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Forced Air ventilation for small home studio - My early sketched ideas - please advise

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Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby adamotyril » Wed Dec 11, 2019 3:35 pm


I’m starting the process of researching a ventilation system for a small ‘room within a room’ soundproofed home music studio, set up in a room in a terraced house.

I’m only starting at the beginning of this planning process - so I’m only thinking in terms of basic layout and possibilities here, and about how it could work in the spaces that I have available


The ‘studio’ , such as it is, will consist only of one soundproofed and sound treated room (that’s all the indoor space I have available).

But I am assured (from another thread) that it’s a big enough space to do some playing and recording and monitoring.

Because I’m going for a fully sealed room within a room set up, I’m told that having a ‘forced air’ ventilation system will be essential.

I am also aware that this is quite a difficult thing to achieve, since moving air tends to make sound, and quite a bit of physical set up will be needed.

On the negative side, yes, i’m confined to a fairly small single room area for my soundproofed music room.

On the positive side, however, I have a garden right next to the room that i can do what i like with,

Reasonably sized structures (perhaps a shed or box to house fans, and any air ducts etc) can be located in this space

Having said that, i’d still like to keep the garden useable as a normal garden if possible.

On this basis I’m doing some PRELIMINARY and VERY BASIC thinking about what might be possible with the exterior garden space and the adjoining indoor room space available.

I would be very grateful if you can supply and useful and informative comments about these basic , early ideas that i have.

If you don’t think it’s workable, feel free to point me in a different direction.

‘Basic approval’ (or disapproval) along a reasoned basis is very welcome, with explanation, and may not require detailed reference to things like types of fan etc.

However, I certainly will be happy if you also would like to talk in greater depth about more detailed things like types of fan and ducting (even though my own roughly sketched plans do not yet touch on any such detail, it’s just an outline

Because I would like to keep this thread focussed on the question of ventilation, perhaps we should avoid digressing into a discussion of the soundproofing and room-within-room structure itself (unless it’s an aspect of it that strictly relates to ventilation).

Suffice it to say, that i expect to heavily double glaze both the garden facing doors and windows, and create an inner room made of materials such as plasterboard. rock wool etc. The inner room will also have at least one window to take light from the existing bay windows.

Nonetheless - i WILL start my diagram presentation by showing a very basic plan of the floor space of the proposed soundproof room itself (which is basically a rectangular living room, but which has a bay window area at one end facing onto the garden).

Please note, that floor plan notes the size of the interior space of the soundproof room AFTER the room-within-room has been created. (the actual outer room size is bigger)

I assume of course that ducts will be extended in some way to go through both the exterior house wall AND the inner room (obviously)

However, showing the size of the inner room space shows what size of area needs to receive ventilation.

OK, so to get the ball rolling, and to provide an idea against which comments ‘for or against’ can be directed,

I will now explain , with rough diagrams, one set of ideas I have had, and the thinking and principles behind it.

Do feel free to completely reject or criticise it.


1. Because the space available is small, and the garden adjacent to the room, I have presumed that placing as much as possible, if not ALL, the actual ventilation system OUTSIDE of the actual room I’d be using for music. Apart from then ends of the actual ducts bringing air in and allowing air out. I realise that some kind of sound minimising grill or final stage to the duct may well be advised.

2. If electric fans are located OUTSIDE the room, in some structure in the garden, THEY ALSO will have to be subject to some kind of soundproofing…. if i’m working at night, i think i’m obliged generally not to make fan sound in the garden (plenty of other buildings close by, and bedrooms in those buildings in which people could be sleeping.

Because I have full use of the garden, it occurs to me that i can house the actual fans in a shed in the garden. In the plans, i’ve put that shed at the back of the garden…although that makes it further from the house, that is a ‘natural’ place for a shed, and leaves more space in the garden for ordinary use.
As it’s a small garden, maybe this will work, as the air still wouldn’t have to come far.
Also, some kind of shed could probably fairly easily be soundproofed itself (to prevent fan sounds in the area).

BAFFLE BOXES - do I even have the right word here? i think so.
From watching various online videos, i’ve observed that some people create these boxes, in which air that is going places is directed through a ‘snakey’ system of ’S’ bends (or perhaps, softer bends) in order to make it harder for sound to escape into the outside world, or outside world and air moving sounds to be directed into the soundproofed work area. Sound insulation rockwool is packed around the snakey air duct inside the box.

Assuming i’m on the right track here, I’ve suggested that i could direct air through such ‘baffle boxes’ both on the way in and out of a sound insulated garden shed housing the fans (so as to keep that quiet for the neighbours),
BUT ALSO i propose fixing them to the exterior of the lower bay structure, where the inlet and outlet to the soundproof room will be (in this basic plan).
By having then outside the house, but fixed on, I’m obviously avoiding any cutting down of the space i have available in the room.

I realise that these ideas will involve quite a bit of detailed work in terms of making them rain and weather proof… that is obviously a factor of detail that would come up ‘down the line’. I’ve also heard that if you get wet and mould in these boxes (which are also full of rock wool insulation) you end up quite possibly conveying a damp, mouldy organic smell into you room. So keeping it all dry could represent quite a challenge, and could represent a defect in my basic plan. Maybe a dehumidifying element could be handy.

these possible defects to my basic plan occur to me

1. The length of air duct that would carry air from the shed housing the fans to the room would be quite long, perhaps six meters….could that length pose a problem ? does it require a lot more fan energy to send air over a distance that long?

2. The proposed entrance point for the air into the room that i sketch out is LOW in the room. This could be a problem, as i think i’ve seen in videos that the input is normally up high, for some reason. However, i’ve put it low simply because that is a convenient area of wall where it can come in….the rest of the bay is mostly window (which will be heavily double glazed)

Now let me provide links to a series of diagrams which ( I hope !) will go some way to explaining more about what my actual initial basic idea is.

