I posted this on my construction thread yesterday morning and I haven't got a response yet, so I am assuming it got burried with the other posts and not many people had noticed it. So I wanna post it separately to get some help.

I am trying to put together a shopping list for everything I will need to buy from home depot to build the riser and the stage this weekend.

I am planning on building an 12 inch riser (5ft deep, 12 feet wide) and assuming the stage will have the same 12" height but will be about 40" deep and 14 feet wide.

I assume I need the following basic items:


2"x8" standard untreated lumber for both the stage and riser (as many as I need to set at 16" on center.

2"x10" pressure treated lumber for the outside frame touching the concrete floor.

2 x 3/4" layers of plywood to cover each platform (stage and riser) with one layer of 30 pound roofing felt in between. (So by then I should have a finished riser height of about 11" or so. And Carpet/Pad should add another 1/2" to 1" to complete my 12" riser requirements.

Joist hangers for 2" x 8" lumber to connect to the pressure treated front and back studs, which will enable the non-treated lumber to be about 1"-2" off the concrete/slab ground, and to be flush with the upper edge of the treated studs to make a flat level surface to place the two layers of plywood

30 pound roofing felt to place under stage and riser

Sand to fill under the right and left side of the stage where subwoofers would be placed ?

Insulation (R-19) to stuff between joists/studs inside riser and stage

Screws to attach joist hangers to main outer frame of riser and stage.



So here are my questions:


If I plan on adding a bullnoze lip, or what some call "overhang," should I add a couple of extra inches (1.5" - 2") of double-plywood surface to the front, right, back of riser - since left side will go against wall) ? I like that look, plus I may incorporate some light rope underneath the lip/overhang. I am assuming the same goes for the front of the stage too.

One I have that plywood surface over the riser and stage, do I actually buy special bullnose to go around that edge or will the carpet and padding create that smoother round surface automatically. do I need to do anything else to prep for future light rope under lip/overhang?

Regarding sand vs insultation between stage joists. Can I add just insulation, or do I have to incorporate sand as well. If so, are there specific areas where I have to really put in sand in the areas underneath the subwoofer, near bass traps?


Also, how much of a gap room do I need to leave between the stage platform and the front wall and two side walls? I heard that if the stage is not decoupled from the 3 surrounding walls (back and two sides), the low frequency vibrations will travel througout the walls/ceiling.


About the screen wall, once I have it framed. How do I attach it? Where does it attach to? Side walls? Ceiling? or is it screwed down to just the stage?


Last question regarding U-boats? If I am planning on buying 2x10 pressure treated wood for the front, back, and two sides of each platform, and I am using joist hangers to hang the standard non-treated 2"x8" studs so they dont touch the ground and are flush with the upper part of the treated studs, plus I am laying the entire structure over 30 pound roofing felt, do I still need U-boats?


If we have any u-boat advocates in the forum, can you give me an idea how many I need to buy? Is it one u-boat per stud/joist? They are fairly cheap, so if you think I HAVE to have them, can you please give me an idea on how many I would need for a 14'x4'x1' stage and 12'x5'x1' riser?

Is there a tutorial about how to use u-boats? I did a quick search and I didnt find anything helpful.

Thanks again!


P.S: Please note that I am aware that 2x8 and 2x10 lumber is not really exactly 2x8 or 2x10, so I may need to get something slightly wider or just pick up what will work for me.

If I plan on adding a bullnoze lip, or what some call "overhang," should I add a couple of extra inches (1.5" - 2") of double-plywood surface to the front, right, back of riser - since left side will go against wall) ? I like that look, plus I may incorporate some light rope underneath the lip/overhang. I am assuming the same goes for the front of the stage too.

you can do that, or you can buy a regular flat/curved moulding or even some quarter-round trim, and nail it around the perimeter of the stage/riser. the carpet will cover this and will naturally make a small curve to the top and bottom as it is wrapped around it.

