there is one company in 1 Puchong doing that. With high ceiling you may want to do one that you can see below like a half storey than one that is at the attic.

For such a thing you better get a pro to do it and not any contractor as it involves structuring to hold the whole (new) floor especially when you are not going to build new pillars to strengthen it, new pillars is add on obstruction below. You may wnat to have railing instead of covering the whole area. Half or less than half of the area is ideal provided the area is big enough to accommodate a study "room"/area. For 22' x 14' you can make a 10' x 14'. Get them to draw so that you can visualise. if later you find that it is not as nice you can always extend to cover the whole area but you got to tell them you might do that in future so that when they build they prepare such a way that is easy to extend to the whole area later. Anything larger than half (ie. 11 x 14,) say a third of leaving one third it is undesirable, in my opinion. You cannot have 22' x 7' or anything 22 x X, it looks funny from below. and a child may try to look below areas that can't see and fall from railing.

Not forgetting wiring below for lighting.