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post #1 of 49 Old 08-28-2018, 04:00 PM - Thread Starter
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Mississippi Design and Build

Time to start a thread I guess. I'm guessing this will take like 50 years to finish, but have questions now and want to keep everything together, so here goes.

I'll reserve a few to come back (from the grave) and post completed pics, then start with the questions.

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post #2 of 49 Old 08-28-2018, 04:01 PM - Thread Starter
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post #3 of 49 Old 08-28-2018, 04:01 PM - Thread Starter
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post #4 of 49 Old 08-28-2018, 04:33 PM - Thread Starter
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OK, so we are finishing up house plans (just waiting on construction drawings from architect), and will hopefully start construction on our dream home before the fall rain sets in. This design will leave me a sizable area underneath the roof on 3rd floor that can be dedicated to theater, lobby, equipment etc.

I have a couple of early construction questions that might affect some of those final construction details, and once all that is set and I can nail down final dimensions of the space to work with we can start talking about actual room design in more detail.

1. Roof rafters. The unsupported span from one knee wall to peak is around 18 ft. Looking at span tables for doug fir and southern pine, I'm thinking that would probably require 2 x 12. We will have i-joist for flooring system 2nd and 3rd floors. Does anyone have any experience using i-joist for roof framing? Looking at their span tables, it seems like I could get away with the 9.5" deep joist, maybe even spaced wider at 19" or 24". In a room under the slope, a couple of inches depth translates to several inches wider room and we all know every inch can be used. Any thoughts here?



2. Knee wall and sub-floor, early isolation considerations. With living spaces below the theater I will make a good effort on sound isolation. At a minimum I'll do the sub-floor, rubber mat, and then two layers of sub-floor floating on the mat. There will be a knee wall to support some of the rafter span (roughly where dotted verticals are above), for now I'm assuming at roughly 6' ceiling height. Would you guys recommend the support wall be outside the floating sub-floor? I'm guessing so... and if so, would you then construct another knee wall that is decoupled and sits on top of the floating sub-floor assembly as a form of room within room, or just clips/channel/dd/gg on the single knee wall? The answer to that probably affects where I have them place the structural knee wall. Doing a double wall means I'd move the support wall out a little to keep finished ceiling height on target.

Trying to think of anything that might affect actual house framing. After that is more general sound isolation strategies within that framed space, HVAC, electrical, etc. Then I can worry about the layout of the room itself!

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post #5 of 49 Old 08-28-2018, 06:02 PM
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every picture I've seen using I-joists for roof rafters have them hanging off a load bearing ridge beam at the peak,

https://www.jlconline.com/how-to/fra...ood-i-joists_o
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post #6 of 49 Old 08-28-2018, 06:58 PM - Thread Starter
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Hmm... interesting. I missed that not insignificant detail when reading about i-joists. The center two story mass of the house is a simple gabled roof so really simple and I thought would avoid the issues with i-joists in valleys etc, but from gable to gable is like 50 ft or so. Can't support a ridge beam with posts along its length if I want theater room inside! I'm sure a translam or steel ridge beam could support the load over that span but that sounds like a whole lot of expense to add a half a foot in room width.

So thanks for pointing that out!

Any thoughts on whether to have single knee wall off the floating subfloor, on the floating subfloor, or one of each in a decoupled wall scheme? One end of the theater will be against gable end... could do two walls or staggered studs there if I didn't mind the extra few inches. Other end will be non structural interior wall dividing space between theater and lobby/stairs. Could do whatever I want with that wall.

But... I don't see a practical way to keep room within room going on the sloped roofline wall/ceiling part on each side. No way to support that without building an entire second roof structure.

So assuming just clips and channel there. And if just clips and channel there... should it just be clips and channel everywhere?
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post #7 of 49 Old 08-29-2018, 04:56 AM
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I'm not sure that it has to support the entire 50 ft long load since the rafter configuration does support some weight at each rafter position. This is a question for your local experts and I-joist supplier.
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post #8 of 49 Old 08-29-2018, 10:21 AM - Thread Starter
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Yeah seems you're right again. Doing more reading making a shear connection at lower end rafter to wall plate and ceiling joists apparently isn't impossible but enough of a pain that no one does it. Will probably come down to how the cost falls out for each option.

Looking at span tables even for dimensional lumber I think I have a little wiggle room to move the knee/purlin support wall out half a foot or so each side before a break point triggering next rafter size or spacing. So I think I will to give some flexibility down the road on double wall or not.
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post #9 of 49 Old 09-01-2018, 12:20 PM - Thread Starter
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Any thoughts on insulation strategies for the space between roof and finished theater ceiling between the roof rafters? Have been doing some reading. Very confusing. Seems that there isn't even a consensus on what satisfies code regarding need of barriers or not, where those barriers are placed, venting up or down, etc. Much less what is the preferred approach.

My builder does spray foam in a lot of houses. Not sure if that is appropriate when I need to put clips/channels and a finished ceiling on the rafter underside. Good or bad experiences here?

