Garage -> Studio Build

[Paulus87]

Separate question:

In the gap between the exterior and interior leafs, I plan on filling that gap with insulation. Should i put something on the concrete floor so that the insulation is not touching the concrete? Could moisture from the concrete saturate the insulation?

Sorry I can't help much with the electrics questions you have but regarding your question above, do you have an insulated concrete slab or is the concrete poured directly into the ground? You surely have a damp proof membrane below?

If you are concerned then you could stick some transparent impermeable plastic to a section of the concrete, seal it air tight and then leave it for a week or so to check if there's any water droplets forming under it. If there's none then you're good to go, if you have some then I would put plastic over the concrete, then a layer of foil faced rigid foam insulation and then the cavity insulation on top of that.

Paul

[Jag94]

do you have an insulated concrete slab or is the concrete poured directly into the ground? You surely have a damp proof membrane below?

If you are concerned then you could stick some transparent impermeable plastic to a section of the concrete, seal it air tight and then leave it for a week or so to check if there's any water droplets forming under it. If there's none then you're good to go, if you have some then I would put plastic over the concrete, then a layer of foil faced rigid foam insulation and then the cavity insulation on top of that.

Paul

I am not sure, but I'm assuming since the concrete was poured in 1936, that it's just concrete poured directly into the ground. Right now I don't have any membranes on the concrete.

At this stage, I'm simply putting the first layer of insulation into the stud bays of the exterior (existing) leaf. The interior leaf frame has been built and is standing up, but I haven't put them in place yet, or secured them to the concrete.

I was about to put the frame in place, then just fill the gap in between the interior/exterior frames with the 2nd layer of insulation, then fill the interior frame with the 3rd layer of insulation, and thought about the insulation touching the concrete foundation in between the gaps. I don't remember reading about this in Rod's book, or in any of the build threads, so I thought I'd ask.

When it comes time to do the hardwood floors, I was going to put 6mil plastic first, then an underlayment, then the hardwood flooring. Is that 6mil plastic the type of plastic you're referring to?

Id be concerned with putting foil faced rigid insulation in between the sill plates of the two leafs because the gap is just about 2", so if the insulation touches both leafs, would that not create a flanking path all the way around the entire garage?

[Paulus87]

do you have an insulated concrete slab or is the concrete poured directly into the ground? You surely have a damp proof membrane below?

If you are concerned then you could stick some transparent impermeable plastic to a section of the concrete, seal it air tight and then leave it for a week or so to check if there's any water droplets forming under it. If there's none then you're good to go, if you have some then I would put plastic over the concrete, then a layer of foil faced rigid foam insulation and then the cavity insulation on top of that.

Paul

I am not sure, but I'm assuming since the concrete was poured in 1936, that it's just concrete poured directly into the ground. Right now I don't have any membranes on the concrete.

At this stage, I'm simply putting the first layer of insulation into the stud bays of the exterior (existing) leaf. The interior leaf frame has been built and is standing up, but I haven't put them in place yet, or secured them to the concrete.

I was about to put the frame in place, then just fill the gap in between the interior/exterior frames with the 2nd layer of insulation, then fill the interior frame with the 3rd layer of insulation, and thought about the insulation touching the concrete foundation in between the gaps. I don't remember reading about this in Rod's book, or in any of the build threads, so I thought I'd ask.

When it comes time to do the hardwood floors, I was going to put 6mil plastic first, then an underlayment, then the hardwood flooring. Is that 6mil plastic the type of plastic you're referring to?

Id be concerned with putting foil faced rigid insulation in between the sill plates of the two leafs because the gap is just about 2", so if the insulation touches both leafs, would that not create a flanking path all the way around the entire garage?

Ah yes, I didn't realise the gap was so small - I was thinking you could leave a gap between the sill plates and the rigid insulation but yes, In that case, don't use the rigid insulation.

I'm concerned that you don't have a damp proof membrane... moisture from the outside getting into the concrete could then rot out all your timber framework, if your outer leaf studs have been there for quite sometime already and you don't see any problems then it's probably fine, but even so, I think I would at least put the plastic over the entire face of the concrete and then install the inner frames on top of that membrane. Did you use treated timber? And you will definitely need to put plastic down before laying any type of flooring down on it anyway, otherwise you're just asking for damp problems.

