You'll want to make sure that landscape areas around the house are properly graded so that water drains away from the house without exception. Since the objective of irrigation is that plants get watered regularly, specific irrigation layout depends a great deal on planting layout. Sometimes, irrigation lines and some spray heads might be within 12" of a foundation, but the water will be spraying AWAY from the foundation. It's easier to control water spraying away from a foundation than to control water coming from heads set farther away and spraying toward the foundation. But, again, the exact configuration depends on plantings. But you'll never want irrigation spraying on to the house. Chances are that the only problems you'd have from irrigation placed close to a foundation is when there are maintenance issues (broken spray heads or pipes) that are ignored for any length of time. These things should be inspected periodically and fixed quickly if there are issues. Scheduling irrigation so that soil doesn't become waterlogged is another factor to pay attention to. An espalier doesn't require that its roots are watered any closer to the house than any other landscape irrigation.