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 Post subject: Garage -> Studio Build
PostPosted: Wed Jun 17, 2020 11:11 am 
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Location: Los Angeles, CA
Hello all, here is yet another garage conversion story. I'm amazed you guys aren't sick of these by now. haha.

Before I get started, I wanted to thank everyone on this forum who has contributed to helping people with their DIY studio builds. I have spent the last 5-6 months researching and planning my build, and the information on this forum (and others like Gearslutz and homerecording) has been insanely helpful. So a genuine, heartfelt THANK YOU goes out to those of you who have given your time to help.

Ok, my build.

The Plan:
My wife and I bought our first house (finally), and I am excited to finally be able to build a rehearsal/recording studio in the garage. My goal is to convert the garage to a rehearsal space that contain my drums. I am in 4 bands at the moment, so I have a lot of practicing to do, and it'd be nice to be able to practice without worrying about my neighbors hate me. I have been known to practice for 8-10 hours a day, so simply asking my neighbors to tolerate the noise is not fair to them. Being able to record in there is a close 2nd in terms of priority. I will also likely be having full band rehearsals a couple of times a month.

I figure it will take me a year to complete the project, including research, planning, design, construction, and room treatment. Like I mentioned earlier, I have been researching and planning for about 5 months already, and have started construction 3 weeks ago. I am doing the majority of the work myself, so it has been extremely slow going, but that was to be expected. I am working with a structural engineer because of the roof issues i'll explain later in the post, and I will be consulting with an electrician when it comes time to do the electrical (my plans for that will be detailed below as well). I may hire a contractor to help with things I'm concerned about, but I'm really trying to keep this as DIY as possible to keep the costs down.

Budget:
I originally thought I could do this for $10,000, but after doing some initial research and material sourcing, I realized that number was going to go up. Initially I was looking at a materials cost of around $20,000, but I started to learn more about what REALLY works in sound isolation (again, thanks to forums like this, and Rod's book). I learned that using the right materials IN THE RIGHT PLACE makes more of a difference than MORE materials. I am now working with a materials budget of $15,000 and so far that's looking pretty good. I'm keeping track of every penny spent, so I'm on schedule. I am not including room treatment in this budget, just isolation materials. I will re-evaluate budget when I get closer to treating the room.

Isolation Needs
I had a friend walk around the property with a spl meter while I played at close to full volume. I had him take measurements at key points around the property. My biggest concern is my neighbor to the west. His house is about 30 feet from my garage, and i was getting levels of about 81dbC on that side of the garage, and 93dbC in front of the garage where his house is closest to. I am aware that with my budget and construction methods, the absolute MAXIMUM I could achieve would be about 70db of TL... and that's if everything is done perfectly with no mistakes. Realistically I know to expect probably 50db of TL, and if I got that, I'd be OK with it. My budget isn't very big, so planning and making sure I do this right the first time is a priority.

Garage Specs
The garage is on the smaller side. It was built in 1936. It is unfinished which is nice because that's less work to take down any drywall or plywood on the interior and I can get right to beefing up the exterior leaf. The exterior is stucco (approx 1 inch thick), and the roof is simple roof sheathing with roof shingles on top. The studs and rafters are 2x4 (1 7/8 x 3 5/8), and the garage door is metal.

The inside measures from stud face to stud face
17' 7 1/2" x 15' 4" x 8' 1" high (to the top of the top plate).

The peak of the roof is 11' 4", and is a 4/12 roof pitch. There is a ridge board (not ridge beam) that measures 5 1/2" by 3/4".

The floor is concrete slab on grade, and in fantastic condition considering how old it is. I took a 4ft level and placed it all over the floor in every possible direction, and it's level with no dips or bumps. there are some small hair line fractures, and a some very small chips here and there, but nothing to be concerned with.

Attachment:
Frame1(small).jpeg




There are two horizontal ceiling joists, and 2 diagonal rafter ties. See below.

