I want light and sound isolation

[gullfo]

you could purchase the HVAC equipment and perhaps do some of the installation, but the final connections and refrigerant load should be done by professionals to ensure it is properly tested and loaded.

the drywall is often attached to the wood. so the carpenter must have some other reason they're thinking it cannot. best practice is to add a layer of OSB or plywood over the frame to increase rigidity and also later enable you to attach things to walls and ceiling without it depending entirely on the gwb for support.

[gullfo]

so to answer the questions:

no major issues. if you do a proper job sealing the space and creating the isolation layers w/ the inexpensive mass (gwb), use decent but affordable sliding doors (i'd say back to back pair) and use the lightweight insulation in the walls, and about 30-50% absorption coverage, you should meet your isolation requirements.

i would check with the carpenter to fully understand the "wood will warp" statement as that doesn't seem correct unless something is wrong with the wood itself... in which case, that should probably be fixed first

a split unit is fine. the fresh air plan seems good - cover those holes with silencers on either side of the openings. make sure you plan on making the units serviceable for filter changes, cleaning etc. if moisture may be an issue (internally from people or externally) consider an ERV/HRV unit to both push in air and pull air out via heat exchange and filters to solve the air flow and energy efficiency.

[Soundman2020]

Source of the post Sorry, I can't figure out how to get the photos upright, and the drawings have to be downloaded.

There's a bug in the Forum software that turns some photos "sideways", for unknown reasons, even if you rotate them properly in Photoshop or something similar. I've tried to trace the bug and fix it a few times, but no success so far. So even that's probably the problem there! Not your fault: the software's fault.

and the drawings have to be downloaded.

The forum software only displays images directly, not PDF. I looked for a plugin to show PDF files as images, but I could not find anything. I might have to right some code myself... one day!

OK, I'll try to get back to you on your actual questions now....


- Stuart -

[Soundman2020]

The walls are 40cm thick rammed earth (Pisé – a traditional construction technique in my area of France). But one of the 4 walls is stone (40cm thick

That should get you pretty good isolation. The weak points will be the ceiling, doors, windows and HVAC, probably.

Budget is 13,000€ and I’ll be doing everything myself.

You have about 30m2 of floor area, so that works out to roughly €430 / m2. Probably OK (although studios almost always end up costing more than you ever imagined they would! )

I would like to get 50db of reduction, any more would be icing on the cake.

That's a reasonable goal. Doable.

One essential element is to use the barn door opening to allow in light.

I mentioned this before, and Glenn did too: a pair of sliding glass doors, back to back, would do what you want. With Glenn's idea of lockable sliding barn doors on the outside, for security. There are different "standard" sizes for glass sliders: get the biggest ones you can afford, and get them with laminated glass. Even better is acoustic laminated glass, if you can find a source for that where you live.

I suspect that the 30db reduction between the future studio and the bedroom is a good indication of what I would achieve if I simply closed and insulated the barn door opening and and the ceiling.

Right! So you only need to go 100 times better... I kid you not! dB is a logarithmic scale, which basically measures the difference between two levels. A difference of 10 dB means 10 times more intensity. An increase of 20 dB (going from 30 to 50) means 10 x 10 = 100 times the intensity. So you need to block about 100 times more energy than your current bedroom wall is blocking. That sounds like a really big amount, and it is, but it is achievable in your situation. If you needed to get to 60 dB, that would be an increase of 30 dB, so 10 x 10 x 10 = 1000 times the intensity... probably not achievable, unless you also have ten times the budget!

The pisé/stone walls are a great starting place, but it needs to be closed. For the barn door opening, I’ll use a commercial sliding glass door.

A single glass door of they type you can typically buy in a "Home Depot" type store, with ordinary glass in it, will give you a total of about 25 dB isolation. Maybe 29 if it is really good. You would need two such doors, in parallel ("back to back") to get the isolation you need. And they would need to have better glass than then typical 5mm or 6mm window glass. A pair of sliding glass doors, back-to-back, with laminated glass in them, and a good separation between them, can get to the level you want. But when you buy them, do pay careful attention to getting doors that have really good seals around the sliders! That's critical to getting high isolation.

