Garage Conversion advice

Jsenior78

Novice Member
Hello all

I am currently in the very very early stages of a dedicated Home Cinema garage conversion. In the current financial climate and with other renovation work going on around the house, this project takes second place but with a little siphoning off of a few pounds here, few pounds there, im managing to get some bits done.

The room is approx 4.5m long, 2.8m wide and 2.4m tall. Garage door will be going and bricked up. Ill probably be using 50 or 100mm studs around with genie clips, double S/Proof boards and probably tecsound and green glue. Aiming for as near a room in a room as possible. Screen size will likely be in the mid -late 90s (inches) prob about 95. AT of course and all speakers will be in wall. Im also thinking of putting a TV behind the screen for more run of the mill viewing, ie sports events, concerts where i may want the lights on perhaps.

On that note, The screen wall is going to be unusually deep at about 24/25cms. This is due to a gas meter. If i can afford to move it outside i might but currently it has to stay. Think im looking at 10 or so feet to the MLP.

Ive tried to sketch up what im hoping to achieve and attached two pics. One is the overall room and then also to scale is the speaker placements im proposing. Currently working towards being able to get a 7.1.4 in?

Hope theyre readable!! Im after any advice/tweaks you could suggest to hopefully iron out any issues beforehand.

Should anyone be able to decipher what ive drawn and provide any advice i would like to offer my thanks in advance for taking the time to read.

(If you recommend it i can of course redraw the pics but im no architect haha)

Cheers
James
 

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Atomicus

Active Member
You preferably want an air gap between the stud wall and the brick if you want a true room within a room, plus new joists for ceiling of course. I did something VERY similar myself a couple years ago. Genie clips will only do so much, but if you can't air gap, it's better than nothing. How will you get air in/out of the room? That will be an important consideration.

I kept the garage door in my case, but I had no choice due to being unable to change the appearance of the front of the house.

I've since moved but I've added some photos below of the build.

Annoyingly the John Sayers forum seems to be no more, as I found that an invaluable resource for info. John Sayers passed away last year, so that may be the reason the site is down.

Happy to answer any questions.
 

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Last edited:

Jsenior78

Novice Member
Hi Atomicus

Thanks for the advice. Very much appreciated.

My crude drawing doesn’t unfortunately show the make up of my stud walls but it'll have a small 10-15mm airgap. Im pretty much following the advice from Soundstop.co.uk and the distances/thicknesses on the plan include the gap.

For air movement, if i can get it past the boss then was looking at an AC unit of some description. Seen a couple but not looked into at any length yet.

Speakers wise im looking at Focal/Kef in walls as they are about in my current budget. It was more whether the speaker placement and distances from the MLP looks doable?
My bookmarks section of my browser is looking more like a novel I've got that many pages open haha

I love looking at previous builds (all bookmarked haha) as its not only inspiring but you spot something you dont think of. Like in your pics are those speaker back boxes you've jnstalled? How did you incorporate the insulation/soundproofing around /behind them? Ive got a mixture of 50 and 100mm studs and the KEFs for example are about 85mm +\- On the 100mm i dont see any issue if i put boxes in but with the 50 i could see it being a bit tight. Or have you made the boxes themselves out of soundproof boards?

Cheers
 

Harkon321

Well-known Member
For air movement, if i can get it past the boss then was looking at an AC unit of some description. Seen a couple but not looked into at any length yet.

Speakers wise im looking at Focal/Kef in walls as they are about in my current budget. It was more whether the speaker placement and distances from the MLP looks doable?
My bookmarks section of my browser is looking more like a novel I've got that many pages open haha

I love looking at previous builds (all bookmarked haha) as its not only inspiring but you spot something you dont think of. Like in your pics are those speaker back boxes you've jnstalled? How did you incorporate the insulation/soundproofing around /behind them? Ive got a mixture of 50 and 100mm studs and the KEFs for example are about 85mm +\- On the 100mm i dont see any issue if i put boxes in but with the 50 i could see it being a bit tight. Or have you made the boxes themselves out of soundproof boards?