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post #10 of 49 Old 09-01-2018, 03:40 PM
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insulation codes are very regional and you need to check your local code office for what is recommended in your area. As for spray foam you need to maintain some distance between the foam and the channel so it does not effect the movement of the "spring system". I've been in an attic that was insulated with spray foam (White Oaks Theater) and it did a great job of insulating in the Alabama heat when applied in the roof rafter area. In his case the attic was unfinished.
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post #11 of 49 Old 09-01-2018, 06:25 PM - Thread Starter
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The two attics I had a chance to look at during construction that used spray foam were unfinished as well, and it was applied pretty indiscriminately over joists and everything else. I will have to check on whether it can be kept cleanly between joist cavities to allow for finished clip/channel/drywall installation. At least some of the rafters will be finished regardless of my actual room design, though I hope to disguise that as much as possible with soffit/tray design.

My builder will of course be a big help and guide as far as local codes go. But reading other forums, even for a specific code seems there is a lot of disagreement on whether certain solutions meet code or not. Guess I'll have to be friendly with the inspector early on.
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post #12 of 49 Old 09-03-2018, 01:19 PM - Thread Starter
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Sketch of clip/channel/DD/GG wall and ceiling detail on floating floor along the room sides.



I could move the actual support/purlin wall out half a foot, and construct an inner wall sitting on floating floor and decoupled from roof rafters with IB3 clips. Lumber is pretty cheap, guessing cheaper than the IB1 clips and channel required for this configuration.



Which would you guys do? Front and rear wall I suppose I have space to do a double wall as well. One end is exterior gable wall, the other is interior non structural. Would take about a foot off the theater length for complete double wall both ends. Could cut that down some with staggered stud on interior wall end.

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post #13 of 49 Old 09-05-2018, 08:38 PM - Thread Starter
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Exact prices will depend on just what lumber yard, where I find resilient channel, whether I would order value clips or more expensive isolation clips etc. But a napkin calc says the clip/channel isolated sidewall is roughly the same price as the double stud with inner wall sitting on floating floor and top connected with IB3 clips.

I'll be doing clip and channel on flat and sloped parts of ceiling for sure so no big deal to just keep doing the same on side walls. Is there a compelling reason to do one or the other for this smallish part of the total theater shell?
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post #14 of 49 Old 09-06-2018, 07:30 PM - Thread Starter
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Room size and seating. Would like the ability to accommodate friends for movie night. Our family is 5. Could easily see inviting another family of 5. More isn't out of the question. I would prefer a bar seating in the rear for extra, and for eating during games etc.

My preference for screen width is in the 55 deg range. I'd like my front L/R to be at 60 deg, so I'm expecting them at or just outside of screen frame edges. Here's a sketch showing two rows of 5, 7' between, and bar seating behind. The screen width (2.4:1) shown is at 60 deg so would actually be not quite as wide at ~55 deg.

Thoughts on viewing distance, whether I'm going to hamstring myself too much with PJ choice? I'll take a look at side profile sight lines next. If you can make out the text, I have plenty of ceiling height in the center of room (up to 12'), but headroom at edges on riser and under a soffit might get a little more challenging.

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post #15 of 49 Old 09-06-2018, 07:50 PM - Thread Starter
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Guess I should mention that a primary driver and desire for this room is for it to be a top notch audio room for pure music enjoyment, not just movies/TV/games. So some things in my initial sketches have departed somewhat from traditional layouts.

Like the desire to have the prime seat equidistant from all speakers. Or the desire to use dipole mains requiring some space behind for optimum performance. In this sketch, the side walls at about 8' ceiling height would be fabric with additional room behind for acoustic treatments. Speakers would probably be exposed in room simply because its hard to disguise a big dipole in a column a couple of feet out from the wall.

But now's the time to poke holes and convince me otherwise.
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post #16 of 49 Old 12-07-2018, 07:49 PM - Thread Starter
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OK guys, would love some input now. Plans are finished, dotting i's on financing, will start pulling permits in a week or so.

Attached is the final dimensions of the space I have to work with. I plan to put a knee wall up at maybe 5 foot ceiling height with a false fabric wall closer in at maybe 8 foot or so. The stairs come up heading to the left then make the turn along the side wall.

A big issue is where to place a restroom? I need to locate drains and plumbing for toilet, bathroom sink, bar sink...? This doesn't necessarily have to be on plans submitted to city for permitting but obviously has to be decided pretty early.

Because of the stairwell configuration, it sort of splits the space on that end of the room. I was thinking lobby at the side where stairs enter this floor, but the only way to access the other corner will probably be through the theater room. Unless I want to sacrifice a few feet of room length. I'll attach a concept sketch of the room so you can see what I mean.

It would be ideal to use sound isolation techniques on the theater walls only but that would require a door going to restroom and probably equipment closet to be just as heavy etc as the main theater entrance. I could use isolation techniques around the restroom and equipment area too and then use a standard interior door, but construction seems a little more complicated.

I've looked at turning the room 90deg but that issue doesn't go away. Not sure the one corner is large enough to lobby and restroom. And equipment would still probably be in other corner and need access anyway.

What do you guys think?




