John Sayers' Recording Studio Design Forum Archive

Hey all,

I'm back for my 2nd studio build. You can see my first one-room studio build here: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=13828. I used this forum and Rod Gervais' book (Ver.1) to get me through that. Now I'm back and have RG's (Ver.2) in hand to help with the new build. The first studio was clips/channel but this new studio will be a room-within-a-room (MAM) build.

I've attached a diagram of my house and the carport. The carport (outlined in thick black lines) will be enclosed and converted to a garage and then converted to a studio.
On that note, I've got a few questions.

1) On the diagram you'll see that there is a 4' 6" wide breezeway between the garage and the house. If I have 2 leafs in the garage/studio, will the house be close enough that it acts as a 3rd leaf? How close does a wall have to be to qualify as a leaf?

2) On the diagram you'll see a red rectangle. That is where I was thinking of putting a small 4'x7' bathroom (just a sink and a toilet). How do the walls of the bathroom effect the 2-leaf rule? Meaning, do I build in the inner leaf so that it accommodates for the bathroom and therefore the bathroom walls act as the inner leaf? My concern is then I would need to put in a solid core/sealed studio door for the bathroom ($$$). On the other hand, if I just build a room-within-a-room that follows the walls of the garage and then build a bathroom inside the 2 leafs, won't the bathroom walls act as a 3rd leaf? What's the best way to do this?

Hopefully that 2nd question makes sense. If not, let me know and I'll try to SketchUp something that illustrates my concerns.

Thank you in advance for your help.

realdoyle wrote:1) On the diagram you'll see that there is a 4' 6" wide breezeway between the garage and the house. If I have 2 leafs in the garage/studio, will the house be close enough that it acts as a 3rd leaf? How close does a wall have to be to qualify as a leaf?

Given that the house and garage are independant buildings then I don't believe the house wall acts as a third leaf. And even if it did, the fact that it's a 4ft wide breezeway and not an enclosed area would make the effect minimal as far as I understand. Technically i'm not sure how close a wall would have to be to act as a third leaf, but I think it would be more to do with the wall being part of the studio structure itself. The house is very close however, so I proabably don't need to say that isolation is going to be very important.

realdoyle wrote:On the other hand, if I just build a room-within-a-room that follows the walls of the garage and then build a bathroom inside the 2 leafs, won't the bathroom walls act as a 3rd leaf? What's the best way to do this?

I guess technically it would act as a three or even four leaf system if you have plaster on both sides of the bathroom, but again, I think the effect would be minimal given that the 'air gap' (being the bathroom itself) is wide acoustically speaking.

If you built the inner leaf so that it follows the walls of the bathroom and stayed with a genuine 2 leaf system it does mean putting an airtight door on the bathroom. Which, as far as budget and studio building go is a fairly small outlay. My doors are made of two sheets of 16mm MDF screwed together to match the density of the plaster board walls, with rubber seals around them. Effectively the doors cost about $80-$100 each. If that kind of outlay is going to break the budget for your build then you'll have a mild heart attack when you cost out the rest of it

all the best,

Steve

If you built the inner leaf so that it follows the walls of the bathroom and stayed with a genuine 2 leaf system it does mean putting an airtight door on the bathroom. Which, as far as budget and studio building go is a fairly small outlay. My doors are made of two sheets of 16mm MDF screwed together to match the density of the plaster board walls, with rubber seals around them. Effectively the doors cost about $80-$100 each. If that kind of outlay is going to break the budget for your build then you'll have a mild heart attack when you cost out the rest of it

Hey Steve,
Thanks for the feedback. I think our (yours and my) door estimates are way off from each other. For instance, I was reading in Rod Gervais' book about how you want to install heavy duty closing mechanisms because these super-doors can weigh a lot and you don't want fingers getting closed in these doors. OUCH! Some of the door closers I've researched start around $200 each. And that is not including the actual door itself! So your estimate of $80-100 for a complete door is way off from mine. Plus, I'm having to pay someone to install my doors, so there is that added cost.
Regardless, I'm fine with putting in the super door for the bathroom if that is really the best solution for my build. I just didn't remember having to close massive doors when I used the restroom at the studios I've recorded at in the past.

realdoyle wrote:Regardless, I'm fine with putting in the super door for the bathroom if that is really the best solution for my build.

