A new soundproof drum room

[Soundman2020]

It’s thinner, more dense but quite expensive and a little bit restrictive to build…

Yep! Those are, indeed, the pros and cons. About twice as dense as drywall, hence you can have half the thickness and still get the same mass. So compare it that way: is one sheet of 8mm fiber-cement board cheaper than one sheet of 16mm drywall?

I found some drywall sheet 25mm (1”) thick, 24.3kg/m².

Nice! That's not very common. Most places don't stock such thick, heavy stuff. But that will work fine.

I have a contact who could provide me sheets of oak wood, It seems to be pretty dense, 6cm thick could be enough I think without lead if it’s 1000kg/m3 or higher.

Wood is roughly 750 kg/m3, give or take about 200 (depending on type of wood). Lead is about 12,500 kg/m3. So your wood has to be seventeen times thicker. 1mm of lead = 17mm of wood, roughly. Even if you have a very dense wood, it would still need to be about fourteen times thicker... 6cm wood = roughly 3.5mm lead.

Also, compare costs. Lead is expensive, yes, but not as bad as you might think.

2.90*2.70*1.98 (25cm air space + 5cm drywall, so -30cm from each wall/ceiling). Do you think there is something to do to get a better room ratio, reduce/increase the air gap of walls or even inner room

You can probably reduce the air gap a bit. 25cm is a lot. You could probably get away with 15cm.

I was wondering if it’s really bad if I make an air gap of only 18cm (instead of 25) between the two ceilings to keep 2.05m height inside the room ?

For the ceiling, I would definitely consider reducing the gap to maybe 10cm and using an exotic sandwich of high density materials. Maybe 16mm MDF, 3mm lead sheet, 9mm fiber-cement board. That's over 65 kg/m2. Equivalent to five layers of 15mm drywall, in 28mm instead of 75. Of course, it would not be cheap! But it would gain you 19cm of height, vs. where you are now. But for that type of mass, you will need fairly large joists, to handle the high dead load.

and 2 boxes outside the room screwed on the outer leaf.

Don't attach the boxes to the leaves, if you can avoid it! Rather, support them on some type of HVAC isolation mount. Make the leaf penetration hols a few mm larger that the size of the sleeve, and pack with backer rod and caulk, to decouple as much as possible. It won't make a huge difference, but enough to be useful. If you can do 20 things as you build that each improve your isolation by just 1/2 dB, then you made a difference of 10 dB, which is major: that makes it twice as good, subjectively. Only half the as much sound gets through. Little things matter, in studio construction!

If I did understood well, boxes will be linked by two with flexible duct inside the airgap and I have to make different diameters to slow down or speed up air flow in order to stop the sound

Right. The cross-sectional area of the air flow should change suddenly by a factor of about 2 (or a half) at a couple of points.

and reinforced with those metal beam going through. In fact, those seems to be old little train rails as they are thinner and curved on top of the slab

That's an interesting way of making reinforce concrete! First time I heard of that.... I wonder if the spacing is about right for a train.... maybe that's an old tram track or something weird, that just got concreted over?

I’m actually feeling like I’m an archeologist

Maybe you'll find some buried treasure!

unless I break the slab along the future wall, but I want to have your opinion before doing anything like this

It's probably not necessary. Cutting a slab is a bigger deal than many people think. Slabs have foundations under the edges, so if you cut the slab, you remove it from the foundations! So you need to dig back under the edge of the slab where you cut it, and pour new foundations... You could do that if you really want to, but only if you are aiming for very high levels of isolation. If that's the case, it might be just as easy (and about the same cost) to properly float a new floor.... but that would eat up a lot of head room.

Here's another idea: If you break the slab out completely, you could dig down many cm, pour a new separate slab with new foundations down lower (or a coupled slab with a floated concrete floor on top), and gain even more ceiling height.... For example, if you dig down 50 cm, you could have a 10cm base slab, 10 cm air gap, floated 10cm slab, and also gain 20cm room height... It sounds like a huge job, but it might not be as bad as you think... although it would not be cheap!

I thought filling the gap with concrete, like I just did for the threshold I'm going to brick up

That would be the easiest, yes!



- Stuart -

[UndeadCrow]

Hello There

Wanted to take some time to give you some news.

I unfortunately paused the project because of a painful tendinitis I have on my right thumb... It's very frustrating, I couldn't make it move forward since I demolished the concrete wall by hand. Very wrong idea to force myself to continue despite tiredness and pain...
So for now I'm waiting for it to heal, and hope I can get back to work soon !

