Mixing studio in England

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mixer76
Posts: 1
Joined: Sat Jul 25, 2020 5:38 pm
Location: England, UK

Mixing studio in England

Post by mixer76 »

Hello everyone,

I’m planning to build a single room studio at the end of my garden from the ground up. As I have no prior construction experience I’m looking to see if I’m on the right track with my plan, and there’s some questions I have that I’ve summarised at the end.

Purpose

The room will only be used for mixing (mostly pop, hip hop, electronic music), with myself working alone 95% of the time.

The main goal is for the room to have enough isolation not bother the neighbours (and vice versa), and for me to be able to make mix’s that translate well. Current situations have recently forced me to work out of a small spare bedroom so ultimately anything that’s an improvement on that is welcome!

Equipment inside will be fairly minimal as I mix in the box, so will be just a Mac, audio interface, 2 (maybe 3) pairs of monitors, and monitor controller. Furniture wise again will be minimal; likely a desk, chair, maybe a small sofa for the back of the room. There will of course be acoustic treatment as well. Once the build of the room is finished I plan to use the room EQ wizard software to help determine what treatment is needed, but for now I’m mostly focusing on the build.

Isolation Requirements

I’ve been taking outside level readings at the property line using a Extech 407730 meter set on dBC slow. The lowest reading I’ve taken was 52dBC and the highest reading was around 71dBC (this was very brief when a car with loud sub drove by). On average the level seemed to be hovering around 56dBC.
When I’m mixing the level I’m monitoring at is metering around 76dBC.

The Extech meter has an accuracy of 2db so to be on the safe side lets say the lowest outside reading is 50db and I’ll say my monitoring level is 78db. I believe this means I’ll be looking for around 28dB of isolation. Is that about right? That doesn’t seem like lots but as I mix a lot of bass heavy genres I’ll need that isolation down to the low end. To note the studio will be 1m from the property line and the nearest house is 15 meters away so I’m guessing that will also give a little more isolation.

Also according to the UK government's website permitted noise levels in the UK are 34 dBA if the underlying level is no more that 24dBA, and 10dBA above the underlying level of noise if this is more than 24 dBA. I’m not sure how this would factor into my calculations though as it’s in dBA not dBC.

The Construction Plan

After reading various books, such as Rod Gervais’, various posts on this forum, and discussing back and forth with my builder (he’s just a regular builder not a studio one) this is what we’ve come up with;

Floor

Going for an insulated floor. We’ll be digging down so that we lose minimal ceiling hight;
• Earth
• Damp proof membrane
• 75mm thick Celotex insulation board
• 100mm thick Concrete - Once poured this will take us to ground level
• 50mm thick Screed Floor
• Underlay
• 20mm Laminate Flooring

Walls

Outer Leaf;
• Rendering or Hardie Plank cladding - Hardie plank will look a lot better but I’m worried it will create an extra air gap therefore creating a triple leaf. Am I correct in thinking this?
If we go with Hardie Plank it will then be;
• 18mm Timber Battens
• Breathable membrane
• 18mm thick OSB3 board (10.8Kg/m2)
• 18mm thick OSB3 board (10.8Kg/m2)
If instead we render (which is the way I’m leaning to) it’ll go straight to;
• 18mm thick OSB3 board (10.8Kg/m2)
• 18mm thick OSB3 board (10.8Kg/m2)
Total Mass - 21.6Kg/m2

Air Gap;
• 100mm x 47mm timber studs (16” OC) - this will be attached to the OSB. Just to note I’ve checked with the builder 100mm x 47mm is the dry measurement
• 100mm thick Isover Hi-Cav CWS glass mineral wool insulation (48Kg/m3) - this will fill the gap in the timber studs
• 41mm Genie Clip RST isolation clips and furring channel - Does the 41mm gap this creates need to be filled with insulation?
Total air gap - 141mm