If this was a new build you would have:
soil - hardcore - ballast - sand - DPM - rigid insulation - plastic membrane - concrete - possibly another plastic membrane (depending on code) - underlay - flooring.

I appreciate it's impossible for you to do that now, but I would definitely use at least one plastic membrane and a moisture resistant foam underlay for a tiny bit of insulation.

Once the membrane is down then putting the insulation between the frames shouldn't be a problem anymore.

Paul

[Jag94]

Ah yes, I didn't realise the gap was so small - I was thinking you could leave a gap between the sill plates and the rigid insulation but yes, In that case, don't use the rigid insulation.

I'm concerned that you don't have a damp proof membrane... moisture from the outside getting into the concrete could then rot out all your timber framework, if your outer leaf studs have been there for quite sometime already and you don't see any problems then it's probably fine, but even so, I think I would at least put the plastic over the entire face of the concrete and then install the inner frames on top of that membrane. Did you use treated timber? And you will definitely need to put plastic down before laying any type of flooring down on it anyway, otherwise you're just asking for damp problems.

If this was a new build you would have:
soil - hardcore - ballast - sand - DPM - rigid insulation - plastic membrane - concrete - possibly another plastic membrane (depending on code) - underlay - flooring.

I appreciate it's impossible for you to do that now, but I would definitely use at least one plastic membrane and a moisture resistant foam underlay for a tiny bit of insulation.

Once the membrane is down then putting the insulation between the frames shouldn't be a problem anymore.

Paul

Ok good info here. Yes, I used pressure treated lumber for the sill plates. I wasn't going to put the frames on anything, but if you think it's a good idea, I can do that. I haven't bolted the frames in place yet. It will be a bit of a chore, but with some help I can probably lay out a layer of 6mil plastic on the floor, then put the frames on that. When it comes time to put the hardwood floor down, i'll use a good underlayment before the floors go on the concrete.

When I put the 6mil plastic down, should I be sealing it at the edges in some way? Use caulk? Special tape?

Thanks for being so responsive.

[Paulus87]

Ah yes, I didn't realise the gap was so small - I was thinking you could leave a gap between the sill plates and the rigid insulation but yes, In that case, don't use the rigid insulation.

I'm concerned that you don't have a damp proof membrane... moisture from the outside getting into the concrete could then rot out all your timber framework, if your outer leaf studs have been there for quite sometime already and you don't see any problems then it's probably fine, but even so, I think I would at least put the plastic over the entire face of the concrete and then install the inner frames on top of that membrane. Did you use treated timber? And you will definitely need to put plastic down before laying any type of flooring down on it anyway, otherwise you're just asking for damp problems.

If this was a new build you would have:
soil - hardcore - ballast - sand - DPM - rigid insulation - plastic membrane - concrete - possibly another plastic membrane (depending on code) - underlay - flooring.

I appreciate it's impossible for you to do that now, but I would definitely use at least one plastic membrane and a moisture resistant foam underlay for a tiny bit of insulation.

Once the membrane is down then putting the insulation between the frames shouldn't be a problem anymore.

Paul

Ok good info here. Yes, I used pressure treated lumber for the sill plates. I wasn't going to put the frames on anything, but if you think it's a good idea, I can do that. I haven't bolted the frames in place yet. It will be a bit of a chore, but with some help I can probably lay out a layer of 6mil plastic on the floor, then put the frames on that. When it comes time to put the hardwood floor down, i'll use a good underlayment before the floors go on the concrete.

When I put the 6mil plastic down, should I be sealing it at the edges in some way? Use caulk? Special tape?

Thanks for being so responsive.

It's just an extra pre-caution. You're using treated lumber but even that can rot out if it soaks up enough moisture, I saw this first hand on my build where there was an exposed sole plate end that I didn't see until 3 years later and water got in there and it's pretty compromised already.

If you can, get some sort of rubber to put on the bottom faces of the sole plates, it will fill in any little imperfections in the concrete/wood where air can leak through, or if not just caulk the bottom faces really liberally before erecting the frames. Then caulk all the way round the perimeter to seal it to the concrete.

Paul

[Jag94]

It's just an extra pre-caution. You're using treated lumber but even that can rot out if it soaks up enough moisture, I saw this first hand on my build where there was an exposed sole plate end that I didn't see until 3 years later and water got in there and it's pretty compromised already.

