[ken weaver]

the room is 12 ft. long and 8ft. wide, there is 2, 2x6 floor joists. i would like to add two or three more for the weight of a large bathtub and ceramic tile, can i take two 10 ft. 2x6 set each end on the concrete sill and sandwich them in the middle with bolts and washers. and /or set concrete blocks in the middle with shims for each additional joist?

 

[ken weaver]

the room is 12 ft. long and 8ft. wide, there is 2, 2x6 floor joists. i would like to add two or three more for the weight of a large bathtub and ceramic tile, can i take two 10 ft. 2x6 set each end on the concrete sill and sandwich them in the middle with bolts and washers. and /or set concrete blocks in the middle with shims for each additional joist. under the floor joist is a 3ft. crawl space.:whistling2:

 

[fixrite]

so if I understand this correctly.....your floor joists are NOT set at 16" centers.....by my calculations you are missing 4 floor joists at a minimum.