Inner Leaf;
• 15mm thick British Gypsum Gyproc SoundBloc F (14.1Kg/m2) - this will be attached the the furring channel on the isolation clips
• 9mm thick Plywood (5.8Kg/m2) - this is so I can hang panels anywhere
• 15mm thick British Gypsum Gyproc SoundBloc F (14.1Kg/m2)
• Plaster and paint finish
Total mass - 34Kg/m2

Using the TL calculator spread sheet (thanks to Gregwor and audiomutt for creating this great tool) this wall construction (assuming I go with rending instead of Hardie) gives me;
TL of leaf 1 - 32.37
TL of leaf 2 - 35.23
F0 (empty cavity) - 43.97
F0 (insulated cavity) - 31.52
F1 - 390.07

Here’s the TL with insulation graph;
Wall TL graph.png
Ceiling

Going for a flat roof with a slight fall. We’ve tried to keep the construction similar to the walls so that the results aren't too different.

Outer leaf;
• 3 layer roof felt
• 18mm thick OSB3 board (10.8Kg/m2)
• 18mm thick OSB3 board (10.8Kg/m2)
Total Mass - 21.6Kg/m2

Air Gap;
• 75mm to 0mm tapered timber furring piece - this is to give the roof a slight fall.
• 150mm x 47mm timber ceiling joists (16” OC) - these will be going across the length and connecting into to a steel beam (that will be going across the width) to break the span. Will the steel beam cause any problems for isolation?
• 150mm thick Isover Hi-Cav CWS glass mineral wool insulation (48Kg/m3) - this will fill the gap in the timber joists
• 41mm Genie Clip RST isolation clips and furring channel - Same question as wall; does the 41mm gap this creates need to be filled with insulation?
Total air gap - 191mm (excluding the tapered furring)

Inner Leaf;
• 15mm thick British Gypsum Gyproc SoundBloc F (14.1Kg/m2) - this will attach the the furring channel
• 9mm thick Plywood (5.8Kg/m2) - this is so I can hang panels anywhere
• 15mm thick British Gypsum Gyproc SoundBloc F (14.1Kg/m2)
• Plaster and paint finish
Total mass - 34Kg/m2

Using the TL calculator this ceiling construction gives me;
TL of leaf 1 - 32.37
TL of leaf 2 - 35.23
F0 (empty cavity) - 37.78
F0 (insulated cavity) - 27.07
F1 - 287.96

Here’s the TL with insulation graph;
Ceiling TL graph.png
Dimensions

The max external dimensions that I’m allowed (I have planning permission granted for this) are;
H - 3m
W - 4.22m
L - 6m

This will give me interior dimensions of;
H - 2.575m
W - 3.758m
L - 5.538m

I’ve put this into both the Amroc and Bob’s Gold calculators and the results seem good;
Ratio - 1:1.45:2.15
Falls within the bolt area
Close to M. M. Louden: 1971: 4th best ratio" 1 : 1.5 : 2.2
1.1w / h < l / h < ((4.5w / h) - 4): Pass
l < 3h & w < 3h: Pass
No integer multiple within 5%: Pass
Bonello plot seems reasonably smooth
Volume - 53.59m3
Floor area - 20.8m2

Overall I think this construction is the best use of the area I have to work with as it's just about big enough to use as a good starting point to treat, and also give's me the isolation I’m looking for. The volume is above 47m3, which I believe is the bear minimum for a good room, and the floor area is just above the recommended 20m2. As the TL graphs shows the wall (using the wall as its TL is slightly weaker than the ceiling) should get 31db TL at 80Hz and 24db TL at 63Hz. This should mean I get my required 28db TL down to around 71Hz. Given the studio will be 1 meter from the property line and the nearest house is about 15 meters away I think this should give me enough isolation not to annoy the neighbours. Am I on the right track with this?

Door

I already have a spare unused door that I’m planning to use for the outer leaf. It’s a RockDoor Ultimate Arcacia 50mm (44mm rigid core) thick composite door. It’s considered one of the best doors for security and durability which is important as being in the outer leaf it’ll be exposed to elements. As it was initially intended to be used as a house front door it does have a letter box and small glazed window but I’m told these can be taken out and filled in.

