I will have a landing running from the back door, then four or five steps to ground. Do I need to place metal flashing where the landing attaches to the house, or some other means of protecting the house from moisture intrusion? The landing and stairs will be of poured concrete.
Typically, concrete steps are set onto a slab and not physically attached to the building. There should be about a quarter to half inch gap between the step unit and house. In most installs, a piece to flashing or ice & water shield is placed under the threshold down to the foundation, then covered with a 3/4" trim board. This protects the house from water invasion and also gives a nice look, as the trim can be painted to match the siding etc. The steps are then rested near the trim board. I use pressure treated lumber for the trim board. If you put the steps hard up against the trim or house, expect rot in a few years if it is not pressure treated.