We're on a slab and had to run plumbing to our island for a prep sink. The distance was about 10 feet for us, since it was on the diagonal. They dug a trench in the slab, laid the pipes, and poured new cement into the trench. This added about $1,500 to our costs, but we think it was well worth it, given how much we use the prep sink.

I will warn you, though. You have NEVER seen so much dust as you will see when they are digging that trench!

I couldn't find a pic of the trench itself, but you can see where they dug it in this pic (this was days later, and you can still see where the camera flash picked up the dust particles in the air)...

Thanks so much, holligator. That is exactly the kind of info I was looking for! Can I ask what region of the US you're in? We're in southwest Louisiana; I'm just curious if your price would be comparable to what I could expect...

The dust--ugh, that does not sound good at all :-( Of course, if I can't convince DH that we *need* to do this, I won't have to worry about that part!

I'm outside Houston (not that far away) and had to go into the slab twice -- once to run gas to the island when we bought the house, then again to run water to the island and connect to the drain line when we moved the cooktop and put a prep sink inthe island instead. Both times, it was less than 5 feet and $500. We also paid a plumber about $150 to come out and help us verify the location of the drain line from the kitchen sink going towards the cleanout at the front of the house. That gave us an idea of how to approach the change and determine that it ws possible as well as to get bids on the work. Now that I have and have used that prep sink a while, I'd have paid a lot more, but it would have been a lot harder to know how worthwhile it was going to be.

lascatx and alku05--your input has been so helpful. This gives me hope that it might be doable. All of your answers give me at least a reference point re: some of the things I should be aware of. Thanks!

lascatx, we're practically neighbors (ok, well sort of, but not really! LOL) We're only about 2.5-3 hrs to Houston, depending on where we need to go once we actually get to Houston. We have fond memories of when we lived in Katy as newlyweds (we then returned to my hometown). Still have some very dear friends that we enjoy visiting there when we can. We've made lots of trips to the Medical Center area for various medical issues over the years, too. Love to visit, but we don't miss the traffic!

What kind of flooring are you planning on using over the trenched area? If you're using something glue-down, you will have to wait until the concrete is cured, possibly 30 days or more. If you're doing floating floor or carpet, you won't have to wait. I don't know about tile. Just another thing to consider!

Just curious, but do any of you have post tension slab? I want to add a fireplace to our family room, but to raise the hearth, the city wants the mason to drill into the slab to secure the fireplace in case of an earthquake. The post tension rods pose a problem because, if you hit one, it can cause serious damage.

I have been following this thread with interest. We are in So. CA and have a "post-tension" slab. Does anyone have experience with these?

If you want to see my slab mess you can look at my demolition diary (scroll down from there). I'm in SoCal, with slab, but I have to admit I don't even know what "post-tension" is. There's some fill in the front of the house, but I don't think this was a concern in the kitchen.

Regarding the floor after the trenching, there's goop my artisan tile setter used, called anti-fracture membrane. It takes a couple of days to put down, but not a month of curing. It's supposed to keep the tile from breaking if the new concrete expands and shifts at a different rate than the old.

When you're considering the sink relocation, remember the plumbing vent and fall of the drain line, as well as running the water. It's important to be able to drain into your existing line (since you don't want to dig up the whole house), and vent somewhere feasible. For mine, before we even started demolition, the master plumber traced where the vents were, and sent the camera robot into the drains to see where they were, at what depth, and at what rate of fall. I was very lucky that they could tie into what was there without much trouble. It's much better to do it this way than just start digging and take your chances.

The dust CAN be controlled. Just act a little hysterical around the GC. :-) Mine brought in the thin plastic sheeting from Home Depot, and put it over everything. Well, his helper did. :) It also drapes the open wall between the dining room and living room, and covers the kitchen door. There isn't an outside lock, so one of the guys comes in, opens the kitchen slider, comes back and tapes the kitchen door, then goes around. Too much dust escaped when they removed the dining room door, however, even though there were drapes between DR and LR. A solid barrier is...solid, and it took them awhile to get the shrouding just right. If you have an open plan, several separate layers become crucial. But it can be done. Although dust is inevitable, I've had remarkably little to deal with, and since I have respiratory issues I was expecting the worst.

plllog,
LOL at acting hysterical around the GC. I can do that!And thanks for the tips--all very pertinent to my situation.

ella so cal & jeri,
Obviously I don't have any helpful advice for you :-) but you may getter a better response if you start a new thread w/ your question(s). As you probably already know, the posters here are not only knowledgeable but so very generous in sharing their experiences and expertise.