How do you arrest water leakage in concrete roof slab?

Answer 1

I would hire a leak detection company first. They should be able to pinpoint the leak to within 1 foot. A leak detection company is not always a plumber, but they can be. Ask them. Use someone like United Leak Detection or American leak detection Than I would consider either jackhammering thru the floor and fix the pipe, or bypassing all that and just run new lines thru the walls and or attic. If you are in a warm climate this can be a better option for you. In cold climates, you need to have a second story so that freezing is not a problem. Problem is that your leak might just be the first one of many to come. Thus therefore, I would recommend just bypassing all the jackhammering and such, and just have the plumber run new lines.

So my answer is: run new lines thru the walls or attic. Unless you can't then you won't.

Answer 2

First, identifying the source of the leak is absolutely critical. Otherwise any fix employed is a shot in the dark.

If there are any joints in the horizontal plane, those need to be inspected for a proper seal.

Depending on the conditions, you also need to be aware that concrete is a porous material that absorbs water and it will pass completely through a roof slab that has not been waterproofed. Another consideration is that unless a concrete slab has been stabilized [see StableCrete.com] the internal chemistry of a concrete will migrate out to a surface. This migration to the surface will cause delamination of any surface membrane or coating applied. Happens commonly to paint applications with alkali burn and peeling.

If a roof membrane is installed and has developed an area where water is entering, this water under the membrane will penetrate the concrete and wind up on the underneath side. How much or little water will depend entirely on the porosity of a concrete roof deck that has not been waterproofed!