Foam insulation and open web joist

Hi, I’m in Montreal, Canada. English is not my first language (I speak french), so I’ll try to do my best. I have a new house (1 year old) with half of the basement usable for my studio. This is the planning phase (Design). I wish to build a control room and a live room. The space that I can use is in the basement and is doing a “L” shape and the electric panel is in the corner :cry: . I can’t move it so I have to leave an easy access to it (I've read that somewhere on the forum…). I have a Sketchup file for more details (real scale in inches). I want to be able to record loud drums (heavy rock) without bothering my neighbors (20-25 feet away). I want to do the inside-out wall system because I don’t have a lot of space and it will drop the cost a little bit to. I’d like the live room to be big enough to have 2 or 3 people in it. I have read the Rod Gervais’s book at least 3 times and I still discover (or understand) new stuff each time… :D . I’m reading this forum for months now. It’s amazing! I’ve ordered a spl meter and will take measurement of how loud I am as soon as it arrives. Edit: loud drums inside, 100 db C, outside, 80 db C. My budget is around 5000-10000$ edit: I'll do the job myself except for ventilation. Existing basement: ¾ of the basement is not used and I want to use ½ of the whole basement for my studio leaving ¼ for lounge tv etc… room. It is a concrete slab so I’ll build my boxes right on it. No floating. The height is 7’8” from slab to joist. The joists are open web joists 13” deep 19.2” OC sitting on the 8” poured concrete foundation. There are already plasters (1/2”) on walls all around the basement on a 2x3 frame. The ceiling has no plaster yet. The air gap between the foundation and the plaster is filled with sprayed foam (polyurethane, I think) 3-4” thick! It’s even thicker between the joists just over the foundation walls, up to 6” and maybe more. Effective for heat in winter but very bad for sound insulation! Look at the photos to see what I mean. So first of all, I want to do a big box that will contain 2 separate smaller boxes: control room and live room. 1- I want to beef up my external leaf which is the ceiling and that little portion between the foundation and the upper floor. For the ceiling, can I add mass between joists the same way as a normal joist because open web joist only give 1 ½” of surface to put support for the mass. There is a lot of nails to…. 2- little portion between the foundation and the upper floor : since there is sprayed foam, that is almost impossible to remove, is there an easy way for me to add mass and leaving all that insulation there? Or do I have to remove it all to finally put some mass on the very exterior leaf? It is a really narrow place to work… I understand that if I leave the foam there, I’ll create a third leaf and it is to be avoided. 3- The existing walls are literally melted in that insulation making them almost impossible to remove. Can I leave them there and build separates boxes. It’s going to again create a third leaf (and eat space) but since the third leaf is 12” poured concrete with earth on the other side, maybe I can just ignore these walls? Or at least I can remove the plasters… 4- Electric panel: It is in the corner where I want to build and I have to leave an access to it. Can I just put a door to access it from the studio or do I need an open corridor without any door to access it? 5- Before the slab was poured, they’ve put some blue foam panels under to isolate from cold and then pour the concrete slab over it. Will the slab crack under the load of the studio? I’ve included a sketchup file that shows a plan with a corridor to access the panel, but I lose a lot of space this way. I can live with it if it’s the only way. I used the Eric Desart 1, 1:35, 1:85 ratio for CR. It’s a good size due to my low ceiling… and is maybe better than louden’s first ratio… I’ve put my others attempts to show others possibilities. I’m very open to any design if someone have an idea. Thanks Yohann

Rest of the pictures

Sketchup file...

here is plan view of the basement walls.

After reading a lot on the forum, I discovered that the sprayed polyurethane is closed cell and that it is part of the leaf it is sprayed on. So I may be able to trim it and add my mass layer over it (tightly) and it will still be on the same leaf. Am I right? I've draw a little graph to show... And I've removed the plaster on the existing wall to avoid 3 leaf system.

maybe an other possible desing with an access to the electric panel... not the best for the mixing room because of the door... Any comments?

Don't forget to put in Firestop.

Thanks for answering Ro. Firestop: for inside out ceiling, How am I supposed to do that? I'm supposed to put the ceiling at the very end (droping it over new walls) so the firestop have to be done before. And I don't want to remove the actual wood frame right next to the fondation. Any idea how to do that? In Rod's book, it's easier because you can put the backer rod and the caulk after framing but before putting the plasters. For inside out ceiling or walls, evrything is already done when you lift it up and it makes it impossible to put the rod and caulk. :cry: . I'm a little bit stuck now... Yohann

It seems that I just have 2 possibilities that are going to work. Which one would be the best? photo 22 or photo 23? 22 is maybe more code compliant but 23 have more space... humm... :? I would really like to see an other desing if someone have an idea.... I'm not a really good designer so... please help me. Feel free to answer my original questions to (top of the post)... I'd really like a feedback. Maybe it's not clear? if it is not clear, tell me and I'll try to explain it better. Thanks Yohann

buchton wrote:

... for inside out ceiling, How am I supposed to do that? Yohann

Yohann...an inside out ceiling? This is just too much work boss. I believe you are setting yourself up for failure and possible injury by attempting to construct a ceiling of this type.

I've read somewhere that the ceiling can be small modules joined together on top of the new walls, but I have to agree, it looks a bit difficult to rise them up... :cry: and maybe sound will leak where the modules joints. I'll check with my city for the electric panel issue next week. I still have no answer to leave an open access to the panel or if it can be behind a door (photo 23). and for the existing windows, I hope they don't have to be still openable...

ok... after rethinking a lot, I won't do any inside-out walls. That is gonna be a lot easier for me. So here is my final desing. What do you think?

HI, I think it's the best idea, as far as emergency exits. Pic 22 would not have been legal in OZ. Having the only exit through the control room. How low are the ceilings?

I've just talked with an inspector and they told me that the existing windows have to be still accessible and openable in an emergency case. So I'll keep them there and I'll do openable window for the new rooms. Kind of small door with window in it. This way, the existing windows will be still accessible. And for the access to the electric panel, it's ok to be behind a door, as far as it is accessible. The height is now 7'8" from slab to bottom of joist. after my new room is done, it will be around 7'2" inside. (I'll leave 1" between joist and new independent ceiling(2x4), so 3-1/2" plus 2 x 5/8" gypsum) is it to low? I don't have a lot of options there...