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post #481 of 507 Old 03-21-2019, 05:59 AM
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Quote:
Originally Posted by Audixium View Post
Question: has anyone pulled a 2nd layer of drywall after Green Glue was applied? It seems a bit unlikely that they could get a smooth surface on the 1st layer. If there was residual Green Glue would you apply slightly less in that section? Any other ideas?
Although it's not glue, it bonds like glue. It would be impossible to remove without destroying the under layer. MUCH faster and easier to start over...and cheaper, considering the GC is likely paying the contractors to do things again.
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post #482 of 507 Old 03-21-2019, 06:53 AM
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Time is really important when you are dealing with Green Glue, if a week has gone by the GG has begun it's journey from milkshake to dense rubber band. Once it reaches the rubber band stage it will be nearly impossible to separate the layers without significant damage to the first layer. Usually 30 days. If they are successful in removing the second layer you would apply green glue to the new sheets as if there wasn't any up to begin with, there will be no such thing as already enough in place, what remains will be a splotchy mess and you will probably actually need to scrape some areas to make it smooth as some paper from the second layer will be left behind.

Your earlier pictures indicated to me that your clips were closer than 48OC. so even though you don't have your channels 16OC you may have enough clips to support the added weight of a third layer.

I think the smartest course of action is to start over. If possible with a different crew. However I would try to remove a sheet from the ceiling TODAY to further research your situation.

Just another reminder to everyone following in your footsteps. Always supervise the Green Glue application. Diggs came home from work to find his crew left half his supply of Green Glue untouched. I've been on a job where they start lifting a sheet into place and I say where is the GG and they say they "ran out" looking around sitting outside the door were two untouched buckets. These guys want to get the job done as quick as possible and they fall into a rhythm of working like they have been doing for years and that doesn't include squirting the glue.

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post #483 of 507 Old 03-23-2019, 06:30 AM - Thread Starter
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Quote:
Originally Posted by TMcG View Post
Although it's not glue, it bonds like glue. It would be impossible to remove without destroying the under layer. MUCH faster and easier to start over...and cheaper, considering the GC is likely paying the contractors to do things again.

Quote:
Originally Posted by BIGmouthinDC View Post
Time is really important when you are dealing with Green Glue, if a week has gone by the GG has begun it's journey from milkshake to dense rubber band. Once it reaches the rubber band stage it will be nearly impossible to separate the layers without significant damage to the first layer. Usually 30 days. If they are successful in removing the second layer you would apply green glue to the new sheets as if there wasn't any up to begin with, there will be no such thing as already enough in place, what remains will be a splotchy mess and you will probably actually need to scrape some areas to make it smooth as some paper from the second layer will be left behind.

Your earlier pictures indicated to me that your clips were closer than 48OC. so even though you don't have your channels 16OC you may have enough clips to support the added weight of a third layer.

I think the smartest course of action is to start over. If possible with a different crew. However I would try to remove a sheet from the ceiling TODAY to further research your situation.

Just another reminder to everyone following in your footsteps. Always supervise the Green Glue application. Diggs came home from work to find his crew left half his supply of Green Glue untouched. I've been on a job where they start lifting a sheet into place and I say where is the GG and they say they "ran out" looking around sitting outside the door were two untouched buckets. These guys want to get the job done as quick as possible and they fall into a rhythm of working like they have been doing for years and that doesn't include squirting the glue.
Thanks guys. Based on how hard it was for them to remove smaller sections of the second layer I'm assuming as noted that the first layer surface just wouldn't be acceptable. So - start over.

Can that apply only to the ceiling and the walls get the 3rd layer? The top of each wall might need some adjusting due to the ceiling demo, but just wondering if that is an option.
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post #484 of 507 Old 03-23-2019, 09:18 AM
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post #485 of 507 Old 03-23-2019, 06:10 PM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post
yes
GC has agreed to demo both ceiling layers, redo, and add a 3rd layer to the walls.

But the comment below made me go back to review my photos...

Quote:
Originally Posted by BIGmouthinDC View Post
Your earlier pictures indicated to me that your clips were closer than 48OC. so even though you don't have your channels 16OC you may have enough clips to support the added weight of a third layer.
It looks pretty much like 36OC based on my joist spacing (which I measured/modeled in Sketchup years ago and could pull if needed). So, instead of 48x16 I probably have 36x24. Does anyone know how to do that load calculation? Calling all engineers... @Black Banshee . I think that if the ceiling clips can take the load, the best choice would be a 3rd layer.

