John Sayers' Recording Studio Design Forum Archive

Hi my name is Chris (UK), first time poster.


First I would like to thank John and everyone else that gives knowledgeable advice on this site. It has been invaluable.

I am currently in the proses of building my first studio from the ground up mainly for mixing/production and occasionally recording drums.

i'm focusing on getting the outer shell built. Concrete base is down and block work is almost complete so I am now working out the details of installing a flat warm roof with skylight windows.

I am 90% there but need help with a few parts that I am unsure about and would like some verification on my workings out using the TL calculator.


Location/ Use

• Situated at rear of my garden
• Building is 15m from closest neighbor
• Closest road is 30m away
• I’ll be using it for drum recording and mixing (day & Night)
• Estimated isolation needed 50db+


Walls Construction

Outer Leaf
• 100mm cinder block (rendered on outside, painted on inside)
• 10mm gap
Inner Leaf
• 2” x 4” stud wall (Insulation filled)
• Vapor barrier
• 18mm OSB

This will give me an air gap of around 100mm between leafs.


Roof Construction

Outer Leaf
• EPDM
• 120 mm PIR insulation board
• Vapor barrier
• 27mm OSB and Gyprock
• 2” x 9” joists

Inner Leaf (Inside out ceiling)
• 18mm OSB
• 2” x 6” joists (50mm insulation)
• Cloth covering

This will give me an air gap of 250mm between leafs.


Floor

• 12 inch concrete base
• DPM
• 100mm PIR insulation board
• DPM
• Electric under floor heating
• 40 mm screed (liquid flow screed)


Internal dimensions
• Width 4.6m
• Length 6.1m
• Height 2.5m (Front) height 3.2m (rear)


Acoustic treatment – yet to be fully designed
• RFZ - Soffit mounted speakers
• Ceiling will be treated with 50mm rock-wool
• Rear wall 50cm fluffy insulation or hangers
• Side walls, adjustable panels to increase/decrease reverberation time


Windows doors ect…
• Entrance is in the front corner (Not the best idea) with inner and outer doors separated by air lock.
• 2 Skylights in roof/ceiling.


Transmission Loss calculator Results

I am satisfied with the TL of the walls as they have lots of mass with the cinder block outer leaf. Though I am a little unsure of how to work out the overall TL of a system when the results are in blocks of frequency’s.

This is the result for the laminate glass skylights using 12.5mm glass.
I accepted a lower TL on the roof/windows when I found out how much 25mm laminated glass would cost me.

Then the roof TL to match the windows

I worked out the roof using a combination of OSB and Gyprock as it is cheaper than OSB. I’m unsure if this goes again any building regs at the minute.



Looking at the detail of a warm roof, the outer and inner leafs are coupled via the lower roof deck joists.
Using a second set of joists for the inside out ceiling will decouple the leafs but now allows cold air from the walls to entre the warm roof space.
Q1: Looking at the roof/walls detail above do you think filling the box space labeled A with insulation will stop the bridging of cold air into the warm roof or will I have to use acoustic calk to seal between the ceiling and roof joists labeled B, compromising the TL through coupling.

Q2: Does the EPDM on the roof act as a third leaf because it is essentially creating a sealed space between it and the roof deck where the PIR rigid Insulation is?
Or does the roof deck, rigid insulation and EPDM act as one solid mass?
(See pic below, no joists are shown for simplisety)

I would like to put 100mm light fluffy insulation in between the ceiling and roof deck creating a hybrid roof which will increase the isolation but negativly change the due point. There is the fact that the ceiling will have 50mm of insulation on the internal side changing the due point further.

Q3: Is it a bad idea to do this? or do I just need to hire someone to calculate the due point properly to see if it will work. (I think I just answer my own question there.)


Thank's to anyone that gives me the time of day, it is very much appreciated....

Regards Chris

kehoe wrote:Hi my name is Chris (UK), first time poster.


First I would like to thank John and everyone else that gives knowledgeable advice on this site. It has been invaluable.

I am currently in the proses of building my first studio from the ground up mainly for mixing/production and occasionally recording drums.

i'm focusing on getting the outer shell built. Concrete base is down and block work is almost complete so I am now working out the details of installing a flat warm roof with skylight windows.

