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Garden timber studio - walls

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Re: Garden timber studio - walls

Postby jmch » Mon Oct 29, 2018 1:28 pm

James Perrett wrote:
jmch wrote:What will the exterior roof need to be? My budget definitely won't stretch to a concrete roof. James, if I tile the exterior roof and put acoustic plaster board under the rafters, with a gap before the interior double board ceiling:
- will that be enough mass to match the block walls?
- won't there be another air gap between the board under the rafters and the tiled roof (the 3 leaf set up?)

That roof construction is exactly what I have here - using fairly substantial tiles. It won't quite match the block walls but on mine there's a bigger air gap between the layers which helps. The larger air gap also reduces the effect of the 3 leaves and, most importantly in my case, allows for thick roof joists to ensure that the inner ceiling wouldn't bend too much if I found that I had to use 3 layers of heavy plasterboard.

James, I'm going to copy your roof set up. Is the void of your roof ventilated? Does it need to be?

James Perrett wrote:
jmch wrote:Also, on the exterior block walls, my builder is talking about putting batons on the outside of the block, and putting the timber cladding on them. Will the gap between the block and the cladding matter? Should I insulate that?

My biggest worry would be the outer cladding resonating with the vibrations coming through the wall and therefore radiating more noise to the outside world than the wall alone. I'd suggest some kind of damping material behind the cladding although I'm not sure exactly what material to suggest as you also need air circulation behind the cladding to prevent damp patches.

It looks like we're going to seal and paint the exterior block wall rather than clad it. Although it won't look the prettiest, I guess that takes away the risk of resonance. What do you think?
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Re: Garden timber studio - walls

Postby James Perrett » Mon Oct 29, 2018 3:08 pm

If you are using a breathable membrane under the tiles then I don't think that the roof needs any additional ventilation (but I'm not a roofing expert). I made sure that any insulation was at least 100mm clear of the membrane to allow air to circulate.

I have render over the blocks which seems fine.

Cheers,

James.
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Re: Garden timber studio - walls

Postby jmch » Mon Oct 29, 2018 3:21 pm

OK mate, thanks for that.

John

James Perrett wrote:If you are using a breathable membrane under the tiles then I don't think that the roof needs any additional ventilation (but I'm not a roofing expert). I made sure that any insulation was at least 100mm clear of the membrane to allow air to circulate.

I have render over the blocks which seems fine.

Cheers,

James.
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Re: Garden timber studio - walls

Postby jmch » Wed Nov 14, 2018 5:14 pm

Guys

My outer block walls (no longer timber as posted previously) and outer roof are now pretty much done. I'm turning my attention towards ventilation (not having a/c at least for now).

The plan is to have and one in and one out vent above the door with ducting laid in the roof cavity (surrounded by fluffy insulation) and then coming down through the inner ceiling (double fire board green glued together with RW3 on top).

The intention is to to have home made baffle boxes mounted at the top of the internal walls so that the ducting feeds straight from the ceiling into them and then out. (I wasn't planning to have any on the outside.)

Some questions I have:

1. How will having these baffle boxes wall mounted affect the acoustics? I was going to have them away from the corners as I envisaged bass traps in the corners. If they were central on opposite walls, would that work?

2. Will it matter that both the inlet (passive) and outlet (fan) were both high on the walls?

3. The idea is to put the electric extraction fan at the outer block wall in the roof space rather than nearer to the inner room, to reduce noise. Does this make sense?

4. Should I consider some sort of humidity detector which would kick start the fan when needed even if I'm not there?

5. Can anyone recommend a good fan based for my space of 36 cubic metres?

6. Should I be going for an HRV unit? If so, can anyone recommend one?

Thanks on this.

John
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Re: Garden timber studio - walls

Postby James Perrett » Wed Nov 14, 2018 6:17 pm

I've not used baffle boxes - just long lengths of acoustic ducting (the use of acoustic ducting is important) snaked around the roof space. The fan that I used was the 125mm one at

http://www.fantronix.com/acatalog/TT_Mi ... t_Fan.html

It isn't particularly quiet so mount it away from anywhere that you want to be quiet. I have both inlets and outlets in the ceiling.

I use a plug-in temperature controller with a convector heater to prevent condensation - I've set it so that the temperature doesn't go below 12 degrees (most bits of kit seem to specify 10 degrees as the minimum operating temperature so 12 degrees seems sensible). I'll bypass the temperature control when I need the studio warmer.
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Re: Garden timber studio - walls

Postby Wonks » Wed Nov 14, 2018 6:29 pm

Baffle boxes are good if you make them so that the pathway has a lot more cross-sectional area than the ducting feeding the baffles box. This reduces the air velocity so allows more of the sound energy to be absorbed by the materials in the baffle box over the air's transit time through the baffle. Standard ducting doesn't absorb much sound, so baffles/silencers are a good idea if you have the space to fit them in.
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Re: Garden timber studio - walls

Postby Sam Spoons » Wed Nov 14, 2018 7:41 pm

Tony335 has built his own in his major studio build https://www.soundonsound.com/forum/viewtopic.php?f=24&t=43047 about halfway down page 5
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Re: Garden timber studio - walls

Postby jmch » Wed Nov 14, 2018 8:21 pm

James Perrett wrote:I've not used baffle boxes - just long lengths of acoustic ducting (the use of acoustic ducting is important) snaked around the roof space. The fan that I used was the 125mm one at

http://www.fantronix.com/acatalog/TT_Mi ... t_Fan.html

It isn't particularly quiet so mount it away from anywhere that you want to be quiet. I have both inlets and outlets in the ceiling.

