Bricks, Masonry, Asphalt and Concrete - Water leakage at block foundation

What is the best thing to use on a block foundation to prevent water from penetrating block. Also put sand in block to insulate before putting top plate on block. Noticing mildew on inside of garage at block foundation and some dampness like water is penetrating from outside in.

Concrete Masonry Units are porous. For below grade work they should be treated to help prevent excess moisture in the wall. Is the exterior of the wall accessable? What, if anything was used on the exterior? Starting at the bottom, at least a 4" PVC draintile w/filter fabrick should be placed at the base of the wall. New construction typically gets a cement paint like coating... "Thoroseal" with Acyrl 60 as a bonding agent. (Old and new concrete repel one another) Then after that has set, a heated liquid coating of asphalt foundation coating is applied to the cement coat. Then, as another preventative layer, a 1/2" to 1" thick piece of insulation, either expanded polystyrene or fibered insulation sheeting is placed next to the asphalt coating. (The insulation membrane acts as protection when you backfill up against the foundation.) Gravel next to insulation...and on top of the draintile, and soil all the way up.

I am sorry to hear that you filled the cores with sand. Was the sand dry? Or was it the left over sand from the jobsite... and full of moisture. If the sand was from the job... the water in it had to go someplace... so there's your inside moisture. Sand is NOT recommended as a filler.

You would have been better off filling the cores with those "styrofoam peanuts" leftover from all your UPS Christmas Packages. You see, a concrete block, unless foam filled under pressure, really has very little R-value. The exterior face shield is connected to the interior face shield by 3 connective webs.

Wait for your sand to dry out... and have the efflorescence disappear on its own. Then you might try a Drylok Masonry Sealer on your inside walls.

Of course, there could be several other things wrong with the way these walls were constructed, so maybe some others could offer their ideas...

Good luck!

www.southsidebuilders.com

The block wall is 7 courses high, 4 being above grade. I did use a black sealer which was for this purpose below grade on this before backfilling but there were no drain tiles installed. All the grade surrounding the block foundation slopes away from the block. I have realized that putting the left over sand in the block was NOT the brightest thing to do. I am just concerned that the block or mortar joints will deteriorate due to the water. The area I have noticed the efferescence is on the interior side of my garage which has approx. 3 courses above the floor. On the exterior side of this wall I have attached a wood deck directly to the block and below my vinyl siding. The work was done approx. 5 years ago and the block has a wet look after each rain assuming it is getting in the block and penetrating the block. Of course the sand is preventing it from drying out thoroughly. Is there a clear sealer I can apply to the exterior of the block to prevent the water from penetrating and is it possible to just install a mortar type stucco finish to the exterior side of block to prevent waster seepage. The home is in Kentucky. Once again, thank you for your expertise.