Unless you're building your whole internal wall system to match the isolation value of one of rod's super doors then there's no point in installing one for your bathroom. You'll only get as much isolation as the weakest link in your build.

If your internal leaf consists of two layers of drywall on studs, then theoretically, you can make a door out of 2 layers of drywall with a wooden frame as long as it seals airtight. Same material density, same isolation. Now of course, a drywall door is going to fall apart pretty quickly, so building one out of two sheets of MDF is pretty close to the same density and isolation.

If your internal leaf consists of 6 layers of drywall, then a door made of 2 layers of MDF isn't going to be enough and will therefore be the weak point in the construction so you'd have to make it a lot heavier.

So before you decide how your bathroom door is constructed, you need to figure out what you're doing for the construction of your internal leaf, which is governed by how much isolation you require in the real world.

all the best,

Steve

So before you decide how your bathroom door is constructed, you need to figure out what you're doing for the construction of your internal leaf, which is governed by how much isolation you require in the real world.

Hey Steve,
Thanks for talking this out with me but I think we got away from my initial question. I totally get your point about making sure the doors match the isolation values of the walls but I was concerned with the process of building a bathroom within a 2-leaf build. I know you gave me your thoughts on this but I'd also like to hear some thoughts from other forum members to see if they agree that the large air-gap within the bathroom would negate any 3 or 4 leaf negative effects.

If the bathroom walls don't need to be part of the Mass in my Mass-Air-Mass build, then I'll just build a couple basic bathroom walls with a simple bathroom door. However, if the consensus here is that the bathroom needs to be built as part of the 2-leaf equation, then I will definitely take your advice on making sure my bathroom door matches my walls.

I was just reading through the 2nd Edition of Build It Like The Pros and became really confused when reading the section on "Dealing With Existing Roof Structures" (page 284). Rod is talking about the importance of venting for existing roofs and how you either have to choose to (quoting from the book:) "deal with this issue on top of the roof or live with a 3-leaf system."

So Rod goes onto say you can either:
A) strip the entire roof to add mass to the outside, add insulation and then re-shingle.
or...
B) use a Styrofoam product called "proper vent" to maintain the air space between the bottom of the roof deck and the insulation.

I understand the concept of Option "A" but Option "B" confuses me. I tried googling "proper vent" and I think I understand how it is installed between the rafters of a cathedral ceiling but I don't understand if that is all there is to it and if so, how does that create a 3-leaf system? Is the Styrofoam Proper Vent really going to have enough mass to act as a 3rd leaf?

Also, does the Proper Vent actually need to "vent" to the outside or is it just there to create a pocket of air? If it does need to vent to the outside then how does that happen while maintaining an air-tight outer leaf structure?

I guess I missed this thread before... But "better late than never", I guess!

1) On the diagram you'll see that there is a 4' 6" wide breezeway between the garage and the house. If I have 2 leafs in the garage/studio, will the house be close enough that it acts as a 3rd leaf? How close does a wall have to be to qualify as a leaf?

No, at that distance the house wall won't be a third leaf. You can figure out how far away it has to be by using the MSM equation two-leaf walls (which is simpler than the one for 3-leaf). The equation goes like this:
Even though you have three leaves, just plug in the numbers to this 2-leaf equation for the two leaves that are far apart (4'6" in your case), and look at the number you get. As long as the resonant frequency of that leaf pair is at least an octave below the lowest frequency that you need to isolate, then you are fine.

If you REALLY want to be absolutely certain, then use the full 3-leaf equation to make sure:
But for that sort of distance, it's pretty clear that you won't have a 3-leaf problem. Yes, in theory, the effect is still there, but in practice the frequencies and levels are so low that it simply isn't an issue.

How do the walls of the bathroom effect the 2-leaf rule? Meaning, do I build in the inner leaf so that it accommodates for the bathroom and therefore the bathroom walls act as the inner leaf?