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I think the smartest course of action is to start over. If possible with a different crew.
I'm assuming the clips really won't take the additional weight with current spacing, so the plan for the ceiling is to start over. It will be the same crew on Monday, but the GC has agreed to directly and continuously supervise. I'm going to try to work from home on 2nd layer days as well.

Ideally the clip spacing will allow a 3rd layer.
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post #486 of 507 Old 03-23-2019, 06:29 PM
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a layer of 5/8 drywall is around 2.2 lbs per sq ft. so 3 layers is 6.6 lbs. per sq ft.

A clip is designed to hold 30 lbs.

calculate the area x 6.6

divide by the number of clips.
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post #487 of 507 Old 03-25-2019, 01:15 AM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post
a layer of 5/8 drywall is around 2.2 lbs per sq ft. so 3 layers is 6.6 lbs. per sq ft.

A clip is designed to hold 30 lbs.

calculate the area x 6.6

divide by the number of clips.
I took area x 6.6, then divided by 30 lbs to get the minimum number of clips - around 100. I ordered 185 clips since I'm also doing a 15x10 room. I need to see how many clips are left (if any).

When I calculate based on the 36OC pattern, an extra channel up front, one extra on each side of the soffit, and an extra in the rear it is close to 130 clips. Crew may show up in the morning so I need to figure this out.

Looks promising for the the 3rd layer on the ceiling...
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post #488 of 507 Old 04-27-2019, 03:55 PM - Thread Starter
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Overdue update...

I ended up having the contractor pull both layers from the ceiling and start over there, while adding a 3rd layer on the walls. Of course, with proper GG application and supervision. I was good with that approach and it saved me 5/8" height.

The drywall joint results are significantly better than the first go 'round. I took a sharpie to the original second layer and marked up the theater room with over 20 defects - they addressed them all. Progress is slow, but I hope they catch stride after getting past demo and re-build. (so glad they took the dumpster away today)

With that...the pics

Theater side of entrance, door hinge side with that 3rd layer


Due to expanding soils we have to "float" basement walls per county code. I was planning to do what BlackBanshee did with MLV, but the drywall sub said the inspectors will let this pass. I hope so - it saves me time and money.


Soffit framing - rear wall


Looking towards front left corner - I am still at one with my pole


Front wall


After a little drywall..

Rear soffits



Front


After putting the flex duct in the soffit framing - very tight fit getting through the corners due to the way they framed



Projector location

Going to build an "open" hush box


Looking towards rear wall


From this angle your can see the OSB + DD + GG approach for the main hvac trunk - hope this helps


Soffit designs

I'm glad we went from this...


To this...





While the light layout came from the renders (next post). I need to make sure the contractor understands/marks the location of the Atmos speakers before they start framing the inner soffit.

Question: won't a 2x2 for the lip block an LED light strip? I need to change this part of the plan...I've saved a bunch of previous alternatives. Any suggestions/favorite approaches?


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post #489 of 507 Old 04-27-2019, 04:09 PM - Thread Starter
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This won't be the final result, but this is a good target.

Not planning to have side columns due to the recessed surrounds



Front soffits with can lights


Looking towards the rear soffits - the pj box is crude at this point and the fabric panels will stop at the rear of the butcherblock countertop


The rear half of the room will have a standard textured finish with specifically placed panels on the rear and sides


that carpet is bad...
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post #490 of 507 Old 05-19-2019, 02:35 PM - Thread Starter
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HVAC - Linear Slot Diffuser won't fit the soffit space?

My contractor said that the HVAC guys were having a hard time finding a slot diffuser that will fit in the soffit. They are therefore suggesting using a standard linear torpedo boot. They're also trying to see if this register/diffuser can't just be made to fit that space, instead of something off the shelf. Then just put a factory grill on it.

I told the contractor that his belief that it will work is different than measuring the airflow. I said I would be measuring, so I suggest they put a bit of calculation into the decision.

