Expert: Dan Griffin - 4/17/2010

Question
Hi, Dan, I'm re-tiling my laundry room floor.  My house is a split-entry built in 1972 in Ramsey, Minnesota.  Sand comes in along the floor at the outside wall.  It is slightly damp.  When I clean it up, more comes in over time. It doesn't come into the bedrooms on the same side of the wall.  I sometimes see ants and once a very small tree root, yet there are no visible cracks.  There is a copper pipe going into the floor nearby for my water-heat baseboard, but I doubt that the sand is coming in there because there is too much and it is nearer the wall. At times, I've cleaned up as much as a half-pound of sand in a year. It seems to be concentrated along a 1 1/2 to 2 foot area.  Any solutions? The walls are concrete block.  Thank you very much for your time.  Joe

Answer
Joe, these things are miserable.  The problem can be from so many different things.

The sand is probably "fill sand" used under the floor slab to level the subgrade before pouring the concrete.  It could also be used to bed any below grade piping - think water, sewer, heat loop.

Is the problem related to rain and snow?  this would indicate a need to improve grade, remove flower beds, even dig up and seal the outside.  If there is a French drain sytsem on the outside is it functioning well and where does it go?

If the problem does not seem to be related to outdoor weather, then I would suspect a leak in some one of the piping systems.  A hole doesn not need to be large to move lots of sand.

We have a fella here that specializes in tracing under slab leaks.  He can pinpoint them within 5".  Without more information, I'm sorry I can't help much.