Can anyone advise me on build costs of skyscrapers/ large offices?

****************
I know that there is a huge increase over 50 floors in the cost per sq ft
Also about 65 to 70 stories.
And one jump at about 20 to 25 floors.

***********
But can anyone give rough rules of thumb etc ( or something more specific)
on how the cost of a skyscaper in say NY or the US , or London or a major UK city could be estimated?
eg for x floors and x sq feet.

*********
I notice that many Uk cities have high rent prices yet no very high rise development.
eg Birmingam UK is as expensive as Chicago , but has no big skyscrapers- q puzzling?

Anyway thanks all
TRumpton.
********************

This is a interesting topic. I remember sitting in on a meeting awhile back and this very topic was discussed. There is a $125(CAN) cost increase per sqft when rising above 60-storeys. (Residential Tower)

This was a few years ago, during the height of the condo boom in Toronto. The actual cost may be different now and in other markers.

It's true construction costs rise like a stairway when it comes to costs/f2/height, allthough it would be very hard to give you an insight at what heights or at what factor, not even roughly. That depens on:
- the function of the building. Residential towers tend to be heavier then office towers
- building code and height planning regulations. At some building height law might require sprinklers for example
- construction method. In general, steel will get you higher for the same price then concrete
- slenderness of the tower
- geographic elements. Soil, earthquakes, wind factors

In The Netherlands, rough treshold heights are 70 meters, 110 meters and 150 meters.

Interesting question, but it is a moving target. Technology changes now so that 60 story apartments you see as a trend now in Hong Kong would not have happened perhaps only 5 years ago. Not withstanding the site issues or factors mentioned above. ONe way of looking at it is with dimensions (not spatial)

weight increases as you go higher soyou have to start moving to a larger steel I beam, or rebar, or box, and or deeper pilings,

waste is another. due to dimensions in how certain materials are produced the more standard sized or weighted the material the cheaper, if there is a variance from this the waste factor is another thing to look at

Mechanical , Electrical , etc, system jumps at certain levels. You keep going to a higher level and soon the relative marginal increase in use will be higher in price to get. Specially when one starts talking of custom specs.