Once I have that plywood surface over the riser and stage, do I actually buy special bullnose to go around that edge or will the carpet and padding create that smoother round surface automatically. do I need to do anything else to prep for future light rope under lip/overhang?

as i said above, you can do either but if it were me, i would build the riser with no overhang and then by a moulding that has a nice round (half circle, etc) and nail it to it. this will make a nice round edge, but again, the carpet will naturally make a small curve around any surface it is wrapped around.

Regarding sand vs insultation between stage joists. Can I add just insulation, or do I have to incorporate sand as well. If so, are there specific areas where I have to really put in sand in the areas underneath the subwoofer, near bass traps?

some have put sand only in the areas where their speakers/subs go and the rest of the stage insulation. from what the "experts" here have all told me, you want the stage to have as much mass as possible to eliminate all vibrations from the speakers/subs. so if it were me, i would fill the entire stage with sand, obviously lining it with plastic so it does not directly touch the concrete below it. the riser should only be insulation so it does not act like a drum. if you are placing speakers/subs on the riser as well, then fill that also entirely with sand.

Also, how much of a gap room do I need to leave between the stage platform and the front wall and two side walls? I heard that if the stage is not decoupled from the 3 surrounding walls (back and two sides), the low frequency vibrations will travel througout the walls/ceiling.

that is true. 3/8 or 1/2" is plenty, and be sure to fill that viod area with either expanding foam or acoustic caulk.

About the screen wall, once I have it framed. How do I attach it? Where does it attach to? Side walls? Ceiling? or is it screwed down to just the stage?

i would screw it to the stage very securely and for the side walls and ceiling, use something RSIC-DC04 clips to decouple it. look at this link for further info and if need be, do a search here (there is plenty of info on them). but basically, you would attach the rubber part to the stage wall and the steel to the actual ceiling and side walls.
http://store.soundproofingcompany.com/product_p/clips-rsic-dc04.htm

Last question regarding U-boats? If I am planning on buying 2x10 pressure treated wood for the front, back, and two sides of each platform, and I am using joist hangers to hang the standard non-treated 2"x8" studs so they dont touch the ground and are flush with the upper part of the treated studs, plus I am laying the entire structure over 30 pound roofing felt, do I still need U-boats?

not really. pressure treated lumber can sit directly on concrete, hence why many use it here. however, i would still have these pieces sit on foam roll or plastic. all new basements are built this way as this plastic/foam material makes a barrier between the lumber and concrete, minimizing dampness/moisture. i would definitely do this. if you don't know what i mean, when you go to HD, ask a rep to show you foam roll (its a roll about 5" thick x 50' long and usually white or pink or blue) or even ask for the plastic that is used to line lumber when placing it on concrete floors.

If we have any u-boat advocates in the forum, can you give me an idea how many I need to buy? Is it one u-boat per stud/joist? They are fairly cheap, so if you think I HAVE to have them, can you please give me an idea on how many I would need for a 14'x4'x1' stage and 12'x5'x1' riser?

Is there a tutorial about how to use u-boats? I did a quick search and I didnt find anything helpful.

Thanks again!

don't think you really need them at all if you do as stated above. if you are set on using them, then you don't need the foam/plastic lining as the lumber will never touch the concrete floor. if you are set on buying them, then use atleast 2 on every 5' piece and stagger them if possible. not sure if they do anything in terms of decoupling the stage/riser from the concrete, but if that is the case then i would go with them. it is much less surface area touching the concrete and it may help with further vibrations. if you get no further responses on u-boats, search the forum further and see what some have done. many answers are actually in build threads, so be patient and read everything carefully. it will pay off in the end.

I just extended the plywood (3/4") over the framing by 2" for the overhang. Much more secure and easier than using a molding. We carpeted ours and it looks great. We didn't even miter/bevel the edges. The carpet rounded it out nicely.

I also planned my riser so that I would have to make as few cuts as possible with my plywood. For example, I made the riser framing 7'8" wide overall and as such, I could use 8' plywood and still get my 2" overlap on each side without cutting it.

My carpet installer suggested a 1" overhang however if you want to stick a rope light under your lip you will probably want at least a 2" overhang.

