Waterproofing?

You mean the walls and floors of the shower/tub area or outside the normally wet area? You cannot not waterproof the tub/shower area as that will leak to your neighbor downstairs and have mold grow behind the walls.

I am talking about the entire full floor and the 2 full walls adjacent to/touching the shower stall/bathtub -- in the bathroom.

All floors and walls (usually up 6-12") in bathrooms and kitchen floor if installing tile

You should use Laticrete

Thanks Primer.
How crucial is this?
Is the waterproofing/Laticrete for direct water leakage/spills, or is it also for helping moisture buildup/mildew protection?

Also-- do you think this is necessary for the kitchen as well? (where the sink is)

I moved into a brand new condo many years ago. In both bathrooms the builder put in sheet rock throughout with no waterproofing. After the warranty on the apartment expired, my tiles started falling off the walls. There was a leak from the upstairs bathroom that ran 8 hours on a holiday weekend before anyone noticed. I was away on vacation and the building called me about the leak. The walls caved in around the bath tub and the other walls were buckling. The tub and sink were damaged by the falling tiles. I had to gut the whole bathroom and waterproofed to an excess.

UE98,
I think it is necessary, we install it in every bathroom and kitchen. better safe then sorry

Thanks Primer. The offer I'm getting is an additional $2500 for both kitchen and bath waterproofing (1 floor and 1 wet wall in each room). What laticrete do you use? HydroBan? HydroBarrier? Lataproxy? Do you recommend an actual membrane (sheet) or is it fine to just use whatever product?

We use Hydroban. 1 wet wall? doesn't make sense, they should at least waterproof the floor, up 6" on walls and full walls in the shower and tub area. I just charged a client 2400 to waterproof 2 bathrooms and a kitchen

Yes, the floors are included in that price. As for the walls, I guess it's 2 walls for the shower (in a corner) and 2 for the sink (also in a corner) in the bathroom. The bath and sink share a wall, so really, 3 walls + floor in bath, and just floor and 1 wall (where the sink is) in the kitchen... for that price.

How negotiable are GCs when it comes to their estimates? Of course, it all changes once the work starts, but I'd like to find someone who is willing to be flexible (if such a thing exists).

UE98,

I think most GC's are flexible but it really depends on several factors
1. Is the GC busy? if he is then he will probably not be so flexible (supply and demand)
2. How badly does the contractor want the project (There are some projects the a contractor might take because they feel it will get them more business)
3.Some contractors (not all) go in higher expecting the client to negotiate

I don't understand the point of waterproofing an area that isn't typically wet. Obviously showers and tub surrounds should be waterproofed, but if there's a leak, the water is still going to go somewhere. Is water spilling out into your living room that much better than having it in your bathroom?

I think people hear "waterproofing" and get lulled into a false sense of security without really understanding what will happen if something goes wrong, especially since you cannot easily anticipate where a leak will come from. A pipe above your apartment that leaks for 8 hours is going to cause material damage somewhere, waterproofing or not.

"Better safe than sorry" is why you buy insurance.

I had our bathroom shower water proofed with a product called redgard. It is painted on over the cement board and becomes a membrane. Then the tiles are laid. The waterproof is to prevent water from getting through the tiles and spreading into your walls and damaging wooden structures or growing mold. The water should drip into your tub. I actually applied the redgard myself in a few hours. I dont understand the 2,500 price, water proofing should be standard with a bathroom renovation. I would think a GC would need at most 2 days to lay a membrane in a 6 x 8 shower area. Water proofing would not prevent damage from an upstairs neighbor with a leak. Water will still flow from inside their wall to yours behind the membrane. Water proofing the floor makes no sense, if you have any kind of constant slow or fast leak, the water proof isn't going to stop gallons of water from seeping in your floors. It might slow it down at most.