at night, and I'd like to do so without my neighbors and family being bothered.

Like I said, I'm a victim of "learned it on the Internet, so it must be OK." I thought I had a plan by combining a bunch of different things I gathered over the years. Here's what I had come up with...

First, I wanted to build a concrete block structure. I had heard that the density of the wall, along with the trapped air space, would be a good way to attenuate the sound. Plus, block is more "hardy" than wood, meaning, I can take my time with it and it isn't hurt much by being out in the weather during construction (I am disabled, so that is a big plus, as it would likely take some time to construct with my doing the work). Using more Net-knowledge, I figured on a slab floor that would not be touching the blocks of the walls. Then, typical roof truss construction.

That is the complete exterior, shelled in. Furthering my downward search engine spiral, I figured on floating a second floor atop the first one on neoprene pads, again, not touching the block walls. Here's where it gets confusing to me (again, thanks to the WWW). I figured on building new interior wall framing, allowing an air gap between it and the concrete, atop the floated floor. After reading about differing thicknesses of materials, I thought I could go with 5/8 drywall, a layer of fiber board, then 1/2 drywall. On the second ceiling, 5/8 drywall with a bunch of insulation above it, then maybe a suspended ceiling beneith it (oh, and drywall on the original structure's ceiling too). I never did come to a decision on windows (should I or shouldn't I, and how).

Now, after reading just a little on this site, it appears that the two air spaces are a bad thing (air in the block, air between the walls). Further, nails/screws penetrating all the way to the stud from the innermost layer of drywall seems to ruin it all anyway (how am I going to sandwich fiberboard without fasteners holding it all together).

In short, it looks like the whole plan came tubling down after finding myself amongst a group of people who live this stuff (read:you all).

It looks like I was about to do nothing more than make the building supply people happy, instead of the neighbors! I plan to do alot more reading around here, and asking more questions as I go, but it looks like my plans to build this spring are slowly slipping away as I realize-- I don't really know what the heck I'm doing!

Like I said, I'm gonna do alot of reading, so don't discount me as one of those who ask their questions then jet out. But feel free to give any advice or anything, you know, get me pointed in the right direction. I do tend to catch on pretty quick! Heck, this time last year, I was planning to build a rectangle studio (and learning a bit about that is the reason I don't have one built THIS year). Thanks for having me, and I'll try not to ask too many dumb questions.

z60611 · Post by **z60611** » Wed Aug 18, 2004 4:53 pm

Because you're building a new structure, you may wish to consider the interior dimensions (H x W x L) for optimal modal sizing, if you fall back on a rectangular studio.

concrete block structure. I had heard that the density of the wall, along with the trapped air space, would be a good way to attenuate the sound.

The increased mass of the wall will help LF TL. The airspace in the concrete block can be filled with sand or mortar or cement.

AVare · Post by **AVare** » Wed Aug 18, 2004 6:22 pm

Adding to the excellent remarks from Z60611 regarding filling the blocks, the use of fiberboard in between gypsum is of questionable value. We (the collective) have not seen any sound isolation tests with the material used showing an advantage. Ergo don't bother with it.

As far as the screws through tot he studs, the wall will be floating from the concrete block so coupling to that is not created. If you want a bunch of test on concrete block walls with various finishes added have a look at

http://irc.nrc-cnrc.gc.ca/fulltext/ir586.pdf

If you want a comparison with a similar construction using RSIC clips, have a look at

http://www.pac-intl.com/pdf_test/test_f ... report.pdf

Kinetics makes similar clip. ISOMAX I think is the name they use for it.

In case you haven't picked up on it in your research, we place a very high importance on having actual test data to judge the performance of walls, and focus on the TL values. As the physics works out, a wall that has sufficient TL at low frequencies will almost invariably have considerably better TLs at higher frequencies.

BTW doing an educated guess, building your wall with the 2 layers of gypsum and the RSIC clips would have an STC of around 78 and greater than 37 TL from 50 Hz up. Fantastic performance.

If you want to compare those figures with gypsum type construction, the following has 350 wall constructions tested. It is a huge a document, but it is very helpful all the test data. Did I mention the importance of having actual test data?

http://irc.nrc-cnrc.gc.ca/fulltext/ir761/

It's great to help you with your design, as opposed to telling you what was done wrong and what has to be torn to it right!

Could you update your profile so that we have an idea where you are? As the discussion turns to materials, availability of materials, costs, etc they vary wildly from region to region, must less countries and continents!
I won't even mention insulation companies with differrnt designations in different countries and different products having same designations in different countries!