Meanwhile, a friend's friend architect went home and told me I should better make a thin concrete screed on the ceiling slab and should reinforce all this slab with two 10cm 'I' shaped metal beams (perpendiculary to the train rails). In fact, those train rails have been concreted in between, but not enought to cover it over completly (the top of the rails exceed a little the top of the slab). I think I'm going to do so.

Don't attach the boxes to the leaves, if you can avoid it! Rather, support them on some type of HVAC isolation mount. Make the leaf penetration hols a few mm larger that the size of the sleeve, and pack with backer rod and caulk, to decouple as much as possible. It won't make a huge difference, but enough to be useful

I'm not sure I understand the very right way to do it decoupled from the walls

It's probably not necessary. Cutting a slab is a bigger deal than many people think. Slabs have foundations under the edges, so if you cut the slab, you remove it from the foundations! So you need to dig back under the edge of the slab where you cut it, and pour new foundations... You could do that if you really want to, but only if you are aiming for very high levels of isolation. If that's the case, it might be just as easy (and about the same cost) to properly float a new floor.... but that would eat up a lot of head room.

Here's another idea: If you break the slab out completely, you could dig down many cm, pour a new separate slab with new foundations down lower (or a coupled slab with a floated concrete floor on top), and gain even more ceiling height.... For example, if you dig down 50 cm, you could have a 10cm base slab, 10 cm air gap, floated 10cm slab, and also gain 20cm room height... It sounds like a huge job, but it might not be as bad as you think... although it would not be cheap!

In fact, there is no foundations under this part of the house, that's an old construction, with wall directly right on the ground (that explain the damp you saw on the lower part of the walls), and the ground has been concreted in between the walls. But I'm not very confortable with the idea of breaking it out completely. It's sounds like it would have been better to demolish this entire outbuilding to start a new one from scratch with true foundations, good walls and everything, but it's too big for myself and my wallet . I'm gonna go with what I have.

[Soundman2020]

I unfortunately paused the project because of a painful tendinitis I have on my right thumb... It's very frustrating, I couldn't make it move forward since I demolished the concrete wall by hand. Very wrong idea to force myself to continue despite tiredness and pain... So for now I'm waiting for it to heal, and hope I can get back to work soon

OUCH! I certainly understand that, to a certain extent. I've had that in my wrist and arm, once or twice. Not pleasant!

architect went home and told me I should better make a thin concrete screed on the ceiling slab and should reinforce all this slab with two 10cm 'I' shaped metal beams

Sounds like a good plan! As long as it is safe to do that, and meets your local building regulations, then that would certainly help.

wall directly right on the ground (that explain the damp you saw on the lower part of the walls

oops! That's a problem that you must be very certain has been fixed before you can build your inner leaf. If there's any chance at all that the damp might return, then that would not be good....

It's sounds like it would have been better to demolish this entire outbuilding to start a new one from scratch with true foundations, good walls and everything,

Yep! That probably would have been better. But it is what it is, and as long as there's no damp in the walls or slab, and it can support the load of the studio safely, then that will work fine.

- Stuart -

[UndeadCrow]

Hello there ! Here are some news and photos ! It’s not moving forward very fast, but it’s moving, this is something !
Stuart, if you remember, you suggested me :

It's probably not necessary. Cutting a slab is a bigger deal than many people think. Slabs have foundations under the edges, so if you cut the slab, you remove it from the foundations! So you need to dig back under the edge of the slab where you cut it, and pour new foundations... You could do that if you really want to, but only if you are aiming for very high levels of isolation. If that's the case, it might be just as easy (and about the same cost) to properly float a new floor.... but that would eat up a lot of head room.
Here's another idea: If you break the slab out completely, you could dig down many cm, pour a new separate slab with new foundations down lower (or a coupled slab with a floated concrete floor on top), and gain even more ceiling height.... For example, if you dig down 50 cm, you could have a 10cm base slab, 10 cm air gap, floated 10cm slab, and also gain 20cm room height... It sounds like a huge job, but it might not be as bad as you think... although it would not be cheap!

I had to remove the inconvenient gas hose you saw on page 1, I thought to cut a trench in the slab to no have it in my air space anymore.

By cutting it, I just find out the ground slab is very thin, about 5 maybe 7 cm on a gravel and debris bed and is quite friable... No way I can bulid a wall, or inner leaf on that !

