treatment for porl and patrick continued

[porl]

Steve,

We have drawn up some basic construction plans of how we think the booth should be put together. They can be found at:

http://www.btinternet.com/~samandporl/cutaway.html

At the moment we would just like to know if you think this is a good way to build our booth. We can get into the more involved stuff later (doors & windows etc.). As you can see, we have reverted back to a floating wood floor - as we feel much more comfortable working with wood.

Things to note:

The floor joists are thinner than those we talked about to accommodate the slots in the neoprene U boats

The ceiling joists are 4x2" rather than 10x2" as at the moment we are unsure of why the 10x2" joists are needed if they do not need to be attached to the existing ceiling

We will need to talk in depth at a later time about how things are attached to each other ie. screws / glueing and joining walls at the corners

The outer wall is attached to the existing floor and the ceiling is "resting" on the walls.

In the meantime if you need to revisit any of the other plans, let me know and I'll post them up.

Hope this is OK.

Porl and Patrick.

[knightfly]

Hey Porl, still no code CD-roms - they supposedly shipped them, but no show yet.

As to using 2x4's for ceiling joists, it won't work if your walls will be the ceiling's only support - according to span charts, you'll need at least 2x8's if they are on 600mm centers, #2 or better grade, and running the short direction. This is for 20 psf live load, 10 psf dead load, which would allow for multi=layer ceiling construction.

Your floor shouldn't need 2x8's tho, 2x6 or even 2x4 should be fine for that.

Other than that, your drawing looks fine so far.

I've been curious, what do you plan to do about the big windows? They will be a weak spot in the isolation for sure. Glass (for a second, heavy lauer) is expensive, and building plugs for the windows will lose any feeling of openness.

I've been trying to think of a way to seal just your outer walls to the existing ceiling with its uneven joists, so that you could do a drop ceiling inside the booth's inner walls and have a complete room-in-room thing going - Thing is, the outer wall would have to actually SEAL to the existing concrete ceiling (softly though) then the inner ceiling could be built by resting the joists on neoprene directly on the top plates, then the ceiling drywall put on Resilient Channel and floated inside the wall perimeter (with rockwool above), and caulked after each layer. This would give excellent isolation... Steve

[porl]

Steve,

Hope you are well..

Ok, fine. I'm making the following assumptions about your reply based on my current understanding of it - maybe you can let me know if what I assume is correct.

10x2" ceiling joists are needed because 4x2" joists would not support the ceiling board layers, right?

The ceiling joists are made into a frame (600mm spacings) with the lengths laid across the shortest distance between walls. The 2" side of the joist timbers bears down on the walls.

Are we putting RC and boarding on the ceiling frame INSIDE the booth only ? If so, my drawing needs amending. I am currently boarding etc. the WHOLE ceiling first and then putting it into place across both set of walls.

There are some logistical things about attaching the outer walls to the existing floor and ceiling - namely that our building supplier can only supply 3m lengths for steel studs and our existing floor to ceiling height is 3.4m. If there's a way around this, it obviously will save money and time.

With regard to the windows and doors - at the moment we're working on the basis that we'll use a 700x600mm double leaf perspex window at 16 & 24mm thicknesses and two 2000x900mm solid core doors. The door and window walls will have a larger air gap placed between them to compensate a little - however we'll come to this after we've decided on how we're building our floor, walls & ceiling etc.

Anyways, if you could let us know about the ceiling & wall stuff that would be great for now.

Thanks,

Porl.

[knightfly]

Hey, Porl - here's a tidbit or two - First, a quote from the USG manual (you did download it from the top of this forum, right?)

"Steel studs may be conveniently spliced together when required. To
splice two studs, nest one into the other forming a box section, to a
depth of at least 8".
Fasten together with two 3/8" TYPE S Pan Head Screws in each flange.
Locate each screw (shown above) no more than 1" from ends of splice."

Cool, huh?

Here's a basic drawing that outlines the way I see your room being built - Kinda limited docs, so let's go ahead with the questions... Steve

[porl]

Dear Steve
Thanks very much for your reply and the plans they are very useful.
We had a thought about modifying the original plan to build a complete outer wall inside our studio. Do you think it would greatly compromise the transmission loss of the booth if we just built two outer sides to the booth (in addition to the floating inner booth) and incorporated the existing block walls with insulation as illustrated here: http://www.btinternet.com/~samandporl/usingwalls.html

Our thinking was that on two sides of the existing room we have block walls, and doing it like this would greatly reduce the costs and implementation problems for us.

Another question we have is about accomodating existing sprinkler pipes in the ceiling for the outer walls. At the moment we are thinking that we will have to cut holes in the plasterboard and caulk heavily around them as they cannot be removed, unless you have a better solution.
In the meantime we are studying the USG handbook. We are getting there slowly.

