FINISHED IN 2020! Sharward's Partial Garage Conversion

[sharward]

OK, here goes -- three revised illustrations for your review. I've changed some things, beefed up some things, and (hopefully) refined some things.

Although not represented in the illustrations, the finished height inside the inner room will be 8 feet, plus or minus an inch or two. (My condolences to those working in basements or garages without the luxury of a 10' foot ceiling like I have in my garage! )

Although it goes against my "sandbox for fairly easy access to framing structure" idea, I'm leaning heavily towards using brick and mortar as both my mass and my finished floor surface, in 3' x 3' sections separated by redwood 2x4s. You'll also notice that the subfloor beneath the bricks and mortar is completely within the walls, making it conceivably easier to cut through the subfloor floor to the framing structure if the need arose. (It's hardly an "easy" method, given the bricks and mortar I'd have to chisel through... But it beats ruining the entire floor -- only one or a few 3x3 sections would need to be sacrificed.

Looking forward to your thoughts on these revised illustrationis. Steve, you mentioned you had some ideas to improve upon my old ones, and I'm hoping I read your mind on some of them.

1. 1st illustration: Anatomy of the walls close up. There's a 3" gap between the wall framing. I decided to cut strips of gypsum to go between studs on all the existing walls, not just the outer wall. This additional work will eliminate my need to add drywall to the living space walls inside the house, including texture, paint, baseboard and casing adjustments, and trimming carpet in one of the rooms. I'm assuming this method is equivalent to that effort; if not, please let me know, and I'll bite the bullet if need be.
   
   2nd illustration: Anatomy of the floating floor structure and the ceiling. I don't think it would be wise to add more than one layer to the existing sheet rock on the outer leaf. Hopefully the 9" gap between leaves is sufficient to make up for this. Biggest change is in the height of the floating floor, using 2x6s and anticipating up to 3 1/2" of leg height, accounting for the slope of the garage floor.
   
   3rd illustration: Updated floorplan. I was trying not to have the door open towards the cars, but for ease of entry and exit, especially when loading/unloading gear, I decided to make it a straight shot. The door swings open in the corner and should miss the front of the car parked on the left side of the garage. Note that the "step" serves as both a split of the 15" hight to the inside room floor surface as well as a sound lock between the doors. Please let me know if this is sufficient, or if I should separate the doors more, or do something else entirely here. I plan to use two solid core 36" doors, the outer door being fire rated to meet code for separation between the garage and living space.

Thanks so much for all your help on this!!

[knightfly]

Top pic - no changes I can see; for in-wall insulation, the fluffy stuff works about as well as the more expensive kind - if this is used, stay with UN-faced and fill to about 1-1.5" over, then compress with inner wallboard for damping.

Where/what is your vapor barrier on the stucco wall?

Inner walls - if space will be same temp as house, no vapor barrier needed as there will be no air infiltration without temperature delta.

2nd pic - no changes.

3rd pic - no changes, other than "weakest link" question - is the wider gap due to construction necessities? If not, other walls (and ceiling) will probably negate the extra inch and a quarter.

4th pic - ceiling - how new is this construction, and have your trusses already lifted as much as they are likely to? This is cause to use clips to mount ceiling wallboard to top plates, so trusses can "lift" as they cure - this can be over an inch in some cases, and will crack ceiling wallboard if improperly done. For this reason, paragraph F may be a bad idea.

Sway brace - one commercial version -

http://www.kineticsnoise.com/arch/kwsb.html

Mason industries has others IIRC, or there's the DIY approach in Aaron's thread, about page 16-17.

3 layers wall/ceiling, inside leaf - stagger joints leaving 1/4" gap each time, caulk as you go, so you have a zig-zag joint with multiple caulk seams. Point G - I'd save the rockwool for acoustic treatment inside; unfaced standard fiberglass slightly overfilled will give within 1-2 dB of the same performance at less cost, and the rockwool will be needed for corner killers, etc, inside the room and under the floor.

5th pic - floor detail - have you done a moisture test yet? Tape a piece of plastic against the floor for a day or two, pull it up - if there's a drop of moisture on it, seal the floor. If not, seal it anyway...

I would leave the gap between inner and outer door frames porous, so the wall cavities can breath - if you run a dehumidifier, leave the outer door closed and inner one open when not in use. The porous gap between doors will keep from having a high vacuum making the doors hard to open as well as allowing some moisture escape.

Guitars and pianos, etc, like a constant humidity of 40-42% - you can get an inexpensice and accurate humidity meter here (most are either expensive or crap)

http://www.natlallergy.com/allergy/prod ... eadid/1526

I bought two of these; they read within 1% of each other in the same location, usually exact. Use them to "dial in" the useless knob on your dehumidifier to a REAL 40%...

