Old Rootes + International House = A-H + I = A-I
Old Rooes has 8 block, International House is another block and New Rootes has 7 blocks. Each is given a letter
First Old Rootes building has blocks A, B, C and D
Second Old Rootes building has blocks E, F, G and H
International House is given the initial/block I
First New Rootes building has blocks J, K and L
Second New Rootes building has blocks M, N, O and P.
Blocks are generally separated by stairwells, however there are a few exceptions - some blocks may not all be on the same side. It may be the case that to get from room 8 of G block to room 9 of G block, you actually need to go up G block's stairs to the first floor, then walk along to H block and come down those stairs to get the other room. It's a bit confusing at times