Just my 2p

Air Con, ,if you go for it, just be careful on the db, some are a lot quieter than others. I think I was looking at the Mitsubishi Zen. Also make sure it doesn't blow across back of your neck.

If you're screen is less than 100", then you might move your seating forward a touch and give yourself a little more room to rear surrounds. I'd also move rear surrounds in closer together. I based mine on the video by Anthony Grimani on Youtube.

I built sound proofing boxes for my in walls and that has worked really well. If you've only got 50mm depth you can build a box in the wall and then have a surround on the wall side to build it out. A bit like a spacer plate on a light switch?
 

Harkon321

Well-known Member
You also mention a single sub. I'd run cable to all four corners and allow enough slack to allow you to move to any point on that wall. Gives you options for different placement or dual subs down the line.
 

Atomicus

Active Member
If you're going with an air-gap, I think you'd save money by skipping the genie clips. The air gap will do more for you. Mine was a bit bigger, but I was very happy with the end result. I went OSB with SB Plasterboard and Green Glue.

Yes those are soundproof boxes I built for the ceiling speakers. They were lined with very high density rubber, and Rockwool.

I was amazed how well the room kept the sound, but it took a lot of effort.
 

Jsenior78

Novice Member
Just my 2p

Air Con, ,if you go for it, just be careful on the db, some are a lot quieter than others. I think I was looking at the Mitsubishi Zen. Also make sure it doesn't blow across back of your neck.

If you're screen is less than 100", then you might move your seating forward a touch and give yourself a little more room to rear surrounds. I'd also move rear surrounds in closer together. I based mine on the video by Anthony Grimani on Youtube.

I built sound proofing boxes for my in walls and that has worked really well. If you've only got 50mm depth you can build a box in the wall and then have a surround on the wall side to build it out. A bit like a spacer plate on a light switch?
Hi Harkon

Thanks for taking a look and helping out.

Ive read about putting lots of bends to diffuse the sound. Does that relate to the Dbs you mention or does the actual room unit make a din too? What kind of db would tou think wud be good to aim for?

I dont think ive seen the video by Grimani but will try n find it. The screen size has been dictated by the space available and it is looking at a max of 100, maybe even as low as 95-98. It had occured to me about stealing an extra foot or so from the seating, that would in turn aid the placement of the rear atmos to closer to 45Deg. As for the rears, i put them there thinking they needed to be inline with the fronts. If its not so critical id like to move them in from the side walls. They did look a bit close.

Like the spacer idea for the speakers. Very innovative haha How deep were your boxes in the end? And re the sub. Ill be putting power to all corners so defo why not a cable or two to future proof. Great idea.
 

Jsenior78

Novice Member
If you're going with an air-gap, I think you'd save money by skipping the genie clips. The air gap will do more for you. Mine was a bit bigger, but I was very happy with the end result. I went OSB with SB Plasterboard and Green Glue.

Yes those are soundproof boxes I built for the ceiling speakers. They were lined with very high density rubber, and Rockwool.

I was amazed how well the room kept the sound, but it took a lot of effort.
The sound getting out and up into the room above is a big factor. Almost a selling point to the missus wud be that she wud hear very little, if anything!! Hope im not putting too much faith in soundproofing. Hence why ive gone to throw as much tech at it as possible. What size airgap/studs/rockwool etc did you work with? How effective has it been for you?
 

Harkon321

Well-known Member
👍

If you for a mini split unit then the unit itself makes a noise. If it’s just a vent and you can put the unit outside then it’s the noise from the vent and noise travelling out the room via the vents that’s a consideration. Imagine it’s the former.

Grimani videos. You’ll need a cup of tea, it’s long, but the guy is the guru.