And for the upper part of the opening, I’ll build a wood structure with OSB 3 and 15cm of wood fiber insulation panels.

Here again you will need two such walls (one for each sliding glass door). Inner leaf and outer leaf. You will also need more than just a single layer of OSB on your two leaves. You need to get a lot of mass on those walls. I'd suggest at least this: Start with a layer of 19mm OSB nailed to the studs, then put a layer of 16mm drywall over that using Green Glue in between those two. Do that for each of the two walls, to create a proper two-leaf MSM system, like this;
What is MSM? How does it work?

I’ll create a false ceiling, by hanging metal rails from the roof joists and attach OSB 3 panels.

Here too, that alone won't get you to 50 dB of isolation. You'll need to add more mass to that. A single layer of 12mm thick OSB will only get you maybe 25 dB of isolation. Here too I would suggest doing the same as for the walls: a layer of 19mm OSB on your new metal ceiling joists, then at least one layer of 16mm drywall on that, with GreenGlue in between. Even better would be two layers of drywall. You'll need to ensure that the supporting structure is strong enough to take all that weight safely.

I’ll build a wood inner structure completely decoupled from the walls and ceiling

I’ll leave about 5cm between the studs and the pisé wall (pisé absolutely needs to breathe, and I figure this is convenient for sound isolation as well).

General rule of thumb; In order to get the MSM resonant frequency low enough, you should have a minimum air gap of about 4" (10cm) between the inner leaf surface and the outer leaf surface. More is better. So, assuming that you are using 2x4 studs, which are about 9cm deep usually, and you leave a gap of 5cm between the studs and the outer-leaf wall, that would give you a 14 cm air gap. That's good. If you can spare even more space, then leaving a 10cm gap between studs and wall would give you nearly 20cm
of air gap (about 8"). That's excellent! Of course, that reduces the floor area of the completed room, so do take that into account as well!

Between the studs I’ll have 15cm of wood fiber insulation panels.

Do check on the acoustic properties of that insulation first! The normal recommendation for studio isolation is either mineral wool or fiberglass wool insulation. If you use mineral wool, then you would need a density of about 50-60 kg/m3, and if you are using fiberglass it would need to be 35-45 kg/m3. Each type of insulation is different. In fact, it's not really the density that matters, but rather a property called "Gas Flow Resistivity" (GFR). That's a measure of acoustic impedance, and that's what matters most. I'm not aware of any acoustic research on wood fiber insulation, so I have no idea what the correct density would be, in order to get the right GFR. You can't just use any old insulation and hope it will work. It has to have properties that are acoustically useful. For example, polystyrene insulation has very good thermal properties, but is totally useless acoustically, so you will never find it used in studios.

The floor will be insulated with rigid wood fiber panels, and probably OSB on top.

Probably not a good idea. The bare concrete floor is an excellent surface, acoustically. If you want to make it look nicer, you could stain or polish the concrete, or use laminate flooring with an acoustic underlay... which is also good if you want to have a floor that looks nice and also feel nice to walk on, softer than concrete. But putting an OSB layer on top of joists with an air gap under it, will create a resonant chamber. Usually not a good idea for a studio floor! (There are ways of doing that, but it needs careful design).

Double flow CMV for air exchange. The in/out vents will each have a baffle box.
For heat/cooling a mini-split heat pump. (In France you can buy these from a hardware store and install them yourself, you just need a specialist to check the seals and insert the liquid refrigerant.)

As Glenn said: definitely get the specialist in to do the refrigerant! I have installed and even repaired mini-split systems myself, but I'll always call in the expert to do the checking and filling.

Are there other easy/cheap sound reduction additions that would be worth my while that I haven’t thought of?

