Ask the Experts: Slab leak FAQs with Luis Mascareno
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Plumbing 08/15/12

Ask the Experts: Slab leak FAQs with Luis Mascareno

Bill Howe Plumbing slab leak locator, Luis Mascareno tells us what his customers ask most often when they’re dealing with a slab leak:

Q: How long have you been specialized in slab leak location and repair?

A: I started with Bill Howe Plumbing about 11 years ago and I’ve focused on slab leak location and repair for the past seven years.

Q: Are you able to tell the cause of a customer’s slab leak?

A: Most slab leaks happen because of the age of the homes. On average, homes that are 25 years old or older are more likely to have a slab leak than newer homes. I tend to get called out to the older areas of San Diego most often.

Q: In your experience do insurance companies tend to cover the cost associated with the slab leak?

A: I get this question more than any other: it really all depends on your insurance company and the type of coverage you have. But in my experience, insurance companies typically cover the cost of the slab leak location (service to accurately identify where pipe under slab is leaking) and the cost to repair any damage the leak may have caused (in most cases, repair to drywall and/or flooring). Since I do this so often, I am used to working with the insurance companies to get them all of the information they need in order to determine what they can cover. Customers like that we can take care of the leak right away and work with the insurance company while we’re doing it to take that burden off of their shoulders.

Q: What are the different types of repair options for slab leaks and what are the benefits to each?

A: For residential properties the most common solution is a reroute and for commercial properties the most common solution is a direct repair. A direct repair is when we jackhammer into the floor to expose the pipe and a reroute is when we cancel the line and re-direct the line overhead. Typically residential property homeowners don’t want to ruin their flooring so a reroute is a cost effective and non-invasive solution. Every situation is different and I make sure to talk with my customers to make sure we determine the best fit for them, whether that’s a cost-effective solution or the most long-term solution like a repipe which is when we reroute all of the water lines under the slab.

Q: Take us through the leak location process.

A: One a hot water slab leak it’s easier to locate the leak because of the hot spots. Cold water slab leaks require an analysis of the home to check each fixture by pressurizing the line with a pressure gauge on one of the hose bibs to see if the gage level drops. Once it’s determined it’s a cold water slab leak, I use an electronic sound devise that allows me to hear and pinpoint leaks under a concrete slab. The location process usually takes between one and two hours. An experienced slab leak locator will be able to precisely locate the leak in most cases. There are situations that can hinder an exact location (i.e. leaks under shower pans and cabinets), however a leak location can still be performed successfully.

Q: What do you like most about working on slab leaks?

A: I like that slab leak jobs are challenging. I feel my experience in slab leak repair has brought me from a good plumber to an excellent plumber. You need to have knowledge and experience to do this type of work well. I also like the gratitude customers have when the work is done.

If you’d have a question for one of our experts for the next Q&A, let us know in the comments!

Expert San Diego Slab Locator

Luis Mascareno, Expert San Diego Slab Leak Locator at Bill Howe PLumbing!


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  1. Thank You Very Much. You really made my life easier by explaining repiping, reroute. I’m a little confused though at least I know repiping will not be like putting a bandaid on the problem. Thank You Again.

  2. Patrick

    I had foundation raised. Their plummer says have above ground leak. Cold line pressure test drops 10 lbs. they were right that 2 L shaped valves under sink were about to go out/ were weak. They say no leak under foundation. Also no sound by facets, which indicated pipe leak under slab?

    Another plummer did various tests today, and says leak is in cold water lie under slab. I had water running in house and after turning 1 sink’s supply line off , one after another, and checking meter spinner after each one was turned off, I saw the suspect valves under sink leak a bit. The spinner only stopped moving ( slow anyway) after that sink’s valves were shut off.

    This sounds like no leak in slab. Any ideas? Can “weak” valves under sink cause drop in pressure? a slow stream from toilet tank flapper into bowl? Please reply. VERY important


    • Lori

      Did you ever get an answer to this question? I am very interested as this has happened to me as well

      • Bill Howe

        Hi Lori-

        I have sent you a direct email in response to your query! Thank you-Julie

  3. Roger

    I had a hot water leak under my slab. It was located and repaired. The dirt under the slab appears to be clay. Apparently I had this leak for quite some time. After the repair the insurance company called in a company to dry out the concrete. They pulled up the carpet and padding. An electronic device is used to measure concrete moisture. The numbers are varying from almost zero to 95. They installed 6 fans and two dehumidifiers in the rooms to dry the concrete. AFter 6 days some of the concrete is drying out but not all. The moisture is spotty around the rooms.
    Any ideas how to handle this problem. I am guessing water is sitting in the clay soil under the concrete causing this spotty problem.

    • Yuliana

      Hi Roger,

      Did your floors end up drying completely? How long did it take? We are 1 month into a hot water slab leak and while we’ve addressed the damage related to the leak, the concrete slab is still showing patches of moisture and efflorescence deposits. We have polished concrete in our house and are worried this will be a permanent look.

  4. Thanks for sharing some of the FAQs of customers about slab leaks, there are many unique causes of slab leaks but the most common is the clay below the foundation and it can affect even the newer homes but Luis is also right that most of the old homes with 25 years and above are more likely to have slab leaks.

  5. Mark Dana Floden

    Great information on this site.
    The description of leak detection using pressure and sound gauges was particularly useful as was your description of the typical insurance coverage.
    My house is in San Antonio. If you were in that area I would definitely call on you.
    Best wishes.

  6. Spencer Webster

    We have had slab leaks in the past and had them repaired. Now I have noticed 2 warm spots on the floor that week to come and go. When I check the meter at the street is isn’t moving. I can’t imagine a leak that would heat the floor that doesn’t register on the meter.

    Is this normal or should I have it checked?

  7. This might be a stupid question but here goes. If I have a slab leak from the cold water supply ( toilet ) wouldn’t the water be running all the time even if I have the shutoff valves closed? I can open up the valve and the water meter starts turning rapidly at times but then will stop all of the sudden. In around 5 minutes it’ll start back spinning again. When I cut the water supply to the toilet off the spinning stops. Seems if I have a slab leak the water would run all the time considering it’s under pressure right? I’m not a plumber by no means and as I said this could be a stupid question. Oh, I have replaced the flapper in the toilet and it’s working fine. Thanks

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