I am 90% there but need help with a few parts that I am unsure about and would like some verification on my workings out using the TL calculator.


Location/ Use

• Situated at rear of my garden
• Building is 15m from closest neighbor
• Closest road is 30m away
• I’ll be using it for drum recording and mixing (day & Night)
• Estimated isolation needed 50db+


Walls Construction

Outer Leaf
• 100mm cinder block (rendered on outside, painted on inside)
• 10mm gap
Inner Leaf
• 2” x 4” stud wall (Insulation filled)
• Vapor barrier
• 18mm OSB

This will give me an air gap of around 100mm between leafs.


Roof Construction

Outer Leaf
• EPDM
• 120 mm PIR insulation board
• Vapor barrier
• 27mm OSB and Gyprock
• 2” x 9” joists

Inner Leaf (Inside out ceiling)
• 18mm OSB
• 2” x 6” joists (50mm insulation)
• Cloth covering

This will give me an air gap of 250mm between leafs.


Floor

• 12 inch concrete base
• DPM
• 100mm PIR insulation board
• DPM
• Electric under floor heating
• 40 mm screed (liquid flow screed)


Internal dimensions
• Width 4.6m
• Length 6.1m
• Height 2.5m (Front) height 3.2m (rear)


Acoustic treatment – yet to be fully designed
• RFZ - Soffit mounted speakers
• Ceiling will be treated with 50mm rock-wool
• Rear wall 50cm fluffy insulation or hangers
• Side walls, adjustable panels to increase/decrease reverberation time


Windows doors ect…
• Entrance is in the front corner (Not the best idea) with inner and outer doors separated by air lock.
• 2 Skylights in roof/ceiling.


Transmission Loss calculator Results

I am satisfied with the TL of the walls as they have lots of mass with the cinder block outer leaf. Though I am a little unsure of how to work out the overall TL of a system when the results are in blocks of frequency’s.

wall 1.png

a wall 2.png

This is the result for the laminate glass skylights using 12.5mm glass.
I accepted a lower TL on the roof/windows when I found out how much 25mm laminated glass would cost me.

window 1.png

a window 2.png

Then the roof TL to match the windows

roof bulk 1.png

roof bulk 2.png

I worked out the roof using a combination of OSB and Gyprock as it is cheaper than OSB. I’m unsure if this goes again any building regs at the minute.



Looking at the detail of a warm roof, the outer and inner leafs are coupled via the lower roof deck joists.

warm roof detail.png

Using a second set of joists for the inside out ceiling will decouple the leafs but now allows cold air from the walls to entre the warm roof space.

ROOF DETAIL.JPG

Q1: Looking at the roof/walls detail above do you think filling the box space labeled A with insulation will stop the bridging of cold air into the warm roof or will I have to use acoustic calk to seal between the ceiling and roof joists labeled B, compromising the TL through coupling.

Q2: Does the EPDM on the roof act as a third leaf because it is essentially creating a sealed space between it and the roof deck where the PIR rigid Insulation is?
Or does the roof deck, rigid insulation and EPDM act as one solid mass?
(See pic below, no joists are shown for simplisety)

3 Leaf.JPG

I would like to put 100mm light fluffy insulation in between the ceiling and roof deck creating a hybrid roof which will increase the isolation but negativly change the due point. There is the fact that the ceiling will have 50mm of insulation on the internal side changing the due point further.

Q3: Is it a bad idea to do this? or do I just need to hire someone to calculate the due point properly to see if it will work. (I think I just answer my own question there.)


Thank's to anyone that gives me the time of day, it is very much appreciated....

Regards Chris

Hi Chris,

You have most things in hand.

Regarding the cold air coming up from the walls, well:

1. you should fill the gap between the inner and outer leaves of the walls with fluffy insulation, or you could use Rockwool which won't gain you any better TL but will be better for thermal.

2. You can get Rockwool fireblock which you can install at the wall/roof junction. This will keep everything decoupled, safer/better fire rating and prevent the cold air. Also, I don't think you need to caulk that junction you pointed out but even if you did it would not really couple the leaves together if you used a flexible non hardening caulk.

