Attic studio conversion - advice needed

[Superhuman]

Hey guys, first time posting in this area of the forum (I'm a guitar guy) so please bear with me!

I'm converting my attic for a home studio (recording and mixing guitars, bass and some vocals - no drums). I'm looking for some advice on finishing it out with particular regard to soundproofing.

The attic room is under a pitched a tiled roof with a timber frame on a block on block structure with block party wall between the neighbours house (semi-detached). So far I have insulated between all of the trusses with Kingspan thermal boards and rockwool, the plan is then to slab this with rockwool backed fireboard before plastering and fitting some kind of acoustic foam.

The floor: The cielings below are under a suspended timber structure, I have added steel beams for load bearing capacity and added further hanging joists above the original set. In between each joist has been packed with rockwool with a plywood floor above. The plan being to then add special accoustic flooring (a rockwool type compound under a ply-type board). Then I was just going to add a heavy carpet on the floor and put my studio desk and amps etc up on foam/rubber blocks.

The stud partition walls between the studio room and the eave storage will be packed again with Kingspan thermal boards (60mm) and rockwool and slabbed with rockwool backed plaster board on each side. In the eaves themselves the floor is not an additional hanging floor but will be heavy ply above the existing joists (packed with rockwool), I will then add rockwool backed plywood flooring which will then be carpeted.

Foam etc should help with the reflections etc and a heavy trap door with thermal board covered with heavy blankets will be used to close off the covering below the access ladder (no stairs access).

Is this sufficient for soundproofing so that the wife and kids don't hear anything late at night? If there is anything extra that needs doing now is the time so I am all ears and open to suggestions. I'll try to post some pics of the room later on to give a better idea of what I'm talking about.

Hope to hear from someone.

Thanks,
Dave

 

[RICK FITZPATRICK]

Is this sufficient for soundproofing so that the wife and kids don't hear anything late at night?

Impossible to predict from your description. There could be all kinds of flanking paths. HVAC, structural connection, non caulked joinery, hollow core doors...etc.
But I'll try to address a few things.

So far I have insulated between all of the trusses with Kingspan thermal boards and rockwool, the plan is then to slab this with rockwool backed fireboard before plastering and fitting some kind of acoustic foam.

Slab what? I don't understand. Are you saying you plan on fastening "rockwool backed fireboard" to the underside of the trusses as a ceiling SHIETHING, and then PLASTER the fireboard? First off, the terminology is a little unusual. Is "fireboard" the same thing as GYPSUM DRYWALL, or better yet, SHEETROCK? And what do you mean "rockwool backed"? Do you mean the "fireboard" comes with "rockwool" factory applied to one face of the "fireboard", or are you referring to the "rockwool" already in place between the trusses?

As to "plastering", are you referring to what we call "taping and texturing", or are you saying you actually will PLASTER(total different process/product)
The only thing I can offer at this point is MASS is the only thing that attenuates sound. And DECOUPLED MASS works better. IF I were you and had the budget, I would use RESILIANT CHANNEL or RSIC clips to DECOUPLE either 2 layers of 5/8" drywall(fireboard?) or one layer with one layer of plaster(if PLASTER is actually a layer and not Tape/texture), from the framing. Caulk all joints. And if possible, use Green Glue between the layers of drywall. I makes two layers act as one.

I assume this was only the ceiling you are referring to. What about the perimeter walls. Are ALL of them BLOCK? And by BLOCK, are you referring to CONCRETE CINDER BLOCK? Do these BLOCK walls extend from foundation to the roof framing on all 4 sides? It is very difficult to visualize what you are dealing with here. Please post some pictures and a plan. Furthermore, what is your plan regarding the walls? Are these blocks hollow or filled? I assume filled. And you say

I have added steel beams for load bearing capacity and added further hanging joists above the original set.

Hanging? Hanging from what? Do these joists rest on the steel beams? Do they form the framing for a new floor above the cieling below? Sounds like it, but the term "hanging" throws me off.

.

In between each joist has been packed with rockwool with a plywood floor above.