Many thanks for all your help

Porl And Patrick

[knightfly]

I'm sorry Porl, I shouldn't have assumed anything - you've come up with what I should have mentioned earlier. There is no need (in fact it would be harmful) to duplicate the function of your existing block walls, as long as they don't have holes in them like you described the party wall between you and your neighbor.

You already have one leaf of a 2-leaf wall on those two sides, and the low freq isolation in those directions, due to their mass, should only need a couple layers of wallboard on metal studs (with rockwool insulation) to finish out an effective barrier.

The last drawing I posted is just for walls you're building from scratch - on the other two, you'd just do the part from the edge of the floated floor inward (including the Perimeter Isolation Board around the floor)

Your overall goal should be two, and ONLY two, leaves of mass separated by an air space, completely around your space in all directions. For the floor and ceiling and two outer walls, half of this is already in place. The only place you need to build double leaves are the two inner walls that aren't there yet. If at all possible, there should be no SOLID coupling whatever between the outer leaves and the inner leaves. How that's accomplished can vary with the situation, such as what's already there, etc -

For inner studs, if your local supplier doesn't have versions that are rated for load-bearing wall construction you will need to go back to using wood studs. If that happens, you will DEFINITELY want to use Resilient Channel to mount all the inner layers of wallboard on - I'd recommend the RC anyway, since load-bearing steel studs are not as flexible as the other ones and that flexibility is where they help isolation between inner and outer leaves of the wall.

The sprinkler pipes are going to be a pain in the ass, even on a GOOD day - between the water inside them (if they're still active) and the steel pipes, they will transmit any structure-borne sound right into the cavity above your room.

The best you can hope for if you can't get rid of them, is to seal around them tightly (but with the flexible acoustic sealant) and keep the inner leaf of your ceiling (the only one I added in the drawing) as heavy as possible but with dissimilar layers (a layer of 6mm or 9mm gypsum wallboard between two layers of 15mm wallboard works well) - then, if you use thicker rockwool up there than in the walls, it should keep any flanking noise the pipes bring in under control.

Another thing that could help there, is if you could find some resilient supports for pipes and re-mount the portion of the pipes that enter your area - this may not help MUCH though, because ANYWHERE the pipes are rigidly mounted to the concrete they will transfer sound, and once it's in the concrete it will radiate EVERYWHERE. This is just one of the reasons your room needs an inner, flexibly isolated leaf consisting of several layers of wallboard mounted on Resilient Channel and hermetically sealed with the "good stuff".

As near as I can tell, the order your construction needs to happen would be floor first (running power in and caulking thoroughly), then inner walls (including RC and wall board), then inner ceiling frame, then inner ceiling RC, then ceiling panels, then the two outer walls... Steve

[porl]

Steve,

This is great news and thanks for the info on the sprinkler pipes - we'll check with the building architects and see if we can get them removed - my feeling is that they are a defunct left over from the building's days as a factory anyway we'll see.

With the money saved by not building the two outer walls, we can maybe look at using some posh materials for the doors . I think (barring the windows and doors for which we'll leave blanks in the wall for now) that we are ready to go away and draw up some actual construction plans for the two outer walls and the booth as a whole.

We're working on some door designs and for the window we are looking at the SAE stuff.

One final question, is there a spec we should be looking out for with the RC. All of the local suppliers are calling it Resilient Bar?

Other than that, thanks for all your patience and help.

Porl.

[knightfly]

Porl, there are various ways to go for Resilient mounting of wallboard, but few if any of the newer ones have been tested to the extent the original design has - I'll let you read the various threads that are already here on RC for general details, other than to say that the ORIGINAL RC-1 seems to have been discontinued, and that's the style that virtually ALL wall designs you see STC specs for were tested with.

The closest I've found to the original are the ones sold by Auralex as RC-8, and one made by Dietrich called RC Deluxe - here are links to both -

http://www.dietrichindustries.com/bigdp ... sories.htm

http://blindfaith.homestead.com/auralex.html

On the Auralex page you need to scroll down a little over half the page.

Note in the pix that both these products have very long slots in the web between mounting surfaces - this is like the original RC-1, which had 1" solid and 3" with a slot, so that there was 25% coupling.

There are several threads here on RC, I'll let you read through those rather than repeat myself... Steve

[porl]

Steve -

Thanks for the RC info.

maybe for the construction materials section:

Check out this link for door seals - http://www.lorient.co.uk - also in the US .
These guys sell retail and generally are about a quarter of the cost of one stop acoustic specialist stores. They also deliver small orders for a small fee..

All the best.

Porl.

[knightfly]

Cool, Porl - by all means, post it in the Materials section, thanks for the link.

Finally got a UPS Tracking # for the IBC CD-roms, should be here in a day or two. We'll see what revelations THAT brings (sigh)

Have you done any more "sleuthing" as to available (possibly useful) building materials in your area? Such as Structural versions of the metal framing? Just asking, it's always good to have options... Steve

[porl]

Steve,
At the moment we're heads down in the USG handbook which is proving extremely useful and infomative. We'll put some contingencies in for different types of materials if the ones we would like aren't available.

