Carport to Studio Build

Hey all, I've got a question about installing the vapor barrier in my studio build. According to Rod Gervais' "Build It Like the Pros" book, he suggests putting the vapor barrier on the inner leaf walls. However, only a portion of my studio was built with a room-in-room design. So do I only put up the vapor barrier in the studio room walls that go along the perimeter of the building (no inner walls) or does it go on all of the walls including the Entrance and Bathroom walls even though they won't connect/seal to the studio walls? I hope this makes sense. I've attached my room plan.

The purpose of the vapor barrier is to control the movement of water vapor between the room and the wall cavity. If you only put it on part of the cavity, then you are not controlling that... it needs to go around the entire room. - Stuart -

I was doing some research on my own a few days ago about vapor barriers and came across this article by a seemingly well respected expert in the field of construction and vapor barriers. His name is Joseph Lstiburek PhD and the "Undertanding Vapor Barriers" PDF is on the Stanford.edu website. http://web.stanford.edu/group/narratives/classes/08-09/CEE215/ReferenceLibrary/Moisture%20Control/Understanding%20Vapor%20Barriers.pdf. If you scroll down to Page 8 (Figure 11), you see an outline of the elements suggested for a frame wall with stucco in "mixed-dry" or "hot-dry" regions (which I believe Los Angeles, CA falls into). This diagram shows that no vapor barrier is needed as long as the stucco wall has building paper drainage plain, which they did when they installed the stucco. There was another article that I found (still looking for the url) but it also said that vapor barriers wouldn't be needed if your wall assembly was built air tight. It said that the drywall would act as the vapor barrier if it was sealed well (which mine should be if all the caulking and taping goes to plan). Anyway, I'd love feedback on this information I've found. I'm not an expert but it seems like it applies to my circumstances and it seems like it is from an academic source. Thanks!

There was another article that I found (still looking for the url) but it also said that vapor barriers wouldn't be needed if your wall assembly was built air tight. It said that the drywall would act as the vapor barrier if it was sealed well

Not so sure about that! Drywall is permeable.... that's the entire reason for having vapor barriers! - Stuart -

realdoyle wrote:

If you scroll down to Page 8 (Figure 11), you see an outline of the elements suggested for a frame wall with stucco in "mixed-dry" or "hot-dry" regions (which I believe Los Angeles, CA falls into). This diagram shows that no vapor barrier is needed as long as the stucco wall has building paper drainage plain, which they did when they installed the stucco. There was another article that I found (still looking for the url) but it also said that vapor barriers wouldn't be needed if your wall assembly was built air tight. It said that the drywall would act as the vapor barrier if it was sealed well (which mine should be if all the caulking and taping goes to plan). Anyway, I'd love feedback on this information I've found. I'm not an expert but it seems like it applies to my circumstances and it seems like it is from an academic source. Thanks!

I'm curious if you ended up following this diagram for the wall? It seems like another unavoidable 3 leaf situation with the stucco > drain gap > OSB/plywood/"exterior gypsum sheathing" > insulation > drywall? Also noticed it specified "non-paper faced exterior gypsum sheathing" for that middle layer, which I'm assuming isn't standard drywall?

Any progress on this build? I'd really love to add it to the "completed studios" thread! :) - Stuart -

wadesey wrote:

realdoyle wrote:

If you scroll down to Page 8 (Figure 11), you see an outline of the elements suggested for a frame wall with stucco in "mixed-dry" or "hot-dry" regions (which I believe Los Angeles, CA falls into). This diagram shows that no vapor barrier is needed as long as the stucco wall has building paper drainage plain, which they did when they installed the stucco. There was another article that I found (still looking for the url) but it also said that vapor barriers wouldn't be needed if your wall assembly was built air tight. It said that the drywall would act as the vapor barrier if it was sealed well (which mine should be if all the caulking and taping goes to plan). Anyway, I'd love feedback on this information I've found. I'm not an expert but it seems like it applies to my circumstances and it seems like it is from an academic source. Thanks!

I'm curious if you ended up following this diagram for the wall? It seems like another unavoidable 3 leaf situation with the stucco > drain gap > OSB/plywood/"exterior gypsum sheathing" > insulation > drywall? Also noticed it specified "non-paper faced exterior gypsum sheathing" for that middle layer, which I'm assuming isn't standard drywall?

Hi Wadesey, Ended up going with stucco/osb/plywood for the outer leaf and then insulation/osb/drywall/drywall for the inner leaf. The studio is done and I'm really happy with the sound isolation I've achieved. I can beat the hell out of my drums and you have to be within 6 feet of the studio in order to hear anything. Exactly what I was going for.

Soundman2020 wrote:

Any progress on this build? I'd really love to add it to the "completed studios" thread! :) - Stuart -

Hey Stuart, Thanks for the prompting. I just went through my photos and will be posting them along with details about what I did to finish the build. I'll let you know when I'm done with this thread. For now, here are the pics of the carport torn apart. This is when my heart sank and I questioned if I was in over my head... could I really pull this whole thing off??? -doyle

Photos of installing those plastic rafter vents (as suggested in Rod Gervais's book).

