Rehearsal+Recording space

Hi all! A friend bought a new two story space to build a recording/rehearsal space, a control room downstairs and classrooms and production suites upstairs. There are no main streets near. CR entrance is about 30 meters far from street (actually a dead end). Noise level was between 50-60 dB (C weighted) in the middle of live room space (with no doors) during midday. The place is surrounded like this: N) Apartment W) 1/2 back yard, 1/2 neighbor cafe's kitchen S) Control room E) (Two buildings) 1st one's basement and 2nd one storage. Upstairs) No neighbor contact. - Place is in raw construction phase. So every hardcore modification is possible. - 62 m² recording area will be used for both rehearsal and recording. - Musical genre will vary from (mostly) pop to rock bands so I'd like to be prepared for 120-125 dB for max level. (Drum kit (which will be on a drum raiser), guitar and bass amps, monitor speakers for rest of the band, etc.) - There are steel reinforcing bars. Good for earthquake, bad for lowering ceiling space. (Those beams in Control Room, I can't touch them) - Control room will have two big sliding doors, right next to main mix position and back of rehearsal mix position. It's a special requirement for daylight. We will use portable solution to get rid of glass reflection (or wooden shades?). I will try to use the best possible thick glass (it's called "acoustically laminated), framing and locking mechanism. I'm also going to see if it's possible to angle sliding doors outwards. Walls: Outer and inner walls are (fire) brick and rendered. Inner walls also has 150 cm high ceramic tiles. - Wall width is about 20-25 cm on West, ~30cm on East, not sure about North but should also be ~25cm and 44cm on South. - I'm unable to supply Green Glue right now. Ceiling: I consulted to an architect regarding to ceiling construction and asked if it's possible not to use hangers and design load bearing walls. He replied that it should be no problem with iron studs, since galvanized steel will be too thin to carry the load. I'm waiting for his detailed calculations. - Ceiling is like this. It should have at least 15cm cement layer on top of wood. Floor:Floor is cement and will be leveled first (grout?) and applied waterproofing sheet (the one that's being applied by flame guns). GOAL: - Keeping neighbors at peace during loud sessions. - Not disturbing music classes upstairs. - To fit in 10,000$ (except doors, windows, interior acoustic) - Get it done ASAP since we're short of time. STC rating of 2 withes of 4" brick wall is 52. Which leaves me with 73 dB requirement. I sketched a wall layout: - What kind of water (humidity) and heat isolation material is needed on final render layer? Or 10cm mineral wool is already enough for heat? - Which one is wiser for walls: 1) Brick wall // Screwing (2 layers) gypsum [or a better material] to existing wall // 10cm non filled air gap // 10cm mineral wool // 2 layers of drywall 2) Brick wall // Screwing (2 layers) gypsum [or a better material] to existing wall // 10cm mineral wool // 2 layers of drywall 3) Brick wall // Screwing (2 layers) gypsum [or a better material] to existing wall // more than 10cm (how much more?) mineral wool filled air gap // 2 layers of drywall 4) none of the above ,) [edit: I think screwing won't let air tight mounting. So I should mount first layer on studs (John's inside out system?) Detailed drawings are coming...] - Any gain by alternating gypsum thicknesses? There are three kinds of gypsum available here: 12.5, 15 and 18mm. I mean like 15-18-15 or 12,5-18-15 etc.? Or 3 layers is overkill? (even with 2 layers, is alternating [15+18] a good thing?). - For ceiling: Here are the drawings 1 and 2. Should I leave more airspace or one more layer of 5cm rockwool helps better. [I chose 40 kg/m³ rockwool for (maybe very subtle but) better low freq. isolation.] Please note that steel beam and the channel carrying gypsum don't touch. Is total decoupling overkill for this ceiling? Do other options (hangers, directly attaching channels to beams) cost too much isolationwise? (HVAC ducts will need about 20-25 cm) - For floor: I don't intend to float otherwise it's absolutely necessary. Any recommendation is appreciated. Thank you all!

Looks like a pretty well thought out plan. The ceiling structure looks good pending you architects further review. Just use the light insulation in your air gaps and walls. Save the heavy stuff for your inner treatments. Use 3x 5/8" drywall instead of trying to vary it. On the ceiling, over the steel beams, between the joists - seal any gaps just in case but the upper concrete should be plenty of mass.

Thank you very much Glenn.

Just use the light insulation in your air gaps and walls. Save the heavy stuff for your inner treatments.

I'll keep that in mind.

Use 3x 5/8" drywall instead of trying to vary it.

O.K. I revised the plans.

On the ceiling, over the steel beams, between the joists - seal any gaps just in case...

What would you recommend as sealant? Wood isn't in good condition btw. Lots of moisture inside. I'm also going to ask the constructor guys.

...but the upper concrete should be plenty of mass.