Regarding the hybrid roof situation and the risk of condensation due to the extra insulation under the roof deck you can call someone Rockwool technical support (even if you're not using Rockwool products you can just pretend) and they will simulate your exact proposed assembly and tell you if you have a significant risk of condensation or not. I actually did this myself today and the lady was extremely helpful and very knowledgable.

Regarding the EPDM being a third leaf - well no, not really. The PIR is a weird one because it is sort of a mass and sort of full of air. In any case it will not significantly reduce your isolation. Your proposed assembly is how I design a lot of roofs for my clients, if a warm roof is what they want. But even if you went with a cold vented roof you would need to have a "third" leaf anyway, otherwise there would be holes for the vents compromising the outer leaf... unless the inner leaf is massive enough or the isolation requirements are not high. With timber framed buildings a third leaf is usually the only way to do it. BTW, have you looked in to using SIPS for your roof? It may be a lot cheaper, quicker and easier than building a timber frame.

Regarding your overall TL - well it's only as good as your weakest assembly. So you can use that to give you an idea of what you can expect. If you're talking STC value then you look at the TL at 500hz which in your case is 70... but this is not very useful for a recording studio since you will be listening and recordings sources that go much lower than 125hz.

Looking quite good so far, but I'm not sure about your acoustic treatment decisions...For example, I know you don't have much height but 50mm of insulation on the ceiling is not much of anything, unless you are only concerned with controlling high mids and highs. Do you have a floor plan or 3d sketchup?

yeah. what Paul said.

(Removed due to being irrelevant)

(Removed as irelivant)

the eye of Sauron! and the listener looks like a ghoul! what have you wrought!

make sure your speaker isn't centered floor to ceiling.

(Removed as Irelivant)

Paulus87 wrote:

kehoe wrote:Hi my name is Chris (UK), first time poster.


First I would like to thank John and everyone else that gives knowledgeable advice on this site. It has been invaluable.

I am currently in the proses of building my first studio from the ground up mainly for mixing/production and occasionally recording drums.

i'm focusing on getting the outer shell built. Concrete base is down and block work is almost complete so I am now working out the details of installing a flat warm roof with skylight windows.

I am 90% there but need help with a few parts that I am unsure about and would like some verification on my workings out using the TL calculator.


Location/ Use

• Situated at rear of my garden
• Building is 15m from closest neighbor
• Closest road is 30m away
• I’ll be using it for drum recording and mixing (day & Night)
• Estimated isolation needed 50db+


Walls Construction

Outer Leaf
• 100mm cinder block (rendered on outside, painted on inside)
• 10mm gap
Inner Leaf
• 2” x 4” stud wall (Insulation filled)
• Vapor barrier
• 18mm OSB

This will give me an air gap of around 100mm between leafs.


Roof Construction

Outer Leaf
• EPDM
• 120 mm PIR insulation board
• Vapor barrier
• 27mm OSB and Gyprock
• 2” x 9” joists

Inner Leaf (Inside out ceiling)
• 18mm OSB
• 2” x 6” joists (50mm insulation)
• Cloth covering

This will give me an air gap of 250mm between leafs.


Floor

• 12 inch concrete base
• DPM
• 100mm PIR insulation board
• DPM
• Electric under floor heating
• 40 mm screed (liquid flow screed)


Internal dimensions
• Width 4.6m
• Length 6.1m
• Height 2.5m (Front) height 3.2m (rear)


Acoustic treatment – yet to be fully designed
• RFZ - Soffit mounted speakers
• Ceiling will be treated with 50mm rock-wool
• Rear wall 50cm fluffy insulation or hangers
• Side walls, adjustable panels to increase/decrease reverberation time


Windows doors ect…
• Entrance is in the front corner (Not the best idea) with inner and outer doors separated by air lock.
• 2 Skylights in roof/ceiling.


Transmission Loss calculator Results

I am satisfied with the TL of the walls as they have lots of mass with the cinder block outer leaf. Though I am a little unsure of how to work out the overall TL of a system when the results are in blocks of frequency’s.

wall 1.png

a wall 2.png

This is the result for the laminate glass skylights using 12.5mm glass.
I accepted a lower TL on the roof/windows when I found out how much 25mm laminated glass would cost me.

window 1.png

a window 2.png

Then the roof TL to match the windows

roof bulk 1.png

roof bulk 2.png

I worked out the roof using a combination of OSB and Gyprock as it is cheaper than OSB. I’m unsure if this goes again any building regs at the minute.