Attachment:
Existing RafterTie(small).jpeg


One thing that has been extremely helpful was learning how to use sketchup. It has been outstanding for allowing me to really visualize what I'm going, but also helping me source the right amount of materials. I will post pictures as I go. I hope it makes sense.

I have a 40amp sub panel being fed from the main panel in the garage, but I am going to upgrade that to a 60amp subpanel.

There is a gable end vent on the same end as the garage door, but no soffit vents or ridge vent, which is going to cause a problem - detailed later in this post.



Design Plan for Garage:

I will be building a single room, no booths, no separate mixing station. I do most of my recording by myself, so I don't need a separate space for that.

Exterior wall will look like this:
Stucco > 3/4" OSB > 5/8" drywall (backer rod and caulked around all drywall pieces)
pink fluffy inside stud bays as well as cavity

Interior Frame (walls and ceiling):
2x6 frame stuffed with pink fluffy
3/4" OSB > Green Glue > 5/8" Drywall > Green Glue > 5/8" Drywall
The perimeter of all drywall will be spaced 1/4", and 3/8" backer rod will be stuffed around and caulked. I will be using the staggered drywall installation method I have seen in Rod's book and all over this forum. Ceiling first, North/South walls 2nd, East/West walls 3rd, allowing space for backer rod and caulk.

First step is to beef up the existing outer leaf.
- I have already installed strips of 3/4" OSB into the stud bays, and secured them in place with wood cleats. I have caulked the edges.
Attachment:
IMG_3024StudBay(small).jpeg

Attachment:
StudBay2(small).jpeg

Attachment:
IMG_3032StudBay3(small).jpeg

Attachment:
IMG_3033StudBay4(small).jpeg


- I had a few sheets of drywall left over from a previous project, so I cut those up and filled a few stud bays. I will fill the rest when I am ready to order more drywall.
Attachment:
IMG_3035StudBay6(small).jpeg


I left a gap of about 3/8" around the drywall to stuff with 1/2" backer rod. I then caulked (didn't take picture of that yet). I have decided that 3/8" gap is too big, because if there are uneven studs (which there are plenty of), it causes much larger gaps. So I have decided after these bays I will be doing 1/4" gap with 3/8" backer rod.

The 3 walls including one gable end are complete. I can't do the ceiling yet because of a few problems.

I want to remove the ceiling joists to allow for more ceiling space. this was the first reason I contacted a structural engineer (the second was to make sure the structure could handle all the added mass). I had seen a thread of someone else's build on gearslutz, and they had an architect design small gussets that could be attached at the top to help support the structure when removing those ceiling joists. I showed my SE the design, and he was not ok with it. He was too concerned that with the added mass, the walls would lean and the roof would collapse. Apparently that's not good. So we came up with a gusset idea, but on a MASSIVE scale.

His design calls for rafter ties no less than 2ft from the ridge, with plywood on both sides. Here is his design...
Attachment:
Design1(small).png


I have a few concerns with this design, but I won't go into that right now. We're still working on fine tuning it at the moment.

But a bigger problem is venting. I was really close to ready to start working on the ceiling when I remembered reading about how important it is to vent the roof. So I started looking into it and learned that I have some things to work out first. We'll get to my questions at the end.

I will be building a new inner frame to create the room in a room. I will be using 2x6s for all framing with 24 OC, because Rod says that's the way to go. lol. I will be filling the cavity with pink fluffy.

I will be closing off the garage door, ceiling it, and building a wall to connect to it to make it one massive outer leaf.

I plan on using a 2 door system for entry into the space.

Attachment:
Frame3(small).jpeg

Attachment:
Interior Frame2(small).jpeg



Electircal:
To achieve maximum isolation, I plan on having the sub panel, and all outlets face mounted onto the drywall so there is just 1 hole in the wall where the power is being brought into the room. I will be using metal conduit and metal boxes so I can run a STAR grounding system with isolated receptacles for all studio/music gear.

HVAC
I will be using a wall mounted mini-split for heating/AC, and an ERV for air circulation. I have seen many baffle box designs and haven't quite figured out how I'm going to do that yet, but it is on my mind to get planning with it because I need to figure that out before I can start building the interior frame. I know I will be placing baffle boxes inside the room, even though they will be quite large.



