Need to Modying a plan and keep Golden Section Dimensions

Hello all, This is my first post so I tried to read the announcement on requirements before posting so please forgive me if I leave something out. I am from Darlington, SC. I am in the process of looking at house plans to build a new house. I found a house plan to work with and want to work with the architect/contractors to make my garage space a studio. I have Not started Construction yet. Still trying to Modify plans I have a lot of room for budget. The buget is from $5,000 to $10,000 in building the studio. The garage space in my house plan calls for a 19'-6" X 20' with at least an 8' foot ceiling, but I have decided to modify the garage to add more space. The Studio plan I want to use is from an article"Building your Cottage Recording Studio" by Robert Dennis. The image is attached to this post. In the plan, the Entrance/Office space is 8'-6"X8'. I want to have room for a small bathroom 5'-4"X5' in this office space. If I take the Entrance/Office space to 10'X11' that will throw my Golden Section Dimensions off. How do I get back on track to make sure my dimensions are 1 (high) 1.6 (deep) and 2.6 (wide)? Will I have to modify the Control room or Studio? After making modifications and looking at the overall plan, how much would you say this whole studio without modifications would cost? After Modifications Would I be over my $5,000 to $10,000 budget? Thanks

You mention "golden section" but don't give ceiling heights; if it's your live room that's supposed to be 1:1.6:2.6, that would put your ceiling at 6.25 feet. Also, if this is to be a dedicated space, you will (I believe) cause more problems with parallel walls than you would by deviating from golden section ratios - right now, if your dim's are 8x10x16 (assuming "normal" ceiling heights) you already have a "hole" in your modal distribution (Bonello method) at around 80 hZ, and again in the 40-50 hZ range. The parallel walls will require more absorption placed on walls to combat flutter echo (only part of which is audible from a "clap" test, the rest will color your recordings without being obvious WHY) - IF you can add ceiling height to your dimensions, we can help you find good ratios and (if you're up for it) maybe a better layout... Steve