Looking at the detail of a warm roof, the outer and inner leafs are coupled via the lower roof deck joists.

warm roof detail.png

Using a second set of joists for the inside out ceiling will decouple the leafs but now allows cold air from the walls to entre the warm roof space.

ROOF DETAIL.JPG

Q1: Looking at the roof/walls detail above do you think filling the box space labeled A with insulation will stop the bridging of cold air into the warm roof or will I have to use acoustic calk to seal between the ceiling and roof joists labeled B, compromising the TL through coupling.

Q2: Does the EPDM on the roof act as a third leaf because it is essentially creating a sealed space between it and the roof deck where the PIR rigid Insulation is?
Or does the roof deck, rigid insulation and EPDM act as one solid mass?
(See pic below, no joists are shown for simplisety)

3 Leaf.JPG

I would like to put 100mm light fluffy insulation in between the ceiling and roof deck creating a hybrid roof which will increase the isolation but negativly change the due point. There is the fact that the ceiling will have 50mm of insulation on the internal side changing the due point further.

Q3: Is it a bad idea to do this? or do I just need to hire someone to calculate the due point properly to see if it will work. (I think I just answer my own question there.)


Thank's to anyone that gives me the time of day, it is very much appreciated....

Regards Chris

Hi Chris,

You have most things in hand.

Regarding the cold air coming up from the walls, well:

1. you should fill the gap between the inner and outer leaves of the walls with fluffy insulation, or you could use Rockwool which won't gain you any better TL but will be better for thermal.

2. You can get Rockwool fireblock which you can install at the wall/roof junction. This will keep everything decoupled, safer/better fire rating and prevent the cold air. Also, I don't think you need to caulk that junction you pointed out but even if you did it would not really couple the leaves together if you used a flexible non hardening caulk.

Regarding the hybrid roof situation and the risk of condensation due to the extra insulation under the roof deck you can call someone Rockwool technical support (even if you're not using Rockwool products you can just pretend) and they will simulate your exact proposed assembly and tell you if you have a significant risk of condensation or not. I actually did this myself today and the lady was extremely helpful and very knowledgable.

Regarding the EPDM being a third leaf - well no, not really. The PIR is a weird one because it is sort of a mass and sort of full of air. In any case it will not significantly reduce your isolation. Your proposed assembly is how I design a lot of roofs for my clients, if a warm roof is what they want. But even if you went with a cold vented roof you would need to have a "third" leaf anyway, otherwise there would be holes for the vents compromising the outer leaf... unless the inner leaf is massive enough or the isolation requirements are not high. With timber framed buildings a third leaf is usually the only way to do it. BTW, have you looked in to using SIPS for your roof? It may be a lot cheaper, quicker and easier than building a timber frame.

Regarding your overall TL - well it's only as good as your weakest assembly. So you can use that to give you an idea of what you can expect. If you're talking STC value then you look at the TL at 500hz which in your case is 70... but this is not very useful for a recording studio since you will be listening and recordings sources that go much lower than 125hz.

Looking quite good so far, but I'm not sure about your acoustic treatment decisions...For example, I know you don't have much height but 50mm of insulation on the ceiling is not much of anything, unless you are only concerned with controlling high mids and highs. Do you have a floor plan or 3d sketchup?

Hey Paul, I'm just replacing the external roof on my garden studio (two leaf timber build with about a 6" cavity between the two roofs). I was going to wedge PIR in the joists to attempt to get a warm roof and keep within 2.5m, but hadn't thought of using SIPS panels. Do you have any pictures or examples of doing that? Sounds like it could be a really good solution...

Thank you

nickrice5 wrote:

Paulus87 wrote:

kehoe wrote:Hi my name is Chris (UK), first time poster.


First I would like to thank John and everyone else that gives knowledgeable advice on this site. It has been invaluable.