That depends on how you want to use the bathroom! If it is NOT going to be within the isolated part of your studio, then just build it as a normal bathroom: no worries about 2-leaf or 3-leaf or anything else. But if you want it to be inside of the isolated section (which I don't recommend), then it needs to be isolated like any other room: full 2-leaf treatment. In other words, if the bathroom door opens into the control room, live room, or an isolation booth, then it has to be treated as though it were an isolated room. But if the door opens to the outside world (office, corridor, lobby, etc.) then there's no problem. Of course, if one of the walls of the bathroom is part of the isolation wall for the isolated section of the studio, then that wall cannot have any plumbing, ventilation or electrical installations in it, since it is one of the two leaves that is creating the isolation system.

if I just build a room-within-a-room that follows the walls of the garage and then build a bathroom inside the 2 leafs, won't the bathroom walls act as a 3rd leaf?

Once again, the distance across the bathroom to the opposite wall is likely plenty big enough that you won't have a 3-leaf problem there.

What's the best way to do this?

Personally, I would never design a studio where the bathroom opens directly into one of the studio rooms (CR, LR, etc.), for oh so many reasons. Among them: aesthetics, odors, humidity, noise, cost, etc.). I would build the bathroom so that the door opens only into a non-isolated area of the studio. In your case, it could open onto the breeze way, or the courtyard, or even inside the wall, if you happen to have a lobby, office or entry way in that area.

Unless you're building your whole internal wall system to match the isolation value of one of rod's super doors then there's no point in installing one for your bathroom. You'll only get as much isolation as the weakest link in your build.

Yup!

If the bathroom walls don't need to be part of the Mass in my Mass-Air-Mass build, then I'll just build a couple basic bathroom walls with a simple bathroom door. However, if the consensus here is that the bathroom needs to be built as part of the 2-leaf equation, then I will definitely take your advice on making sure my bathroom door matches my walls

Once again, if any of your bathroom walls are also part of a 2-leaf isolation wall, then that wall is going to need special attention: No plumbing, switches, vents, etc can be in that wall. It has to be "just a plain flat wall". And of course, it needs the correct mass (surface density) to create the MSM conditions you are aiming for. This applies regardless of whether or not the bathroom is "inside" or "outside" the isolated part of the building.

I understand the concept of Option "A" but Option "B" confuses me. I tried googling "proper vent" and I think I understand how it is installed between the rafters of a cathedral ceiling but I don't understand if that is all there is to it and if so, how does that create a 3-leaf system? Is the Styrofoam Proper Vent really going to have enough mass to act as a 3rd leaf?

I think you are missing the point that Rod was making there. If you have to vent the underside of your roof deck, then you have no choice but to create a 3-leaf roof system. It's not that the vent system does it for you: it's the implication that if you are required to do that by code, then you have no choice: the vented roof deck will always be the final outer "3rd leaf" in this case, and you'll have to build the other two leaves to complete the system.

On the other hand, if you are allowed to NOT ventilate your roof deck, you can then add the necessary mass and insulation right below the deck, seal up the entire thing, and that will be your outer leaf for a normal two-leaf system.

I'm pretty sure that's what Rod was getting at, although I haven't read that chapter in a long time...

Also, does the Proper Vent actually need to "vent" to the outside

Yes it does! That's the entire purpose: it must have an inlet at some point (usually under the eaves), and it must have an outlet at some point (usually the ridge line). It is called a "vent" system because it... well... it "ventilates". Convention draws in cooler air at the eaves, runs it along the underside of the roof deck where it picks up the heat and humidity, then it runs out through the ridge vent. That's how it ventilates the deck.

If it does need to vent to the outside then how does that happen while maintaining an air-tight outer leaf structure?

That's the point! It doesn't! Which is why, if you have to ventilate your deck, then you have no other choice but to create a 3-leaf system, because your outer leaf (the roof deck) cannot be sealed air-tight in these cases, and therefore you cannot create the sealed cavity all around the room that you need in order to get an effective MSM system.


- Stuart -

But for that sort of distance, it's pretty clear that you won't have a 3-leaf problem. Yes, in theory, the effect is still there, but in practice the frequencies and levels are so low that it simply isn't an issue.

Thank you Soundman2020 for the MSM equation and taking the time to address my 3-leaf concerns. That puts my mind at ease.