If you can match your walls with good doors/seals, you should be able to have a kick drum at around 95 dB inside before it will be audible outside on a quiet night - hearing threshold @ 50 hZ is around 55 dB, the TL of your walls @ 50 hZ will be roughly 42, with an STC of around 72-75. So even though it might not be a good plan to play death metal at 3 am, I doubt your neighbors will be calling the cops under normal circumstances... Steve

[sharward]

So much to cover, so y'all forgive me for getting a little "quote happy" here.

Where/what is your vapor barrier on the stucco wall?

I don't know yet. I'll find out when I tear off the existing gypsum off that wall though!

Inner walls - if space will be same temp as house, no vapor barrier needed as there will be no air infiltration without temperature delta.

Define "same temperature." I wasn't planning to run the HVAC in the studio unless it's occupied.

3rd pic - no changes, other than "weakest link" question - is the wider gap due to construction necessities? If not, other walls (and ceiling) will probably negate the extra inch and a quarter.

I'm tweaking the images so that the gap is consistent around the perimeter. Previously, I had planned on going with 6" between frames. However, I'm adjusting it to 11 3/4" between leaves, which means the distance between frames will be either 4 3/4" or 6", depending on whether or not I'm doing the "gypsum strips between studs" trick.

4th pic - ceiling - how new is this construction, and have your trusses already lifted as much as they are likely to? This is cause to use clips to mount ceiling wallboard to top plates, so trusses can "lift" as they cure - this can be over an inch in some cases, and will crack ceiling wallboard if improperly done. For this reason, paragraph F may be a bad idea.

House first sold in March 2000. I actually ran across an article in my framing research about the truss uplift phenomenon. For what it's worth, it rarely gets below freezing in my world, and summers are not humid here. Also, the garage is not heated, and the space between leaves won't be directly temperature controlled.

I have a neighbor with the same exact floorplan as mine. He framed a wood shop in the corner of his garage -- almost the same footprint as my studio plan. I can ask him how he did his walls and take a look at them -- that might give us a hint about how much, if at all, we should be concerned about this.

Sway brace - one commercial version -

http://www.kineticsnoise.com/arch/kwsb.html

Mason industries has others IIRC, or there's the DIY approach in Aaron's thread, about page 16-17.

I saw the illlustrations and later photographs of the DIY brace -- very cool. My situation is a little different in that I need to mount the brace to the opposing wall stud, rather than a ceiling joist like Aaron did.

Crazy ass idea: What if I temporarily fastened a horizontal 2x4 to each wall's opposing stud, then made 2 cuts about 7/8" apart, leaving a 7/8" gap (kind of like this: ||= =|| ), then wedged a piece of 1" thick EPDM inside the gap (kind of like this: ||=0=|| )? Then I could wrap the concoction with plastic or tape to keep the wedge from getting loose and dropping out. Do you think that would work without risking turning it into a flanking path?

3 layers wall/ceiling, inside leaf - stagger joints leaving 1/4" gap each time, caulk as you go, so you have a zig-zag joint with multiple caulk seams.

Yeah, I knew you were going to say that. (I've seen illustrations of that on other threads lately, so I know exactly what you're talking about.)

Point G - I'd save the rockwool for acoustic treatment inside; unfaced standard fiberglass slightly overfilled will give within 1-2 dB of the same performance at less cost, and the rockwool will be needed for corner killers, etc, inside the room and under the floor.

Thanks for the tip! You're saving me $ already...

5th pic - floor detail - have you done a moisture test yet? Tape a piece of plastic against the floor for a day or two, pull it up - if there's a drop of moisture on it, seal the floor. If not, seal it anyway...

I haven't yet, but I will. FYI, the blue masking tape on the floor that marks the outer perimeter of the studio space has been stuck on the floor for months, and it's stuck pretty good. (Does that stuff breathe?)

I would leave the gap between inner and outer door frames porous, so the wall cavities can breath - if you run a dehumidifier, leave the outer door closed and inner one open when not in use. The porous gap between doors will keep from having a high vacuum making the doors hard to open as well as allowing some moisture escape.

Excellent idea! How about pegboard as a "fake wall" in the "between doors" area?

Guitars and pianos, etc, like a constant humidity of 40-42% - you can get an inexpensice and accurate humidity meter here (most are either expensive or crap)

http://www.natlallergy.com/allergy/prod ... eadid/1526

I bought two of these; they read within 1% of each other in the same location, usually exact. Use them to "dial in" the useless knob on your dehumidifier to a REAL 40%...

Great tip! Thanks...