Unfortunately I was brought in after upstair's hardwood was installed. Pouring some more concrete earlier would be nice. There's a product called "Betopan". Performance data looks good on paper. I wondered if mounting these panels right below steel joists makes any good (even the pricey labour cost) but then realized that it would be a three leaf system (Gypsum/Air-R.wool/Betopan/Air.-R.Wool/Upstairs). - Which cheaper material can I replace OSB2 with? Any recommendations? - Does using Betopan instead of OSB may provide any good? (even it's pricey: 1m² / 18mm / $9.55 --> where 18mm OSB2 is $7.87/m²) - Should the outer framing be higher or keeping it at inner wall level is ok? (I added the sketchup file) Thank you very much Mehmet

Impala wrote:

What would you recommend as sealant? Wood isn't in good condition btw. Lots of moisture inside. I'm also going to ask the constructor guys. - Which cheaper material can I replace OSB2 with? Any recommendations? - Should the outer framing be higher or keeping it at inner wall level is ok?

the moisture is a big concern. sealing that space up and still having moisture in there will result in mold. that space if it has moisture will need to be corrected. the wood not bing in good shape could be due to rot from the moisture and since it's holding up the 150mm concrete, needs attention. once corrected though you should have enough mass there. the outer walls: if the brick/render/tiles is thick enough (and it sounds like it is) you may have enough mass there already and add one more layer (total 4x) of drywall on the inside wall. the OSB should be fine for the floor, or even plywood if that's less expensive. the betopan is probably not going to help much. also the wall trim - keep it off the new floor about 5mm. the moisture - is the floor dry? if not, then you should fix that as well.

Thank you Glenn. Here's the situation:

gullfo wrote:

once corrected though you should have enough mass there.

I'm afraid he already had hardfloor installed when I arrived there, but I will advise this appropriate method anyway.

the outer walls: if the brick/render/tiles is thick enough (and it sounds like it is) you may have enough mass there already and add one more layer (total 4x) of drywall on the inside wall.

Do you mean that putting 2 layers on outer wall is no good but 1 more layer inside instead like this? - Is 20cm gap o.k. or 15cm is good too? - Is using dowels to keep rockwool in place acceptable or is it considered short circuiting?

the OSB should be fine for the floor, or even plywood if that's less expensive. the betopan is probably not going to help much.

I'll stick with OSB then. Plywood is more expensive.

also the wall trim - keep it off the new floor about 5mm.

You mean the space where the backer rod+caulk is?

the moisture - is the floor dry? if not, then you should fix that as well.

That will be fixed.

the dowels should work. insulation hooks, mesh, etc also work. i'd go with lighter stuff in walls unless you have the budget. yes, move the drywall to the inside wall. 20cm gap is nice, 15cm will be ok. keep in mind the gap is measured mass to mass not stud to exterior. so if you have a 15cm gap between the stud and exterior wall plus 10cm stud, you have a 25cm gap. on the floor you show baseboard trim contacting the floor. lift that baseboard up and you can add some backer rod and caulk in there if needed.

i'd go with lighter stuff in walls unless you have the budget.

We may push the budget but I prefered 40 kg/m³ for better low freq performance. Are you suggesting lighter than that? Like glass fiber?

yes, move the drywall to the inside wall. 20cm gap is nice, 15cm will be ok. keep in mind the gap is measured mass to mass not stud to exterior. so if you have a 15cm gap between the stud and exterior wall plus 10cm stud, you have a 25cm gap.

In my current drawing I have 20cm then.

on the floor you show baseboard trim contacting the floor. lift that baseboard up and you can add some backer rod and caulk in there if needed.

O.k. I revised. I can use colored caulk there.

yes, you could go with the light 12-18/kg/m3 for both the stud and brick walls. use the heavy stuff on the inside where you will need the bass absorption.

Hi again, Drywall construction labour (framing and multiple layers) seems about to exceed our estimates and masonry became an option since the rough construction men still working inside. I was trying to pick between AAC (Autoclaved Aerated Concrete) and sand filled hollow clay bricks and came accross with another brick: Pumice. It's cheaper than AAC and rated 52 dB Rw (though I couldn't locate a lab report on web site). I would prefer this bricks (filled with sand and a good stucco finish) if it beats (or euals) 4 layers of 15mm gypsum. Any real life experiences with sort of material? (btw. I'm studying NRC's masonry wall document.) Thank you.

it does seem a bit light in mass (then again it's pumice...) but it might be a good option with sand and proper rendering. maybe contact their engineers and explain it's use in a double leaf wall and see what they have to say. the AAC on the hand does have some indications its reliable in this application.