Andre

Joey-T · Post by **Joey-T** » Wed Aug 18, 2004 11:51 pm

Thanks for the great responses. I'll be checking out those links after bit for sure. I'll get my profile adjusted as soon as I finish this post (no idea why I didn't fill in the location, I always fill in locations when joining a forum).

One more question before I go off to reading land... you said...

BTW doing an educated guess, building your wall with the 2 layers of gypsum and the RSIC clips would have an STC of around 78 and greater than 37 TL from 50 Hz up. Fantastic performance.

Are you talking about just the stud wall with two layers of gypsum, or are you also counting a sand-filled block exterior structure? Again, thanks. I'm of to fix the profile and read at those links.

AVare · Post by **AVare** » Thu Aug 19, 2004 1:51 am

Are you talking about just the stud wall with two layers of gypsum, or are you also counting a sand-filled block exterior structure?

I am referrign to the complete double wall structure. Specifically working from outside to inside:

8" hollow filled concrete blocks
2x4" wood studs on 24" centers
mineral wool between studs (~2.5lb/ft3 density, 3" thick)
RSIC clips and hat channel
5/8" gypsum board
1/2" gypsum board
(the the two layers of gypsum board fastened together with screws)

All the data in the links is daunting, but especially with your location vs a vs three streets, you need hood isolation. You will be spending a good chunk of money and time ion this project. The more you know about the benefits/ tradeoffs of each wall design, the better you can make the best decision for your construction.

I'm looking forward to your developing the design, and hopefully (hint) pictures in your studio build diary.

Andre

dymaxian · Post by **dymaxian** » Thu Aug 19, 2004 11:42 pm

If you'll be floating the floor off the concrete sub-floor, you won't have to worry about either isolating the concrete slab from the concrete block outer wall or using RC on the interior walls. If you float the floor on neoprene or whatever, and then build the walls up off of that, and then build an interior ceiling off those walls, you'll have an inner layer of wall that is totally isolated from the outer layer. All will be well.

As far as addition to the house vs new building, here's a couple things to think about:

Adding onto the house means a structural connection to the house. Since you'll have an isolated inner layer in the studio (at least I'd strongly recommend it, especially since you're building new!) this may not be a big deal. If you're going to isolate the inner walls and floor and ceiling from the outer layer, it doesn't matter much whether the outer layer is a new building or part of the house. It just means there's a good chance that the house won't be quite as sound-isolated from the studio. This may or may not be a big deal.

The other thing is about space on the lot- if you build a new building, you'll have to keep it a certain distance from the main house and property lines, plus depending on where you live building codes for an outbuilding may be a pain in your ass. Adding on to the house will probably give you more space inside the studio to work with, and it sounds like you're looking for a pretty big space to do all the stuff you want it to.

HTH

knightfly · Post by **knightfly** » Fri Aug 20, 2004 5:25 am

On top of the already great help you've gotten so far - check this out, starting mainly with the paragraph "The most do-it-yourself friendly and economically sensible, wall building method we've found is concrete block dry-stacking, wherein you surface bond concrete masonary units ("CMU"s) for the home's walls." -

http://www.thenaturalhome.com/passivesolar.html

Don't miss this link -

http://www.thenaturalhome.com/drystackblock.htm

also, do a search on surface-bonded concrete block - that's what I used to find those above. I have a book I've yet to get time to go all the way through, that has an article on surface bonding -seems like a 'way easier way to do blocks.

You would still need to fill the blocks and do the inner air/mass add-on for serious isolation, though... Steve

Joey-T · Post by **Joey-T** » Sat Aug 21, 2004 3:52 am

Wow, thank you all for your great replies! As to the add-on vs. seperate structure debate, I think that will come down to cost and/or personal preference. With the shape and dimensions of my property, ANYTHING I do is going to involve going through a variance process. I've already went thru it once for a privacy fence.

I'm filling up a notebook with info that your links have provided so far, and I still am only part-way through the links! Its better to study and have money spent on what works, rather than a pile of money that doesn't work. I did think of a couple other questions while reading along though...

1. Obviously, drums and percussion instruments make a ton of sound (or noise, depending on which side of the privacy fence you are on!). After a bit of reading and looking at some of the floorplans on this site, I was thinking of a multiroom setup (drums in their own room, piano, etc). In my situation, I'm not sure if this is what I want... it'd be great for recording, but not very good for the "jam sessions." Anyway, on setups like this, do people generally treat the rooms differently? I mean, obviously, keeping exterior noise out is a concern for all rooms, but as far as keeping the interior sound from bleeding out, would drum rooms be treated based on the sound they produce, and the same for other "single use" rooms?

