New HT Project: Construction questions

[Space]

I'm not who you think I am

[MatrixDweller]

On a short wall with a door in the middle RC or RISC is pointless anyway. RC makes it so that the wall has a bit of spring to it and separates it from the studs, RISC takes it a step further. The door frame and assembly will short out any of those benefits however. They are really only good on straight un-opened (meaning no doors or windows) walls like in a townhouse or duplex's shared wall.

A double wall would be a better option. Better than staggered stud also because there would be no demolition necessary. With to door on the theater side of the double wall it should help. A double wall with insulation and double drywall would probably get the STC rating up in the 60's. Sound could flank up through the roof or the floor though. That sound being low bass only most likely.

[tenzip]

OK, now I'm a bit more confused.

Let me state what I'm pretty sure of, then ask some more questions. (A floor plan of the entire second floor would help, I think.)

The new HT is going to be above the garage area. I assume the screen/display will be at the end furthest from the living areas.

How are you accessing the new HT room? Is there a stairway from the garage, or a door/opening direct from the living area 2nd floor?

That floor plan you're going to post will really make things clearer, I hope.

[DucatiR]

salvasol wrote:

What Chris and I are wondering is... What are your plans for the space between second floor of the main house and HT space???? ...Are you building another room??? ...How are you going to access the HT??? ...From second floor through the open space above main house??? ...

In the new attached SketchUp file I ripped the roof off the space in question. It is standard web trusses. Considered modifying the trusses and putting a hallway thru (engineering actually worked out!) but too much money! Stairs will be going up from inside the garage. So the space between the main house and HT is about 26 feet of air gap. From David's last comment it sounds like I should be fine? I also attached a plan view showing the layout of the space above the garage (thanks Chris!).

Thanks for your patience. I should have provided a plan view from the start.

Duc

http://www.hometheatershack.com/gall...dex.php?n=1122
http://www.hometheatershack.com/gall...dex.php?n=1124

[hddummy]

Yeah...i think you have no need for special sound proofing in this space. Most people are lucky if they have a good wall between a bonus room/theater and their bedroom, but you have 26' of insulated attic space. That not only decouples the theater wall from the rest of the house, but gives a lot of time/distance for sound to be absorbed before it reaches the house. If you can still hear it after the fact, you can add OSB to some of those trusses and make some solid barriers.

[MatrixDweller]

There would be some vibration transfer from the floor and wall into the studs. As long as you take care of that the rest of the house should be oblivious to what goes on in the theater room. You have quite a bit of built in soundproofing already.
- The double drywall layer will take care of the wall portion quite a bit.
- The floor structure, seeing that it's insulated will prevent the room below from resonating.

If you were to build the equipment room where the screen is, you would have even more separation. I don't know if that would work though seeing that you would have a door or doorway with a curtain on your front wall (space issue?).

[DucatiR]

Framing is underway this week. Will post pics this weekend.

Ventilation duct work will be installed next week. I have read several posts about reducing sound from the ducts: flex duct and labyrinth or baffle. The HVAC contractor will be using flex duct. My question is on the labyrinth design and location. I've read about mdf box around the duct for some distance (15 feet??) and packing the space between box and duct with insulation. Correct?

Please see the attached rough sketch of the room. Outside the sides of the room is the remaining taper of the roof. It may be possible to wind the duct through the open web of truss work as illustrated in green. Building a box around the duct may be possible but I think challenging. Is another option to build the labyrinth behind the screen wall as shown in red and run a long straight section back to the inlet/outlet vents in the room? Or does the straight run re-introduce noise issues? I'd have more room to maneuver in the open attic space behind that wall.

Other options??

Duc

[bpape]

Without the box, just bending the flex duct won't help much with mid and low frequency isolation.

When you do the bends, you don't have to come all the way back at 180 degrees. You can just run a few feet, bend 90 to go up or down, then run, bend again, etc. Might be easier to do the boxing that way.

Bryan

[DucatiR]

Thanks for prompt reply Bryan. Attached is another duct run design along the side of the room. And this does look easier to build. Due to space constraints of the the trusses I'm limited in how long the runs can be along 2 of the 3 axis. Using this design the numbers would roughly be:

90bend - 90bend - 30"vert up - 90bend - 4'horiz - 90bend - 30"vert down - 90bend - 90bend - 4'horiz, etc.

I can get 15'+ with that design. Will that accomplish the isolation objective?

Also, I've read about using a larger box at the end of the run and a large grille to help reduce face velocity of the air flow. Is that advisable? Effective?

Thanks much. Duc.

[bpape]

That would work great.

The general 15' is assuming 3 5' runs with 3 90 degree bends. What you've laid out is actually better - though more work.

Bryan

[MatrixDweller]

The more bends the more sound attenuation (from room into HVAC). Line the ducts with linacoustic or SUPERDUCT RC or other HVAC acoustical material and you'll be pretty happy. A silencer could save you a bit of duct work though. A silencer is basically constructed like a car's muffler.