Problems/Questions:

1 - My immediate concern is the roof venting issue. As I see it now, I have 2 options.

a: build a warm roof
b: figure out how to vent each stud bay along the ceiling, and put vents in the soffits at the roof edges. Right now, the soffits are completely closed off.

How can I vent each stud bay? Is that even possible? Would I have to dismantle the roof to do it? If that were the case, I figure it'd be easier/cheaper to just do a warm roof. My only hesitance to that is the roof was just replaced like 4 years ago. It's in great condition.

Am I on the right track in my thinking here?

2 - Another concern I have is a moisture barrier for the garage door. When I go to seal it up, do I need a moisture barrier, and where do I put it?

3 - When it comes to ERV for air circulation, I want to make sure I have this correct. The projected volume of my room will be roughly 1,900 cubic feet. (14x15x9). 1,900/60 puts me around 32 CFM (cubic feet per minute). If my unit can push 40 CFM, is that sufficient? Or am I not calculating this properly?

How does the rest of this look?

I commend anyone who is still alive after reading this. lol.


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PostPosted: Sun Jun 28, 2020 8:31 am 
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Ok I have a bit of an update. I had a couple of different roofers come by to give me a quote on installing a hot roof. While both quotes were WAY more money than I had anticipated, doing a warm roof seems like a much better option than installing a ridge/soffit vents and creating a 3 leaf roof. It's also not so much the 3 leaf that's bothering me, but how much more difficult it is going to be to isolate the middle leaf once I have my huge gussets installed. With a warm room, beefing up the outer layer will be fairly straight forward.

I just have a couple of questions.

Originally, I had planned on putting in 3/4" OSB in between the rafter bays (like I did in between the stud bays of the walls), and then putting 5/8" drywall in the rafter bays (again, the same as the walls). That would give me 3 layers on the roof (7/16" OSB roof sheathing > 3/4" OSB > 5/8" drywall).

If I do the warm roof, the existing shingles will be removed, and a water/ice sealer will be installed on the existing 7/16" OSB roof deck. Then 2" Thermasheathing insulation boards (R14 value), then 7/16"OSB again (for a nailing surface for the shingles), then shingles.

I already have the 3/4" OSB that I was going to put into the rafter bays... but can I just use that 3/4" OSB instead of new 7/16" OSB as my top layer nailing surface for the shingles? Would this help me maintain my isolation? If this is possible, this would actually save me money (since I already have the 3/4"OSB, and wouldn't need to purchase more 7/16" OSB), and a lot of time since I won't have to install it in the rafter bays.

So instead of this

Attachment:
Roof Cross Section1 (small).jpeg


I'd get this

Attachment:
Roof Cross Section2 (small).jpeg


Would this work in keeping that entire exterior leaf one giant solid isolated leaf? Does it matter if the 3/4" OSB is above the insulation, or below the roof deck?


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PostPosted: Mon Jun 29, 2020 2:20 am 
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Location: Cork Ireland
I hope someone with local build experience chimes in. Many of the words you use are unknown here. So I can only speak on Acoustic issues.
The various harder insulation, Poly this and that, are thermally let's say 3 times more effective than fibre. Here a typical 4" board replaces a foot of fibre. Our houses have BER thermal certs which affect their sale value. But these boards have pretty much zero acoustic effect or benefit.
Also here, and may not apply to you at all, warm layers can cause problems with condensation, mould, rot.

So hopefully a practical or professional builder with USA Code and other knowledge will help out now?

Have you got Rod Gervais' book, Build it like the Pros?

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http://www.irishacoustics.com
http://www.soundsound.ie


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PostPosted: Mon Jun 29, 2020 3:46 am 
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Hi,

Here's a diagram I've drawn of how you can build a cold roof and still maintain your air tight 2 leaf isolation assembly.

