2 floor. Attic. Lifting ramps

Bought a plot of 1-storey brick house 6 ? 8.

For a large family friends is not enough space. Objective: minimal means, the timing to increase the living space.

Chew-advise:

In the attic (2-symmetrical pitched roof under the iron) to make 4 more rooms. 2 rooms have one of its walls gables (in these rooms with 2 beds - purely to sleep). 1 room - in the middle of the attic - it's another 2 beds. And poslednyayaya, also in the middle of the attic - a hall.

Question - how to construct a central part of the lifting ramps - they will only be raised in the summer and are firmly fixed ... (frames, pillars ...). I would like to avoid disassembling and modifying only the middle parts of slopes.

PS: insulation, vapor and waterproofing means.