I need to get two ducts that provide power and data to a garden office under the ground floor to under the stairs. In order for it to look the neatest it will be dug into an existing concrete slab (where the new patio will rest on) and concreted over. Where it meets the house I have the option to take it up the wall above the DPC through an air brick and under the house. This does leave me having to try and hide two 50mm ducting pipes on the wall for 600mm so I would prefer to continue straight through the brick work below the DPC and then seal around the ducting with expanding foam. Can I drill below the level of the DPC without causing a problem in the future? I won't actually be penetrating the DPC just going under it.