Attachment:
Cold roof assembly.jpg


This diagram is for a cathedral ceiling, but the same applies with a flat ceiling too. It's not a 3 leaf assembly really since the roof has lots of holes along the top and bottom (vents), it is merely a rain screen for your 2 leaf assembly.

If you have the space you can apply the outer leaf mass layers directly on the bottom of the rafters instead of between the rafters, that will depend on how big you need your air cavity.

Vent your soffits, there needs to be a continuous 10000mm2 air gap, so if using the 70mm round soffit vents that equals 1 vent every 160mm.

And also vent your ridge. I find this calculator super useful for working out exactly what you need in order to meet building regs:

https://www.owenscorning.com/roofing/co ... calculator

Hope that helps, let me know if you have any questions.

If you go the warm roof route then that's great, much more efficient, simpler and faster.

However make sure it is done 100% correctly otherwise you will have terrible problems with moisture rotting out the entire place. 1 little hole or breech in the VCL in the wrong place could cause moisture to get in but not be able to dry out (due to zero vents) which will spread until it's too late... you'll only notice it once water starts dripping down onto your gear from above which is bad enough, but then you'll realise that the entire roof and inner and outer leaves will need to be redone!

It is a very simple and in theory easy way of building a roof and it should be excellent if done correctly, but if you're not going to install it yourself then I would be watching the roofers/builders like a hawk. There's a lot of people out there that claim to know what they're doing but in reality do shoddy workmanship and rip people off. If it were me, I'd rather get up there and do it myself since all the materials are relatively light weight once the roof deck is on.

Paul


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PostPosted: Mon Jun 29, 2020 4:11 am 
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Location: Los Angeles, CA
DanDan wrote:
I hope someone with local build experience chimes in. Many of the words you use are unknown here. So I can only speak on Acoustic issues.
The various harder insulation, Poly this and that, are thermally let's say 3 times more effective than fibre. Here a typical 4" board replaces a foot of fibre. Our houses have BER thermal certs which affect their sale value. But these boards have pretty much zero acoustic effect or benefit.
Also here, and may not apply to you at all, warm layers can cause problems with condensation, mould, rot.

So hopefully a practical or professional builder with USA Code and other knowledge will help out now?

Have you got Rod Gervais' book, Build it like the Pros?


Hi DanDan,

Thanks for chiming in. First off, yes, I have Rod's book and have gone through it several times (and am currently going through it again, haha).

The poly iso insulation is not meant for soundproofing (but for thermal insulation), my understanding is that as long as it maintains contact with the OSB, it is keeping the leaf one solid leaf and not causing a 3rd leaf.

@Paulus87,

I've seen you post that diagram before. It is very clear, and I was about to start cutting the ridge and soffit vents when I revisited the warm roof option.

My concern with doing the ridge/soffit vent idea, is the large gussets that I will be installing in the rafters makes it impossible to add the layers directly to the underside of the rafters. So I would have to put the layers inside the stud bays, and while that is totally doable, it's just a lot of work.

One of the roofing guys actually suggested I do the warm roof myself. He saw what I was doing, all the work I had done and was like, "Dude, you're pretty handy, you can probably do this yourself." Another roofer with a different company didn't think I needed to do a warm roof OR vent. He thought it was good enough the way I have it (which I don't think is correct).

The only reason I don't want to do the roof myself is because I have never done any roofing before. I guess I can start watching videos on how to do a roof. Maybe I'll be able to learn just enough.

In your drawing, you have the vapor barrier on the room side of the studs of the interior wall. Does it matter what climate you're in when determining where that vapor barrier goes?

What about the moisture barrier for the garage door? Do I need it, and where would it go?

Thanks for chiming in. You're help and expertise has been extremely valuable.


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PostPosted: Mon Jun 29, 2020 4:29 am 
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Location: Wales, UK
Jag94 wrote:
DanDan wrote:
I hope someone with local build experience chimes in. Many of the words you use are unknown here. So I can only speak on Acoustic issues.
The various harder insulation, Poly this and that, are thermally let's say 3 times more effective than fibre. Here a typical 4" board replaces a foot of fibre. Our houses have BER thermal certs which affect their sale value. But these boards have pretty much zero acoustic effect or benefit.
Also here, and may not apply to you at all, warm layers can cause problems with condensation, mould, rot.

