Expert: Bruce E. Johnson - 5/26/2009

Question
QUESTION: I HAVE BEEN INFORMED BY A STRUCTURAL ENGINEER, THAT MY MOISTURE BARRIER BELOW MY SLAB IS BREACHED IN NUMEROUS AREAS. BECAUSE OF THIS I HAVE MOLD, MILDEW, STALAGMITES GROWING IN THE GROUT OF MY TILE FLOORS. THE HOUSE IS BUILD ON SLAB ON GRADE. NO AIR OR CRAWL SPACE. CAN THIS BE REPAIRED?

ANSWER: Hi Lori, If you have a basement and the slab is in the basement you can help by making sure there is a footing drain installed around the basement to keep water away from the slab.  If it is a slab on grade you can make sure that the land around the slab slopes away from the slab to keep moisture away from the problem area.  There are mildew and mold products you can use to get rid of the mold clean the grout well and seal it..There are concrete sealers for the bare concrete portions..I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com


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QUESTION: THIS IS A NEW CONSTRUCTION HOME BUILT SLAB ON GRADE. THE BUILDER HAS ALREADY RE-GRADED THE PROPERTY TO SLOPE AWAY FROM THE HOUSE, INSTALLED FRENCH DRAINS AND PERIMETER DRAINS, REMOVED TILE AND APPLIED CONCRETE SEALANT, REMOVED FILL AND REPLACED IT WITH CEMENT OR BETTER DRAINING FILL. NOTHING HAS WORKED. THE STRUCTURAL ENGINEER SAID IT CAN'T BE REPAIRED. IS THAT TRUE?

ANSWER: Hi again Lori, well if all of the above have been done then it is possible that there is nothing left to do but remove the slab and redo it...However if there is this much moisture coming up through the floor it's possible that there is something else going on here like a water main leak, an artesian type spring or well pumping water to the surface or a sewer leak...Personally I don't see how this slab is still getting water to it with the french drains and perimeter drains working properly..I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com


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QUESTION: HI BRUCE,
THANK YOU FOR YOUR TIME IN ANSWERING MY QUERIES. WE KNOW IT IS NOT THE WATER DRAIN OR FEED LINES OR THE SEWER LINES. THE PLUMBERS HAVE BEEN HERE THREE TIMES RUNNING PRESSURE TESTS (ONE FOR 24 HOURS) AND RUNNING CAMERAS UP AND DOWN THE LINES TO THE MAINS AT THE STREET. NO PRESSURE WAS LOST AND NO LEAKS WERE FOUND. ALSO, THE GEOLOGIST SAID THAT DUE TO THE AMOUNT OF CALCIUM CARBONATE GROWTH AND THE FACT THAT IT IS WHITE, PRETTY MUCH TELLS HIM THAT IT IS A NATURAL OR UNTREATED WATER SOURCE. HE AGREES WITH YOU THAT IT IS PROBABLY SOMETHING ARTESIAN. NEEDLESS TO SAY THOUGH EVEN IF THE WATER SOURCE WAS FOUND, THERE ARE STILL NUMEROUS BREACHES IN THE MOISTURE BARRIER. THE PLUMBING RUNS BELOW THE SLAB AND THE MOISTURE BARRIER. WHAT WOULD IT TAKE TO REMOVE AND REPLACE THE SLAB?

Answer
Hi Lori, the slab will have to be jackhammered up, all the rubble removed, a new vapor barrier installed, and a new slab poured..it will cost about ten dollars a square foot..maybe less but in that price range...whether or not your builder is responsible will be for someone else to decide....I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com