If you can match your walls with good doors/seals, you should be able to have a kick drum at around 95 dB inside before it will be audible outside on a quiet night - hearing threshold @ 50 hZ is around 55 dB, the TL of your walls @ 50 hZ will be roughly 42, with an STC of around 72-75. So even though it might not be a good plan to play death metal at 3 am, I doubt your neighbors will be calling the cops under normal circumstances...

STC of 72-75! (I know, STC isn't the be-all-end-all number, but it's bragging rights! )

How much you think my nudging the inner frames to 11 3/4" will improve the low end TL? Do you think it's worth the precious few inches I can barely afford? (With the adjustment, it looks like the finished room width will be about 8' 3" not counting treatments. There's also the unpleasant fact of my having the width almost match the height. I'm willing to sacrifice sound quality within the room to achieve higher TL, but I want to make sure I'm not shooting myself in the foot somehow.

Thank You Thank You Thank You Thank You Thank You Thank You

You know what I really hate (and love) are nights when I am at my whits end having sweated over my plans for hours and I see no hope in sight.

Then I post my -- Impossible Problem -- on the fourm here.

The next morning I check my mail and our host Mr. Sayers or one of the other Moderators has posted the perfect solution to my impossible problem. it's especially effective with Mr. Sayers posts -with his full color to scale drawings detailing my fix. (Of course followed by his monaker "Cheers" )

Amen to that!!!

[sharward]

Updated per above feedback...

[knightfly]

Sway bracket - maybe this, from Kinetics -

These are offset 1-1/2 inches (how convenient; same thickness as a 2x4 )

You'd just need to offset the inner wall studs by3'" (along the length of the wall plate), then put this between an inner and an outer stud near the top of the wall, probably one every 4 feet or so. Sorta like this... Steve

I'll wait til you re-compile your Q's after phone consult for the rest... Steve

[sharward]

Sway bracket - maybe this, from Kinetics...

I've checked the Architectural Noise Separation on the Kinetics Web site, but I don't see the product that you described.

While I understand the overall concept, I'm not clear on how that contraption will resist tipping towards the outer leaf wall. It looks like it would resist tipping away from the outer leaf wall, but that tipping towards would cause the two pieces to slide apart.

What's your impression of my "crazy ass idea"?

What if I temporarily fastened a horizontal 2x4 to each wall's opposing stud, then made 2 cuts about 7/8" apart, leaving a 7/8" gap (kind of like this: ||= =|| ), then wedged a piece of 1" thick EPDM inside the gap (kind of like this: ||=0=|| )? Then I could wrap the concoction with plastic or tape to keep the wedge from getting loose and dropping out. Do you think that would work without risking turning it into a flanking path?

[z60611]

Beautiful drawings.
In "Floating Floor Anatomy" do you have two parallel horizontal vapor barriers ?

In Ontario Canada it's against building code to have presure treated lumber indoors. We have to put something between concrete and wood instead ( like thin foam ) because otherwise the wood sucks moisture out of the concrete.

[sharward]

Beautiful drawings.

Aw, shucks! Thanks for the kind words.

In "Floating Floor Anatomy" do you have two parallel horizontal vapor barriers ?

In Ontario Canada it's against building code to have presure treated lumber indoors. We have to put something between concrete and wood instead ( like thin foam ) because otherwise the wood sucks moisture out of the concrete.

Actually, I believe it's OK in California to use PT lumber indoors. If not then we're in deep sh%* because my house is full of it! Over the summer my wife and I suffered a plumbing disaster due to a defect in a toilet supply line: Half our house got flooded while we were out to dinner! I took lots of pictures over the course of the deconstruction/reconstruction, including the attached photo that shows a pressure treated soleplate dividing our living room and my wife's office, taken the night of the flood.

Nevertheless, based on Steve's suggestion (above a few posts) and other advice I've received, I'll probably seal the floor before any walls go up. And I'll probably also use PT for the soleplate, just to be extra safe.

By the way, the house is all put together now after the flooding, and looks terrific. It even passed a $1,000 mold certification with flying colors. We had to live in a hotel for 3 weeks, our animals had to be boarded for 4 weeks, and it took about 8 weeks for everything to be 100% completed, the builder filed a $75,000 claim against the manufacturer of the defective part, and our homeowners' insurance wasn't ever involved.

If that water intrusion hadn't happened, the freakin' studio would have been built by now!

Oh, and on the floating floor, I do plan to use plastic sheeting between the masonry floor and the subfloor it will sit on. I'm planning to use redwood around the perimeter of the masonry and within the field to separate the brickwork into sections. (Redwood is, of course, naturally less prone to decay, and I think it will "fly" with the inspector -- I'll definitely make sure though!)

