Expert: Bruce E. Johnson - 2/15/2011

Question
QUESTION: Hi Bruce,
I'm turning my garage space into a photo studio.  (Approx. 16' X 20' space.) There's some cracks in the cement and during heavy rains water seaps in from below the paved surface.  What the bestway to seal the cracks.  Also, does it make any sense to use Drylock and paint the entire floor with it, and the perimeter concrete blocks?  

Thanks

Wayne

ANSWER: Hi Wayne, it's not good news that water comes up through the floor when it rains.  This indicates positive water pressure which is tough to stop.  There are some hydraulic cements out there that might penetrate enough to seal the cracks but it sounds like there was never a vapor barrier installed under the slab to prevent passive water intrusion.  What you have is active intrusion, in other words, the water is under pressure to seek its own level which appears to be above the slab level.  You need to find out why the water level is higher than the slab level.  Your exterior ground might be graded so that water is surrounding the slab at a higher elevation and water gets in that way.  Is there any way to improve the drainage around the building?  That would be the first thing I would look at.  As far as the slab goes, sealing the cracks with an injectable epoxy is a possibility.  Putting an epoxy or acrylic sealer over the entire floor may do the trick if the water pressure isn't too high.  Too much hydrostatic pressure from external forces will possibly cause any floor sealer to bubble up or delaminate.  There are some pourable self leveling urethane caulks out there that will seep into the cracks and seal them.  I hope this information helps please feel free to write again regarding this or other matters sincerely bruce e johnson..bejohnsonconsulting.com

---------- FOLLOW-UP ----------

QUESTION: Hi Bruce,
The water seems to seap in through cement cracks easily, but also goes away quickly.  The garage is on a slight slope, and on the slope side the dirt forms a small hill.  I've been grading down the slope, as I want to possibly relocate the tools to a future shed behind the garage.  Also, there's a rain gutter behind the garage with no down spout, so I need to get a down spout and attach a flexible drain pipe at the bottom and reroute rain away from the garage.
    I'm wondering if that 2'X 5' X 16' slab inside the garage is causing undue pressure?  I'm planning on jack hammering that out to give me more floor space and ceiling height.  That would give me 12' more of floor space......keeping just 4' of concrete slab at the door.
    I like the idea of putting an epoxy or acrylic sealer over whole floor.  Do you have the product names?

Thanks
wayne

Answer
Hi again wayne, If you are going to go through the work of removing the slab then I would definitely install a vapor barrier on the bare earth prior to repouring the new slab.  I didn't understand your comment about the 2x5x16 slab you were talking about.  As far as sealers and epoxies go, all major paint companies Sherwin Williams, Valspar, Glidden, all make epoxy floor coatings.  Be sure to follow the manufacturers instructions especially regarding etching and preparing the slab prior to the application of the materials.  Most even have instructions on how to seal or prepare any cracks before coating.  If you can work out your exterior drainage problems that will help solve your problem also.  I hope this information helps please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com