So hopefully a practical or professional builder with USA Code and other knowledge will help out now?

Have you got Rod Gervais' book, Build it like the Pros?


Hi DanDan,

Thanks for chiming in. First off, yes, I have Rod's book and have gone through it several times (and am currently going through it again, haha).

The poly iso insulation is not meant for soundproofing (but for thermal insulation), my understanding is that as long as it maintains contact with the OSB, it is keeping the leaf one solid leaf and not causing a 3rd leaf.

@Paulus87,

I've seen you post that diagram before. It is very clear, and I was about to start cutting the ridge and soffit vents when I revisited the warm roof option.

My concern with doing the ridge/soffit vent idea, is the large gussets that I will be installing in the rafters makes it impossible to add the layers directly to the underside of the rafters. So I would have to put the layers inside the stud bays, and while that is totally doable, it's just a lot of work.

One of the roofing guys actually suggested I do the warm roof myself. He saw what I was doing, all the work I had done and was like, "Dude, you're pretty handy, you can probably do this yourself." Another roofer with a different company didn't think I needed to do a warm roof OR vent. He thought it was good enough the way I have it (which I don't think is correct).

The only reason I don't want to do the roof myself is because I have never done any roofing before. I guess I can start watching videos on how to do a roof. Maybe I'll be able to learn just enough.

In your drawing, you have the vapor barrier on the room side of the studs of the interior wall. Does it matter what climate you're in when determining where that vapor barrier goes?

What about the moisture barrier for the garage door? Do I need it, and where would it go?

Thanks for chiming in. You're help and expertise has been extremely valuable.


Ok - the guy that said to leave the roof as it is without vents or doing a warm roof is either an idiot or didn't fully understand what was going to happen with your build. If you were to leave the room as it is without loads of insulation up tight against the roof deck or walls and didn't seal the hell out of every seam/gap/crack then sure, it would probably be fine. But, as soon as you put insulation (especially up in the ceiling) with no air gap or venting then it will for sure sweat.

Vapour barrier goes on the warm side of the insulation in cold climates like the UK. check with your local building regs to find out where it needs to go in your particular case. You may or may not need it... OSB is often used as an acceptable vapour barrier in passive house builds, which is very similar to how we build studios, so you might be fine without one... just check.

Regarding your garage door, well since you're blocking it up, just treat it like the rest of your wall, wherever you put the vapour barrier on your wall will follow with the garage door as well. Moisture barrier, are you talking about to stop rain getting in? Well you need to do that for your walls as well... so it'll be the same as whatever you do for that, some sort of external cladding I'm guessing?

Paul

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PostPosted: Mon Jun 29, 2020 5:46 am 
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Yeah, I don't think he fully understood what I was doing, although he did seem to be very knowledgable about roofing.

Also, I've seen you calling it a "warm roof" many times, but I don't think people refer to it that way here in the states. When I said "warm roof" I got blank stares, but then when they explained their process, they were explaining exactly what a warm roof is, but just not using the term warm roof. ha. When I type in warm roof, mostly everything that comes up is in the UK, and a LOT of it is for flat roofs. I'm having a hard time finding resources for the "warm roof" here in the states. It looks like they use the term "hot roof" here in the states, although it doesn't seem to be common.

I'll keep checking the vapor barrier requirements here in Los Angeles.


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PostPosted: Mon Jun 29, 2020 6:35 am 
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Jag94 wrote:
Yeah, I don't think he fully understood what I was doing, although he did seem to be very knowledgable about roofing.

Also, I've seen you calling it a "warm roof" many times, but I don't think people refer to it that way here in the states. When I said "warm roof" I got blank stares, but then when they explained their process, they were explaining exactly what a warm roof is, but just not using the term warm roof. ha. When I type in warm roof, mostly everything that comes up is in the UK, and a LOT of it is for flat roofs. I'm having a hard time finding resources for the "warm roof" here in the states. It looks like they use the term "hot roof" here in the states, although it doesn't seem to be common.