Thanks again for the tip, Z. And I also welcome any/all other feedback, as I'm still very much in the "pencil" stage on this thing.

[sharward]

I have a neighbor with the same exact floorplan as mine. He framed a wood shop in the corner of his garage -- almost the same footprint as my studio plan. I can ask him how he did his walls and take a look at them -- that might give us a hint about how much, if at all, we should be concerned about this.

I was able to see my neighbor's wood shop today and talk with him about what he encountered. The north wall he built is just a few inches farther north than mine will be, so he missed the truss when he fastened his top plates. I think he said he secured his top plates directly into the hat channels that run north-south on 16" centers perpendicular to the trusses.

Although his taping job was a little worse than average, I did not see any signs of movement where the new wall met his ceiling...... yet.....

[knightfly]

Hey Bob, if you put a floated floor on TOP of PT lumber and float WALLS on THAT, isn't the PT stuff technically as "outside" as your sill plates are?

Just a thought; haven't seen the actual "language" on that one - it may also be in the IBC, hafta check that when I'm on nights soon, I have the entire IBC and NEC on my laptop just for things like this... Steve

[z60611]

knightfly

Hey Bob, if you put a floated floor on TOP of PT lumber and float WALLS on THAT, isn't the PT stuff technically as "outside" as your sill plates are?

No. If there isn't a breeze between there and the neighbour's house across the street, it's not outside. i.e. it's the wind blowing away the contaminents that makes it safe.
Different communities have different issues/problems, and different chemicals in their PT wood. Here, because we have lots of really nasty little critters, and a building code that says not to use it inside, it wouldn't surprise me if whatever they put in pressure treated wood here is vastly horrible stuff.

[z60611]

sharward:

I do plan to use plastic sheeting between the masonry floor and the subfloor it will sit on.

The reason I was asking about the vapor barrior is that it appeared to me as if you had two parallel vapor barriors separated by about 8". 'K' in your drawing shows two vapor barriors.
I assume that they're both closed on the ends, otherwise there's no point in the vapor barrior.
If they're both closed on the ends, then what you've created is a bag with wood in it.
Normally when dealing with vapor barriors you only have one, that way both sides can wick moisture away and dry out as the temperature changes.

[Sword9]

it wouldn't surprise me if whatever they put in pressure treated wood here is vastly horrible stuff.

I'm pretty sure that arsenic is involved in a lot of PT lumber, at least in the midwest.

[knightfly]

http://www.strongtie.com/productuse/PTWoodFAQs.html

Mystery solv-ed, as Clouseau would have said...

[sharward]

'K' in your drawing shows two vapor barriors.

I assume that they're both closed on the ends, otherwise there's no point in the vapor barrior.

If they're both closed on the ends, then what you've created is a bag with wood in it.

Normally when dealing with vapor barriors you only have one, that way both sides can wick moisture away and dry out as the temperature changes.

Hi Z,

Great stuff -- thanks so much for the input.

I'm nodding my head on the outside, yet inside I'm still a little unclear.

Yes, there are two vapor barriers involved. One is for the concrete floor in the garage. Steve recommended sealing it, and that seems like a great idea. The other is for the brick and mortar floor on the floating floor framing structure, which I have opted to do in lieu of pouring a concrete slab.

I think I see your point about having basically a sandwich, where the two pieces of bread are vapor barriers -- and I can see why that might not be good. However, since there will be close to a 12" air gap around the perimeter of the floating floor (between the inner leaf and outer leaf walls), and the fact that there will be 9 1/2" to 11 1/2" between the barriers, variable due to sloping of garage floor, I was/am hoping that would be enough air space and escape hatch for any vapor to migrate sideways.

Steve and I also discussed the possibility of a dehumidifier being installed in the area between the doors and leaving the walls in that area unfaced to allow the gaps to breathe easier. The inner door can be left open when the room is not in use, which will help condition the air in there.

Do you still see this as a "bag with wood in it" situation? If so, and assuming that is bad, do you have any suggestions on how to avoid it?

Also, I read Sampson's PT Wood FAQ, which did answer some of our questions about the "nasty stuff" they used in the past (i.e., arsenic). However, I'm not sure the mystery's solved completely.

If I'm sealing the slab, do I still need PT sole plates and floating floor legs?

...two exterior grade, heavy pre-hung doors at least 3 feet apart with good seals...

Steve, do you recommend that I nudge my doors 2 1/2" feet farther apart and change the orientation of the inner door so that it opens into the space between the doors? I was debating whether or not to do that when I moved the doors over, since the swing of the door burns so much floor space anyway, and I might benefit from the larger distance between the doors for the sake of isolation.

Thanks again for your insights! You guys ROCK.