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post #17 of 49 Old 12-07-2018, 10:29 PM
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What if you sacrificed a few feet of room width and placed the restroom where my green box is located? That would keep guests from having to ever access that opposite end space.




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post #18 of 49 Old 12-08-2018, 07:21 AM - Thread Starter
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Yeah I've thought about squeezing restroom into that corner, but equipment seems most likely headed to the other corner (which just so happens to sit right above the homes primary network/structured wiring closet on 2nd floor and would be an ideal location as far as cable runs and ventilation/cooling). So I'd still need access to the other corner.
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post #19 of 49 Old 12-08-2018, 07:25 AM
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But would your guests need to navigate in there? I assumed you would still keep equipment there; it’s a great spot for that. Hmm...


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post #20 of 49 Old 12-08-2018, 08:22 AM - Thread Starter
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Well, it's a plenty big enough area in that corner for restroom and equipment.

I'm having a hard time seeing how to avoid a second door in the theater room that accesses this space.
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post #21 of 49 Old 12-08-2018, 08:23 AM - Thread Starter
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I got an email with response from Bulldogger but don't see his post in this thread. ?
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post #22 of 49 Old 12-08-2018, 02:47 PM - Thread Starter
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Copying Bulldogger's questions here since his post seems to have disappeared?

Quote:
1. Did you go with the I-joist? My architect advised that I double my joist even though they might meet the span. Reason being is that with all of the extra weight of the type of build I planned, sound reduction, he felt the floors would be bouncy which wouldn't be the right direction for sound reduction
Yes, floor system will be ijoist. There are enough walls on second floor that the span lengths won't be bad. Don't anticipate stiffness being much of an issue so just need to address sound transmission through the structure.

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2. The support wall does not have to be outside the floating sub-floor. You leave a gap between the wall and the floor and use a sound proofing caulk between the wall and the floor.  Your trim covers the gap.
Not sure I follow. Can you sketch it perhaps? If I have a double stud structure seems easy enough to have outer wall on subfloor and inner wall on floating subfloor. Still not decided on where I will use staggered stud, double wall, or clip/channel. Need to sort out basic layout first.
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post #23 of 49 Old 12-08-2018, 02:51 PM - Thread Starter
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One thing I'm seeing is primary seat will be very close to center of the room. Not ideal at all. Earlier drafts had a little more room length with several more feet behind the barstools I had planned on using for thick absorption or maybe deep diffusers. Final dimensions didn't leave much room for that.

Also thinking I may mirror the entry door for bathroom/equipment closet and move the equipment rack to the back wall where door is currently shown. I'll attach a sketch of that later.

Downside of restroom in that corner is that the door is at riser height. Toilet drain can't really be at riser height so there would have to be steps down somewhere to get back to floor level. I'd love to have it in corner of lobby area but just don't see enough room for it there.

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post #24 of 49 Old 12-11-2018, 12:49 PM - Thread Starter
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Thoughts on lobby and bathroom placement? I'm not fond of needing steps down into bathroom from riser height but don't see a good way of avoiding it without flipping room 180 and entering from the front?



Sight lines for this layout suggest a 16" riser will be needed. No problem with ceiling height over seats but will have to look at entrance door if at riser height and what soffit configurations would be OK.

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post #25 of 49 Old 12-11-2018, 07:39 PM
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Do you think it would feel awkward walking directly into the bathroom from the theater space? I’m wondering, and don’t laugh at my comment please, but what if someone stinks that bathroom up, and walks out back into the space, would there be any residual smell leaking into the room!? (First world problem here)... I keep gravitating towards having the bathroom up near the entrance.

Would there be enough room in that corner where it’s located to... square the bathroom off to the lower left hand corner, swap the rack and door that currently are interfering with the room, and have a door for both the av rack and bathroom? Or too much / over complicated?


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post #26 of 49 Old 12-11-2018, 08:28 PM - Thread Starter
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I'd like the bathroom in the lobby area too... just not enough room. Its the ceiling height with sloping roof that causes issues.

Plenty of room for bathroom and equip on other side where I show them now. I could have door from theater open first into equipment closet, then a door from there to bathroom. But more likely to look like a mess when someone opens that door.
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post #27 of 49 Old 12-14-2018, 05:43 PM - Thread Starter
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Any other suggtions? I feel like I've been looking at this layout in one version or another for so long it's hard to see it any other way. Maybe there is a complete shakeup that works better I haven't thought of.
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post #28 of 49 Old 12-16-2018, 09:50 AM
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Ok, would you be willing to decrease the number of seating for the space? Doing this would allow you to decrease the width (still would be a large-feeling space) while maintaining the same luxurious feel and would give you more room to be creative with where you place your restroom.


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post #29 of 49 Old 12-16-2018, 10:17 AM
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Won't you need a landing for those steps?

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post #30 of 49 Old 12-17-2018, 10:03 AM - Thread Starter
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Quote:
Originally Posted by brazensol View Post
Won't you need a landing for those steps?
The steps up into theater from lobby and bathroom? Yeah maybe so. I just sketched those in quickly to get an idea. Need to look at local codes to see how much landing is required before a door. Thanks for pointing that out.
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