1. Firstly, here is a very rough plan of the floor space of the room I intend to ventilate. Please note that this is the useable space available AFTER the double room within a room is fitted. I have NOT BOTHERED to represent the double room structure, so as to make the drawing simpler.
Please note that a typical bay window structure exists on the left side of the diagram. This is a typical victorian bay window thing, with central garden doors , and a window each side (all of which will be heavily double glazed) ... ed-public/

2. Here, i represent the basic dimensions of my small garden, showing it as a rectangle. The house is to the right, and the bay structure visible, this time with the bay shape affecting the shape of the garden space outside. ... ed-public/

3. Here is a basic representation of the idea of having a shed in the garden that houses the fans, and where the air would go i and out of the shed, and in and out of the house ... ed-public/

4. Here is a sketch of the inside of the soundproof room which shows the basic location of the air in and out holes (vents). Please note I have NOT represented any of the room within room soundproofing TO KEEP THE DRAWING SIMPLE. ... ed-public/

5. Here’s a very basic sketch representation of where and how the air would enter the room - all i’m trying to show here is that I would affix a baffle box to the *outside* of the bay’s brickwork, which would go between the air duct coming from the shed housing the fans, and the hole that goes into the house ... ed-public/

6. Finally, here’s a basic concept sketch of how I imagine setting up the shed housing the fans. Note that the back fence of the garden is at the top of the drawing, the house is now out of picture, but ‘below’ the diagram. The idea here is to supply the shed with electricity (of course), house the actual fans inside the shed, soundproof the shed and baffle the points where the air comes in and out of the shed, then send the air down a duct towards the house and soundproof room ... ed-public/

Thanks very much if you can provide any comments, criticisms, or better alternative plans, or tweaks to my basic idea for a forced air ventilations system to a small soundproof room/studio in a terraced house.

Also, if you wish to suggest some more detailed information about suggested equipment, that is also most welcome

with regards
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Re: Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby Sam Spoons » Wed Dec 11, 2019 4:43 pm

This sticky thread (at the top of the DIY forum page) goes into considerable detail about how Tony designed and built his ventilation system. It may answer some of not most of your questions.
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Re: Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby James Perrett » Wed Dec 11, 2019 10:51 pm

First I'll preface this by saying that there are others on here (like Wonks and Max) who have more knowledge of ventilation systems than I do but these are my initial thoughts...

I think you are making this far more complicated than it needs to be. How much height do you have? If this is a typical Victorian house you will probably have high ceilings. We had something like 4m high ceilings in a previous house so we simply built the studio to be around 2.5m high and fitted the fan and all the ducting in the space above the inner ceiling. If you use long lengths of acoustic ducting snaked above the studio you probably won't need baffle boxes either.

The key to quiet ventilation is to keep the air velocity low which means using larger ducting and larger fans running at a lower speed. I use 125mm ducting in my current studio but 150mm might be even better.

Another point that I noticed from your pictures is that you have the inlet and outlet very close to each other. This will probably set up a small area of circulated air between them while the air in the rest of the studio will stay put. It is best to put the inlet and outlet at opposite ends of the room.

Finally, I've always had most success by pulling the air through the studio rather than pushing it so I'd always place the fan on the outlet.
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Re: Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby Studio Support Gnome » Thu Dec 12, 2019 9:53 pm

the proposed design will not properly ventilate the space, most of the air will go out straight away....

Better to drive air in at one end from the ceiling with a couple of non diffused downward facing terminals , , and extract air out at the other end near ceiling level.

this will cause the fresh air to mix effectively at the far end and then draw through the whole room.

using diffusor grilles causes turbulence noise, so simple open ring or slot terminals is the way to go.

failing that , if ducting is impossible to get down the other end, direct it straight in , not across the angle, near , but not AT floor level and use Coanda valves to achieve a laminar flow that will get further in to the room, do this on both sides , and then put a rear extract point in centre of the recess

Flow rate for IAQ1 should be >15.1 litres a second per person (default target is 20 l/s per person ) based on maximum expected capacity.

however, it should be noted that Coanda valves produce more high frequency noise when operating at higher velocities than other valves... due to the nature of the perforated faceplates.

the ideal terminal is just a hole, no grille = no additional turbulence noise

I would recommend investigating the use of a heat recovery ventilation system for this purpose.... (MVHR)

but then, in fairness, these days, my day job involves designing just such things for major manufacturer of ventilation products...

I have designs for effective baffle systems..... both to keep the airflow itself quiet (self noise) and to prevent ingress and escape of noise

But people pay me money for that ...
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Re: Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby Wonks » Fri Dec 13, 2019 11:04 am

Those indoor air quality rates keep going up and up! Not really helping reduce global warming. More efficient to have a CO2 sensor controlling variable speed fans so that they run at a minimum rate until the room starts getting full and then they start to ramp up, but won't run at maximum unless it's really required.

However that is a bit OTT and relatively expensive for a relatively small space. But multiple speed/variable speed fans and a simple manual speed selector switch/speed knob might be useful to reduce running costs and also minimise noise when required.
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Re: Forced Air ventilation for small home studio - My early sketched ideas - please advise

Postby adamotyril » Fri Dec 20, 2019 9:21 am

Thanks all of you for your helpful responses.

In particular, locating the ventilation system inside the fairly ample ceiling cavity area sounds like the next thing to look into.

As well as serious help and consideration of how i can access any fans, where and how far apart in and out points are

Whether i'm drawing or pushing air

consideration of slow fans, lots of options to do with types of equipment

I accept that this is beyond my actual pay grade so i think it's professional consultation plus building specs or not at all

Responses appreciated !
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