Personally, I would never design a studio where the bathroom opens directly into one of the studio rooms (CR, LR, etc.), for oh so many reasons. Among them: aesthetics, odors, humidity, noise, cost, etc.). I would build the bathroom so that the door opens only into a non-isolated area of the studio. In your case, it could open onto the breeze way, or the courtyard, or even inside the wall, if you happen to have a lobby, office or entry way in that area.

I hadn't thought of those issues associated with putting the entrance to the bathroom right off of the Live Room. Yikes! Okay, I'll take some time to brainstorm some alternate layout ideas. Might be time to design a hallway/storage area for the bathroom to open into. And just like the bathroom, if I design a 4' wide hallway or entrance area between the outside leaf and the inner leaf Live Room, I shouldn't have any issues with hanging drywall in the hallway or bathroom and it becoming a 4-leaf issue? I'm thinking along the lines of what you said about how the bathroom could open inside the wall. I'm taking that to mean that it would be between the 1st and 2nd leaf. Is that correct?

It is called a "vent" system because it... well... it "ventilates". Convention draws in cooler air at the eaves, runs it along the underside of the roof deck where it picks up the heat and humidity, then it runs out through the ridge vent. That's how it ventilates the deck.

Okay, that makes sense now. One follow up question in regards to insulating or venting the roof; when I was googling to learn more about the Proper Vent installation and came across an article on GreenBuidingAdvisor[dot]com about insulating and vent roofs. There is a section about unvented roof assemblies (http://www.greenbuildingadvisor.com/blo ... al-ceiling) and the author says one of 3 options is: "Install a layer of closed-cell spray foam against the underside of the roof sheathing, and fill the rest of the rafter cavity with an air-permeable insulation."

Have you heard of this solution and does it make sense to you? If not, then my only other option (other than Rod's 3-leaf idea) is to rip off the shingles, lay down structural insulated panels (SIP) and then re-shingle. It would be great if I could beef up the underside of the roof between the rafters using strips of OSB or drywall and then spray the whole thing with a closed-cell polyurethane spray insulation. It would be labor intensive but at least I could save money by not having to tear off a perfectly good roof.

what you said about how the bathroom could open inside the wall. I'm taking that to mean that it would be between the 1st and 2nd leaf. Is that correct?

I have no idea why I wrote "wall" there! What I should have said was "inside the garage". I didn't describe that very well at all! Sorry about that.

What I was trying to say, is that you could have an isolation wall a few feet away from the garage wall, and have your bathroom in that area. In other words, everything beyond that isolation wall would be in the actual studio part of your build, and everything before it would be inside the garage, but not inside the studio. For example, you could have the main entrance door coming in from the courtyard, into a sort of "mini lobby", with the bathroom on the left, maybe a storage room, kitchenette, office, or some such on the right, then the entrance door to the actual studio area straight ahead. So the bathroom, lobby, etc. would just be built like normal rooms in a normal house, with normal walls and no special acoustic isolation, but the far wall of each of those rooms would actually be the "isolation wall" itself. Or rather, more correctly it would be the outer-leaf of the actual studio space.

Not sure if I'm explaining that clearly or not! If not let me know, and I'll draw a quick diagram.

and the author says one of 3 options is: "Install a layer of closed-cell spray foam against the underside of the roof sheathing, and fill the rest of the rafter cavity with an air-permeable insulation." ... Have you heard of this solution and does it make sense to you?

Yup! And it makes perfect sense. I have done that myself, in part of my garage, since I had a condensation problem on the underside of a rain gutter that runs along one edge of part of the roof. I did exactly that: foamed the underside of the gutter and roof in that area, and it absolutely fixed the problem.

HOWEVER! Not all building codes allow that as a solution, especially if there are concerns about heat. In some places, the roof deck could still get hot enough to damage itself over time under some circumstances, so not all building codes allow that. You really should check your own local building codes to see it that is an acceptable solution.

Being forced to go to a 3-leaf system in this situation isn't as terrible as it sounds: The roof deck is generally a long distance away from where your other two leaves would be, so here too the "3-leaf effect" would be very low level, and very low frequency. You can live with it if you have to. As long as you make sure that you have enough mass on your other two leaves, and they are far enough apart and well sealed, you'll be OK. As Rod says: sometimes it really is the best solution, even though people get scared of the terrifying man-eating grisly 3-leaf monster!

