Does this mean you are planning to put a second floor on an existing structure, or you are planning a separate 2 story addition? Where is the bath you are planning in relation to the other plumbing in the structure? What skill set can you personally bring to the table? What type of permits does your municipality require and how long can they remain active? What is the age and current service ampacity of your electrical box? How old is the plumbing and what type is it? Are you on septic or sewer? If on septic, how many bedrooms is it permitted for and is there room to enlarge the system and create another field? What type of bath will this addition have? Fancy multi head shower and whirlpool or simple tub shower? What are your plans to heat and cool the addition? A separate system or redo the home's main system entirely?

Contractors really do not like doing "shells" for homeowners to finish out themselves because 90% of the time, the homeowner will call them back to consult on an issue they don't understand without expecting to pay a consult fee. Neither do banks who may be funding this because there is a much much higher than average default rate on DIY projects. Municipalities who may inspect this do not like it either. Their inspectors have to be educators and it takes much longer to accomplish than if a pro were to do it. To go this route, you really have to be a cash build, and your municipality has to be flexible about open permits. And you have to have a LOT of stamina to be working two jobs for months on end. It doesn't end up saving you much if anything if you actually tally your time and put a value on it.

All of these questions and more would need to be answered before anyone could even begin to give you a meaningful estimate. And then, only local contractors would be able to dial in on the specific price. You could be talking 75K for a low end simple project where you personally do most of the labor or you could be talking 200K+. Bathrooms (and kitchens) are some of the most expensive square feet to create. Just remodeling an existing one is around 15K, and you don't have an existing one to start with.

On the other hand, if this new space can be created as a separate addition where you can live in the current space while it's being done, then it will impact your life less. If you can pay for the whole project in cash and let the pros handle it, then there will be less headaches. If you spec out every detail and product used before you start, you will have a better handle on costs. You will still end up spending a lot of money for very little gain in home value, but the home may become a lot more pleasant and usable to you. If that is worth the money and hassle, then go for it! If the costs seem extreme for the benefit you'd derive, then look at moving to find the extra space you want. That's a very cost effective solution at the moment. You can't build new for anything close to what you can buy...

you can spend a lot or a little, it depends on a lot of different things. Mainly what level of finishes you're planning on, and how many/what style bathrooms etc.

minimum for the shell roof, and siding, and windows, I'd guess probably 40k. it does up from there based upon how fancy it is, windows, gables, shake siding,etc.

Again that is in my area, not yours. I'm on Long Island.

we did a bigger second story, about 1100 sqft up and reconfigured the downstair about 800sqft. Our shell cost was more than that.

I see contractors advertising packages for around 80K by me for a second floor, if they really give you a good project for that, its a good price.

My other comment is sqft doesn't matter as much as what you want to get in that sqft. bathrooms are expensive, bedrooms and closets are not. Going over existing house is cheaper than doing a 2 story additon. I guess what I'm saying is if you have a 900 sqft lower floor, doing 900 on the upper isn't much more expensive than doing 650 on the upper assuming you're demoing the entire second floor. the extra 250 feet isn't that costly, if its bedrooms and closets without fancy trim or fancy windows. You want to use that for a master bath... then it becomes significantly more.

Thanks for your input thus far.

To clarify, I have modest experience doing tile and sheetrock and am generally "handy." That is not to say that I personally would be doing all the interior work, but would be assisting family members who are "donating" their time. In the family we have a licensed electrician and a licensed plumber (plumber will be able to get me someone to to the tile work for some bare rate should the need arise).

The addition will cover an equally sized first floor.

I can likely finance something in the 50K range without too much difficulty on my own.

Any recommendations for contractors working in the Montgomery County, PA area who do "shells?" Full additions?

Granted it costs money... but I would say, pay people who do their trade to do most of the work. They're just better.

I have to say, I found it amazing watching my framer frame the shell, the siding crew side the place, the sheetrockers, the floor guys etc.

I am somewhat handy, probably not as handy as some, but have some siding, framing, sheetrock. To see my 2000sqft house sheetrocked in 1.5 days I was amazed, sided in around 2-3 days.

I'm not saying you have to pay for everything, but things like sheetrock, insulation and flooring the pro's really can fly throuogh it.

just to clarify I mean specialty trades, ie not GCs