2. This question is mostly cosmetic I think, but I can't seem to locate the answer. Could be that I'm not using the correct search terms or something. Anyway, when a room is floated inside another room, what do you do with the passageways? In other words, for example, the door to the studio... is there something you use to fill the space between the two walls, or is it left open, where one could see the cavity between the walls? What do you do here? It seems like just leaving it open would make it easy for critter problems, not to mention looking unfinished. But it also seems that if there is something there to seal it up, then a "bass drum effect" might take place when both doors are closed.

I've actually come a long way with trying to learn what I want. I originally was going to construct about a 32x48 building with a bit less than half of that a "live stage" with a control room in the corner. With the other half, I was originally going to have a few tables and chairs, as well as (gasp!) a pool table. This would have been great for the weekly karaoke parties (don't laugh, the kids love it and I get good singing practice with it, as well as entertaining friends). It was going to be like a bar, but without the booze. Then, after a lot of thought over what I wanted to do with my original music, this didn't seem like a conductive setup to what I want to do. Plan A-- great for karaoke, jam sessions, partying and entertaining, but not very good for trying to make professional-sounding recordings of my original stuff. So, I guess I'm trying to find a balance, which means seperate rooms might be a negative issue too. So I guess I'm farther back in the planning stages than what I thought!

Plan B is slowly forming, using a similar-size building, only split in thirds-- you walk in, and there's a smaller area for entertaining (the pool table, table and chairs, etc). The second third would be like a live stage facing the first area. This would be good for the jam sessions and the karaoke parties. Pretty much, these two thirds would be the original plan, only reduced. Then the last third would be isolated from the rest-- a more professional environment for serious recording. I thought maybe centralizing the control room to be able to see into the rooms of the isolated areas (drums, piano, etc), yet have a window available to the stage area.

I realize that this is a rather large and unusual project for a "home" setup, but my family and friends take music pretty seriously, be it simple old karaoke, or playing instruments. It is a big part of our lives, and a bonding-point in our family. Plus, like any other musical family, we have other interests, like swimming and playing pool. If I end up coonsidering a structure this large, it will require removing the building that currently houses the pool table (the garage I mentioned that I use now). This building is right off the swimming pool, so it was a natural place for the pool table- just open the door, and instant access to the table for non-swimmers. As it stands right now, we can EITHER use the table OR set up for jamming/karaoke, but not both. Just no room. And trying to record anything at all is out of the picture totally. As you can see, I have some unique needs! Heck, everyone has issues, right? Any ideas would be great.

Just for information, between 48-52 feet is about the max length I can get away with without major problems (read: moving an 18x33 pool). I can toy with the width a bit though. Unless someone sees a major problem with my current idea-- which is only an idea right now-- I can post a pic of the working idea if you like.
Thanks again!

AVare · Post by **AVare** » Sat Aug 21, 2004 7:30 am

First of all, it is great your posting here before any Construction has started. Especially good being the concept phase. I will be posting on the studio design forum, because that is more appropriate for what we are discussing, shortly, but to answer a your direct questions first.

Drum isolation is noise (in the industrial sense, not musical remark)isolation. Treated the same way as any noise source. With modern recording techniques, the isolation is needed more to keep the drum tracks clean, not keep instrument tracks clean. A close miced amp does not need protection from the drums. The drum overhead mics do need protection.

The walls between the iso doors, depending on the space between the doors can be treated like studio/control room widow construction: a flat surface with a cut to isolate all covered with sound absorbent material and a decorative fabric; or if the space is quite large, it can be used as an iso booth in and of itself and just normal studio techniques used.

A couple of questions that will help us. What ceiling height and roof height are you considering?

From what I have read and guess from reading between the lines the spaces, wanted for the building are desired to be for:

live performance
recording performance with isolation for at least drums, maybe piano also
recording control room
socializing with pool table, bar type area and social center (couch etc).
now guessing
-pool change area
-pool utilities
-toilet

Is this close?

As I wrote, look in the studio design are for my next post to you.

Andre
Looking forward to your posts

Joey-T · Post by **Joey-T** » Sat Aug 21, 2004 11:04 am

Come to think of it, I guess this should be in the design area. I guess I figured "studio design" meant the electronics one chooses. But to answer your questions...

Ceiling height- undecided. Thought about 12' total, which would give 10' on the stage with a 2' stage height. Considering the studio portion would be behind the stage, I thought it may be "convenient" to have its floor height the same as the stage.

Building useage: all corect except for the swimming pool equipment and changing room. Pool equipment is already housed in a garden shed, and adequate changing/shower facilities are provided from the house. Only the fact that the new structure's entrance would be close to the pool is the reasoning-- entertaining. Some can be swimming while others are singing, playing pool, or enjoying/partaking in a jam session.

A toilet is desired... some of my best ideas come about in there.