Photos of insulated plywood (looks like space ship) and then the tar paper before stucco on the outside.

Inner framing begins. This is a room-within-room job. Left a 1 inch gap between outer frame and inner frame. Had framers build a wall in front of garage door and put 2 layers of drywall on the outer side (with green glue).

Insulating 1st and 2nd leaf walls/ceiling.

I don't remember seeing this on other folks threads but i quickly realized that putting up 3 layers (1 OSB and 2 drywall) would make me run out of stud, especially in the corners. A 2x4 stud is only 1.5" and just 2 sheets of 5/8" drywall would take up 1.25" leaving only a 1/4" of stud to secure that last sheet. So I added 2 extra studs to all the corners in my main recording room. I also had to add extra studs to the wall where the AC unit was being installed because I need to have all 3 layers put up in the middle of the wall where the AC unit was going to go but still needed the rest the wall open so that the AC guy could run the conduit between the 1st and 2nd leaf framing. In order to have the joints of the 3 layers overlap (not just butt up to each other on the same seam), I need to have extra studs so that I could stagger the ends of each layer. You can see it in the middle photo where the AC conduit is being run.

AC unit install...

Fresh air ducting... supply side.

Fresh air install... return side. Note: I tried having the fan suck air out of the room and pull the fresh air in but that didn't work for me. It actually made my studio door open slightly and made the room less sound isolated. So I switch the ducting on the fan and had it blow the fresh air into my room. This worked much better and actually pushed the door tighter against the seal. I posting this here because I had actually gotten the advice to do it the first way from someone's thread here on the forum. Maybe it worked for them but not for me.

tried having the fan suck air out of the room and pull the fresh air in but that didn't work for me. It actually made my studio door open slightly and made the room less sound isolated.

To me, that suggests two issues together. 1) Your automatic door closer is not the right one for the job, or you don't have it set with enough pressure to keep the door sealed; and also 2) Your ducts are way undersized! If there's a higher static pressure in the supply duct than than there is equivalent pressure from the door closer holding the door closed, then there's something major wrong with the air path in the supply duct. So let's start by checking your numbers: 1) What static pressure did you calculate for your entire duct system? 2) What is the designed flow velocity through your intake duct, and also through the supply register into the room? 3) What is the designed flow rate through your intake duct, and also through the supply register into the room? 4) What is nominal flow rate for the fan you are using? 5) What is the nominal flow velocity for the fan you are using at the design static pressure? You will also need to get a gadget to measure all of those, and confirm that the real conditions in your duct system really are meeting the design conditions, because something big is wrong somewhere... - Stuart -

To create the 2nd leaf for the ceiling, I decided to maximize the ceiling height by leaving exposed beams and putting the 3 layers (OSB, 2 layers of drywall with green glue) between each rafter. This was MUCH more labor intensive but I'm glad i took the time and did it this way. First, I installed 1x3's (screws and liquid nails) along the sides of the rafters so that I could have something to screw the OSB and drywall into. I caulked the perimeter of each layer and any seams.

First, I installed 1x3's (screws and liquid nails) along the sides of the rafters so that I could have something to screw the OSB and drywall into.

WHOAAA!!! Hang on there! :shock: You did WHAT??? You specifically made a hole bunch of thin resonant cavities in your ceiling? You deliberately made a three-leaf ceiling, tuned to a high frequency? Big mistake! That will trash your low frequency isolation. You seem to have misunderstood the procedure for "beefing up" the outer leaf. That has to come out and be re-done properly, if you want good isolation. It's a sad situation, but that's the plain truth. - Stuart -

Soundman2020 wrote:

First, I installed 1x3's (screws and liquid nails) along the sides of the rafters so that I could have something to screw the OSB and drywall into.

WHOAAA!!! Hang on there! :shock: You did WHAT??? You specifically made a hole bunch of thin resonant cavities in your ceiling? You deliberately made a three-leaf ceiling, tuned to a high frequency? Big mistake! That will trash your low frequency isolation. You seem to have misunderstood the procedure for "beefing up" the outer leaf. That has to come out and be re-done properly, if you want good isolation. It's a sad situation, but that's the plain truth.

Hey Soundman2020, So I know it's been over a year since we last talked about the 3 leaf issue but if you go back to the first page of this thread you'll see that the 3 leaf roof problem was unavoidable unless I wanted to completely redo the roof (which I didn't want to do since it was newly installed in 2013). You're advice was "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... :)" As for the cavities, that is not the final pic. I made bass panels for each and every ceiling bay. It was a huge pain in the a$$ but it turned out well. And the ceiling cavities are not thin. They are composed of the same materials as the walls. OSB>caulk>green glue>drywall>caulk>green glue>drywall>caulk. Also... I don't want be a spoiler but the studio as been completed for a few months now and the isolation is great! I'm a drummer and can play in the middle of the night while my 2 year old sleeps in his room (only 10 feet between the wall of studio and wall of his bedroom). You can't even tell I'm playing when standing in his room. The physics of the MAM design is truly amazing.