Ayn red flags going off here?
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post #491 of 507 Old 05-19-2019, 03:03 PM
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In pro designs I've seen many compartmentalized soffits used as pressurized plenums to deliver air to a long section large enough to slow the air down. It needs to be lined. This is a standard cheap torpedo boot.









it will probably be noisy.

slot diffusers are available in custom sizes from HVACquick.com. https://www.hvacquick.com/products/c...Linear-Grilles

They are having a tough time coming up with a boot for up in the ceiling, usually they need to be custom made if they want metal ductwork and they need to be lined with linacoustic. $$$.

My position when working with HVAC contractors is to tell them "your job is to deliver the air to a room in a round hole in the ceiling where I specify. If I come along and build a soffit after the fact that acts as a duct muffler that is my choice. leave me alone!" Of course it they tip off the inspector you may be screwed.

Locally a guy got his contractors to make a long box out of duct board and the flex duct was attached at one end. Then the box was laid on top of the drywall (with a hole in the box and a matching cutout in the drywall) and the grill installed. The contractor was happy and the client was happy because it was quiet. Working with ductboard is cheaper and quicker than making a custom metal boot.
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post #492 of 507 Old 05-21-2019, 08:51 PM - Thread Starter
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Work is crazy, home this week. GC asked me to review this...




My head is going to explode - not very Zen, but just wow.

He wants to finish soffit drywall. I don’t think I can move forward.

Moral support?


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post #493 of 507 Old 05-22-2019, 05:29 AM
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Sorry I'm unable to tell you that your HVAC will be dead silent. You basically have some metal trumpets aimed at your space. In a Big Bucks theater project when you sit in it alone with the lights off (humming) and no gear turned on you literally can't hear when the AC turns on and off. That will be your ultimate test in a couple of months. It is the same quiet as required in recording studios. In the HVAC world it is referred to as building to a NC20 standard (Noise Criteria). Residential contractors are usually not familiar with that guideline. That is why the simple test of on/off works.

Looks like you could actually do the on off test now if you have a door on the room.
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post #494 of 507 Old 05-22-2019, 09:19 AM - Thread Starter
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@BIGmouthinDC
Thanks Jeff - no door yet and the HVAC system is in the adjacent room.

Questions:

1. In theory, if the airflow measures below 250CFM that should help right?
2. Could adding linacoustic (or other material) inside the trumpet boot help?

Should I tell them to yank it out and build with ductboard?
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post #495 of 507 Old 05-22-2019, 12:23 PM
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1)Yes, 2)Yes, and what you can tell them is your call. Are they standing behind their work? once the room is complete and it is too noisy what is the remedy? I suspect that would be a pissing match if they have all your money.
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post #496 of 507 Old 05-24-2019, 05:02 AM - Thread Starter
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I put my ear up to the boot and turned on the system (via Nest app). I could not hear anything through the vent. I felt the airflow on my face, but no noise. I was a bit shocked. I could hear system noise coming from the room entrance (no door).

I went upstairs and could immediately hear vent airflow noise throughout the entire floor and specific vents from 10 feet away.

I don't have an air speed meter, but am ordering one today. I'm optimistic..
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post #497 of 507 Old 05-24-2019, 05:50 AM
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Sounds like you might be happy and your experiment is a good indication that your setup will be fine. I want to caution you that once you get a door and the room gets all it's treatments the background noise will be significantly lower and then you might be able to hear something. One project I worked on it wasn't until the room had a double door system installed that the homeowner got irritated by air turbulence noise of his home grown dead vent air exchange setup. His problem was a beefy fan motor on too small ductwork. Unfortunately we couldn't just reduce the fan speed because the room would overheat. We had to do surgery on his double drywall ceiling and rework the duct work. Until the room was dead quiet you couldn't hear it, once the doors went in it was the nosiest component in the room.
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post #498 of 507 Old 05-24-2019, 04:46 PM - Thread Starter
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Quote:
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Sounds like you might be happy and your experiment is a good indication that your setup will be fine. I want to caution you that once you get a door and the room gets all it's treatments the background noise will be significantly lower and then you might be able to hear something. One project I worked on it wasn't until the room had a double door system installed that the homeowner got irritated by air turbulence noise of his home grown dead vent air exchange setup. His problem was a beefy fan motor on too small ductwork. Unfortunately we couldn't just reduce the fan speed because the room would overheat. We had to do surgery on his double drywall ceiling and rework the duct work. Until the room was dead quiet you couldn't hear it, once the doors went in it was the nosiest component in the room.
Thanks Jeff - I appreciate the warning. I didn't provide the GC any guidance other than "slot diffuser (with example photos) & < 250CFM". He did ask me to review/approve the "trumpets" prior to him moving forward with sealing up the HVAC soffits with DD+GG. His plan is to start that work on Tuesday.