I checked out this NRC paper. The TL table on page 20 shows values for 190 mm lightweight blocks (in my case AAC) with various surface finishes. I'm only taking one side bare samples into account, which suits my situation. (73,74,76,81,82,103,104,105,106 and 113) Wall #113: Side 1: 3mm plaster - Side 2: bare. This wall is the best at 63Hz (36dB) and 80Hz (34dB) and just 3dB less than wall #106 at 100Hz (31Hz). The difference widens more obvious at higher frequencies and #106 becomes the best choice (one side bare considered). But the problem is wall setups other than 73,74 and 113 creates a three leaf system, so #113 stands as my best option. And it will get better with stucco applied. I'm adding revised drawings but something bothers me about ceiling construction. Is it good or bad using this type of hollow iron beams? Constructor guy turned my load bearing wall idea down (because the distance's too wide)and recommended vibration isolators for ceiling. There are two types available: 1 and 2. I couldn't search the forum about the hangers yet but is determining the required amount is simple as: - Calculate the total weight (plus lighting, plus clouds etc.) - Divide the total to per hanger's capacity - Find how many is needed and distribute evenly? Thank you Mehmet

Essentially correct on the suspension isolators. Also consider in safety factors for any seismic requirements. In the wall - air plays a key role and you do not want the rigid insulation contacting both surfaces as it will provide a coupling effect that is not good.

Here are the latest drawings for ceiling & floor & wall. Targeted TL (as STC) is: Walls: Outer -> 52 dB on paper / 48 dB estimated Walls: Inner AAC -> 48 dB on paper / 44 dB estimated Walls: Inner (Gap+Drywall+Current stucco etc.) -> 4 dB (wild guess) Total: 96 dB Max noise estimated: 120 dB 120-96=24 dB

db calculations aren't just simple addition and subtraction in most cases... realistically this suggests about 75db in the low frequencies for the walls, and about 6db less than that on the ceiling (which from a construction standpoint using isolation mounts etc seems fine). at this point the main issue will be flanking due to the inner walls effectively being coupled to the underlying floor. pretty much once you get past 50db or so your flanking takes over as the main source of sound penetration. given it's an earth damped floor you may find that you're only leaking out around 35-40db at maximum internal volume levels.

Well, do rubber strips help under AAC blocks in terms of flanking as shown in the drawing? (Deflection to be calculated)

yes but also make sure you're not short circuiting things by having the rendering contacting the floor as well.

Hi again! The project hasn't started during upstairs construction. Now we're about to get back on track.

On the ceiling, over the steel beams, between the joists - seal any gaps just in case

Cellulose based spray is available here. Would it be an option to help sealing the old wood ceiling's cracks? Here's the lab report showing performance of 5cm and 3cm applications. (I should note that I've searched the forum and not taking this cellulose option as an alternative to rock wool filling. The ceiling will still be hanged and the space will be r.wool filled) There's an opportunity that we may use Green Glue. So I revised the wall layers like this: - Outer wall - Render - 10cm 50kg/m³ rock wool - 5cm air gap - 12cm hollow brick (dry sand filled) - Render - 15mm drywall - Green glue - 15mm drywall I'm hoping to reach down to a reasonable TL from ~120dB. By the way the old window spaces in live room are bonded. I'll try to put PA speakers inside and get loud to see where do we stand now. Thank you.

Hi, I've made some measurements after inner wall stucco work of live room has finished. We've put 4 PA speakers on corners and played a rock tune with loud drums and heavy guitars. I stood at the red dot, pointing the SPL meter north and cranked the volume above some "bearable" (actually it was above bearable for me) point to create a worst case scenario. I should state a few points though: - No doors are installed at the moment. We just leaned against a few OSBs to see what we can get. So there's flanking (green line). - Ceiling of the live room is still the same. So there's also flanking from ceiling/upstairs (yellow line). - Stucco is missing from 1m x 1.5m area where it reads 70,7 dB. I know that the excel table is not a scientific masterpiece (specially the last line) but it may give an idea. For the ceiling I'm considering cellulose based insulation. The product available here is called Celluspray (homepage is here). When you consider the current situation of ceiling, this looks like very promising on flanking issue. (Sprayed cellulose will cover wood joists all over. I left joists visible in my painting to help to visualise). Thank you.

Hi, It became apparent that the ceiling height will be minimized so much, so we will dig up a sample area and see how deep we can go. I think Keith's slab design would be applicable for us too.

Status update: - Digging has started - An overlooked major detail by previous constructor (actually it looks more like a scam than overlooking) needs to bi fixed. Support I-beams (which were added later) are not burried into cement supports, instead left to lay on top concrete layer. Beams are totally useless right now. Construction team is going to fix this parallel to digging. - Cellulose insulation company will start first layer on sunday. Thank you.

Photos from 1st day/layer of ceiling cellulose spraying. Excavation is also progressing.

After evaluating the situation with our consultant architect, it was decided to pour a mat foundation and stick & weld steel pillars to it. Would like to hear your ideas about the work plan. (Sketchup is attached to the next post) (I forgot to add rebars in slide show. It will be between rhrsl_foundation_002.jpg and rhrsl_foundation_002.5.jpg) Thank you.

Here's the Sketchup file. You can also review my plans for vapor barriers. Thank you.

so you're using the mat foundation to back up the individual slabs for each room?

For live room, the main idea is to build a heavy duty cage to support the structure in case of an earthquake. And it's going to support the slab also. It looks like that control room's reinforcement scheme won't be as complicated as live room's. (Btw. steel pillars in drawing are not to scale. There are thicker/wider ones on actual project) Thank you