If you can, get some sort of rubber to put on the bottom faces of the sole plates, it will fill in any little imperfections in the concrete/wood where air can leak through, or if not just caulk the bottom faces really liberally before erecting the frames. Then caulk all the way round the perimeter to seal it to the concrete.

Paul

Ok, so I was originally going to use a sill sealer like this... https://www.homedepot.com/p/Owens-Corni ... /202080947. It does an adequate job of sealing the space under the sill plate, but it doesn't do anything for moisture build up. I was also going to caulk the shit out of the sill plates once they were bolted to the cement.

But if you're suggesting I put a layer of plastic down first, wouldn't I then be caulking the sill plates to the plastic and not the cement?

[Paulus87]

It's just an extra pre-caution. You're using treated lumber but even that can rot out if it soaks up enough moisture, I saw this first hand on my build where there was an exposed sole plate end that I didn't see until 3 years later and water got in there and it's pretty compromised already.

If you can, get some sort of rubber to put on the bottom faces of the sole plates, it will fill in any little imperfections in the concrete/wood where air can leak through, or if not just caulk the bottom faces really liberally before erecting the frames. Then caulk all the way round the perimeter to seal it to the concrete.

Paul

Ok, so I was originally going to use a sill sealer like this... https://www.homedepot.com/p/Owens-Corni ... /202080947. It does an adequate job of sealing the space under the sill plate, but it doesn't do anything for moisture build up. I was also going to caulk the shit out of the sill plates once they were bolted to the cement.

But if you're suggesting I put a layer of plastic down first, wouldn't I then be caulking the sill plates to the plastic and not the cement?

The sill sealer is fine, you could use that. You still bolt them down into the concrete, and yes just seal them to the plastic.

If you prefer not to use the plastic under the frames then that's your decision, are you building this to code? If so perhaps get advice from a local inspector or trusted builder?

Paul

[Jag94]

The sill sealer is fine, you could use that. You still bolt them down into the concrete, and yes just seal them to the plastic.

If you prefer not to use the plastic under the frames then that's your decision, are you building this to code? If so perhaps get advice from a local inspector or trusted builder?

Paul

I think I'll go with the plastic. It'll be a pain in the ass, but I'd rather prevent the possibility of wood rot, even if it's not likely to happen. That coupled with the sill sealer, plus caulking all sides of the sill plates should be pretty good.

Is there a specific type of tape that works best for securing the plastic to either cement or the sill of the exterior leaf?

Thanks for the input.

[Paulus87]

The sill sealer is fine, you could use that. You still bolt them down into the concrete, and yes just seal them to the plastic.

If you prefer not to use the plastic under the frames then that's your decision, are you building this to code? If so perhaps get advice from a local inspector or trusted builder?

Paul

I think I'll go with the plastic. It'll be a pain in the ass, but I'd rather prevent the possibility of wood rot, even if it's not likely to happen. That coupled with the sill sealer, plus caulking all sides of the sill plates should be pretty good.

Is there a specific type of tape that works best for securing the plastic to either cement or the sill of the exterior leaf?

Thanks for the input.

There are certain tapes designed for the job, try an online hardware store or insulation supplier, or passive house building website etc...

Paul

[Alexd001]

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 taxi aéroport 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?

I do remember vaguely reading on this forum that using it in this manner increases LF isolation.

[Jag94]

It's been quite a while since I did an update, but i've been hard at work. This build is taking a lot longer than I anticipated, and I'm severely over budget. But, as they say, if you're not over budget, you're doing it wrong. Well, if they don't say that... I just created a new saying.

I haven't been as good as I should be with taking pictures, but I'll post what I have.

I left off with building of the wall frames. I hadn't placed them or bolted them in yet... I still had a few things to do before I got to that. First up, was widening the existing entrance doorway. It was a 28" x 76" door - which if you've ever tried to carry anything larger than a grocery bag through, you know that's just too damn small of a doorway. My goal was to open up the doorway to make way for a 36" x 80" door. I had to re-frame the doorway, and beef it up to handle the new (not yet purchased/built) super-door for the exterior. If you remember, I had to remove some overhead ceiling joists that were original "old-growth lumber", so I cut them to size and added them to create new King, Queen, and Jack studs. i then built an even better/stronger header than the joke of a header that was there to begin with. Hopefully you can see the results in the pictures below.