Yes! A product called "GreenGlue", made by the "Green Glue Company". It isn't glue! (despite the name). You can't use it to stick your drywall to something. You just spread it between the layers of drywall, and hang the drywall in the normal way (nails or screws). It's a visco-elastic damping compound that does good stuff, and greatly increases the isolation. Here's an article I did on it: The truth about Green Glue

the ceiling is a normal MAM construction. But given that the outer leaf is still mostly protected from the elements by the porous roof, would it be wise to add insulation on top of the false ceiling?

Always! The insulation in an MSM (MAM) wall or ceiling is a critical part o the system. It provides the acosutic damping in the cavity, which is very necessary. Completely filling the air cavity but without compressing the insulation, is the best option. That gives the highest isolation. But for really deep cavities, that can be expensive. In that case, as Glenn mentioned, filling it at least half way is an alternative, as long it is at least 10cm (4") thick. And the right type!

How could I make airtight seals between the tongue and groove panels of OSB? And then between the OSB panels and the pisé walls?

Caulk. Any type of bathroom/kitchen caulk will do, as long as it remains soft and flexible even after it has fully cured. Personally, I recommend Sika 11FC, as that does a good job at a reasonable price, and seems to be available in most countries around the world. Sealing EVERYTHING is the key to good isolation. Even a tiny gap or crack that you didn't notice can have a strong negative effect on your isolation. Be very careful with your sealing!

When doubling drywall, each layer needs to be sealed with drywall mud and ideally the seams need to be staggered, correct?

Right. You can sometimes substitute caulk for mud-and-tape: it's faster to apply, and give a better seal.

My carpenter who’s helping with the framing tells me that I can’t attach drywall directly to the wood studs because the wood will warp and cause problems in the drywall. This doesn’t seem right to me - any thoughts?

I have NEVER heard of that before! Attaching drywall to wood studs is very, very VERY common. It's the way houses are built in the USA. And offices. And shops. And schools. And churches. The only reason I can think for studs to warp, is if they were not properly dried before being installed. Good quality studs should not warp after they are bought. They might already be a bit warped when you buy them (if they are low quality), but running them through a thicknesser or power plane can fix that, if it is too pronounced.

But in any case, as Glenn already said, the best idea is to put a layer of OSB, MDF or plywood on the studs first, then put your drywall on top of that, The OSB greatly increases the structural integrity of the wall, and it also means you have a nailing surface all around your room. Without that, you can't nail into drywall just anywhere: you can only nail where there is a stud. But if you have a nice thick layer of OSB on the studs (eg 19mm), then you can nail anywhere you want, without needing to find a stud.

I could conceivably build the doors with a significant air gap between them. If I built the 25cm or 50cm apart, would I actually be gaining sound reduction? What would be the ideal distance?

Yes! There's an equation for calculating that. The size of the "air gap" (distance between the two leaves of the wall) affects the resonant frequency of the wall system. Bigger gap = lower frequency, which also implies better isolation. Of course, there's an optimal distance beyond which you don't get any more benefit. 25cm would likely already be very good, assuming that you also have enough mass in the glass (thick laminated glass, rather than ordinary window glass). More mass = better isolation.

Also, would an acoustic curtain be a helpful addition between the two doors?

Maybe it might help a little tiny bit, but not enough to be worth the cost and hassle. It would be helpful at frequencies that don't need help, and not helpful at frequencies that do need it. Just use suitable thick insulation around the perimeter of the cavity between the doors.

And I realize the seals on these doors are the most important/difficult part. Is it pointless to try for more insulation, doubling drywall, or adding green glue, etc. in other parts of the construction, knowing that the double sliding glass door will get whatever isolation it gets, and can’t be improved? In other words, is sound isolation only as good as the weakest link?

It's definitely not pointless, no! But rather than reduce isolation in the rest of the room, work on increasing it for the doors!

