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The Larch Theater (a not-a-19.6-system) - Page 3

post #61 of 380
Thread Starter 
I'll be using it as a reference when rebuilding, to make sure the final result is better than what I started with. It will also be interesting to find out which steps yields the largest impovements. But first I'll get a much worse curve when doing a new one after I've torn the inner walls and ceiling down...
post #62 of 380
Thread Starter 
About all ceiling and side walls torn down, time for a new baseline before starting to go down the rebuild road, new curve is the "noisol" one:

avs16.jpg

The purple arc which most of you cannot read the lable for is the disturbance level use by authorities here - 25dBA for bass rich material, which is my primary but not ultimate goal.

In general, what I've torn down so far seems to have had ~20-24dB of dampening except in the lower bass. (Given that I use music, not test signals, some deviations on measurements are expected.)
Edited by Nightlord - 5/8/13 at 1:51pm
post #63 of 380
Looks like a very involved process. I hope all of this effort gets you the acoustic environment you are looking for when the room is rebuilt!

Just so you know I am subscribed and following along....just not a lot of comment I can add to the discussion.

Keep up the good work!
post #64 of 380
Thread Starter 
Thanks, man! smile.gif
post #65 of 380
More pics! smile.gif
post #66 of 380
Thread Starter 
Nothing particularly different to show, will come when there is.
post #67 of 380
Thread Starter 
Have snapped a few ones now, will post when I've had the chance to upload, timestamp and scale them.
post #68 of 380
Thread Starter 
Here's how the ceiling looked like when all apart from extreme rear end 'cleaned':
avs17.jpg
...looks like new after 13 years. smile.gif

Here's the proof-of-concept for closing up the 'holes'
avs18.jpg
...must say it turned out better than I hoped. So after having done that it was off for more of the same materials.

Will plug the foremost four holes and add drywall to the ceiling in those compartments and then I'll do another measurement to see how much that did.

Perhaps time to order a bucket of Green Glue, if I'm to do another layer?
post #69 of 380
Sorry I haven't been back through the thread to properly understand these photos ... but what exactly do they show ? The joists appear too small and far apart for that to be a floor, plus there seems to be a gang-nail joint near the centre of the span.
post #70 of 380
Thread Starter 
It is a floor. There's an attic full of things above, probably a ton or two, but the heaviest things like spare roof tiles are placed closest to the walls.The rafters was calculated and built by a professional building company. There may be differences in Swedish and your building codes on what's allowed. I've had questions about the 1200mm span and it does not appear to flex walking on it and there is no visual proof of it being bent the slightest anywhere.
post #71 of 380
It looks like standard 2x6 "joists" at 30" on center with standard 2x4s pressed tightly together as the flooring. Definitely different building codes than in the United States, even for an attic storage area!
post #72 of 380
Thread Starter 
It's tongue&groove boards and they are more 1x4. And been in use for 13 years by now.
Edited by Nightlord - 5/10/13 at 4:32am
post #73 of 380
Thread Starter 
The 'easy' compartment done (those where a normal chair was enough to reach), the stepladder ones begun.
avs19.jpg

Per recommendation of a friend, I'm caulking every seam of the T&G before putting the DW. Had to go buy a few boxes more caulk yesterday, went through almost one box (12x 310ml) for the first nine sheets (2'x4').

Vacation period over, so if I can get two up per day, that's take all of May for sure. Hope this effort will be measurable.
post #74 of 380
Will you be putting up one or two layers?
post #75 of 380
Thread Starter 
Quote:
Originally Posted by TMcG View Post

Will you be putting up one or two layers?

Well, given that this is for the outer wall and there will be a non-connected inner ceiling (room-in-a-room construction), I'm wondering how much it will gain me compared to losing me another 12mm ceiling height. I haven't decided on it, I'm finishing this layer and taking a new measurement and will re-plan from there. This is more of a treatment to cancel any leaks/flanking that way. I probably don't have this layer in any of my digital renderings, to be honest.