In fact, I did a studio with a similar situation for a company in LA a couple of years back, and we had to do that as a 3-leaf system. It worked out fine. I just finished designing another similar one for another customer, who is in the process of building it right now, and so far it's looking good. That "monster" isn't as scary as he seems at first glance. You can tame him and get him purring like a little kitten, with a bit of care...

It would be great if I could beef up the underside of the roof between the rafters using strips of OSB or drywall and then spray the whole thing with a closed-cell polyurethane spray insulation. It would be labor intensive but at least I could save money by not having to tear off a perfectly good roof.

If your roof is working fine just like it is, and won't need replacing for many years yet, then I'd suggest just leaving it as it is, and do a 3-leaf kitty-cat...

If you are concerned that this approach would limit your final ceiling height, then you could consider replacing your roof trusses "in situ" (without touching the actual roof deck) with maybe scissor trusses, cambered trusses, or better still, raised tie trusses. That allows you to build your "middle" leaf much higher, and therefore raise your inner-leaf ceilings too. That's what I did in both of the above cases: the one in LA was retro-fitted inside an existing roof, and the other was designed like that from the ground up. Raised-tie in both cases. Both of them ended up with final inner-leaf ceilings higher than 8 feet, even though the eaves are at 8 feet.

Do you have any photos of what is up there right now? Any way of showing us what the trusses and roof deck look like at present, on the inside?


- Stuart -

For example, you could have the main entrance door coming in from the courtyard, into a sort of "mini lobby", with the bathroom on the left, maybe a storage room, kitchenette, office, or some such on the right, then the entrance door to the actual studio area straight ahead. So the bathroom, lobby, etc. would just be built like normal rooms in a normal house, with normal walls and no special acoustic isolation, but the far wall of each of those rooms would actually be the "isolation wall" itself. Or rather, more correctly it would be the outer-leaf of the actual studio space.

Ahhh, okay. I'm gonna Sketch-Up something up here in a minute and see if this is what you are describing.

Yup! And it makes perfect sense. I have done that myself, in part of my garage, since I had a condensation problem on the underside of a rain gutter that runs along one edge of part of the roof. I did exactly that: foamed the underside of the gutter and roof in that area, and it absolutely fixed the problem. HOWEVER! Not all building codes allow that as a solution, especially if there are concerns about heat. In some places, the roof deck could still get hot enough to damage itself over time under some circumstances, so not all building codes allow that. You really should check your own local building codes to see it that is an acceptable solution.

That's great news. Good to know that is an option.

Being forced to go to a 3-leaf system in this situation isn't as terrible as it sounds: The roof deck is generally a long distance away from where your other two leaves would be, so here too the "3-leaf effect" would be very low level, and very low frequency. You can live with it if you have to. As long as you make sure that you have enough mass on your other two leaves, and they are far enough apart and well sealed, you'll be OK. As Rod says: sometimes it really is the best solution, even though people get scared of the terrifying man-eating grisly 3-leaf monster! In fact, I did a studio with a similar situation for a company in LA a couple of years back, and we had to do that as a 3-leaf system. It worked out fine. I just finished designing another similar one for another customer, who is in the process of building it right now, and so far it's looking good. That "monster" isn't as scary as he seems at first glance. You can tame him and get him purring like a little kitten, with a bit of care...

I'm starting to see comparisons between studio building and being a musician: First you learn all the rules (all the "right" notes) and then eventually you learn when and how to break those rules. I think I'm just extra concerned about getting this build right because I moved to a pretty quiet neighborhood and would like to be able to track live drums. I see your point about the roof deck being a good distance away from the inner ceiling (room within a room). It's still a little nerve racking to knowingly build a 3 leaf system after years of people getting scolded on here for doing exactly that.

If your roof is working fine just like it is, and won't need replacing for many years yet, then I'd suggest just leaving it as it is, and do a 3-leaf kitty-cat...

Yes, this carport was newly built in 2013 (by previous owners), so it would be a shame to re-roof it if I didn't need to.