I am currently in the proses of building my first studio from the ground up mainly for mixing/production and occasionally recording drums.

i'm focusing on getting the outer shell built. Concrete base is down and block work is almost complete so I am now working out the details of installing a flat warm roof with skylight windows.

I am 90% there but need help with a few parts that I am unsure about and would like some verification on my workings out using the TL calculator.


Location/ Use

• Situated at rear of my garden
• Building is 15m from closest neighbor
• Closest road is 30m away
• I’ll be using it for drum recording and mixing (day & Night)
• Estimated isolation needed 50db+


Walls Construction

Outer Leaf
• 100mm cinder block (rendered on outside, painted on inside)
• 10mm gap
Inner Leaf
• 2” x 4” stud wall (Insulation filled)
• Vapor barrier
• 18mm OSB

This will give me an air gap of around 100mm between leafs.


Roof Construction

Outer Leaf
• EPDM
• 120 mm PIR insulation board
• Vapor barrier
• 27mm OSB and Gyprock
• 2” x 9” joists

Inner Leaf (Inside out ceiling)
• 18mm OSB
• 2” x 6” joists (50mm insulation)
• Cloth covering

This will give me an air gap of 250mm between leafs.


Floor

• 12 inch concrete base
• DPM
• 100mm PIR insulation board
• DPM
• Electric under floor heating
• 40 mm screed (liquid flow screed)


Internal dimensions
• Width 4.6m
• Length 6.1m
• Height 2.5m (Front) height 3.2m (rear)


Acoustic treatment – yet to be fully designed
• RFZ - Soffit mounted speakers
• Ceiling will be treated with 50mm rock-wool
• Rear wall 50cm fluffy insulation or hangers
• Side walls, adjustable panels to increase/decrease reverberation time


Windows doors ect…
• Entrance is in the front corner (Not the best idea) with inner and outer doors separated by air lock.
• 2 Skylights in roof/ceiling.


Transmission Loss calculator Results

I am satisfied with the TL of the walls as they have lots of mass with the cinder block outer leaf. Though I am a little unsure of how to work out the overall TL of a system when the results are in blocks of frequency’s.

wall 1.png

a wall 2.png

This is the result for the laminate glass skylights using 12.5mm glass.
I accepted a lower TL on the roof/windows when I found out how much 25mm laminated glass would cost me.

window 1.png

a window 2.png

Then the roof TL to match the windows

roof bulk 1.png

roof bulk 2.png

I worked out the roof using a combination of OSB and Gyprock as it is cheaper than OSB. I’m unsure if this goes again any building regs at the minute.



Looking at the detail of a warm roof, the outer and inner leafs are coupled via the lower roof deck joists.

warm roof detail.png

Using a second set of joists for the inside out ceiling will decouple the leafs but now allows cold air from the walls to entre the warm roof space.

ROOF DETAIL.JPG

Q1: Looking at the roof/walls detail above do you think filling the box space labeled A with insulation will stop the bridging of cold air into the warm roof or will I have to use acoustic calk to seal between the ceiling and roof joists labeled B, compromising the TL through coupling.

Q2: Does the EPDM on the roof act as a third leaf because it is essentially creating a sealed space between it and the roof deck where the PIR rigid Insulation is?
Or does the roof deck, rigid insulation and EPDM act as one solid mass?
(See pic below, no joists are shown for simplisety)

3 Leaf.JPG

I would like to put 100mm light fluffy insulation in between the ceiling and roof deck creating a hybrid roof which will increase the isolation but negativly change the due point. There is the fact that the ceiling will have 50mm of insulation on the internal side changing the due point further.

Q3: Is it a bad idea to do this? or do I just need to hire someone to calculate the due point properly to see if it will work. (I think I just answer my own question there.)


Thank's to anyone that gives me the time of day, it is very much appreciated....

Regards Chris

Hi Chris,

You have most things in hand.

Regarding the cold air coming up from the walls, well:

1. you should fill the gap between the inner and outer leaves of the walls with fluffy insulation, or you could use Rockwool which won't gain you any better TL but will be better for thermal.