Remember this. No matter what, this is STILL a MEMBRANE STRUCTURE, and as such will RESONATE at a certain frequency. To improve the Transmission Loss through a membrane, ADD MASS. If you have the ceiling hieght to spare, add a layer of 5/8" DRYWALL OVER the plywood using "GREEN GLUE", and then add ANOTHER layer of ply over the drywall, again with GREEN GLUE/SCREWS. Caulk all joints before adding the next layer.

The plan being to then add special accoustic flooring (a rockwool type compound under a ply-type board).

If you are going to that extent, then it makes sense to "decouple" the wall and ceiling shiething as well. Otherwise you have whats known as WEAK LINK SYNDROME..in other words..why go to all the trouble to decouple the floor only to have the walls and cieling structurally flank right past the floor. At least from what I


The only thing I can offer at this point is MASS is the only thing that attenuates sound. And DECOUPLED MASS works better. However, TRANSMISSION LOSS within a structure is only as good as the weakest link. Decoupling the entire INTERIOR ENVELOPE of the space is the BEST choice for attaining a desired TRANSMISSION LOSS RATING. But its only as good as the detailing of the decoupling, and shorting out any area can significantly reduce this rating. Even little details such as door jamb casing touching decoupled drywall, and lack of thresholds and door seals.

But now comes the biggie. HVAC. What do you have?

fitZ

 

[Rod Gervais]

Just a few clarifications here,

or one layer with one layer of plaster(if PLASTER is actually a layer and not Tape/texture), from the framing.

Actually - you will get better Low frequency isolation with 2 seperate layers of drywall than with a layer of plaster covering a layer of drywall -

plaster over drywall will make the assembly act like one thick layer of drywall - and this is not as good as 2 seperate sheets.

Caulk all joints.

Caulk all perimeter joints (picture walls as panels - and the outer edges should be caulked) apply one coat of tape to all edges of each layer in the field of the panel ..... that will stop the passage of air just fine.

And if possible, use Green Glue between the layers of drywall. It makes two layers act as one.

Actually - it is not a glue and doesn't join sheets together as a single unit - but rather it never sets up and gives added isolation because it will shear as sound passes through it and then dissapate the sound by converting it into heat energy.

BUT - 2 layers of drywall (on each side of a wall) with green glue will perform the same as 4 layers of drywall on each side of a wall.......

The remainder of the points addressed still require a response.

Sincerely,

 

[Supercreep]

Is this sufficient for soundproofing so that the wife and kids don't hear anything late at night?

I'm going to go ahead and say no.

There's things you could do to help, but "soundproof"? So they can't hear anything?

Let's just say "it's possible" without addressing how difficult or expensive (hint: very).

It's probably cheaper to send them to the movies when you need to record bass.

 

[Superhuman]

Sorry, different terminology in Ireland... firstly the thermal board (fireproof and soundproof 60mm compacted foam is cut to size and inserted between the trusses against the felt on the inside on the roof). Rockwool is then packed in to these spaces as tight as possible, then I'll be slabbing it with a special board that is factory made with a rockwool layer and a fireproof surface that is prepped for plastering (for internal finish). These boards are compliant with the current building regulations and are fairly common in block on block contructed houses (here at least).

Re the walls, the house is solid block on all four perimeters. The joists being placed on top of thses with the pitched and tiled roof above. I had H-frame RSJ steel girders placed above the joists (inserted into the gable and the party wall - timber batons are then placed on top of the steel beams and the stud wall is built up above this (separating the main room from the eave space). I also have strips of neoprene placed along the steel and anywhere the new floor makes contact with the existing structure. Joist hanger are then placed on the timbers attached to the RSJ's and new joists are hung from them - rockwool is then packed tight all the way from the ceiling below to the plywood above which is resting on these joists - btw neoprene strips are between the joists and the plywood floor to try and reduce sound transfer.

BTW, the floor is plywood with a layer of rockwool backed plywood on top - I'm not sure whether to use carpet above this or some kind of accoustic mats.

