Hello Brook

Thank you for your question and I will do my best to give you some suggestions.  

First, regarding water.  The soil does appear to be very dry and exposed.  I suspect you are correct in assuming that the overhang of the building is preventing water from penetrating those areas adequately. Phlox prefer medium amounts of moisture and well-drained soil. We did have a very dry spring and early summer so in times like these, it is best to supplement the area with some hand watering.  

 Next spring, sprinkle some slow release granular fertilizer in the area, after you amend the soil, (see below) and then add a few bags of shredded bark to top dress the area.  Personally I do not use pine nuggets or color enhanced bark, but any other type of shredded bark will be fine. This too will slowly decompose and add organic matter to the soil, but most importantly, it will help lock moisture in the soil and prevent it from drying out so quickly. 

The creeping phlox appear healthy otherwise, but your soil appears very 'tired' for lack of a better word. Phlox like hummus rich soil, which means that you should amend your soil with some bags of organic rich matter, such as compost or a compost/manure blend. 

I believe a combination of all these things this will help.

Kathleen