I'll keep checking the vapor barrier requirements here in Los Angeles.


Yes you call it a hot roof, but a flat warm roof or a pitched warm roof, hot roof, whatever is the same process and design. It’s really that simple. Check out Matt risinger on YouTube, he’s currently rebuilding his house to passive house standards including pitched warm roofs.

Btw, regarding your question about the order of your roofing sandwich, depending on your local codes you can actually just put an EPDM rubber roof straight over the top of the rigid insulation, as it is not going to have regular footfall. So that means your roof deck would be your outer leaf with the vapour control layer over that, then rigid insulation and then covered with the rubber.

Paul

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PostPosted: Mon Jun 29, 2020 9:38 am 
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Paulus87 wrote:

Yes you call it a hot roof, but a flat warm roof or a pitched warm roof, hot roof, whatever is the same process and design. It’s really that simple. Check out Matt risinger on YouTube, he’s currently rebuilding his house to passive house standards including pitched warm roofs.

Btw, regarding your question about the order of your roofing sandwich, depending on your local codes you can actually just put an EPDM rubber roof straight over the top of the rigid insulation, as it is not going to have regular footfall. So that means your roof deck would be your outer leaf with the vapour control layer over that, then rigid insulation and then covered with the rubber.

Paul


Ahh, gotcha. Thanks for the tip on Matt Risinger... I'll check it out.

Interesting. But if I put another layer of OSB for a nailer surface for the asphalt shingles, wouldn't that count as more mass to my leaf? It would be way easier to install it in full sheets on top of the roof deck rather than in between the stud bays below the roof deck. no?


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PostPosted: Mon Jun 29, 2020 7:48 pm 
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Jag94 wrote:
Paulus87 wrote:

Yes you call it a hot roof, but a flat warm roof or a pitched warm roof, hot roof, whatever is the same process and design. It’s really that simple. Check out Matt risinger on YouTube, he’s currently rebuilding his house to passive house standards including pitched warm roofs.

Btw, regarding your question about the order of your roofing sandwich, depending on your local codes you can actually just put an EPDM rubber roof straight over the top of the rigid insulation, as it is not going to have regular footfall. So that means your roof deck would be your outer leaf with the vapour control layer over that, then rigid insulation and then covered with the rubber.

Paul


Ahh, gotcha. Thanks for the tip on Matt Risinger... I'll check it out.

Interesting. But if I put another layer of OSB for a nailer surface for the asphalt shingles, wouldn't that count as more mass to my leaf? It would be way easier to install it in full sheets on top of the roof deck rather than in between the stud bays below the roof deck. no?



If you're going to use shingles then yes of course, you'll have to do it that way. But if you decided on a rubber roof (wayyyyy quicker and much more durable) then you wouldn't need to put the OSB between the rafters, you can just put it on top of the existing roof deck, as many layers as you want (providing there is no vapour control layer already down - this must go on last, under the rigid insulation which is on top of your roof deck).

Paul

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PostPosted: Tue Jun 30, 2020 3:52 am 
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Paulus87 wrote:


If you're going to use shingles then yes of course, you'll have to do it that way. But if you decided on a rubber roof (wayyyyy quicker and much more durable) then you wouldn't need to put the OSB between the rafters, you can just put it on top of the existing roof deck, as many layers as you want (providing there is no vapour control layer already down - this must go on last, under the rigid insulation which is on top of your roof deck).

Paul


I looked into EPDM rubber roofs a bit, and it says they're for flat or low-slope roofs. I guess the definition of a "low-slope" roof is 3/12 pitch or less. My roof is somewhere between 4/12 and 5/12. Would a EPDM roof work?


