


To modify Joists without engineer stamp or not
Looking to build my forever simulator. Have an eye XO unit with performance package that worked perfectly in my duplex garage. Fast forward to today and we bought a house I was planning on putting a Sim in the basement. Problem is bottom joists are 7 ft 9 inch. I got a friend's dad to engineer a drawing to see what cutting 3 joists to create a 2ftx5ft or so hitting box to allow Rightys to fully swing driver. This would give around 8 ft 6 inch which is perfect for my height (5'8) flatter swing.
The drawings are good, essentially sistering two 2x10s to each side of the surrounding joists ( so 2 joists will get 2 2x10s on each side) up to the load barring area. Essentially id cut joists 3-5 down, and 2/6 would be reinforced. The 3 joists cut would be supported by temp posts and the swing box would be secured perpendicular with 3 2x10s. So the box would be surrounded by 3 walls of 2x10s. Then alot alot alot of heavy duty hangers
So most contractors want a engineering stamp and my buddy's dad essentially said he wont do that. I can go to a firm and get it stamped for around 2-3k and then permits (what that costs), but essentially I am wondering if it's even worth it going down that route? We are having a baby and we dont plan to move for a very long time. I've seen other redditors do a similar renovation so wondering if anyone else can chime in on what they did? We are weighting the pros and cons and trying to determine if that extra 3-5k of hassle is worth it.....
Tldr: joists modification without an engineering stamp for golf simulator swing box. Do I really need it if I dont plan on selling? Will this cause huge structural damage?
Photo 1 is my roof, 2 is the drawing, 3 is ideally what we'd like to build.
Thanks in advance.