Does anyone have any experience with the self installed mini split heat pumps? I’ve heard mixed reviews, but I figure that if it’s just for a 30m2 room and not the whole house, it might be a good option. The whole thing is about 1500€

It's not hard to do. I've done it, many times. As long as you follow the manufacturer's instructions, it's not a big deal. Mini-splits are great, but do make sure you get the right capacity for your room in your climate! For example, a 24,000 btu/hr unit might do fine for a studio located in a moderate climate where the humidity is low and temperatures don't go much over 26°C or so or much below 5°C, but would be totally inadequate for the exact same studio located in an area with high humidity where the outside temperatures are regularly over 35°C, or below -15°C. Another case: the same unit might do fine for a home hobby studio, which just has two or three people in it at a time and mostly with acoustic instruments, but do terribly for the same studio in the same climate with twenty people inside, and stacks of high-powered electric gear (big amps, stacks of speaker, lots of outboard gear, etc.).

Best advice: do the calculations to make sure the unit you are thinking of is right for you.

- Stuart -

[Almavague]

Source of the post a split unit is fine. the fresh air plan seems good - cover those holes with silencers on either side of the openings. make sure you plan on making the units serviceable for filter changes, cleaning etc. if moisture may be an issue (internally from people or externally) consider an ERV/HRV unit to both push in air and pull air out via heat exchange and filters to solve the air flow and energy efficiency.

Many thanks for the response Glenn! I actually didn't see that you had responded a while back. As it appeared on another page, I didn't know it was there!

Is there a difference between an HRV and double flow CMV? They appear to be the same thing to me. Here in France, they call them "VMC" which in English apparently is CMV. In any case, air exchange is highly necessary - point taken!

[Almavague]

And Stuart - You're the best!! Many thanks for all the clear information. I'm feeling a lot more comfortable going forward.

Just a few clarifications:

Source of the post And for the upper part of the opening, I’ll build a wood structure with OSB 3 and 15cm of wood fiber insulation panels.

Here again you will need two such walls (one for each sliding glass door). Inner leaf and outer leaf. You will also need more than just a single layer of OSB on your two leaves. You need to get a lot of mass on those walls. I'd suggest at least this: Start with a layer of 19mm OSB nailed to the studs, then put a layer of 16mm drywall over that using Green Glue in between those two. Do that for each of the two walls, to create a proper two-leaf MSM system, like this;
What is MSM? How does it work?

I think I probably miscommunicated my plans. On the outer leaf the barn door opening will be closed by the outer sliding door and above, studs and osb on the outside. The inner leaf (decoupled from the outer leaf) will be on the inside of the inner wood structure - with insulation between. Clearly, I wouldn't want to add a third leaf.

But just to clarify what you mentioned about the outer leaf - would you suggest I add drywall to this leaf? Because the outer leaf is exposed to the elements, the outer most layer would certainly be osb. If you suggest I double it (good idea!), wouldn't it make more sense to double the osb? The other way around seems odd to me (from outside to inside: osb, drywall, studs).

Source of the post The floor will be insulated with rigid wood fiber panels, and probably OSB on top.

Probably not a good idea. The bare concrete floor is an excellent surface, acoustically. If you want to make it look nicer, you could stain or polish the concrete, or use laminate flooring with an acoustic underlay... which is also good if you want to have a floor that looks nice and also feel nice to walk on, softer than concrete. But putting an OSB layer on top of joists with an air gap under it, will create a resonant chamber. Usually not a good idea for a studio floor! (There are ways of doing that, but it needs careful design).

Great info - I really didn't expect that! Clearly not doing false floor will reduce costs and add ceiling height. But what about thermal insulation? It's the same concrete slab that goes throughout the room and to the outside. I think during the winter it will remain quite cold. My the floor house (with the same basic construction) stays quite cool all year. This is nice in July and August, but is quite a negative point the rest of the year. I know that standard floor insulation here would be something thin like 10mm of cork or similar, with flooring on top (tile or laminate for example). Are there good underlays that are thermal and acoustic? Maybe I'd be better off just with rugs on the cement?

Many thanks again!!!