Frame 1 Small.jpeg

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Next was cutting the exterior stucco to match the new exterior door frame. I thought this was going to be difficult, but I bought a new Makita angle grinder, and a carbide cutting blade, and it took about 20 minutes and it was done. And not only did it cut easily, but it was smooth, clean, and easy to manipulate. I was extremely happy and surprised by the end result.

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I am still a long way from installing new door jambs and doors, but I was extremely happy that this part of the build was relatively simple.

Next up was cutting massive holes in my exterior leaf to install intake/exhaust ductwork for the ERV. This was anxiety inducing simply because I had spent months adding mass to the exterior leaf, and now I'm putting MASSIVE holes in it! However, I think I did alright. I have a bosch bulldog, which is a fantastic hammer drill that made putting holes in the stucco super easy. Once the 8" hole was made, I caulked the perimeter and stuck some backer rod to the still "wet" caulk. Once it dried, I inserted the wall penetration hoods, and caulked the perimeter. I then went on the inside, and caulked the $hit out of the inside as well. The end result not only looks good, but I'm hoping will suffice in terms of maintaining my isolation.

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[Jag94]

Next was installing the ductwork that would go in between the inner leaf and outer leaf. This is one reason I didn't place the wall frames yet. I needed to be able to install these ducts, and not having to maneuver in between the leafs made this very simple. The vertical 8" rigid ducts are decoupled from the hoods with 8" flex duct. And the same will be done when penetrating the interior leaf. Rod was very adamant that all of my flex duct runs were very short, and he approved of this design. I used mastic, zip ties, and tape to secure the flex duct to the rigid duct. I applied very liberal amounts of mastic to all of the rigid duct to seal any and all seems in the rigid duct. There will be NO leaks in this system.

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Once the ducts were in, it was time to place the frames and bolt them in place. I don't have any photos of this, but... well... I did it. lol. But before I put them in place, I filled the stud bays of the exterior leaf with pink fluffy insulation.

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Next was cutting, and assembling the rafters for the interior frame. I had drawn everything up to the exact inch in sketchup, so getting the measurements for this was quite simple. I laid out a couple of pieces of plywood to create a deck, and cut template pieces of rafters and installed blocks to hold them in place. Now I could easily cut and align the rafters to the exact angles and lengths to join them together.

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[Jag94]

Once the rafters were installed, it was time to start filling the frame with insulation. I had to add a layer of insulation in between the interior and exterior leafs, and then another layer inside the interior leaf. I'm still doing this to the ceiling, as I need several layers to fill the gap.

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I installed the mini-split condenser unit outside, and ran the electrical to a disconnect box myself. I hired an HVAC company to run and connect the refrigerant lines (although I wish I ran the lines myself, and just called them to connect it all when I was ready, as it cost me WAY more than I was anticipating). The interior unit won't be installed until the multiple layers of drywall are up.

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The next part was installing rafter ties to the rafters (which are what are going to be holding my ceiling OSB and drywall). They are now in, and I'm currently filling the gaps with insulation.

I am just about ready to start installing the first layer of OSB. My only hang-up is my electrician. He has been difficult to get ahold of, and I can't install the first layer until I get the electrical set up. Luckily I'm about a week away from that anyway, but it is causing a bit of stress. I will reach out to more electricians tomorrow to see if I can get a move on. However, I liked this original electrician because he has done work in studios before, and is the only electrician I have spoken with that understand what a studio needs. I wish I knew enough about this to do it myself.

[John Steel]

Thanks for posting this update; it's looking good and your attention to detail / method is an inspiration.

This build is taking a lot longer than I anticipated . . .

Yes indeed - If I had five quid for every time I'd thought that . . . Easy for me to say but it seems to me like you're making fairly rapid progress.

I haven't been as good as I should be with taking pictures . . .

I've found that when I'm concentrating properly on one or other aspect of the build, I almost invariably forget to photograph the process.
I'm looking forward to seeing more when you can post it. ATB John.

[Paulus87]

It's all looking good so far apart from one thing that I want to check with you: (sorry if I already asked this, I can't remember)

Have you got pink fluffy insulation pressed up against the roof deck between the outer leaf rafters?

Paul