Yes, coating them is recommended. The 'design' of the brick that I did for this has 4" wide 2" deep grooves horizontally (one) and vertically (2) on the outer s

Yes, coating them is recommended. The 'design' of the brick that I did for this has 4" wide 2" deep grooves horizontally (one) and vertically (2) on the outer surface. The thought was that lumber could be screwed into the brick and then off the shelf siding or drywall could be attached to the lumber. The grooves also provide channels for in wall services (power, water, communications). Some specialty ones for window casements and door casements. The original concept was to set up a processing center in the California high desert near a rail line and provide employment and shelter for anyone who was willing to work at the plant to process the recyclables into stable building materials. Sort of a community that is both saving the world and providing homes, work, and community for those less fortunate.