If you are concerned that this approach would limit your final ceiling height, then you could consider replacing your roof trusses "in situ" (without touching the actual roof deck) with maybe scissor trusses, cambered trusses, or better still, raised tie trusses. That allows you to build your "middle" leaf much higher, and therefore raise your inner-leaf ceilings too. That's what I did in both of the above cases: the one in LA was retro-fitted inside an existing roof, and the other was designed like that from the ground up. Raised-tie in both cases. Both of them ended up with final inner-leaf ceilings higher than 8 feet, even though the eaves are at 8 feet.
Do you have any photos of what is up there right now? Any way of showing us what the trusses and roof deck look like at present, on the inside?

I attached 3 photos of the current roof before any construction (right now there is a small attic space built above the carport so it's difficult to get good pics with my iphone). I also attached the plans approved by the city so you can see what the garage roof will look like before I start any internal framing for the studio phase of construction.
With the raised tie truss framing, would that mean I would have a flat peak at the top (instead of having a cathedral ceiling)?

It's still a little nerve racking to knowingly build a 3 leaf system after years of people getting scolded on here for doing exactly that.

Like most such "rules", there are times when it has to be broken, because it makes sense to do so. As long as you know what you are doing, and design / build it correctly, it works. The down-side is that it costs a bit more, due to the extra materials you need for the "middle" leaf, but the up-side is that it allows you to meet code, not damage your existing roof, and still get the isolation you need.

this carport was newly built in 2013 (by previous owners), so it would be a shame to re-roof it if I didn't need to.

It's brand new! No point in re-doing it. Adapt and modify, yes, but no need to take it all off and start again.

With the raised tie truss framing, would that mean I would have a flat peak at the top (instead of having a cathedral ceiling)?

For the middle leaf, yes. For the inner leaf: optional. It depends on how much extra height you want to get, and how you arrange your rooms in there. With good design you can probably gain a fair bit of ceiling height.

Here's what raised-tie trusses looks like (and also a scissor truss, for comparison):
In your case, it loos like it should be possible. You might need to replace or reinforce the ridge beam (not visible in your photos), but the existing trusses can very likely be modified to raised-tie (also called "collar tie" sometimes): Of course, you'll need a structural engineer to tell you how to do it, and how high the ties can go, but from the photos it looks like it should be pretty easy to do that, if you wanted to gain a couple of feet of height.

Basically, you'd just work on one truss at a time, installing the new raised collar ties then taking out the existing ties. There might be a need for some temporary bracing, but the structural engineer will guide you on that.


- Stuart -

Whoa! Thank you for these example pics. I think my plans should be getting me pretty close to the Raised Tie but I'll check with my engineer to see what needs to done to get me all the way there.

Back to the bathroom layout topic for a second... Take a look at the attached SketchUp and let me know if that is what you had in mind. The outer Purple would be the beefed up garage walls (outer leaf), the inner Green would be the beefed up studio LR/CR walls (inner leaf) and the White walls represent just simple household walls for the bathroom, mini-lobby and storage room. The White walls would just have a single layer of drywall finish on the inside. The Orange section is the "air" space. I apologize for my poor SketchUp skills, I was have a rough time with it this evening.

A new problem I just ran into that I'd love everyone's feedback on:

In this attached photo you'll see a ladder leaning against some storage cabinets. Today my contractor removed those storage cabinets to make more floor space for the studio; however, once they were removed we found out that wall does not have shear wall plywood on the outside and the city approved plans require shear wall plywood on all walls. The plans say that we could put the shear wall on the inside but that will create a 3rd leaf (assuming that the stucco on the outside counts as a leaf???) Does stucco have enough mass to act as a leaf?

I could have them remove the stucco on the outside, put up the shear wall plywood, and then re-stucco but that will cost me at least an additional $3k and I'm already concerned that I'm not going to have the money to finish the inside of the studio. Any creative solutions to this problem?

For example, is there something with lots of mass I could use to fill between the studs (before putting on the shear wall plywood on the inside) to make it one massive closed, single leaf wall. If I had the time and material I could cut strips of drywall to fill that space but that would take me a long time to layer all that in. Just trying to think of creative solutions.

I appreciate your help.

Does code allow you to do the create the sheer structure with diagonal bracing let in to the studs? Like this:
You simply place one or more 1x6s across the face of the studs, diagonally, you cut notches in the edges of the studs and plates so that the 1x6 can be pushed into them, leaving the bracing flush with the studs, then you nail / bolt / screw it in place.