The "holes" will be treated more, so I'm very likely to add a second layer there plus insulation, but I'm not doing that until I have some numbers on how much this single layer does.
post #76 of 380
Quote:
Originally Posted by Nightlord View Post

It is a floor. There's an attic full of things above, probably a ton or two, but the heaviest things like spare roof tiles are placed closest to the walls.The rafters was calculated and built by a professional building company. There may be differences in Swedish and your building codes on what's allowed. I've had questions about the 1200mm span and it does not appear to flex walking on it and there is no visual proof of it being bent the slightest anywhere.

Are the rafters actually the bottom chords of your roof trusses ? Can you show us a shot of the attic ?

I only ask because I'm a structural engineer and I think there must be something else going on above the ceiling, or the rafters simply wouldn't hold up with that gang-nail joint.

Cheers,
post #77 of 380
Thread Starter 
Quote:
Originally Posted by Peter M View Post

Are the rafters actually the bottom chords of your roof trusses ? Can you show us a shot of the attic ?

I only ask because I'm a structural engineer and I think there must be something else going on above the ceiling, or the rafters simply wouldn't hold up with that gang-nail joint.

Yes, that's correct. It's a no on a picture, unless I can find and old one, I won't have access to if for quite a while and I wouldn't want to publish the mess anyway. biggrin.gif But I can describe them;
first of all, they stick out say half a meter, 2 feet on the other side of the walls. There is a single straight riser part | in the center, so it's not a /\/\/\ construction. The other ceiling is full tongue&groove board covered with concrete tiles on. I don't know the slope by memory, but I can almost stand straight in the center inbetween the trusses and I'm 169cm ( 5'8").

Hope that makes sense to you, as a non-native in English, the building construction glossary is a weak side for me, being a computer engineer...

BUT; does that mean I will need to to go bigger on the rafters for the room-within-room build? Even if they'll just be taking the load for OSB+dual drywall and some insulation - not an attic full of junk as well. I will be needing to make a joint too, I can't get full length ones inside. The span will be about 450cm (15 feet). I'll be halving the spacing of them, so one every 600mm, so there will be more of them to distribute the load on. Will 165x45 not do the trick, what will I be needing - 180/200/220?
Edited by Nightlord - 5/12/13 at 10:56pm
post #78 of 380
I think I understand your description and yes it does make sense.

On the size of your rafters ... it's a long time since I did any detailed timber design ... there are many here more qualified than me to answer this, however 165 x 45mm does sound too small for a 4.5m span. I also can't see how the rafters can be successfully joined within the span. You really do have to use single piece rafters.

Cheers,
post #79 of 380
I shouldn't be so absolute in my reply ... if you really can't use single piece rafters, it's going to take heroic efforts to join them properly. Do you have a design for this connection ?

Cheers,
post #80 of 380
Thread Starter 
Quote:
Originally Posted by Peter M View Post

I think I understand your description and yes it does make sense.

On the size of your rafters ... it's a long time since I did any detailed timber design ... there are many here more qualified than me to answer this, however 165 x 45mm does sound too small for a 4.5m span. I also can't see how the rafters can be successfully joined within the span. You really do have to use single piece rafters.

Well, that's an impossibility unless you know a kind you can bend around corners. But I'm warming up to the notion of needing at least 180, I've seen tables of "glue-wood" beams of 180 for that distance.

Otherwise I will have to start thinking of tearing down much more than intended, just to make a hole to get them in...eek.gif It can be a final resort of course, but I will be trying to join one before going down that route.
Edited by Nightlord - 5/14/13 at 10:40pm
post #81 of 380
Thread Starter 
Quote:
Originally Posted by Peter M View Post

I shouldn't be so absolute in my reply ... if you really can't use single piece rafters, it's going to take heroic efforts to join them properly. Do you have a design for this connection ?

Not really. The two obvious ways would be to use two from the shorter side like a tuning fork, or double over on both sides for half a meter or so. Perhaps a couple of big bolts through?
Edited by Nightlord - 5/14/13 at 10:42pm
post #82 of 380
Quote:
Originally Posted by Nightlord View Post

Not really. The two obvious ways would be to use two from the shorter side like a tuning fork, or double over on both sides for half a meter or so. Perhaps a couple of big bolts through?

