House Extension with a Dedicated Home Cinema Room

Harkon321

Well-known Member
We’ve been planning this extension for over two years, with hold ups getting quotes and then lockdown etc. As the digger arrived this week I thought I’d create a built thread to document the progress. The room progress could be slow and steady but I thought it would be nice to document it as we go.

We are extending out the back 4.3m and the full width of the house. Half of this space will extending the open plan kitchen, dining area and then then a small dedicated room. Aiming for a 7.2.4 set up.

Below I've included some of the drawings.
Exterior.JPG

Interior.JPG



These are some of the latest SketchUp drawings I've done whilst planning out the space.


Back of house.JPG

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Indoor New3.PNG
 
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Harkon321

Well-known Member
The part most people will be interested in. The planned dedicated room will is 4m deep and 3.7m wide. This is to bare brick, so whatever soundproofing I do will reduce this significantly.

Planned room
Pic2.JPG
Speaker Layout.JPG


Everything will be cabled back to the AV Rack back left. (I've purchased a 27u Sanus rack which I pick up tomorrow).

LCR Speakers will be MK IW150 purchased from @Seriously Ltd.
Surrounds will be MK tripoles. Love the new in wall tripoles but will see how the budget goes.
Atmos - 4 x IW85
Sub (s) - Will likely initially use the MK V12 for the time being, although long term plan for that to be in the Open Plan area.
 
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Harkon321

Well-known Member
Week 1 - Digger and Dumper truck made short work of removing an old pond (converted in to raised flower bed) and digging the footings.


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First stage signed off by Building Control so concrete on Monday.
 
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Harkon321

Well-known Member
A few more days progress. Footings done, soil dug out and hardcore in for the floor slabs. Enginnering bricks ready for tomorrow and then ready to pour concrete pads.

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I need to decide on the width of the door between the open plan area and the cinema room. Needs to be wide enough to get a sofa through. Thinking 838mm fire door.
 

Harkon321

Well-known Member
Anyone have any thoughts on where I should put the radiator in the cinema room?

Thinking on the left wall (behind the seats) vertical style.

or

Underneath the window - Traditional horizontal convector type. Window is on that top exterior wall (indicated by the rectangle) but will be boarded over on the inside, for soundproofing/light control.

Does under the window give more flexibility for the room in the future?

Rad location.JPG
 

Harkon321

Well-known Member
Managed to pick up a brand new 27u Sanus rack for £280 (rrp £500)
Sanus CFR2127-B1 (Black)

Long drive to collect but it should be perfect for housing the amps etc in the corner. Should make cable management a lot easier as well - never had a dedicated rack.
Sanus.jpg
 

kbarnes70

Distinguished Member
The part most people will be interested in. The planned dedicated room will is 4m deep and 3.7m wide. This is to bare brick, so whatever soundproofing I do will reduce this significantly.
When you say 'soundproofing', is that what you really mean? You are aiming to isolate the room acoustically from, say, the rest of the house or your neighbours?

If so, then my advice would be to not attempt this. If you look at my Cowshed Theatre thread you will see this was an important consideration for me. To effectively soundproof the room and achieve a meaningful drop in dB outside vs inside not only costs a fortune (I estimate about half my budget for the build, exc hardware, went into it) but it also consumes a huge amount of space. I lost well over a metre off my overall width for example. You can see my drawings and the way I did it in the thread.

You have one advantage over me - you are starting a building from scratch and this would enable you to follow commercial studio practice and build isolation in right from the outset. But even this will require you to effectively build a 'room within a room' and will rob you of valuable space, not to mention considerably increasing your costs. Given you only have 4m x 3.7 to play with, I think the end result would be a cinema that was too small. (Remember I have a lot of experience with ultra-small cinemas too - my Hobbit Theatre was 3.5m x 3.5m but had no attempt at soundproofing at all).

Small cinemas can sound amazing as I proved over time, but they are difficult beggars to work with.

If you use a lot of acoustic treatments in your room, which I recommend hugely, to control the inevitable sonic distortions caused by the room itself, then you may find that these help to isolate the exterior of the room to some extent. Acoustic treatments are not intended to bring acoustic isolation - their job is very different - but they can help a little, as well as bringing massive benefits to the SQ.

The Cowshed Thread has a lot of info you might find useful wrt to both soundproofing and acoustic treatments. Give me a shout if I can provide any info that might be useful.
 

kbarnes70

Distinguished Member
The part most people will be interested in. The planned dedicated room will is 4m deep and 3.7m wide. This is to bare brick, so whatever soundproofing I do will reduce this significantly.