[bpape]

Yup. A silencer can work very well over a lot of the range - but still doesn't deal with the bass getting through very well.

Bryan

[DucatiR]

A few construction progress pictures.
First, the linked picture shows the original truss space with camera flash illumination.
http://www.hometheatershack.com/gall...dex.php?n=1086

Second picture is from relatively the same position with framing of walls and subfloor now completed. A little better illumination with the temp construction lights. In the floor is a small box for wiring, controllers, etc. from the equipment room in the background. There are pvc pipes exiting to either side of the room. The equipment room has similar boxes at the very outside edges of the room with another pvc connection between them.

Third picture is one of the ventilation duct labyrinth's nearly completed. I had hoped to complete both of them (supply & return) this weekend. My advance measurements were spot on but assembly took considerably longer than anticipated. Actual duct work will be installed next week.

Duc

[bpape]

Nicely done. Add in the flex duct and a bit of insulation to fill in the gaps and that should be about as quiet as you're reasonably going to get.

Bryan

[DucatiR]

Wow, over a month since my last post. Time flies. I've been working on the all the electrical wiring which took considerably longer than I expected. I should have expected that! Passed the rough-in electrical inspection yesterday! HVAC duct has been run. I still need to get the insulation in and finish the front panels on the mdf boxes.

I'm about to finish up the conduit runs for speakers and cables to the projector before I start with insulating the wall/ceiling cavities. Any recommendations or advice on projector location? I know throw distance of the projector is a factor, but otherwise is it advisable to be closer to the screen or further back? Overhead or behind the front row?? Screen will be about 18-19' from the back wall with a door in the middle of that wall.

Also, how much clearance should I factor for an anamorphic lens assembly? My ceiling will be rather low at about 7'8" or a bit less. A riser would shrink that even more in the back of the room. So I'm thinking I want to mount the projector as close to the ceiling as possible?

Duc

[DucatiR]

Finally posting some pictures of construction progress.

First is a view of one of the hvac vents. The mdf box contains 6" insulated flex duct, voids packed with cellulose blown-type insulation. I sealed as much as possible of the mdf box interior seams. A few inaccessible seams were sealed from the exterior.

Next is the supply return. Due to miscommunication with the contractor I built the boxes too small. He said sticking flex duct inside the mdf labyrinth would create too much resistance for this return branch so there would be very reduced flow. As a result I ended up leaving the boxes open (you can see acoustic sealant on the interior - not yet painted). To try and preserve sound isolation I wrapped the mdf with 5/8" sheet rock and then Roxul. A lot of extra work for a few minutes of miscommunication.

Besides the vent/supply penetrations there will be only 2 other penetrations of the double drywall: outlet and front speaker gang box (other speakers will be wire-hole only and sealed). I built a small frame around the gang boxes and a hinged panel on the back side with mdf, double drywall and Roxul with weather-stripping at the panel door interface. I have easy access to the backside of the wall through the attic for wire addition/change.

Two pictures of some of the conduit I ran for speaker wire, cable, etc. Tried to run 90deg to electrical and some space between conduit/power when parallel whenever possible. The box in the floor includes an outlet for rope light, charger for remote control, etc. Also conduit running overhead in the ceiling for projector and speakers on the screen-wall (box to access the projector cables not yet built).

Finally, 2 pictures of the room with insulation: 1 viewed from the screen wall, the other from the door towards the screen wall.

Wallboard next but taking a few days rest. I have DIY-itis. On the plus side, the contractors that did the framing are acquaintances and offered to help with wallboard for a case of beer each!!

[Bruce Fisher]

Looks great! I've been looking around at ways to reduce the noise from my HVAC too - nice to see what you did.

[bpape]

Looking good. Drywall help for a couple cases of beer - what a deal that is...

Don't forget to provide isolation for all of the electrical boxes too. Those plastic boxes won't stop diddly in the bass.

Bryan

[Prof.]

It's starting to take shape nicely..

[DucatiR]

Happy New Year!! (my last post was in December ) Skiing, girls basketball, work...no time for project - egads! I'm posting a few pictures below of my current status. Apologies for the deluge.

Nothing of the drywall, taping, texture, etc. IMHO, that's a bit like the foundation of a house. 'Yep - that's concrete alright.' In hindsight, the green glue on the 2nd layer of drywall would probably have been good to share.

In any case, when we last saw this project we had insulation and a fair number of pesky outlets for bass waves to sneak thru. But we had a trick up our sleeves after the inspectors left. Passed both electrical and final building inspection last Friday. Here we go...

This HT is accessed from my garage. Here is a view towards the new stairs that were installed.


That first landing presented a tight corner for my furniture, cabinets, riser & screen wall lumber after construction. So I found some nifty OSHA-compliant stair rail mounts that permitted me to build a removable stair rail.


Relatively cheap indoor/outdoor carpet on the stairs considering the garage environment it will be exposed to. But check out that vinyl carpet protector - I don't think I've seen that since my parents house in the 70's.


