Arlan A 45 Wood Log Hobby Workshop Office D.I.Y. building kit | Hud-1 EZ Buildings This building includes 423 sq. ft. of open interior space plus a 55 sq. ft. bonus room. The building is an excellent addition for a homeowner to use as a hobby room, workshop, home office, garden house, guest room, weekend getaway cabin or just some additional living space. This is the perfect building for the DIY and easy weekend project to add more usable space without the expense of a room addition expenses.