When it comes to buying, those prices quoted are becoming more negotiable.

Having read the USG information about steel studs - I am still unsure about gauges. The studs that we are currently sourcing are .55mm which falls between 25 and 24 gauge which the manual says are "not recommended for high density board applications such as Durock brand cement board or Fiberock brand abuse-resistant panels".

What I'd like to know (as I can't readily find any info. about densities of durock etc.) is - do our walls constitute high density board applications - those being 12mm plasterboard > 12mm particle board > 16mm plasterboard laid horizontally over 50mm studs at 600mm spacings?

Or would we need to use tougher studs with RC?

Also you mentioned Homosote in the plans as a perimeter board around the floating floor - could you briefly describe what this is as I haven't come across it.

Thanks,

Porl.

[knightfly]

Porl, I'm not positive but I think multi-layer construction needs to use heavier studs because of the extra mass. If you use heavier studs, you WILL need to use RC since the TL of a heavy steel stud wall is virtually identical to a wood stud wall without RC. Translation - some insulation between the leaves and your RC will make a difference of around 8-9 dB.

Durock is basically just concrete with fiberglas mesh embedded in both sides. It's very heavy. The stuff I've used (for bathroom tile backer) is a little thicker than 5/8" and requires special screws to install.

Homosote is also known as "sound board" or Celotex. It's kind of crumbly, because it's made of shredded paper similar to papier mache. If you can't find that, then a thinner layer of wallboard will do for sandwich construction in walls/ceilings. You would put the 16mm on first, then 6 or 9 mm, then the 12mm. That construction makes for a very good wall.

I hope you're planning on the thicker layer of drywall going on studs FIRST - same if you're mounting on RC. When mounting drywall on RC for walls, the studs are vertical, the RC goes horizontal, and the drywall goes vertical for the first layer. This is partly because gypsum board has more stiffness the long dimension than the short one, and will be less likely to sag that way.

[porl]

Hi Steve,

Here are the door and window plans - the door design has been taken from the ready made doorsets available from the custom audio design site the windows are from the SAE site. Any comments would be appreciated.

http://www.btinternet.com/~samandporl/d ... ndows.html

We have decided to go with wood studding for the main construction with RC as we have satisfactory prices for them now (ie. £1/lin. meter)

With these designs our door is going to be heavy - 45mm solid core door cladded both sides with 10mm MDF. Most of the dilemmas now come from how we make things strong without compromising TL. What I would like to know is:-

Would you recommend we screw or glue the MDF to the solid core door (or both)? Will there be any benefits in terms of TL from one or the other?

With the door design we are planning to hang the door on the 4"x2" studs which shall be placed to make a frame. Is this going to hold the door - or do you think a larger separate frame needs to be incorporated?

We are planinng on using three hinges (large and as strong as is appropriate) - do you think more will be needed.

For ref: final door measurements will be 2040mm x 915mm x 65mm

The only Window question we have concerns the fibreboard between the two frames - is this Ok to be attached to each frame ie. by nails / screws or does it need to be floated?

Thanks,

Porl

[knightfly]

First, on the window I would lose most of the angle, if that's close to scale. all you need to avoid flutter is 1 in 10 splay on each side. so if your window is 800mm tall, you would inset the bottom 80mm on each side. Keeping this splay to a minimum will improve on Transmission Loss at lower frequencies, which you'll need all you can get.

"The only Window question we have concerns the fibreboard between the two frames - is this Ok to be attached to each frame ie. by nails / screws or does it need to be floated? " - I'd float it, wrapped in dark cloth to minimise light reflections/glare.

Is there only going to be a single door, or are you planning one in each leaf of the wall?

Either way, for a door that heavy you should plan on 4 hinges, and ditch the wimpy screws that usually come with hardware - you'll need the heaviest, longest screws that will still fit the countersunk holes in the hinges. At least 75mm if you can find them. Whatever length you end up with, you'll need at least one full stud depth MORE where the door is hinged, to help counteract the flanking caused by the screws reaching through the frame. You will most likely end up with three studs cross-nailed and glued for the door hinge post part of the wall frame.

Because of flanking, you should NOT screw the layers of MDF to the door, but rather glue and press them til dry, using something like a 2-part Resorcinal glue, or heavy duty construction adhesive. The same applies to door handles - do NOT use a standard door set, as these require a thru-hole in the door which will make a VERY negative impact on your isolation. What I did on a couple of doors is to use short, fat screws holding large "barn door" type handles, placed ONLY on the "pull" side.

For latches, magnetic weather strip works good if you can find it. I thought I had a link to a paper by BBC on doors, but maybe it was just in the Everest book - anyway, here's an idea on that - Steve