My air flow meter will be here tomorrow. If > 250CFM it will be a moot point. If measured at < 250CFM I'll want to add the linacoustic (or similar) material and measure again. I assume the 1/2" to 3/4" thickness will increase air speed at the opening. Which got me thinking about measuring after the grill is installed as well.

Are there any alternatives to Linacoustic? I'm going for delivery tomorrow if possible.

I'm going to also use an SPL meter app in conjunction with the CFM meter. I know I'll have some bleed from the door opening, but want to have as much "data" as possible.

Given my GC is taking WAY longer than anticipated I get tempted to just move on with things like this (cue almost not ripping out DD+GG ceiling). I'm not shooting for THX certification level quiet - but just something that wouldn't noticeable during normal dialog. I probably could deal with slight air speed noise in quiet scenes.

Plus, we're definitely selling this house in five years or less. Once the youngest is out of high school the house will be way too big for the two of us. So, I'm already making a list for HT 2.0.

Balance exists, somewhere between <20db and "not noticeable during dialog"...
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post #499 of 507 Old 05-26-2019, 03:58 PM - Thread Starter
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Ok, so this is puzzling...measurement at vent. Upstairs the noisiest vent is 450+.

Will this be enough air exchange?




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post #500 of 507 Old 05-26-2019, 07:56 PM
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Based on duct size calculate cu ft per hour divide by volume of the room to get the number of exchanges per hour. My first reaction is it seams low. If the vent is 12x12 and the flow is onstant over the area that is 2362 cu ft per hour.

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post #501 of 507 Old 05-27-2019, 10:57 AM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post
Based on duct size calculate cu ft per hour divide by volume of the room to get the number of exchanges per hour. My first reaction is it seams low. If the vent is 12x12 and the flow is onstant over the area that is 2362 cu ft per hour.
I was using the ft/m setting. After changing it to CFM I'm more confused.

What is the target # of changes per hour for a basement theater?

Total cubic feet - 3411 (after accounting for soffits)

I ran a calculation that takes Volume multiplied by the number of changes desired per hour divided by 60 to arrive at CFM.

Changes 1 2 3 4
CFM 57 114 171 227

When I use the CFM setting the meter registers ~2400 CFM. Clearly I need to read more of the manual...
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post #502 of 507 Old 05-27-2019, 10:59 AM - Thread Starter
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Plus, one of the supplies isn't connected, and the flex duct is folded in on itself...
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post #503 of 507 Old 05-27-2019, 11:54 AM
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leave it at the original setting. A 12x12 grill sending at 39.4 ft per minute is sending 39.4 cu ft per minute. just multiply the 39.4 by what % of a square ft your vent is like .8 or 1.4 etc. The other reading requires you to tell it the size of the vent. There is probably a set up function for the meter.

You are going to want 10 exchanges per hour +or-

fix the ducts and remeasure.
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post #504 of 507 Old 05-27-2019, 12:19 PM - Thread Starter
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Without opening the other duct I'm calculating 1312 cu ft per hour. I'm going to go open the right supply and measure again.
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post #505 of 507 Old 05-27-2019, 12:29 PM - Thread Starter
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Opened right duct...new readings/calcs:

Left (original) 10" x 4" vent: 157.5 ft/m
Right duct: 226 ft/m

Results in 6392 cu ft per hour. Just under two changes...

EDIT: do I need to include return calcs? I have one return from a flex duct in the left rear soffit, as well as the 6" PJ return w/AC Infinity exhaust fan. Do those play a part in the numbers?
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post #506 of 507 Old 06-15-2019, 03:11 PM - Thread Starter
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Small victory - finally tested the LCR/Sur/Top speaker cable. All good.

Minor setback - received my DIYSG Volt-8 flat packs. They are 1/2” larger in width and height than originally planned. So they won’t fit into the recessed backer boxes.

I’ll work it out, but a bummer because I was so excited to build my surrounds this weekend.



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post #507 of 507 Old 06-15-2019, 05:24 PM
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