I use a plug-in temperature controller with a convector heater to prevent condensation - I've set it so that the temperature doesn't go below 12 degrees (most bits of kit seem to specify 10 degrees as the minimum operating temperature so 12 degrees seems sensible). I'll bypass the temperature control when I need the studio warmer.

Thanks James. Sounds good.

Do you use the humidity sensor on the fan you recommended?

And do you use just the one fan to extract air, or bring it in?

John
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Re: Garden timber studio - walls

Postby jmch » Wed Nov 14, 2018 8:22 pm

Wonks wrote:Baffle boxes are good if you make them so that the pathway has a lot more cross-sectional area than the ducting feeding the baffles box. This reduces the air velocity so allows more of the sound energy to be absorbed by the materials in the baffle box over the air's transit time through the baffle. Standard ducting doesn't absorb much sound, so baffles/silencers are a good idea if you have the space to fit them in.

Cheers Wonks.

Daft question perhaps but does the ducting go through the baffle boxes, or does the ducting run to the baffle box and then just the air goes through the box?

Thanks

John
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Re: Garden timber studio - walls

Postby Wonks » Wed Nov 14, 2018 11:36 pm

Ducting runs to the box, air goes through the baffle box and then ducting on the outlet side of the box.

You would probably want the fan to run under manual control. As long as you can maintain a minimum temperature inside the studio with heaters, there shouldn't be any problem with condensation. Relative Humidity stats (or Humistats) have very poor accuracy. You'd probably have to set them well below the ideal setting to ensure the fan did come on when it should. But to be humid inside then it's probably more humid outside and there's the risk that you end up pulling in more humid outside air that just makes the situation worse. There should be no source of humidity in the unoccupied studio (unless you install a water feature), so the amount of moisture in the space shouldn't vary that much, and the %RH will rise as the temperature falls, and fall as the temperature rises. So don't let the temperature fall too far, and you should be OK.

There are times when you could use outside air to reduce internal relative humidity, but if the temperature in the studio drops too far, then you will get condensation issues regardless. So keeping the studio above a minimum temperature is paramount. To be safe, especially with electronic equipment inside, I'd say 14°C.

You could use far more accurate %RH sensors, internal and external, plus internal and external temperature sensors connected to a programmable control system, but that really is over the top for your needs.

You only really need the fan on for ventilation when using the studio. But unless you manage to get a near-silent fan and use large diameter ducting to reduce air velocities, then there will be times, like recording vocals, that you will want it off. So manual control is by far the easiest method.

It would be best to introduce the intake air low down, as natural convection will then assist the ventilation system, but you can simply run a bit of ducting down the wall if you have to make openings at high level.
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Re: Garden timber studio - walls

Postby James Perrett » Thu Nov 15, 2018 1:47 am

jmch wrote:
Do you use the humidity sensor on the fan you recommended?

And do you use just the one fan to extract air, or bring it in?

As Wonks says, you shouldn't have any problems with humidity provided you use some kind of background heating to prevent the temperature from going too low.

I actually have 4 100mm inlets from the outside going to different parts of the studio and there are 4 corresponding outlets which are combined into one fan. Most of the time with just one or two people in the studio there seems to be enough airflow without running the fan. I only tend to use it when there's a whole band in.
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Re: Garden timber studio - walls

Postby jmch » Thu Nov 15, 2018 11:37 am

Wonks wrote:Ducting runs to the box, air goes through the baffle box and then ducting on the outlet side of the box.

You would probably want the fan to run under manual control. As long as you can maintain a minimum temperature inside the studio with heaters, there shouldn't be any problem with condensation. Relative Humidity stats (or Humistats) have very poor accuracy. You'd probably have to set them well below the ideal setting to ensure the fan did come on when it should. But to be humid inside then it's probably more humid outside and there's the risk that you end up pulling in more humid outside air that just makes the situation worse. There should be no source of humidity in the unoccupied studio (unless you install a water feature), so the amount of moisture in the space shouldn't vary that much, and the %RH will rise as the temperature falls, and fall as the temperature rises. So don't let the temperature fall too far, and you should be OK.

There are times when you could use outside air to reduce internal relative humidity, but if the temperature in the studio drops too far, then you will get condensation issues regardless. So keeping the studio above a minimum temperature is paramount. To be safe, especially with electronic equipment inside, I'd say 14°C.