My boxes were 12mm MDF I think, then 12.5mm soundblok plasterboard cut to fit inside with a bit of green glue in between. I think there’s some photos in my build thread. Sealed any gaps with acoustic sealant.
 

Jsenior78

Novice Member
👍

If you for a mini split unit then the unit itself makes a noise. If it’s just a vent and you can put the unit outside then it’s the noise from the vent and noise travelling out the room via the vents that’s a consideration. Imagine it’s the former.

Grimani videos. You’ll need a cup of tea, it’s long, but the guy is the guru.

My boxes were 12mm MDF I think, then 12.5mm soundblok plasterboard cut to fit inside with a bit of green glue in between. I think there’s some photos in my build thread. Sealed any gaps with acoustic sealant.

Just searched for his vids. He does have a view so maybe a cheeky whisky and get stuck in haha
Id prefer the real deal aircon with the unit outside. Itll be on the side of the house so easily disguised.
Just had another look and think the walls that will have speakers in are all at least 100mm stud so shud be ok with backboxes.
On that note ive watched a few vids about in wall speakers and very few, if any, mention the back boxes. (Even kef didnt mention it) Think thats why i dismissed them.
Hence why its recomended to pop on somewhere like this forum! Glad i did. Cheers gents.
On and Harkon i tried to find your build via your sig but its saying its locked down. You got a link to it please?
Have you got one Atomicus?
 

Harkon321

Well-known Member
Some people fit back boxes to keep the air volume the same on open back speakers. Keeps the bass response consistent. If the speaker is closed back, or you’re not worried about that, then you can leave unboxed. But it’ll ruin your sound proofing, which is the second reason to back box them.
I’ll try and fix my signature. Let me know if it works.
 

Atomicus

Active Member
The sound getting out and up into the room above is a big factor. Almost a selling point to the missus wud be that she wud hear very little, if anything!! Hope im not putting too much faith in soundproofing. Hence why ive gone to throw as much tech at it as possible. What size airgap/studs/rockwool etc did you work with? How effective has it been for you?

Well, I was lucky in having concrete slab between the floor above, which was a kitchen, so hard to say how effective it would have been in a more traditional layout. If memory serves, I had 170mm deep ceiling joists and filled it with double layers of 60kg/m3 Rockwool.
 

Jsenior78

Novice Member
Harkon, ive got onto your thread now. Bout half way thru and its looking good. A little disagreement on there has got me thinking though. Whether i can turn the room around and have a window for ventilation where the garage door is, instead of AC?
Looking at the plan though it wud mean putting the MLP sofa/chairs perilously close to the new doorway or pushing it forward which wud put the viewing distance about 6-7ft which is probably a bit close. What do you think?

Atomicus i think our joists are pretty thick so double rockwool is a definite possibility. Soundstop also suggested a layer of the heavy mass vinyl under the carpet upstairs too so may consider that
 

Atomicus

Active Member
Harkon, ive got onto your thread now. Bout half way thru and its looking good. A little disagreement on there has got me thinking though. Whether i can turn the room around and have a window for ventilation where the garage door is, instead of AC?
Looking at the plan though it wud mean putting the MLP sofa/chairs perilously close to the new doorway or pushing it forward which wud put the viewing distance about 6-7ft which is probably a bit close. What do you think?

Atomicus i think our joists are pretty thick so double rockwool is a definite possibility. Soundstop also suggested a layer of the heavy mass vinyl under the carpet upstairs too so may consider that

A window would be fine for ventilation, but it would certainly kill any sound proofing - at least out in that direction anyway. But if you don't mind that then a window is certainly a cheap solution to the ventilation issue. With all the kit in such a small space chucking out heat (plus the humans), you definitely will need to keep it cool and fresh. A stagnant hot home cinema is not going to be fun for anyone lol.
 

Harkon321

Well-known Member
Agree with the above. Depends if you’re bothered about sound getting out. I just blocked the window up so it reduced the sound getting out significantly. 7ft might be a bit close as well.
 

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