Studio in an 18th Century pleasure garden

First can I say – what an amazing forum! I am new to the whole sound studio thing and could not have imagined that I could have learned enough in a few hours to make me believe that I could actually design and build a studio with your help! So on to my plea for that help…. Location I am fortunate to own a property in Bath, England that is built on the site of a former 18th Century pleasure garden. Music was an important part of the entertainments on offer in the English pleasure garden, so I like to think my plans are very appropriate… Site The room that I would like to convert is the ground floor of a two-storey outbuilding (5m x 3.5m internally) that was probably first built around 1750, possibly as a stable or tack room (see photos). The building is set into a steep slope which means that the back wall is built right against the soil, up to first floor level. The external walls are random Bath stone at least 18 inches thick, and the floor is a 6-inch concrete slab. There is no damp-proof course and although the second storey is dry, the ground floor suffers from damp. I propose to deal with the damp by tanking the inside of the ground floor walls with an appropriate water-proofing compound, however I expect there will still be some humidity to deal with on an ongoing basis. In addition to the main external door, there is second doorway which opens into a timber and glass greenhouse adjoining the outbuilding, which has its own door to the outside. The first floor room has been converted to provide a bedroom and bathroom. There is no internal staircase connecting it the ground floor and it is accessed via external steps. Objectives I have two principal objectives: First, to sound-proof the ground floor room so it can be used as a practice room for my band. The band plays acoustic to light rock with drums, guitars, bass, vocals, etc. Unfortunately I have a near neighbour whose house is only about 10 metres away on the other side of a 6-foot high thick stone wall. Although the neighbour is fairly tolerant, I would prefer not to have to worry about whether the band is disturbing him. I am not concerned about sound penetrating into the room above except to the extent that it then escapes out of that room and reaches the neighbours). Second, to improve the internal acoustics of the room, both for the benefit of our band practices, and with the aim of starting to use the room as a recording studio. I expect I will have to make a lot of compromises because the space is small and if I try and split it into a control room and isolation booth then I will no longer be able to accommodate the band for rehearsals. Although I plan to stick to the first objective initially, decisions that need to be made in relation to the second objective may have a bearing on what I decide to do right now. If I do eventually split the space into two rooms, is it better to have a large control room (doubling as a practice room for the band) and a small studio booth for recording – or a small control room and a large live studio room which would double as the practice room? Plans and specifications I am attaching a Sketchup model of the ground floor of the outbuilding, and also a couple of photos. And here are the main specifications: Dimensions of room: 5.15m x 3.60m. Height to bottom of joists of unfinished ceiling: 2.65m Floor: 150mm thick concrete slab Outer walls: Random Bath stone blocks and lime mortar, 450mm minimum thickness. Bath stone is a soft limestone. Main door to outside: Door 2.0m high x 1.0m wide, made of 30mm thick solid timber. Second doorway (opening into greenhouse with own external door): Currently no door - opening 2.3m high x 1.2m wide. Window: Three fixed leaded glass window panels separated by stone mullions. Total widow reveal size: 1.1m high x 1.5m wide x 0.2m deep. Set 1.2m up from floor. Ceiling: Currently comprising (from the floor covering of the room above downwards): 10mm stone tile 5mm flexible plastic tile mat 15mm plywood sheet 25mm void space containing underfloor heating pipes 10mm plywood sheet 200mm x 50mm ceiling joists at 400mm centres, between which are fitted 60mm celotex polyurethane foam sheets I am attaching a Sketchup drawing illustrating a cross-section of the ceiling. Proposals Here are my proposals, assumptions and questions: Floor – as the building is detached I have assumed there is no need for insulation. Am I right? Walls – I have assumed that their mass provides an adequate sound barrier and so do not need any treatment to stop sound escaping. Is that fair enough? Window – I propose to make and fit a double-glazed barrier using 10mm and 8mm sheets of glass as described in the various articles associated with this forum. Will that keep all the sound inside? Main door to outside – I propose to fit door seals and do no more. Will this be adequate, or will the door be a weak point needing additional attention? I could fit an additional inner door – but is this really necessary? Second doorway (into greenhouse) – I would like to be able to let light in through this opening, and although I would like to keep it as a door, I would consider building up from the floor and converting it to a window if necessary. The door opening itself is oversized in any case and would benefit from reducing in height and width. The questions I have are: What is the ideal door arrangement? The thickness of the walls would allow for two doors, but is that really necessary? Does a double-glazed timber-framed door with 8mm glass panes provide better sound insulation than a 30mm thick solid timber door? Is a sliding door arrangement (whether solid or glazed) desirable and easier to sound-seal than a hinged door, and is there an article somewhere on how to build one? Ceiling – the current constituents are listed above. How much more insulation (and what sort) do I need to add to provide effective sound proofing from the room above? I have about 300mm from the between the bottom of the floor joists of the currently unfinished ceiling and the top of the window reveal. HVAC engineers have recommended that I use this space to make a false ceiling to accommodate ducting for a ventilation system that they want to sell me. Presumably the same space could accommodate artifacts to improve the sound in the room? The HVAC folks are also recommending an air-conditioning unit that would be mounted on the wall and coupled though the wall to an external condensing unit. Can anyone comment on these HVAC issues, based on my plans for the room? Are there particular units that anyone can recommend? Budget Although cost is an issue (isn’t it always?) I would rather spend the time and money to do things properly, rather than put up with a poor compromise or have to start over again (life is too short…) I would be grateful for any comments on my assumptions and proposals, and how realistic my objectives are. All suggestions and pointers are most welcome! Thanks Chris