Gashose.jpg

As this slab has been made between the wall without foundations under it and without steel reinforcements, I’m thinking about breaking it out entirely as you suggested.
After that, I think I will:
- Dig foundations for the new central wall about 50cm deep, concrete for 25 cm height and 40 cm width with steel reinforcement.
- Bulid the wall over it (20*20*50 plain concrete blocks) that will carry “I” shaped metal beams for the load of the ceiling slab
- Dig 15cm for slab foundation against the 4 walls
- Inject damp protection resin in the walls that need it
- Put a damp sheet protection
- Place steel reinforcements
- Concrete for 15 cm (30 to the edges of the walls for slab foundations)


But before doing that or anything else, I have some other things to do… like reinforce the roof’s woodwork, the one an artisan just renovated the entire roofing in november… According to some experts who saw his work, he made several mistakes, not critical ones, but enough to need some prompt reinforcements. I can’t claim anything without lawsuit, which told by a lawyer is illusory. Not very lucky on that one !
Planed next weeks !

roof.jpg

Once done, I will break the wall and after do what I said above.

After that, I’ll still need to :
- Brick up one door and the window
- Put a thick layer of cement-based plaster on the cement-hollow brick wall (that looks damp)
- Place the “I” shaped metal beams to carry the ceiling’s slab load
- concret a screed for 3 cm over the ceiling slab to thicken and seal it
After all of this, I will be able to start the inner leaf !

When I started this project, I was far, far from thinking about that huge work needed to be done ! I’m learning the hard way, but it’s challenging ! Let’s continue to push this forward !

Rooms.jpg

[jeescobarc]

Hello there ! Here are some news and photos ! It’s not moving forward very fast, but it’s moving, this is something !
Stuart, if you remember, you suggested me :

It's probably not necessary. Cutting a slab is a bigger deal than many people think. Slabs have foundations under the edges, so if you cut the slab, you remove it from the foundations! So you need to dig back under the edge of the slab where you cut it, and pour new foundations... You could do that if you really want to, but only if you are aiming for very high levels of isolation. If that's the case, it might be just as easy (and about the same cost) to properly float a new floor.... but that would eat up a lot of head room.
Here's another idea: If you break the slab out completely, you could dig down many cm, pour a new separate slab with new foundations down lower (or a coupled slab with a floated concrete floor on top), and gain even more ceiling height.... For example, if you dig down 50 cm, you could have a 10cm base slab, 10 cm air gap, floated 10cm slab, and also gain 20cm room height... It sounds like a huge job, but it might not be as bad as you think... although it would not be cheap!

I had to remove the inconvenient gas hose you saw on page 1, I thought to cut a trench in the slab to no have it in my air space anymore.

By cutting it, I just find out the ground slab is very thin, about 5 maybe 7 cm on a gravel and debris bed and is quite friable... No way I can bulid a wall, or inner leaf on that !

Gashose.jpg

As this slab has been made between the wall without foundations under it and without steel reinforcements, I’m thinking about breaking it out entirely as you suggested.
After that, I think I will:
- Dig foundations for the new central wall about 50cm deep, concrete for 25 cm height and 40 cm width with steel reinforcement.
- Bulid the wall over it (20*20*50 plain concrete blocks) that will carry “I” shaped metal beams for the load of the ceiling slab
- Dig 15cm for slab foundation against the 4 walls
- Inject damp protection resin in the walls that need it
- Put a damp sheet protection
- Place steel reinforcements
- Concrete for 15 cm (30 to the edges of the walls for slab foundations)


But before doing that or anything else, I have some other things to do… like reinforce the roof’s woodwork, the one an artisan just renovated the entire roofing in november… According to some experts who saw his work, he made several mistakes, not critical ones, but enough to need some prompt reinforcements. I can’t claim anything without lawsuit, which told by a lawyer is illusory. Not very lucky on that one !
Planed next weeks !

roof.jpg

Once done, I will break the wall and after do what I said above.

After that, I’ll still need to :
- Brick up one door and the window
- Put a thick layer of cement-based plaster on the cement-hollow brick wall (that looks damp)
- Place the “I” shaped metal beams to carry the ceiling’s slab load
- concret a screed for 3 cm over the ceiling slab to thicken and seal it
After all of this, I will be able to start the inner leaf !

When I started this project, I was far, far from thinking about that huge work needed to be done ! I’m learning the hard way, but it’s challenging ! Let’s continue to push this forward !

Rooms.jpg

im really without words about your work. congratz!!! keep us tuned about your proyect