Unfortunately I’m unable to find out the doors exact weight. When I spoke to the manufacture they said they don’t weigh individual doors but on average there doors weigh around 60Kg which would give me a mass of 31.81Kg/m2 so I’ll have to work off that. Given the total mass of the wall is 55.6Kg/m2 this means to match I need to find a door for the inner leaf with a mass of at least 23.79Kg/m2. I’m probably going to look for a solid core fire door for this duty.

Window

I know it’s not ideal but after spending many years working in windowless studios I’ve decided to put in a small window in. Plan is to use thick laminated glass in both leafs. If we can source we’ll use glass with an acoustic PVB interlayer. Once I get the weight of the glass we’re going to use I’ll calculate what we need to match the mass of the wall.

Electrics

Going for a surface mounted plastic trunking system for the sockets and switches. For lights I’m planning to go for LED track lighting.

HVAC

This is the area I’m struggling with the most. The more reading up I do the more it goes over my head!

Initially my plan was to go for a Daikin Ururu Sarara split unit as it also provides fresh air. But as this unit doesn’t deal with getting the stale air out I’m not sure it’s the simple all in one solution I was hoping for. I’m presuming opening the door say every hour or so (I’ll be doing this to go outside for ear breaks and go into the house to get water, eat etc) doesn’t do anything to get the stale air out. I’ve also read mixed reviews in general about the Daikin unit so I’m not sure if it’s right the way to go. Does anyone have any experience with this unit and would recommend it? Or is it easier just to go with a mini split and separate ventilator?

Think the best way forward may be for me to speak to a specialist about what would be the best solution and how it’ll be incorporate into the build to make sure the isolation is maintained. Can anyone recommend any UK based HVAC installers with experience in studio installation?

Questions summary

Will having Hardie Plank cladding create a triple leaf effect?

Am I right to be aiming for 28dB of isolation?

Do I need to fill the 41mm air gap that’s made by using the Genie isolation clips with insulation?

Will having the timber ceiling joists connected to a steel beam affect the isolation?

Have I got the right idea with the wall and ceiling construction and the results they’ll give me for isolation?

Would anyone recommend the Daikin Ururu Sarara air con unit?

Any UK based studio HVAC installer recommendations?

Are the other areas I need to consider or anything I'm missing?


I hope all of this makes sense! I look forward to hearing what everyone thinks of the plan.

Many Thanks,
Matt
DanDan
Senior Member
Posts: 637
Joined: Tue Mar 25, 2008 3:31 am
Location: Cork Ireland
Contact:

Re: Mixing studio in England

Post by DanDan »

I am not a Builder so I hope others will join in.

Questions summary

Will having Hardie Plank cladding create a triple leaf effect?

DD- Not sure what that is, but it sounds like a non contiguous layer, with air leaks, so I don't think so.

Am I right to be aiming for 28dB of isolation?

DD- Isolation or indeed almost any sound issue needs to be viewed as a spectrum. Bass is very difficult to contain, or keep out.

Do I need to fill the 41mm air gap that’s made by using the Genie isolation clips with insulation?

DD- always fill the Gap in a Mass Air Mass system. A full light fill is best. The cheapest Acoustic or Partition Rolls do the job here exactly as well as expensive high density batts. Unfortunately fibre insulation is thermally only about 1/3 effective compared to the hard PUR stuff, which has no acoustic benefit! You may need both.

Will having the timber ceiling joists connected to a steel beam affect the isolation?

DD- to be honest there is too much detail to get into properly, and I am not best qualified. But a thought. Plasterboard is generally regarded as the cheapest Mass.
Waka
Senior Member
Posts: 408
Joined: Sat May 20, 2017 7:47 am
Location: Lincolnshire, UK

Re: Mixing studio in England

Post by Waka »

Hi Matt,

Welcome to the forums! It's good to see another English garden studio!

