I've been told that doing a 2-story addition to a house is almost always an automatic $100,000 price tag. I'm wondering if any of you have been through the process and what the realities were.

What I'm looking to do is add a 24' X 21' addition to the back of my house that includes a pantry, laundry and dining room downstairs with a master suite upstairs. We would have it built as a shell so we can finish it out ourselves to reduce labor costs, with the exception of the master bath. I can do the flooring, trim, doors, cabinetry, etc. myself.

edit: The entirety of the addition will be attached to the back of the house. The 2nd story will not be over any portion of the existing structure, with the exception of the roof tie-in.

[This message has been edited by Ryan the Temp (edited 11/18/2010 10:40a).]

I think your estimate is pretty close. There are obviously an infinite number of factors that I don't know, but I would estimate the price tag to be somewhere between $80-$100/sf.

I have done this (had it done) but I really don't have any idea how to give you guidelines on cost. We did a fairly extensive addon to our house about eight years ago and the cost was in the range of $110/sq. ft. But that included interior finishing, plumbing, cabinets, flooring, electrical, and an additional AC unit. No appliances in that cost. Demolition costs and the tie-in to the existing roof are a big factor. The work to open the exterior wall and the roof will have to be estimated specifically for your situation.

We have a sunroom on the back of the house we would demo ourselves. The nice part is the openeing between the kitchen and sunroom was the old back door and we can easily install a door during construction.

The really tough part is having to completely relocate the electrical service panel in order to gain a foot and a half on the addition. Super PITA, but a real necessity.

I don't have any advice but please take plenty of before and after pictures.

Ryan, we are thinking of something similar. We have a detached garage way behind our house. We want to add a second floor that would extend over the driveway up to the house that would serve as a car port. We are a couple years off from doing this, though.

Definitely depends on a ton of variables. As one comparison - we just added approx 400 sq ft (family room plus laundry room) and remodeled the kitchen and another room from studs out, including some wall removal and beams. Kitchen was not top end but pretty nice - granite, custom cabs, in- and under-cab lighting, lots of new recessed lights, etc. All hardwood floors (except laundry room) plus refinished all other HW floors downstairs. Cost approx $135K not counting appliances.

Of course, all the kitchen stuff adds a lot. You can swing the cost by a huge amount depnding upon choices like flooring, numnbers and quality of windows and doors, etc.

Highly recommend getting multiple, detailed bids, checking refernces, and ultimately having your project specified in a detailed contract. It makes a big difference in controlling costs.