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self build dedicated home theatre

Discussion in 'Home Cinema Building DIY' started by Dominic, Oct 17, 2003.

  1. Dominic

    Dominic
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    Its been a while at my current house, and ive now managed to get permission from Mrs Dominic to build a dedicated HC room.

    My plan is to build a 6.5mX3M building for both HC and a study. I have a second baby on the way so need to free up my current office as a bedroon.
    Questions i have relate to the building itself. I have worked out sizes etc and by brother in law is a transport manager of a timber firm, so i plan to build a 4x2 timber framed building sitting on 6 courses of bricks, it will have a shallow pitch roof and possibly tiles. The outside will be clad in feather edge. The inside will be plasterboard with insulation in the studwork, the floor will be timber joists > chipboard/OSB and then carpet.

    Has anyone done a simular construction for a dedicated room ? I read people doing garages and other brick built rooms. Are there issues using timber. will it not absorb the sound and **** the neighbours off.

    Also ive contaced the planing dept and they are happy with the idea so long as its less than 70cubic meters.

    The problem is that now i have to deal with building control, they have sent me an aplication form and i have to submit plans and drawings of my new building How much detail do i need to give them, i dont know depths of footings etc and distances from boundaries ( is it 1m ? )
    But i do know the construction type and how big it will be.


    If anyone have gone down this road, could i pick up some tips. I really dont want to get bogged down with the council and the building regs. Hopefuly it will be enjoyable.

    cheer

    Dom
     
  2. Bassbin

    Bassbin
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    Planning and building regulations vary around the country some authorities are more strict than others. The 70 cubic metres rule is pretty standard but there are still rules you need to follow (your local planning department should have a booklet with some guidelines). A copy of your areas building regulations should be held at your local library so that may be a good place to start. If your getting a builder in to do the work then they should be able to take care of the building regs (depends how much of the project you want to manage yourself). Aside from the depth of foundations (need to check there are no drains in the way) the regulations are pretty strict on wall and loft insulation.

    I would start by drawing a floorplan of your existing property and plot and then make another copy with the planned extension. Make an informal appointment with your local planning office and tell show them you plans (DON'T SAY IT'S A HOME CINEMA THEY'LL GET TWITCHY ABOUT NOISE ETC) just say it's and extra reception room or office. They should be able to give you a view on whether planning permission is required or not.

    I've just got permission to build a huge two storey extension and the local planning office were great. However, the other people have used the same office and had real problems getting on with them so I'd advise a softly, softly approach as you don't want to get on the wrong side of them.

    Godd luck with the project.
     
  3. Dominic

    Dominic
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    thanks for the info, i havent told them its a home cinema, ive said its a playroom/ office. They have sent me a form and no booklet, i really need to pop in and see them. I like the idea of the local lib habing the regs. ( part of my job involves managing the networks for all libs in essex, ) so i could even do this during work time


    I plan to do most of the work myself, but i do know a mate in most of the trades, builder/ groundwork. Spark, roofer etc. and i can turn my hand to pretty much anything.

    I have already drawn(on CAD package) my property and my garden ( to scale) and have includded my proposed extention. I think my next plan is to pop in and chat to the building control chap. My only worry is that im out of my depth and im going to get shafted. Its always the way when you dont completly understand a subject, you just take what the say as given because you cant challange them as you dont have enough info.

    i will let you know how i get on.
     
  4. Gary Lightfoot

    Gary Lightfoot
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    For better soundproofing, use two layers of plasterboard on the inner wall, and fill the cavity with rockwool. Seal all joins with silicon ruibber so to stop any noise leaks - where air can go, so will sound.

    Gary.
     
  5. fufna

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    The trouble with doing that is that you need to recirculate the air in the room.

    I'm currently constructing cavity interior walls in an exterior building and have found that the best way to easily reduce sound leakage is stretched fabric panelling containing dense heavy foam over double skimmed waterproof drywall board.

    taken me 3 goes so far to get the acoustics how I want though!:suicide:
     
  6. Gary Lightfoot

    Gary Lightfoot
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    Accoustics and soundproofing are totaly different things. If you want to stop sound leaking, you have to ensure there are no exits for it. Ventilation is of course, another issue.

    It can be a bit of a balancing act to get them all right.

    Gary.
     