[Soundman2020]

But just to clarify what you mentioned about the outer leaf - would you suggest I add drywall to this leaf?

Only if you use exterior grade drywall, which is designed for that, but then still needs to be covered with exterior siding of some type. This is the stuff: https://www.americangypsum.com/products ... -sheathing But it might not be available where you are, and in any case there are good alternatives. And even then, as I mentioned, it's not the final outer surface: you still need a proper weather-resistant out layer. That could be siding, or waterproof rendering, or something else. Instead of that you could use fiber-cement board for example, which is very high mass (very dense/heavy) and can be used as the outer layer (still a good idea to seal it and paint it, though). Or you could use whatever is common in your area as the outer layer. The idea is just to get lots of mass on the studs first, then put the outer layer over that, to deal with the weather.

Because the outer leaf is exposed to the elements, the outer most layer would certainly be osb.

Even then, it still needs to be covered with something that can handle the elements. Common in the USA (and other places) is to have two layers of thick OSB on the studs, then cover that with something like Tyvek, then put up vinyl siding over that, as the final surface.

If you suggest I double it (good idea!), wouldn't it make more sense to double the osb?

You can do that, but use the highest density material that will do the job. For comparison, the density of OSB is around 600 kg/m2, the density of drywall is closer to 700 kg/m2, MDF is around 750 kg/m2, and the fiber-cement board is around 1500 kg/m2. More than twice as dense as drywall.

But what about thermal insulation?

That's why I suggested laminate flooring (sometimes also called "engineered flooring"), which is usually laid over a thin thermal underlay (2 or 3mm, commonly), but acoustic underlay is thicker and therefore warmer (5 or 6mm at least, more in some cases). Even so, if you live in a very cold climate, then you might need more substantial insulation. ...

I know that standard floor insulation here would be something thin like 10mm of cork or similar, with flooring on top (tile or laminate for example).

That would be great! Cork is an excellent thermal insulator, and also very good acoustically. Here's another option that you might be able to get in your area, or something similar. Not sure about pricing, compared to cork: https://www.ikoustic.co.uk/products/sou ... mutemat-3/ Go with whatever you can get in your area that is inexpensive. As long as it is suitable for laminate flooring, thick enough to give you the thermal insulation you need, and also designated as "acoustic" you should be fine.

- Stuart -

[Almavague]

Here's an update on the project.

Things are moving along. One issue I've run into is my false ceiling for the outer leaf. My plan was to do a suspended ceiling using threaded rods attached to the roof beams. I was hoping to follow Stuart's suggestion of doubling the layers, OSB on the upper/outside and another layer of drywall under/inside. However the threaded rods/metal studs won't support the weight. I've looked into installing a wood structure, but with the roof beams in the way, it's quite complicated and expensive. I'm considering it a no go. So I think I'm stuck with a single layer of OSB 3 15mm.

Here's my question: is there anything I can do to improve this? Don't forget, this is just the outter leaf, the inner leaf will be OSB plus a layer of drywall. Here are a couple things I could imagine:

1. insulation on top of my outer layer. So from inside to outside: drywall, osb, insulation (15cm) OSB then possible more insulation.
2. bigger airgap - I'd loose some ceiling height, but possibly loosing 5cm of ceiling height would have a neglegible effect on the acoustics of the room but a helpful effect on the sound isolation.

Any ideas?

[Soundman2020]

Source of the post One issue I've run into is my false ceiling for the outer leaf. ... Here's my question: is there anything I can do to improve this? Don't forget, this is just the outter leaf, the inner leaf will be OSB plus a layer of drywall. Here are a couple things I could imagine:

I'm not sure why you would want a false ceiling on your outer leaf. THe way you describe it, you would have an air cavity in between those to layers of the outer leaf, which would basically make it a three-leaf system (two leaves on the outer, one on the inner). Why do you need a false ceiling on that? It would be inside the MSM cavity, so it would never be seen, and it would greatly reduce the isolation, so unless there's an underlying need for it that I'm not seeing, you likely don't need that.