2. You can get Rockwool fireblock which you can install at the wall/roof junction. This will keep everything decoupled, safer/better fire rating and prevent the cold air. Also, I don't think you need to caulk that junction you pointed out but even if you did it would not really couple the leaves together if you used a flexible non hardening caulk.

Regarding the hybrid roof situation and the risk of condensation due to the extra insulation under the roof deck you can call someone Rockwool technical support (even if you're not using Rockwool products you can just pretend) and they will simulate your exact proposed assembly and tell you if you have a significant risk of condensation or not. I actually did this myself today and the lady was extremely helpful and very knowledgable.

Regarding the EPDM being a third leaf - well no, not really. The PIR is a weird one because it is sort of a mass and sort of full of air. In any case it will not significantly reduce your isolation. Your proposed assembly is how I design a lot of roofs for my clients, if a warm roof is what they want. But even if you went with a cold vented roof you would need to have a "third" leaf anyway, otherwise there would be holes for the vents compromising the outer leaf... unless the inner leaf is massive enough or the isolation requirements are not high. With timber framed buildings a third leaf is usually the only way to do it. BTW, have you looked in to using SIPS for your roof? It may be a lot cheaper, quicker and easier than building a timber frame.

Regarding your overall TL - well it's only as good as your weakest assembly. So you can use that to give you an idea of what you can expect. If you're talking STC value then you look at the TL at 500hz which in your case is 70... but this is not very useful for a recording studio since you will be listening and recordings sources that go much lower than 125hz.

Looking quite good so far, but I'm not sure about your acoustic treatment decisions...For example, I know you don't have much height but 50mm of insulation on the ceiling is not much of anything, unless you are only concerned with controlling high mids and highs. Do you have a floor plan or 3d sketchup?

Hey Paul, I'm just replacing the external roof on my garden studio (two leaf timber build with about a 6" cavity between the two roofs). I was going to wedge PIR in the joists to attempt to get a warm roof and keep within 2.5m, but hadn't thought of using SIPS panels. Do you have any pictures or examples of doing that? Sounds like it could be a really good solution...

Thank you

Hi,

Check out panelsell.co.uk

And there's a plethora of youtube videos about sips builds.

If you do not decide to go with SIPS then let us know in more detail exactly what you plan to do if you're going for a warm roof conversion... doing it incorrectly due to not having adequate information will be detrimental to your entire building.

Hello again.

I am currently toying with the idea of covering the insulation on my inside out ceiling with a 6mil polythene sheet to keep any insulation fibres from entering the room and to reflect back some of the high end frequencies.

I see John and others do this regularly BUT i am unsure if they do it when the walls/ceiling are external.
As I'm building a detached structure, all the walls are external and the polythene is effectivly creating a second vapour barrier and moisture will be trapped between them.

The only solution I can think of is covering the insulation with pieces of polythene 6"-12" wide with 6"-12" gaps between them then covering the whole thing in a breathable membrane to stop fibres before I finish with a breathable decorative material.

Thanks for the help so far.

Chris

better off with a denser weave fabric than risk trapping moisture.

Yes, or just use a layer of Dacron (polyester wadding) in front of the insulation before the fabric.

Hi all, the studio build was put on hold to welcome my first child to the world and I'm now looking to crack on with the build.

I finished my roof last year and now have a finished outer shell. Currently building internal leaf.

Once the walls/cieling are finished I'm thinking of laying 100mm PIR (Celotex) over the sub slab and pouring 40mm screed on top as my finish floor.

Q: Will the relitively thin screed floor resonate?
Iv read advice like "it won't resonate because there is no void/air gap below it" but this was for a much more massive concrete floor. 6" I think.


Thanks for any help.

isn't the celotex fairly dense material? in general, the primary slab should be decoupled from the walls and other slabs so when you build the walls on it, there is no reason to "float" them.

gullfo wrote:isn't the celotex fairly dense material? in general, the primary slab should be decoupled from the walls and other slabs so when you build the walls on it, there is no reason to "float" them.

Hi, yeh the Celotex is quite dense stuff. Thanks for clearing up my doubts.

I just have one slab which both walls are built on, Its a one room detached build so didn't feel the need to decouple the walls.
Im guessing 12" concrete poured on bedrock won't be transmitting much anyway.

Thanks for the help.