I pulled down a sagging ceiling in one of my bedrooms at the weekend
(as one does). Above it, the joists spanning the room are bowed and
need replacing.

The joists are nailed into the rafters beneath the oak beams that run
the length of the house on either side (they are not attached to the
beams).

What I would like to do is replace the joists with ones above the oak
beams (to expose the beams and create more space in the bedroom).

Bad ASCII art of the side view follows.

What I have (The O's are the oak beams);
/\
/ \
/ \
/O O\
/----------------\
/ \
| |
| |
| |


What I want;
/\
/ \
/________\
/O O\
/ \
/ \
| |
| |
| |

I have 2 bedrooms in this elevation with a brick wall in the middle
(upto the height of the oak beams). The walls are stone to the height
of the beams with brick above. A brick extension runs off a hip in
the middle of the house

The joists are 3"x1 1/2", the rafters are 3"x2", Both are about 10' in
length.. They are spaced about 1' apart along the roof.

Can I do what I want? Is there a good book? Is is diy or do I need
an expert?

Any other information that I should post here?

Thanks,

John