Habitat for Humanity has a cool used building materials place where I live. I found a nice door that met, barely, the code requirements for fire separation from the garage.


The first room is a tight spot but it's only for a small fridge, cabinet and movie storage.


The second room is for equipment storage.


Here is a close-up of the opposite wall with the wire access exposed. The single outlet on the right is a switched outlet for my light generator.


I ran conduit across the ceiling for speakers that will be behind the screen wall and also for the ceiling mounted projector. Here is the equipment room access to that conduit.



The HT room post-texture, pre-paint.


Now what about those pesky outlets required by code but that I'll never use and that create nice little bass leakage? I used a few of those fancy outlets you can adjust back/forwards with a screw. Very nice to adjust to the double dry-wall if you want. But also handy if you want to push it back behind the drywall, cover the box, and then replace the drywall.




The wires will be trimmed back so they just protrude from the wallboard. I'll go back after everything is done and leave small indicator marks. That way if I or future homeowner want the outlets back their location is easily found.

I'm not sure how much space I get so I'll submit this one and follow with my next batch.

[DucatiR]

Next batch catching up on my activity since the inspection. Busy, busy, busy!!!

Here is the door from the equipment room into the HT. It is solid core and I used extra long screws in the hinges. I'm thinking of mounting 5/8 wall board to the HT-room side of the door with a bit of Roxul stuff between it and the door. Just a bit of extra soundproofing. Not sure if this is needed or advisable? but I put a lot of work into the rest of the HT surface area.
Attachment 14188

The HT room looking towards the screen wall now painted in Bittersweet Chocolate.
Attachment 14189

And a view from the screen wall towards the door.
Attachment 14190

Here we can see a air supply vent. There used to be a bass leaking outlet located right below this. Magic outlets!
Attachment 14191

Tonight I just started building the riser. 2x8 construction on 16 inch centers, 6 feet deep and full width of the room.
Attachment 14192

Half a riser?! What's up with that? Those removeable stair rails are cool but the turn at the top of the stairs for the doors maxes out for a 10 foot item. My room is 12' wide. So that 2x8x12 wasn't going anywhere. Sometimes it seems like no matter how much planning I do, I still end up managing a continuous series of complications. But I have progress - positive thinking!!

Here is the floor access for wires that may be required to run from the equipment room. I painted the interior white for better visibility. Plan to install a light that will auto-on when I open the panel.
Attachment 14193
Attachment 14194

I finished tonight when I realized the middle of my riser joists run perpendicular to a crown in the floor. Might be kind of hard to see in the following photo but I basically have a riser that teeter-totters about 3/16" on either side. Complications!
Attachment 14195

Next up is figuring out to deal with the crown, finish the other half then glue/screw to the floor, reinforce the seam in my ex-2x8x12's, then stuff with insulation and cap it. Hopefully the carpet guy can be here next week if I can get all that done this weekend.

Cheers for now.

[Bruce Fisher]

for some reason, your attachments didn't work in your second post (first post was fine)

[DucatiR]

Apparently a problem with pictures in the second post. Trying again below by quoting and editing the post. Hope that is correct procedure.

DucatiR wrote:

Next batch catching up on my activity since the inspection. Busy, busy, busy!!!

Here is the door from the equipment room into the HT. It is solid core and I used extra long screws in the hinges. I'm thinking of mounting 5/8 wall board to the HT-room side of the door with a bit of Roxul stuff between it and the door. Just a bit of extra soundproofing. Not sure if this is needed or advisable? but I put a lot of work into the rest of the HT surface area.


The HT room looking towards the screen wall now painted in Bittersweet Chocolate.


And a view from the screen wall towards the door.


Here we can see a air supply vent. There used to be a bass leaking outlet located right below this. Magic outlets!


Tonight I just started building the riser. 2x8 construction on 16 inch centers, 6 feet deep and full width of the room.


Half a riser?! What's up with that? Those removeable stair rails are cool but the turn at the top of the stairs for the doors maxes out for a 10 foot item. My room is 12' wide. So that 2x8x12 wasn't going anywhere. Sometimes it seems like no matter how much planning I do, I still end up managing a continuous series of complications. But I have progress - positive thinking!!

Here is the floor access for wires that may be required to run from the equipment room. I painted the interior white for better visibility. Plan to install a light that will auto-on when I open the panel.



I finished tonight when I realized the middle of my riser joists run perpendicular to a crown in the floor. Might be kind of hard to see in the following photo but I basically have a riser that teeter-totters about 3/16" on either side. Complications!


Next up is figuring out to deal with the crown, finish the other half then glue/screw to the floor, reinforce the seam in my ex-2x8x12's, then stuff with insulation and cap it. Hopefully the carpet guy can be here next week if I can get all that done this weekend.

Cheers for now.

[Prof.]

It's starting to look like a theatre!..
Keep the pics coming..

[Bruce Fisher]

looking good! amazing that no matter how hard we try to plan - little things still pop up