Planned room
View attachment 1364491
Have you considered moving MLP forward a little? Many people, me included, believe the best screen to MLP distance is a 1:1 ratio of the screen width. In your case this would let you move the MLP forward a tad, which would get you further away from the Rear Surrounds, which would be no bad thing. I would then position the Side Surrounds at 80 degrees, not 90 as shown. This would fill in some of that huge gap between the LCR and the Side Surrounds and give a more immersive experience, as well as remaining well inside ITU specs, if that sort if thing is important to you.

Have you considered an Atmos setup? Your room would be great for that. If not right now, maybe at least wire for it during the build. Just in case you change your mind. Wire is dirt cheap.
 

kbarnes70

Distinguished Member
The radiator is a bit of a problem. If you paint it a dark colour and put it under the window, that might be the best option. The main problem with that is that the rear wall really needs to be treated to stop reflections coming back off it randomly, and the radiator, being a big metal thing, is pretty reflective.

But I can't see any other place that is better. Is it too late to go for electric underfloor heating, which is cheap to install and doesn't cost the earth to run? Especially in a room you won't be using 24/7.

Really, wherever you put it, a radiator is a huge reflective thing and you'd be better without it.

My solution was an HVAC unit. These are cheap enough. They do rustle a bit when the fan is working, but mostly the fan is on very slow speed and I can't hear it over my usual Reference Level -5dB SPL.

With hindsight, I regret not going for underfloor heating in the Cowshed. The HVAC is fine, but underfloor would have been better, and then I'd only use the HVAC for cooling, which I need in the warmer weather. I find I can get the room cold before I start to watch the movie and there's no need to run the HVAC then during the movie (unless we are in heatwave territory, which is rare).
 

Harkon321

Well-known Member
Have you considered moving MLP forward a little? Many people, me included, believe the best screen to MLP distance is a 1:1 ratio of the screen width. In your case this would let you move the MLP forward a tad, which would get you further away from the Rear Surrounds, which would be no bad thing. I would then position the Side Surrounds at 80 degrees, not 90 as shown. This would fill in some of that huge gap between the LCR and the Side Surrounds and give a more immersive experience, as well as remaining well inside ITU specs, if that sort if thing is important to you.

Have you considered an Atmos setup? Your room would be great for that. If not right now, maybe at least wire for it during the build. Just in case you change your mind. Wire is dirt cheap.
Have considered 80deg for surrounds, given that it is a small space to consider front wides.

I'll be running 4 Atmos - MK IW85 in ceiling.
 

Harkon321

Well-known Member
The radiator is a bit of a problem. If you paint it a dark colour and put it under the window, that might be the best option. The main problem with that is that the rear wall really needs to be treated to stop reflections coming back off it randomly, and the radiator, being a big metal thing, is pretty reflective.

But I can't see any other place that is better. Is it too late to go for electric underfloor heating, which is cheap to install and doesn't cost the earth to run? Especially in a room you won't be using 24/7.
Discounted underfloor as couldn't afford to rip up existing slab in the open plan area and it seemed daft to only have it in part of the kitchen. Likely will fit aircon which will be able to heat the room, but I think a rad to keep the chill off in the winter would still be a good shout, plus it future proofs the room should the use change.

Behind the seating (under the window) is probably going to have the least impact on any room treatments, rather than having a large flat metal vertical rad in the corner.
 

kbarnes70

Distinguished Member
Have considered 80deg for surrounds, given that it is a small space to consider front wides.
Yes, I think that would work well for you. Also, you don't really want those side surrounds firing right into the ears of the listeners at each end of the row if you can help it.

I'll be running 4 Atmos - MK IW85 in ceiling.
Oh sorry, I missed that somewhere. Way to go!! You will get a super result!
 

kbarnes70

Distinguished Member
As you are using in-ceiling overheads, you only get one chance on positioning. Might be a good idea to browse the AVS Atmos thread where there is a ton of useful info on Atmos speaker placement.

FWIW, I found that a TF+TR setup worked best for me, with the speakers just about in line with Atmos guidelines. My overheads are on-ceiling and I did move them (twice!) after installation to get more sensation from over and behind me. Could you show me a diagram of your intended ceiling placement? You will need to finalise MLP first of course.
 

Harkon321

Well-known Member
@kbarnes70 Regarding Soundproofing - yes that is what I mean. I've read alot of threads (here and on AVS) but also read Rod Gervais book on Studio Building.

First plan is to set up a 2.1 system in their once it is water tight and see how much transfer I get in to the main house through brick work. I'll take some measurements and then make a decision on what is needed.

Then if, required, the plan would be 100mm stud work, spaced 2cm off brick walls and attached to joists using isolation brackets. (Room within room except the ceiling which is isolated anyway). Then 100mm fluffy insulation, layer of OSB, Green Glue, Layer of soundblok plasterboard. All costed. Have purchased green glue as and when I've seen it cheap, so picked up £500+ of the stuff for £300.

