6 Unit Building Rehab
Foundation and brick walls good,either apartment or business use rehab. 3700 sqft. - Any basic costs to almost gut and update. Probably $150-250? Older part of town.
ps-Just had a granddaughter come into the world. 
fixing a existing struture is always more then new const.you can get new const. down here starting at 75 bucks a sq ft. rehab -remodel is double if not more
Congrats on the granddaughter!!!
It is good to have options and It sounds like by your question on how much would it cost to rehab, that this may be your first multi unit venture. So I would offer this option for your consideration. If you get the property below market, which sounds as though you have, then you have a good amount of equity in it now. What about pulling all bad carpet up, paint walls white if they are in good shape, gut all bathrooms of broken tubs, sinks and toilets. Gut kitchens with bad cabinets and counter tops etc. What you are doing here is allowing another invester to see the property with a clean slate. The bottom line is that you have to do all that stuff anyway if you do the rehab yourself, so if it does not sell, take it off of the market and finish the rehab. Also, you may make just as much if not more by doing a quick flip. You could be in and out of the deal in a couple of months instead of almost a year. You can then take that profit and get another property if passive income is what you are after that may not need as much work. This has worked very well for me. Best of luck!!!
I have seen several wood-siding-to-brick conversions.
Assuming you pour an adequate reinforced foundation to handle the weight of the brick, and you tie the brick in to the existing structure, the problems you are left with are mainly the weather seal between the brick and all window, door and other openings.
Without the free air flow over the existing wood sidings and trim, you are inviting wood rot by sealing up the wood structure so it cannot expel moisture.
After I witnessed the wood rot on a bricked-over home, I would never recommend the procedure.
[addsig]