Not all places allow that, but if your code does permit that, then you have a relatively simple solution...

Maybe they don't allow wood cross-bracing, but they might allow metal strap cross-bracing? Better check your code to see what methods are and are not allowed for sheer walls.

(assuming that the stucco on the outside counts as a leaf???) Does stucco have enough mass to act as a leaf?

Oh yeah! It's basically sand and cement, so even though it isn't all that thick it is pretty dense stuff, and therefore has plenty of mass.

But here's an interesting question: If there is no plywood in that wall, then what is the stucco attached to? There has to be some type of base layer... is it just a wire mesh?

I'm intrigued about how that wall is actually built... And just as intrigued about how it managed to pass inspection if it doesn't meet code! That's a red flag... you might want to get local professional advice about that. I don't want to scare you, but I'm wondering if there are other walls in the house that are also built without the required plywood...

Sheer walls are rather important, as they take on the loads caused by lateral (sideways) forces acting on the house, such as wind loads and seismic loads. In other words, the provide the strength that your house needs to survive hurricanes and earthquakes. If your house has no sheer walls, then it likely would not handle an earthquake very well ... and you do live in California! ...

I'd suggest that you call in a structural engineer to take a look at that wall and also several other walls, to check if they are OK. Hopefully, he'll find that they do have sheer members in them some place, and will give you the all-clear.

I really do hope that I'm totally wrong here, and just being a scare-monger, but it really would be a good idea to check anyway, then yell at me later "Stuart you idiot! It's all just fine!". I'd love to hear that! Since I live in an earthquake zone myself, where things shake, rattle and roll regularly (we had a 5.2 a couple of hours ago... no big deal), I'm just a little trigger-happy when I think about seismic loads and structures...

- Stuart -

Soundman2020 wrote:Does code allow you to do the create the sheer structure with diagonal bracing let in to the studs? Like this:

sheer-wall-diagonal-bracing-01.jpg

sheer-wall-diagonal-bracing-03.jpg

sheer-wall-diagonal-bracing-04.jpg

Hey Soundman2020,
I got really excited by this idea of yours so I did some googling on LA building codes and came across this on page 15 of the building code PDF (http://ladbs.org/LADBSWeb/LADBS_Forms/P ... alCode.pdf). Does that look like what you are suggesting? I just asked my contractor about it and he said he still thinks the inspector would require shear wall, even if we did this diagonal bracing. I'll ask my engineer when he gets here.

Oh yeah! It's basically sand and cement, so even though it isn't all that thick it is pretty dense stuff, and therefore has plenty of mass.

Ahhh, that makes sense. Thanks for addressing that question. Wishful thinking on my part.

But here's an interesting question: If there is no plywood in that wall, then what is the stucco attached to? There has to be some type of base layer... is it just a wire mesh?

Yeah, I agree with your concern. I was shocked when I didn't see plywood on that wall. Yes, it seems like the stucco was just up on the wire mesh. I have no idea how it passed inspection. This carport is only 2 years old and it's the only new construction on the house. The rest of the house was built in the 1940's, so hopefully it's built better than this carport. Again, I'm meeting with my engineer tomorrow, so hopefully he'll give me some insight as to possible solutions that will pass code.

If you have a second, will you take a quick look at the post of mine above the one about the shear wall? Here is an updated sketch to see if that is what you had in mind about the bathroom layout (being in between the 1st and 2nd leaf walls:
I'm still a little unsure how to finish these walls. For example, in the entry area, do I finish the inside with drywall? I'm still really paranoid about breaking the 2-leaf rule. Is it okay that the LR walls will have have 3 layers of drywall (with GG) on the inside, the mini-lobby area will have 1 layer of 1/2" drywall on all the interior walls which are shared with the LR and the outer leaf walls?

And if this layout is correct, how do I finish the inside corners of the entry area since the wall shared with the LR doesn't connect in the corner with the wall shared with the outer leaf?

Thank you for all of your feedback, Soundman2020. I'm really grateful for you and all the other experts on this forum. I'd be lost otherwise.

-Josh