I thought I was being ambitious about blocking out bass guitar allright - I suppose I will probably only record bass when the kids are out. Monitoring and guitar is what is most important for night time.

It's all pretty hard to explain without the pics - I took a few today but won't be able to get them up until the morning at work. Hopefully it will be easier to see what I'm on about then - thanks for all of the advice so far - all good stuff.

 

[RICK FITZPATRICK]

It's all pretty hard to explain without the pics - I took a few today but won't be able to get them up until the morning at work. Hopefully it will be easier to see what I'm on about then - thanks for all of the advice so far - all good stuff.

You should be on this end. Whats that saying...er...a picture is worth 100000 words..or something to that effect..

 

[RICK FITZPATRICK]

Actually - you will get better Low frequency isolation with 2 seperate layers of drywall than with a layer of plaster covering a layer of drywall -

plaster over drywall will make the assembly act like one thick layer of drywall - and this is not as good as 2 seperate sheets.

With all due respect Rod. This totally contridics my understanding of the whole point of Green Goo. Please clarify some points for me.

First, I was under the impression the whole point of Green Gleu was to make 2 layers of a membrane act as one, thereby lowering the coincidence frequency. Why would 2 seperate layers of drywall be better than a composite of drywall and plaster acting as one? I'm all ears
fitZ

 

[Superhuman]

First time posting pics so I hope I get this right!

I could only get stage 1 pics onto my pc this morning, I'll post the updated version later this evening so you can see the additional materials in place.


Pic 1 shows the party wall before being treated - solid block on block construction - you can see the firebreak that we just built up to either side. Rockwool was stuffed in behind this and down the side where the block makes contact with the roof. You can also see the 60mm thgermal boards (with the silver finish) cut to fit the spaces between roof trusses (rockwool etc layers yet to be added on this pic).

Pic 2 shows the RSJ steel beam with the new floor hanging from this - you can also see the original joist below this in the cavity yet filled to the left. The new hanging joists are not making direct contact with the suspended joists below. You can also see the basic frame for the stud wall to the rear separating the room from the eave storage area.

Pic 3 shows the first layer of plywood above the compacted rockwool between the two sets of joists - this ply wood is placed on neoprene strips where there is contact with the joists. You can also see the access point with the four posts where the retractable stairs will be (soundproof hood to be placed over this).

PS there are two large heavy duty double glazed windows on one side of the room - any ideas on how to treat these? I was thinking of a basic heavy duty carpet cover that I could just roll down and fix in place when needed...

 

[RICK FITZPATRICK]

Thanks for the pics! NOWWWWWWWWW I get it. When you said the word "truss's", I was thinking it was a standard room with truss's above. Now I see it really is an attic with what looks like standard "rafter" construction. Total different scenario than what I thought. Words do NOT convey enough sometimes.



And the steel beam...ah, ok. Clad with a rim joist..what a dunce I can be sometimes. Ok. It looks like the beam is supported on the ends but is it resting on the joists below as well? Not that it matters in respect to your questions, but my belly tells me something I'm not getting yet.

Well, for what its worth, here is a couple of sections I drew for another member with a similar project. This illustrates a floating floor like you are describing, AND decoupling DRYWALL via a product called ISOMAX. It is a channel with decoupled brackets every 24" or so, for fastening the drywall to.

However, now I see a couple of things that could put a damper on the whole scenario. First off, is the opening penetrating the floor going to contain
a "drop down ladder" type thing? This is something that needs to be addressed as far as sealing it with the same transmission loss as the rest of the room or it will be a "weak link". Do you have something in mind already?

The second is furring out the block wall for drywall(and decoupling device), although now I see a skylight penetrating the roof assembly. For all intents and purposes, this MAY compromise the party wall isolation from the neighbors. Hard to say at this point. Just a thought though. I will say this. In my mind it looks like a lot of things to address as far as making this whole space decoupled from the structure. Thats not to say it can't be done, but I just don't know if it will help that much considering the penetrations. Anyway, check these out.
fitZ
fitZ

 

[RICK FITZPATRICK]

Forgot these. Dang, getting old sucks.