You could use far more accurate %RH sensors, internal and external, plus internal and external temperature sensors connected to a programmable control system, but that really is over the top for your needs.

You only really need the fan on for ventilation when using the studio. But unless you manage to get a near-silent fan and use large diameter ducting to reduce air velocities, then there will be times, like recording vocals, that you will want it off. So manual control is by far the easiest method.

It would be best to introduce the intake air low down, as natural convection will then assist the ventilation system, but you can simply run a bit of ducting down the wall if you have to make openings at high level.

Thanks for this Wonks.

I take your points re the humidity sensor and manual control. My builder has already recommended I get an thermostatic electric heater and use it to maintain a minimum temperature.

We've also talked about modifying the baffle boxes inside so that one of them will run down the length of the wall and take the incoming air into the room near ground level. I was wondering (perhaps unnecessarily?) about the need to maintain symmetry in the room for acoustics.. so would both baffle boxes - on opposite walls - ideally need to be made the same?

Cheers

John
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Re: Garden timber studio - walls

Postby jmch » Fri Nov 23, 2018 2:46 pm

Quick question guys. What's the consensus on this specific question:

Do I leave the 750mm gap between my two leafs as empty void, or put soft insulation in there?

To recap,
Outer leaf:
Walls - concrete block sealed on both sides
Roof - 2 layers of OSB on top of joists with 1 layer of plaster board and 100mm RW3 insulation between the joists

Inner leaf:
1 layer of OSB then 2 layers of fireboard with green glue between. Both fixed to a timber frame with 100mm RW3 slabs between the batons.

Thanks
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Re: Garden timber studio - walls

Postby James Perrett » Fri Nov 23, 2018 9:43 pm

I'd say that you can leave it empty as you already have the RW3 on one side of the cavity.
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Re: Garden timber studio - walls

Postby jmch » Fri Nov 23, 2018 11:43 pm

James Perrett wrote:I'd say that you can leave it empty as you already have the RW3 on one side of the cavity.

Thanks James. My gap is actually only 75mm not 750mm!

Is it preferable to leave it empty, do you think?

John
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Re: Garden timber studio - walls

Postby James Perrett » Sat Nov 24, 2018 1:52 am

I thought 750 seemed a bit excessive!

Yes, you've already got 100mm of fairly dense Rockwool in there which certainly should be enough to stop sound bouncing around in the cavity.
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Re: Garden timber studio - walls

Postby jmch » Sat Nov 24, 2018 8:30 am

James Perrett wrote:I thought 750 seemed a bit excessive!

Yes, you've already got 100mm of fairly dense Rockwool in there which certainly should be enough to stop sound bouncing around in the cavity.

Thanks. I should have said but the reason I'm asking is that I have a load of the soft insulation which I got for free. And my builder is recommending I put it in the gap. Will it help or could it actually hinder?
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Re: Garden timber studio - walls

Postby Sam Spoons » Sat Nov 24, 2018 11:31 am

I don't think it will affect sound transmission either way but it should increase heat insulation. Whether that is good or not depends but my studio is never too cold with the gear switched on and a few live bodies in there. Ventilation between the walls will be less efficient if it's filled with insulation so condensation on the outer wall might be an issue.
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Re: Garden timber studio - walls

Postby James Perrett » Sat Nov 24, 2018 3:01 pm

If you are planning on having any corner bass traps then the soft insulation would make a good filling for those behind the more dense Rockwool face.

I'd be a bit worried about blocking air circulation if you filled the wall cavities completely with it.
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Re: Garden timber studio - walls

Postby Studio Support Gnome » Sun Nov 25, 2018 2:43 pm

Probably late to the party for ventilation....


use inline mixed flow impeller fans, such as the S&P TDS/turbo silent.... or Airflow Aventa Silent ,


or,

your query about heat recovery.;


it's probably overkill..... but you could use a small MVHR unit , but it will involve more work and space than an inline fan ....

(they also require a condense drain, ducting in and out of building and ducting in and out of room....

but they will remove any condemnation issues with moist air, and reduce the amount of energy needed to heat / keep stable thermally...

but do note they are intended to be run 24/7, not turned on and off at will.

I can point at the Airflow developments DV72 as an entry level unit , and the fact that airflow, like many others do assorted baffle systems and distribution systems with acoustic attenuation built in...

it should be noted that your ventilation requirements ought to be in the region of 10-12 air changes per hour as a normal running rate..... CIBSE guide B puts that asa typical figure for use in a recording studio, (control rooms are separately listed, and i think offhand quote at around 12-14 ACH , but my copy of the specific table is at work and I'm at home.... )


I can also point out that these days..... I design ventilation and heat recovery systems...... For Airflow Developments..... consequently I should also add that other manufacturers also do similar products..... and that ours are not necessarily the cheapest.... (but for the acoustic in line fans, even before I worked here... I used only S&P or Airflow products for the ratio of performance and reliability vs cost..... _ )
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