Planing to put an addition on also. It will be built ground level and connected to my walkout basement. 2 things you need to look out for. #1 Use space for maximum potential with minimal cost. #2 plenty of power. Building the width of a building just a little bigger to allow people to walk through. I'm going with 32' wide. I'll get 4 rows of pins. One row on each side and a double row back to back down the middle. This is the minimum width for 4 rows. You can have a person on every pin and just enough room to for people to walk behind them. 36 wide would be better but I have limited space. 40 would be overkill on price for me. I like to use the 3 foot per pin rule. This will give me just enough room to squeeze in between the games for a simple fuse or battery change. I'm going 40 feet long. This will give me enough room for 13 pins on each side and 10 down the middle. A total of 46 pins. I'll still be able to put another 14 pins in the basement family room if I grow out of the arcade room. As for electric. I'm running to outlets or 4 pins per breaker.

It's cheaper to build up then wide here in the states. Or at least when adding to and existing house.

A 2000 square foot ranch verse a 2000 square two level building. As stated roof size is cut in half but also foundation size is cut in half. The foundation and roofing are the biggest expanse compared to a second level of floor joist. It is by far cheaper to build the 2000 sq two level house.

I agree. I use the 3 feet by 8 feet per pin rule. A 40 feet long room could hold a run of 13 pins. I'll have about 6 inches between heads. On my classic games it will be more like 3 inches between heads.

If you can squeeze out to 32ft it would give you the need walking room without rubbing man junk over each other.