Soundman2020 wrote:

tried having the fan suck air out of the room and pull the fresh air in but that didn't work for me. It actually made my studio door open slightly and made the room less sound isolated.

To me, that suggests two issues together. 1) Your automatic door closer is not the right one for the job, or you don't have it set with enough pressure to keep the door sealed; and also 2) Your ducts are way undersized! If there's a higher static pressure in the supply duct than than there is equivalent pressure from the door closer holding the door closed, then there's something major wrong with the air path in the supply duct. So let's start by checking your numbers: 1) What static pressure did you calculate for your entire duct system? 2) What is the designed flow velocity through your intake duct, and also through the supply register into the room? 3) What is the designed flow rate through your intake duct, and also through the supply register into the room? 4) What is nominal flow rate for the fan you are using? 5) What is the nominal flow velocity for the fan you are using at the design static pressure? You will also need to get a gadget to measure all of those, and confirm that the real conditions in your duct system really are meeting the design conditions, because something big is wrong somewhere... - Stuart -

Hey Stuart, You are totally right. I sacrificed the proper door closer for aesthetic reasons. I'll be posting pics of my door build a little later but I decided to go with an slim track door closer (http://www.qualifiedhardware.com/brands/lcn/1461t.htm) which doesn't provide as much closing pressure but also doesn't have the arms that stick out into the room. I could've done the recessed door closers but I didn't have the budget for that. Flipping the fan ducting solved the inadequate door closer problem for me. And yes, you are right about the duct size being too small. I only had a limited amount of space between the 1st leaf and 2nd leaf ceilings and the 6 inch ducting was all I could fit between the framing of those two ceilings. It's not ideal but it's done and with the nailor vents, it's pretty quiet. Luckily, I usually work by myself or with 1 other person (almost never more than 3 people), so I'm not concerned with running out of fresh air. However, I was thinking about replacing the on/off switch on the wall with a fan speed control dial, which would allow me to control the speed of the fan so that it's not overworking.

I only just noticed this comment from a previous post:

the studio as been completed for a few months now and the isolation is great! I'm a drummer and can play in the middle of the night while my 2 year old sleeps in his room (only 10 feet between the wall of studio and wall of his bedroom). You can't even tell I'm playing when standing in his room. The physics of the MAM design is truly amazing.

Then I'd call that "mission accomplished", for sure! I'm really glad it is working out for you. Good job! As soon as you are ready with the final photos, let me know and I'll add your studio to the "Completed Studios" list. Right at the top! Where it belongs... - Stuart -

Just some photos of the drywall and mudding stages. I never want to hang drywall again. There is something extra miserable about having to do 3 layers. It's like you don't even get to appreciate completing the first layer because you no you still have to do it 2 more times! A friend of mine turned me onto the trick of pouring a little red chalk dust into the mud when doing the final finish layer. Having it tinted red helps you see where the finish mud is (compared to the other layers of mud previously applied). It's especially helpful to make sure you don't sand off too much. One thing I didn't do that I wish I had... use a portable light to see where the imperfections are in the mudding. I found out later that the pros shine lights from different angles throughout their job. Mine turned out ok but any definitely looks like a drummer did it (me!). :shot:

Painting. First time using paint sprayer. Learned the hard way not to use it without the proper protective gear.

Bathroom build starts. This is a 5x5 restroom with only toilet and sink. I had to furr out the studs because some of the studs the contractors used to frame the garage where 2x4 and others were 4x4. Which meant they created an uneven wall surface to hang drywall. So I used liquid nails and screws to bring out the face of the studs so they were all flush with the floor plate. When installing the toilet flange I learned that using an electric drill was not the recommended process. It was much, MUCH easier to get a pilot hole started with the drill and then use a hand wrench to manually screw the bolts into the cement floor. It sounds like manually screwing bolts into concrete would be back breaking work but using those Tapcon screws made it really easy with a wrench. Just make sure you drill the pilot hole first. Just threw in a pic of the bathroom vent fan. I went with the cheapest option at Home Depot for 2 reasons. The cheapest version was the the loudest and was the only reasonably priced option that would fit between 2x4 studs. I planned on putting storage above the bathroom, so I couldn't have the fan stick up above the top face of the 2x4's because the plywood needed to create a base for storage up there. Going back to the "loud fan" being a positive... the bathroom is right next to the kitchenette and I didn't want any "bathroom noises" ruining the mood if a vocalist is trying to make tea while someone is using the bathroom. Having the loud bathroom fan does a great job of masking any errant sounds.