$ per sqft for add-ons

[erpensa]

Hi, I'm new to the board; I've been browsing thru many of the threads. I found an interesting one on $ per sqft for house construction. But am also interested to get an idea of what $ per sqft is for add-ons (such as adding a floor or bonus room above the garage, or just an addition comming off the side of the house). Ours is a 1400 sqft ranch w/cedar siding in Raleigh NC.

Thanks,

Steve

[Rich]

Honestly there isn't much of a difference between adding additional square footage horizontally or vertically.
Think of it this way - with a new additional built horizontally out from the house you will have added cost of a foundation. Building that same thing vertically you have the added cost of removing the existing roof and replacing it with floor joists. Horizontally is a little more expensive but not a whole lot more.
Another facet of any addition is that you will be cutting into existing walls and wreaking havoc with living conditions. There is also additional cost and time associated with the additional coordination.
Even though that's not a concrete answer - it's the best I can give without a full fledged estimate of what you want to do. It could range anywhere from 60 / sf to 500 / sf.

[grumpydasmurf]

I think the sqft pricing structie is a rule of thumb, I really dislike the concept because it's not an exact science. This holds true especially when it comes to add-ons.

I know an experienced estimator can give an accurate guess at cost based on past experience. That's just my opinion.

[Rich]

And it's a good opinion.. it's all speculation until there are a set of plans with a true estimate. The word estimate is just that also - I essentially say - "From my past experience and with the current market prices I feel like I can build the plans at this price". It doesn't cover the up charge on OSB or plywood that could happen in a year.