There is a small seeming exception in regions where housing prices are rising rapidly: if the owner is willing to forgo increasing rent at the rate of housing price increases (which is pretty common among smalltime landlords), then renting can appear to be cheaper than the present-day mortgage for an equivalent property. Of course, in that market as a renter you lose out on appreciation of the house, so renting is only better if you can get bottom-market rates near the top of the market.