Old Cow Shed conversion in Auckland New Zealand

Hello Everyone, After spending considerable hours on this site looking at everyone’s projects I finally have a space to start my own. I am currently in the process of converting an old cow shed out in the country into an office and recording studio. The cow shed had a refurbishment in the past and was made into a liveable space with kitchen and bathroom. This was done quite some time ago and is extremely run down. Some of the original features of the cow shed still remain such as the pit in the floor. See existing attached floor plan and cross section below. I’ve pretty much gutted the place (apart from the bathroom, which I want to keep) and are now in the design phase of the office/studio. The total floor area is just over 65m2. I currently work from home so the requirements I’m after are an office space, control room, small vocal booth and if space allows a studio room to potentially record a set of drums. There is a concrete wall all the way through the middle of the shed which is unable to be moved or taken down. There are couple of existing openings in the wall, a small window (not sure what it was originally used for) and the door way in to the hall. I have spoken to people and there is the possibility of adding or extending the openings if needed. There is also no roof cavity, just a sloping ceiling on rafters. My nearest neighbour is about 200 metres way and as this cow shed is out in the peaceful country side I would certainly like to keep it peaceful. As I said earlier I would like to be able to record a set of drums, so if a drummer decided to go nuts on the drums I would like to be able to isolate as much of that sound as possible. There are also a lot of trees around the shed and when the wind gets up it becomes very noisy inside. The lounge/kitchen side was a tack on to the original shed which is why the walls are timber framing and a particle board floor added to cover the pit. The particle board flooring needs replacing as does the Gib wall lining. Not sure weather to replace the flooring or take the floor down to the original level and just cover the pit or potentially use the pit for something. The bedroom/bathroom side walls are concrete block filled with concrete. There are no wall linings on the internal concrete wall or the concrete block walls Attached is a proposed floor plan I have come up with. I’m basically trying to create 4 rooms plus the bathroom (leaving the bathroom where it is to keep plumbing costs down) with good vision and access from the control room to the studio and vocal booth and good access to the rooms from the office, all this with minimal alteration done to the internal concrete wall. If anyone out there has any ideas for improvements, comments, thoughts or advised I would love to here about it. I’m open to all options and any ideas including moving the bathroom and drastically altering the internal concrete wall if need be. My budget is around the 10K-15K mark but could possibly go as high 20K not including labour. I have a builder friend and once I get the floor plan sorted he should be able to give an idea on the labour required. Thanks heaps.