1. insulation on top of my outer layer. So from inside to outside: drywall, osb, insulation (15cm) OSB then possible more insulation.

Is that just your outer leaf? If so, then once again there's the issue of why you want to put the additional layer of OSB after a 15cm cavity. After you put up the inner leaf, that OSB is going to act like a third leaf, in between the other two.

Take a look at these two articles to get a better idea about why this is not a good idea, unless there's a really important underlying reason:
What is "room-in-a-room" construction?

What is MSM? How does it work?

- Stuart -

[Almavague]

Hi Stuart,

I think this is the missing piece of information: my roof (which you're thinking of as the 3rd leaf) is VERY far from being airtight. It's a tile roof, which keeps the rain out, but other than that it's like a sieve. I can see light through it. So my outer leaf is currently as such: I have my 4 walls and a floor, but the ceiling/roof in terms of sound isolation is non existant. So of the possible ways to make my roof airtight, I've decided that building a suspended ceiling with OSB is the best. And this layer cannot be doubled because of weight.

So, the question I'm trying to resolve is this: For my outer leaf I have 4 very thick walls (great!) and a concrete slab floor (also great) and my ceiling is 18mm of OSB (clearly the weakest link on this leaf). So again, I'll build a wood structure, decoupled from the outer leaf that will hold the insulation and the inner leaf. And my question is: because ceiling on my outer leaf will be the weakest link compared to the walls and floor, would it be helpful to add additional insulation above? So instead of an MAM, it would be an MAMA (mass/insulation/mass/insulation).

Does that make sense?

[gullfo]

qq: are you trying t omake the interior ceiling follow the existing roof line or make it flat? i think what i've read, you want to follow the roof line as much as possible. that large block of wood spanning your walls - do you need it for historical reasons / preservation? or could you replace it with some modern lumber (if needed structurally) like gluelam, truss, etc? that will help in the overall construction to build around it (if needed). then on the ceiling - give nthe porous nature of the tiles, you need a vented air gap there, then (likely) insulation, then a proper mass boundary (we'll call it the exterior), and an air gap (w/ insulation) and an inner mass boundary (your ceiling).

[Almavague]

Hi Glenn,

No, my intention is to have a flat ceiling. The roof structure cannot be altered, and that's one of the reasons I've decided on a flat ceiling.

But either way, if I understand what you've just said, you've suggested that under the porous roof tiles I could put insulation, a proper mass boundry (my flat ceiling), then an air gap with insulation, and the inner mass boundry.

So my original question was: Mass/Insulation/Mass/MORE INSULATION/Porous roof tiles - is this a good idea? Glenn, you're saying yes, correct?

[gullfo]

Yes

[Almavague]

Soundman2020 wrote:
Qr Bbpost The floor will be insulated with rigid wood fiber panels, and probably OSB on top.

Probably not a good idea. The bare concrete floor is an excellent surface, acoustically. If you want to make it look nicer, you could stain or polish the concrete, or use laminate flooring with an acoustic underlay... which is also good if you want to have a floor that looks nice and also feel nice to walk on, softer than concrete. But putting an OSB layer on top of joists with an air gap under it, will create a resonant chamber. Usually not a good idea for a studio floor! (There are ways of doing that, but it needs careful design).

Hi Stuart, I want to come back to this point from a while ago. I believe you were saying that a resonant chamber would be created if I had a framed floor on joists. But what I'd like to do put down a weight resistant insulation and put flooring directly on top. So no joists, no resonant "boxes", unless the whole thing would create create a resonant chamber? Certainly I'd get better acoustic and thermal isolation with this approach than just leaving the concrete floor, right?

I think this is an example of the product I'd find here in France: https://www.rockwool.com/uk/products-an ... oor-en-gb/

[Almavague]

Or perhaps cork would be a similar/better option. This link is in French, but maybe helpful
https://nature-et-developpement.com/ain ... ds-droits/