When treating a block foundation, you should drill a hole in each void so there would be 2 holes per block. The holes should be no more than 18 inches high. Usually you want to drill on the second row of blocks high from the ground. In addition to drilling the holes, you should also trench and treat the outside foundation wall and the inside foundation wall if you have a crawl space. After drilling the holes, you are supposed to apply 2 gallons of solution per 10 lineal feet into the blocks. For filling trenches and drill holes going vertically into slabs, you should apply 4 gallons per 10 lineal feet. Please let us know if you have any further questions. Click on the link below for more information on treating termites.
How To Perform A Termite Treatment