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PostPosted: Tue Jun 30, 2020 11:37 am 
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Jag94 wrote:
Paulus87 wrote:


If you're going to use shingles then yes of course, you'll have to do it that way. But if you decided on a rubber roof (wayyyyy quicker and much more durable) then you wouldn't need to put the OSB between the rafters, you can just put it on top of the existing roof deck, as many layers as you want (providing there is no vapour control layer already down - this must go on last, under the rigid insulation which is on top of your roof deck).

Paul


I looked into EPDM rubber roofs a bit, and it says they're for flat or low-slope roofs. I guess the definition of a "low-slope" roof is 3/12 pitch or less. My roof is somewhere between 4/12 and 5/12. Would a EPDM roof work?



Fully adhered rubber roofs can be used at any pitch. Here’s more info:
https://www.buildings.com/article-detai ... ic-roofing

Whether you choose rubber or shingles, either of your designs will work. Just check with your local code regarding not roofs as well manufacturers of any products you use.

Paul

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PostPosted: Fri Jul 03, 2020 10:48 am 
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Location: Los Angeles, CA
Quick side question. At what point does a layer of mass become a separate leaf? For example, if you have 2 sheets of drywall, how much space in between those to sheets is necessary for it to be considered 2 leafs instead of one?

Here's my situation. My roof rafters and 1st layer of roof sheathing are separated by wood slats that are 7/8" thick. So if I were to put drywall in between the rafters, there would be 7/8ths of an inch between the drywall and the roof OSB. Would this constitute a break in the leaf, essentially creating a second leaf? How big of a deal is it if the external leaf is about 2 feet away from the inner leaf? Does that amount of space in between the inner leaf and the outer leaf help?

Here is a picture to give an idea of what I mean.

Attachment:
Roof Rafters with Slats (small).jpeg


Attachment:
RoofRaftersWithSlats(Small).jpeg


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PostPosted: Fri Jul 03, 2020 10:19 pm 
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Joined: Fri Nov 24, 2017 12:07 am
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Location: Hastings, East Sussex, United Kingdom
Hello & howdo' Jag 94?
Apols for the brevity of my reply but I've got a lot on at the mo'!
Quote:
if I were to put drywall in between the rafters, there would be 7/8ths of an inch between the drywall and the roof OSB.
If you placed your drywall in between the wood slats instead of the rafters you could preserve the continuity of your outer leaf. It would be trickier to build without a doubt but would improve isolation in my view. Also, have you had a structural engineer inspect the structure? I'd recommend you do if you haven't already, so you can be certain that adding the extra mass is safe. Best wishes, John.

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PostPosted: Sat Jul 04, 2020 3:15 am 
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Joined: Mon Feb 03, 2020 6:04 am
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Location: Los Angeles, CA
John Steel wrote:
Hello & howdo' Jag 94?
Apols for the brevity of my reply but I've got a lot on at the mo'!
Quote:
if I were to put drywall in between the rafters, there would be 7/8ths of an inch between the drywall and the roof OSB.
If you placed your drywall in between the wood slats instead of the rafters you could preserve the continuity of your outer leaf. It would be trickier to build without a doubt but would improve isolation in my view. Also, have you had a structural engineer inspect the structure? I'd recommend you do if you haven't already, so you can be certain that adding the extra mass is safe. Best wishes, John.


Hi John,

Thanks for the reply. First, in my post I explained that I hired a SE for a couple of reasons (I don't blame you for not reading that insanely long first post). The first reason is to - like you said - make sure the structure could hold the added weight. The second, was because I wanted to remove the existing rafter ties to increase ceiling space. Together we designed extremely large rafter ties and gussets that will sit a foot higher and will make sure the walls don't lean/roof collapse, and that the roof structure is strong enough for the added mass.

As far as cutting up drywall and putting in between the slats - kill me now. haha. I went and bought 1" EPS foam, and started cutting that up to put in the slats, so that when I put the drywall in between the rafters, it would help keep the continuity of the leaf. Cutting the foam is a pain in the ass, but surely it's easier than cutting up the drywall. I just started to think if it was really necessary, because if not, it would save me a TON of time.


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