You may find my own studio build helpful in your design. Mine is also a timber framed single room garden studio in sunny England! You can find my build thread here: http://johnlsayers.com/phpBB2/viewtopic ... 10&t=21269

I'll try and help you with your questions:
mixer76 wrote:Will having Hardie Plank cladding create a triple leaf effect?
It will, but that's not likely to matter. I looked up Hardie Plank and it seems to be a fibre cement board material. The additional mass will more than likely account for a third leaf effect. I would not count it in any transmission loss calculations (until Greg brings out a three leaf calculator!), just take the extra mass as a bonus.
mixer76 wrote:Am I right to be aiming for 28dB of isolation?
Like you said, legally you can be 10dBA above the ambient levels in dBA at the nearest boundary. So take a measurement using A weighting at the boundary at the quietest time of day. This is your legal responsibility. Measuring in dBC is better for our purposes practically, but the council doesn't care about that.

As DanDan said, your isolation will be easy achive at higher frequencies, but lower frequencies are more difficult.

I don't think that Greg's calculator will be able to give you a good guide as to your theoretical transmission loss I'm afraid, as it assume that you have decoupled walls (aka. room within a room construction). I would play it safe and assume 10dB less effective isolation at all frequencies (especially lows!), to account for the realities of construction and partially decoupled design using genie clips.
mixer76 wrote:Do I need to fill the 41mm air gap that’s made by using the Genie isolation clips with insulation?
As DanDan said, lightly fill (do not compact!) all gaps with low density insulation - loft roll is good, if you can get it to stay in place. I used insulation netting stapled to the studs.
mixer76 wrote:Will having the timber ceiling joists connected to a steel beam affect the isolation?
The steel beam will just be part of your outer roof construction, correct? If so, it should be fine. If you can seal it and lightly fill insulation in the entire air cavity, you shouldn't have an issue.
mixer76 wrote:Have I got the right idea with the wall and ceiling construction and the results they’ll give me for isolation?
The results will be less than Greg's calculator predicts. Remember the calculator is the theoretical transmission loss in an ideal hermetically sealed box. You will have HVAC ducts and doors/windows, so you won't reach those numbers.

Your design seems fine for low-ish isolation (you only need 28dB) so you shouldn't have any issues reaching that.
mixer76 wrote:Would anyone recommend the Daikin Ururu Sarara air con unit?
Like you say, if it can't exhaust stale air then it's not a solution for a sealed room. Opening the door every hour or so might work, but I wouldn't bank on it.
You could either do what I did, a fan for ventilation or ERV (including the usual silencers) and a split system, or go for a ducted HVAC unit which actually does do it all, but the units tend to cost around twice as much.
mixer76 wrote:Any UK based studio HVAC installer recommendations?
I got 3 quotes and went with the most reasonable guy who listened when I mentioned specific needs with regards to studio isolation. Eg. offset pipework running between my leaves to prevent the holes lining up. You may not need to go this level of detail though with your low isolation requirements.

The key issue I had: Do not let them drill a hole so big that they also feed the foam pipe insulation sleeve through the hole. I had to make this very clear. They usually just drill a big hole and stuff the pipes through it, foam insulation and all. Get them to drill a small hole that only fits the copper pipes through, backer-rod, then caulk each one from each side. They can put the pipe insulation right up to the wall, and then another piece on the inside right up against the wall, but I do not want a big hole full of closed cell foam right through my isolated wall assembly. :shock:
mixer76 wrote:Are the other areas I need to consider or anything I'm missing?
The main concerns you need to have are with completely sealing every single gap and opening everywhere. Ask your builder to leave a 5mm gap where the ceiling plasterboard meets the wall plasterboard and the walls meets the floor etc. Then push backer-rod into the gap and use high flexibility silicone sealant/acoustic caulk to fill every gap.
(Backer rod: https://www.sealantsupplies.co.uk/produ ... %20tooling)

Dan
Stay up at night reading books on acoustics and studio design, learn Sketchup, bang your head against a wall, redesign your studio 15 times, curse the gods of HVAC silencers and door seals .... or hire a studio designer.
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