More small bolts will be better than fewer large bolts. My gut tells me you're going to need two pieces about 1m long (one each side) with about 6 bolts (2 rows of 3) on each side of the joint (12 bolts total). This should definitely be checked by an engineer. The bolt holes should be as tight as possible with large washers under the head and nut, and VERY tight.

Cheers,
post #83 of 380
Thread Starter 
Thanks.

Still a few months into the future, I may get a feeling for opening up a hole rather than doing this before I arrive to the point of doing it. Heard of someone using 180mm for 4.5m span with double drywall and that sagged 15mm in the middle, so that seems to be a call for 200mm. That will start losing me ceiling height for sure. ( 180mm is the largest I can using without losing ceiling height if putting drywall directly on the rafters. )

But first things first; let's see how much dampening this layer does and what happens after the LECA-blocks get plaster on them and then plugging the 'holes' even more.

It's good to plan ahead on many eventualities, but one has to keep an eye on the ball too.smile.gif
post #84 of 380
Thread Starter 
Jumping the gun a bit with the modelling of progress, I have one "compartment" left to do before I catch up to the model, but here it is in a cut-through view - you have to imagine the drywall across the first four compartments from where it's blocked in the sides:
Rebuildphase1.jpg

Noticable is also a think line of insulation below the first roof truss - it's filled with expanded foam now - there was an additional flanking hole I didn't realize existed, but handled (in parts) now. smile.gif

If I can keep tempo up, I may be able to do a measurement of the progress on friday/next weekend.
post #85 of 380
Thread Starter 
Here's from the inside. Found a "brick" texture option, so upgraded the tracing with that as well. smile.gif Not an exact representation, but enough to get the feel.
Rebuildphase1_2.jpg

Had a neighbourhood meeting yesterday, so only got to close the second last hole and caulk a bit longer ahead, but that'll save me time later.
post #86 of 380
Thread Starter 
All drywalling in this step done now, so have caught up with the renderings now, too late to do any measurements today, so lets hope tomorrow and the weekend won't rain away so I can't do it.
post #87 of 380
Things start looking and feeling different with the drywall up. Good luck with the weather smile.gif
post #88 of 380
Thread Starter 
Yeah. But that drywall will "soon" never be seen again as that's "the other side of the wall". biggrin.gif

Thanks. Still looking good. Bit hight background noise today too, but I'll accept that.
post #89 of 380
Thread Starter 
Have taken a new measurement today to see just what a single layer of drywall in those openings and towards attic would do. It's by ear noticable that the main leak has moved towards where I've done nothing yet. The door is definitely a weak spot, but I have had thoughts of making that a double door with a better class inner door, so that does not worry me. The electrical box leaks quite a bit, so that will get some tender lovin' soon.

Here's a graph for you anyway:
Closed1.jpg

Blue is where I was with my original problem, red is where I was with everything torn down and green is where I've currently clawed back to.

Little to no effect in the bass, more substantial effect above 1000Hz. I think that was about what I'd expected - perhaps expected a little more effect on the bass, but that's quite within measurement fault territory.

NOT disappointed, this is an improvement on what I didn't have before, so it will work great in conjunction with other fixes planned. cool.gif
post #90 of 380
Thread Starter 
Given that there's all sorts of angle brackets in the 'compartments' making it close to impossible to add a 2nd laywer of DW there, but I still felt it perhaps could be an idea to add some more mass - I had the idea to add bitumen-sheets to the drywall. Managed to do that over the weekend and take another measurement. If it's not variations based on picking very different parts of the track, then the conclusion would be that the lowest bass range got a bit better dampening, 250Hz got slightly worse, then better again up to 2kHz and then slightly worse.
Given I will add insulation as well in upcoming step, I'm not very worried about the high register. 250Hz may be the resonance frequency perhaps?

But if the added ~9dB of dampening figure is correct, then perhaps a 2nd layer of bitumen could be a good idea before it's time for the insulation?
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