you can pretty much ignore most of this level and you don't even need to save anyone and you only need the bricks at the last part in the room with the big chandelier.
thanks to Spilner for the error i made for the last brick
select the invincibility red brick before you start the level as the enemies will swarm you.
select free play, and start with anyone, don't choose someone with water as they can't use it from the start due to this level so choose anyone then switch to a water character as you can then use it, for this solution i will just refer to the water character as frozone as he's easiest to find top right on the selections, but again you can choose who you want as long as they use water.
so first off ignore the person in the first room trapped under rubble and turn left facing north where the main staircase is, change to frozone and put out the flames on the stairs, now just go past everyone.
there are 2 pipes which you need to wait until you can pass each one, then ignore the old lady in the room and the part where the floor collapses and go to the door to the right where the flames are and the handles you can pull, put out the flames, you may have to switch to someone then back to frozone if you run out of water, normally you wouldn't need to but this level is about finding water but it's not needed as you can just switch out and back again to get more water, so after the flames are out switch to mr incredible and smash through the 4 walls.
then there is a short cut scene, in this burning corridor you cannot run through it so you need to smash the door near you and the ceiling will collapse, you now need to pick up the ceiling and move through the corridor, you will be saving someone but it's just part of that action and say 1/3 but you don't need to save the other 2, now you will need to throw someone over using mr incredible but i just chose a flying character and flew over and then switched to the other person and chose a flying character (i used firebreak as im so used to using him, he's 3 down from violet who is on the top row, but use who you want) and flew them over as it's quicker because you will need the 2nd character for 1 brick in the last room.
so once both of you are over the gap change to mr incredible and smash though the door on the right, then switch to the other character and bring them through the door otherwise they will just stay behind, at least they did for me, so i switched to firebreak and flew down the corridor and then into the room (you don't have to build the 2 highlighted objects in front of the family build pad)
so fly past the piano and fly up to the right balcony you can use a lever to drop the chandelier that drops it and you can smash the chandelier to get a brick for building the family pad at the back of the room, before you drop down, fly north and on a balcony will be another brick sitting there, that's brick 1/4 now drop down and smash the chandelier for another brick, that's 2/4 you now need mr incredible to lift the collapsed floor on the right then use frozone to freeze so the floor holds up and mr incredible can then pull the handle for brick 3/4 the last brick is on the ground to the right by using frozone to put out the fire thanks to Spilner for pointing it out as for me that's the last brick 4/4 then just build the family pad,
now you need to use frozone to freeze the ball on the crane arm and once that's done you get the cut scene.
the achievement will unlock during the cut scene which i skipped.
you can do this in roughly about 5 mins, it;s best to have a run through using my solution to get used to the run, and it's pretty much bypass everything you can.
hope this helps.