  7. fufna

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    Actually, acoustics and soundproofing go hand in hand,

    One can help the other when controlling dead spots as well as unwanted live reflections.

    Don't concentrate entirely on one or the other, an acoustically treated room can contain boomy reflections better and thus give you more leeway to actually have air in your room

    Or of course you could just install an entirely decoupled AC system a la pro-studio installs!
     
  8. Gary Lightfoot

    Gary Lightfoot
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    My point is that if you make the room soundproof, then you know the neighbours will not be affected. To compromise on that for accoustics could mean less effective soundproofing.

    for instance you can fit resiliant bar to stop sound transmission which will do a good job, but also totaly remove the bass from the room.

    Decoupling the room works even better - a room within a room! :)

    Gary.
     
  9. Dominic

    Dominic
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    good ideas, here i like the idea of double skinned plaster board and rockwall. I guess my first concern is not to annoy the neighbours and then seocnd to acheive a reasonalbe sounding room.
    What about the roof. My idea was plaster board and rockwall in the loft space, i plan to have a tiled roof so im assuming that will reflect sound better than OSB and felt.
    And then we are back to the ventilation and acoustic trade off. Im thinkin soffet vents for the roof space and air bricks below floor level for the under floor space.

    Im gettng worried about the regulations as this isnt my area of expertise and im out of my depth
    Am i better to just build a standalone building (temporary structue as its only timber) and not involve the local planning / building control. and then at some point connect it to my house by means of a corridor of sorts. ?
     
  10. Gary Lightfoot

    Gary Lightfoot
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    You may have to fit some form of vapour barrier between the wall/rockwool before you fit the plasterboard. This can be plastic sheeting or get the rockwool that comes enclosed in its own plastic. It may be an idea to fit plastic sheeting on the outside before cladding it in feather edge - not sure on this so it may be an idea to find out from a builder or someone in the business.

    The ideal way to isolate the sound from outside, is to place some form of isolator on the floor before laying the floor beams - rubber mounts are one method, though I think Wickes heavy duty 30mm slabs can be used for this. Ensure they are kept away from damp though. A plastic membrane may work for this.

    I have seen floors filled with sand to act as a method of damping bass travel, so this could be used if the room within a room idea isn't required.

    Then build your walls on top of the floor ensuring they don't touch the walls. Lay the roof joists across the walls as normal, but make sure they don't physically touch the ceiling joists.

    Once filled with rockwool and two layers of plasterboard, you should be pretty much isolated from the outside world - though the door is always a problem. A good solid door and sealing should work reasonably well though. Bass will always travel through anything it touches, and only mass can really attenuate it. Isolating the room reduces this considerably. However, if the room is detached, then the chances of the vibrations reaching the neighbours is less, so you may not need to go this route.

    Don't forget the silicon for all edges. It really is very important to stop air leaks otherwise the sound will leak out.

    Ventilation should probably be ducted in and out, so maybe a couple of bathroom steam extraction units could be used. There are probably better fans for this, so look around. Try to find something that is quiet too. :)

    Your ideas of soffits is a good one - columns and soffits are used to break up standing waves IIRC, and are often a feature of Dennis Erskin designed theaters, so for more bedtime reading, go to www.avforums.com and lok in the home theater builder part of the forum for ideas. Try using the search for Dennis's posts, and see what he has said in the past. What he doesn't know about soundproofing isn't worth knowing.

    Other than the rockwool and plaster board, I don't know about the tiles or felt being better for noise reduction. The tiles will have more mass, so may have a better absorbing effect for bass. My loft has plasterboard, vapour barrier, rockwool, roofing felt then roof tiles. Sound leakage is barely perceptable at ground level at normal volumes. I also have some extra 'walls' at lower levels, so this may be helping though.

    I used some of the above methodology in my loft 'conversion', and it works very well. I tackled the echoey accoustics merely by placing carpet on the lower walls and all of the screen wall. It sounds considerably better too. I used a Behringer Feedback Destroyer to smooth out the bass response too. The room is far from ideal, but works well considering the budget that was spent on it. :)

    As for building regs, it wouldn't hurt to ask your local council for guidance - the last thing you want is to build the room and have some neghbour whinge to the council, and have them tell you to pull it down. AFAIK, 'temporary' buildings such as sheds or similar don't need planning permission, so you should be fine (given the size constraints mentioned earlier). I would still ask first though.

    Gary.
     

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