I'm a builder and do this often. without floor covering this is fairly simple. a walk behind concrete saw can be rented 100$ or so. the Cutting takes 20 min then break out the concrete (No jack hammer required). install conduit and a couple bags of cement mix and your done. if your cutting into old tile that you need to match I wouldn't do it. contractor would be making good money at 500$ in my market

thank you all so much for your input.it seems i am having water in the basement only when it rains and after 3-4 days it dries up. how can i or the plumber check whether the water is coming from the ground or from the walls or from the backyard ( which is half cemented ) ?

I have placed tiles, sheetrock, done painting and cement work, some electrical and plumbing. 

If you have it all demoed put cement board around the tub/ shower  surround and where ever else you are putting tile. 

Right now, it's just cement floors and walls, has a toilet and laundry installed.

When reviewing your local codes you may find some of the older garages were built right up against the property line.If the garage is down new set backs come into play & trust me it can be an added expense not being able to used the old cement pad.We built ours for $4500 but the doors, electrics & ancillary mechanicals add up.One we are considering now would be built against the home with an addition (it's a Cape) above the garage for a master bath & closet.Have fun.

If I'm sitting in the dentist's chair I'll ask her about a recommendation for a contractor.

I bought him a portable cement mixer for $2,500 to use on my house since he would have to rent for $150 per day. 

If I'm going to play soccer, I'm researching the field, observing players in warmups, ensuring I'm in the best possible shape to be successful, etc.When it comes to investing, you have to ask yourself if you are going to have a cement foundation up to the standards required in the state of Florida, or if you're going to have a house of cards.

Tenant's dog urinated in the garage and sweep into the cement.