If you are not putting buttkicker or a sub on your riser then I don't see a need to use u-boats. I was going to use U-boats under my stage but then it was suggested by Dennis to use Acoustic Mat instead. Here is a link to the u-boats - they recommend 16" OC.

. that is true. 3/8 or 1/2" is plenty, and be sure to fill that viod area with either expanding foam or acoustic caulk.

Thanks Anthony, when you say void areas, you are simply taking about the gap between the surface of the stage and the wall, not the gap between the entire stage platform and the wall. So in brief, fill the void between the plywood surface (about 1.5" thick) and the wall with this acoustic caulk or foam. I take it you would do that beforeyou carpet the stage.

I just extended the plywood (3/4") over the framing by 2" for the overhang. Much more secure and easier than using a molding. We carpeted ours and it looks great. We didn't even miter/bevel the edges. The carpet rounded it out nicely.

I also planned my riser so that I would have to make as few cuts as possible with my plywood. For example, I made the riser framing 7'8" wide overall and as such, I could use 8' plywood and still get my 2" overlap on each side without cutting it.

Thanks Jamis, thats what I plan on doing, using the plywood as an overhang

My carpet installer suggested a 1" overhang however if you want to stick a rope light under your lip you will probably want at least a 2" overhang.

If you are not putting buttkicker or a sub on your riser then I don't see a need to use u-boats. I was going to use U-boats under my stage but then it was suggested by Dennis to use Acoustic Mat instead. Here is a link to the u-boats - they recommend 16" OC.

I will be using bassk shakers or buttkickers down the road, but they will go directly in the chairs. So I guess no U-boats for me. I will probably just go with roofing felt as I dont want to add much more to the existing height of thr riser, once carpeted it will be about 12" or more, which is almost excessive IMO.

Thanks Anthony, when you say void areas, you are simply taking about the gap between the surface of the stage and the wall, not the gap between the entire stage platform and the wall. So in brief, fill the void between the plywood surface (about 1.5" thick) and the wall with this acoustic caulk or foam. I take it you would do that beforeyou carpet the stage.

basically, the void area is the space from the side of the 2x10 and the wall. a typical stage has three sides of void area, the back, and 2 sides. when you build the stage, if your room is 15' wide, you will make the stage 14'-11" wide leaving 1/2" space against the wall that it does not touch. this area is to be filled with foam or caulk. hope i made i clear.

basically, the void area is the space from the side of the 2x10 and the wall. a typical stage has three sides of void area, the back, and 2 sides. when you build the stage, if your room is 15' wide, you will make the stage 14'-11" wide leaving 1/2" space against the wall that it does not touch. this area is to be filled with foam or caulk. hope i made i clear.

I get it, so the entire height of the 2x10 in the 1/2" space in between. Where can I locally find this acousic caulk or expanding foam? And is it ok the foan is stouch drywall or the pressure treated side of the stage (outer frame)?

No need to fill the voids between the stage the 3 walls surrounding it. Unless you think you stage or your walls will move on their own. As small a gap as you want, just make sure they don't touch.

Bud

true, technically you don't need to but if you leave a 1/2" gap then you will notice it in your room that the stage is not connected to the wall. a small gap maybe 1/4" or less may do the trick of concealing the fact that your stage doesn't touch the walls. if you do want to go the expanding foam route, HD has it and it comes in a red container. not sure how much area you can do per tube, but its cheap. ask a rep and they'll know. btw, if you do go this route, be sure not to fill the entire are up to the top as it expands significantly and will make a mess, protruding out. only fill it half way up and let it expand until it reaches the top. from there, make small amounts to adjust to finished height.

You could always stuff the edge of your carpeting into the small gap rather than trying to fill it with something.... how would you hide that expanding foam anyway?

Make the gap small enough that no one will even see it unless they are right on top of it and are looking for it.

You could always stuff the edge of your carpeting into the small gap rather than trying to fill it with something.... how would you hide that expanding foam anyway?

Make the gap small enough that no one will even see it unless they are right on top of it and are looking for it.

I was almost going to say that too, I will just keep it to a minimum gap of 1/4" or so and make sure to let the carpet installer know to tuck/sandwich the extra carpet in between.