I have worried about room size and the impact this will have but I've tried to be clever with speaker choice to accomodate this. The LCR are in wall so I lose no space up front behind the screen. I'm also considering the inwall MKIW150t triploe surrounds, again increasing the distance from tweeter to ear.

If I don't do the stud work, the on wall equivalent tripoles ate 150mm deep, so they will actually be closer to me than if I don't do soundproofing. o_O
 

kbarnes70

Distinguished Member
@kbarnes70 Regarding Soundproofing - yes that is what I mean. I've read alot of threads (here and on AVS) but also read Rod Gervais book on Studio Building.

First plan is to set up a 2.1 system in their once it is water tight and see how much transfer I get in to the main house through brick work. I'll take some measurements and then make a decision on what is needed.

Then if, required, the plan would be 100mm stud work, spaced 2cm off brick walls and attached to joists using isolation brackets. (Room within room except the ceiling which is isolated anyway). Then 100mm fluffy insulation, layer of OSB, Green Glue, Layer of soundblok plasterboard. All costed. Have purchased green glue as and when I've seen it cheap, so picked up £500+ of the stuff for £300.

I have worried about room size and the impact this will have but I've tried to be clever with speaker choice to accomodate this. The LCR are in wall so I lose no space up front behind the screen. I'm also considering the inwall MKIW150t triploe surrounds, again increasing the distance from tweeter to ear.

If I don't do the stud work, the on wall equivalent tripoles ate 150mm deep, so they will actually be closer to me than if I don't do soundproofing. o_O
You have covered the bases well. What sort of dB level drop outside vs inside are you looking for?

I targeted a drop of 45dB outside vs inside - it was a hell of a lot of trouble and expense to achieve it. Later I found out my neighbours are deaf! Really. I get the benefit of a much lower noise floor inside anyway so I guess the money and cost were worthwhile.
 
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Harkon321

Well-known Member
@kbarnes70 Neighbours being deaf after all that is hilarious.

I haven't worked out a dB level drop to be honest. What I've suggested, (on top of 1 100mm interior wall and 3 x 300mm walls) should give a significant drop.

I guess the only way to check is to play a few clips at reference in the unfinished room and then measure dB inside and outside. Then reduce the volume inside until the noise outside the room is at an acceptable level - and calculate the difference. Not sure how scientific that is but it would give an idea.

Could you show me a diagram of your intended ceiling placement? You will need to finalise MLP first of course.
The start of a sketch that I did - obviously not complete.
TF are 45deg in front and built in to main ceiling. TR are about 40deg behind and built in to the pelmet. Both will need backer boxes as the speakers are open backed. This was just me playing with angles, they will be inline with left and right channels, not near the edge as suggested in the picture.

atmos pos.JPG
 

Harkon321

Well-known Member
Almost up to damp course. Can finally see the outline of the rooms.

IMG_5306.JPEG


Have chosen location of the interior door, to ensure I can fit any sub with a depth 65cm or less on the front wall. Did a quick mock up (chair for MLP and a table that was roughly subwoofer sized :D. Bricks marking where link door will be. Both the wife and the builder think I'm mad I'm sure.

IMG_5310.JPEG
 
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Harkon321

Well-known Member
Right, we've been going two weeks now. Barring a few minor hiccups it's going very well, weather up until now has really helped.

Really wanted to leave hand prints in this - such a child.

IMG_5348.jpeg


Rooms really starting to take shape. If the weather doesn't get to bad we hopefully might have most of the roof done by next week.

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I picked up a pair of MK IW95 speakers in the classifieds yesterday which I intend to use for rear surrounds. I ideally wanted the new MK IW150t tripoles for all four surrounds but it's going to be some time before I can afford a pair of these, never mind two sets! In the meantime the IW95s need a similar wall cut out and will be more than adequate for now.
 
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Harkon321

Well-known Member
Internal block work today. Gives a good idea of the Home Cinema space, now the dividing wall and door gap is in. Screen will be where the existing brown UPVC door is.

Having second thoughts about the level of soundproofing and walls that aren’t shared with the house. Might scale it back and just focus on the linking walls. Time will tell.

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mb3195

Distinguished Member
Good progress mate, keep the updates coming 👍🏻
 

Harkon321

Well-known Member
Architect's protractor seems to have been out by a few degrees which is now playing havoc with getting the correct pitch. Bloody annoying.

In other news I need to choose what flooring we go for in new kitchen/diner/open plan area.
Considering Karndean (or similar) or a decent thick laminate like we currently have.

It's a large area and the Karndean (or similar) is a fair bit more expensive.

Worried that the Karndean stuff will be cold underfoot in comparison to laminate?
 

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