The less work, the better for me :D

Just a quick update, I have talked with Ryan (Roaring Fork Cinema) and he said that if I am framing the stage or riser with four 2'x10' PT lumber, then I can use much smaller studs for the inner studs. I was planning on using 2'x8' for the inner studs, but he said might as well go for 2x4 or 2x6 since they are not gonna touch the ground and will sit flush on the top with the framing 2x10 studs when using the joist hangers. I just wanna run it by here to make sure that's ok, whether I fill the stage with sand or insulation.

-sam


[LIST]
2"x8" standard untreated lumber for both the stage and riser (as many as I need to set at 16" on center.

2"x10" pressure treated lumber for the outside frame touching the concrete floor.

2 x 3/4" layers of plywood to cover each platform (stage and riser) with one layer of 30 pound roofing felt in between. (So by then I should have a finished riser height of about 11" or so. And Carpet/Pad should add another 1/2" to 1" to complete my 12" riser requirements.

Joist hangers for 2" x 8" lumber to connect to the pressure treated front and back studs, which will enable the non-treated lumber to be about 1"-2" off the concrete/slab ground, and to be flush with the upper edge of the treated studs to make a flat level surface to place the two layers of plywood

yeah you can do that but most only do this to save a bit of money. when you buy all the hangars and extra nails to attach them, i dont think the price difference is anything worth talking about. if you do go this way, i wouldnt use 2x4. i think they're flimsy at best. minimum 2x6, but the bigger the better. IMO.

Just a quick update, I have talked with Ryan (Roaring Fork Cinema) and he said that if I am framing the stage or riser with four 2'x10' PT lumber, then I can use much smaller studs for the inner studs. I was planning on using 2'x8' for the inner studs, but he said might as well go for 2x4 or 2x6 since they are not gonna touch the ground and will sit flush on the top with the framing 2x10 studs when using the joist hangers. I just wanna run it by here to make sure that's ok, whether I fill the stage with sand or insulation.

-sam

Depends on the wood and depends on the span. I went with 2x8s for a 6'8" span and still braced them with scraps in the middle to reduce the deflection.

Just FYI on the 1" or 2" overhang... make sure you figure this into your joist spacing. You don't want your tongue and groove to meet 1" or 2" away from the joist, so figure out which overhang you want in advance.

another thing i forgot in regards to the gap for the stage, if you end up putting baseboard trim around the perimeter of the room, it will cover this space.

Do not put expanding foam in the gap between the stage and the drywall. That will just recouple the stage to the walls.

so if it were me, i would fill the entire stage with sand, obviously lining it with plastic so it does not directly touch the concrete below it.



I have the plastic lining underneath the stage framing, so in essence the sand does touch the concrete directly below it. Potential problems?

Forgot that I've got the dri-core between the stage and concrete. So I think not a problem.

I don't see a problem from a logic standpoint. I haven't done this before, but I think the thinking is to keep the sand from wicking any moisture from the concrete. I could be wrong though, b/c I don't even know enough to be dangerous yet. :)

Just FYI on the 1" or 2" overhang... make sure you figure this into your joist spacing. You don't want your tongue and groove to meet 1" or 2" away from the joist, so figure out which overhang you want in advance.


Ok, I understood everything that has been mentioned on this thread. Except for what Twojciac said above.

What does the 2" dual-layer plywood over hang have to do with the joist spacing? What is joist spacing? are we talking about all the 2x8 studs lined up every 16" OC? What do they have to do with the the 2" overhang on the surface?:confused:

I'm guessing he means you don't want the seam between t&g to end up being off a joist. But really if you hang your joists this way [l l l l l] then your t&g seams should go this way ------ horizontal where they join up. Obviously your flush vertical seam if any should be centered over that particular joist. Also take a look at my thread, for a carpeting update. I did my first layer of my 3/4" OSB flush and made a 1.5" overhang with only the top layer. I didn't want the overhang to look extra thinck. My carpet is a medium plush so with the padding it still causes the overhang to look like it had two layers of overhang vs. 1.