Greater Philly is a hotbed of multifamily activity recently--including no small amount of development--but investors aren't scared yet. (Typically housing isn't scary, unless it's in the woods or owned by a wronged widow.)

Rittenhouse Realty Advisors Ken Wellar tells us the attitude for now is make hay while the sun shines.Ken says private capital buyers are very active now due to low interest rates and increased rental growth, and he also expects more institutions to be chasing multifamily properties in Philadelphia in the next three years. Multifamily has been a great investment here due to low vacancy and rental growth in the market over the last couple years, he notes.

Ken and the other founders of Rittenhouse--which set up HQ this month in Philadelphia, in addition to offices in New York and DC--plan to pursue deals across the CRE spectrum. Their experience is diverse: Benjamin Oller (partner) is prez of the Condo Shop; Corey Lonberger and Ken (managing partners) are formerly of Marcus & Millichap; and Mark Duszak (director) is formerly of CBRE. Among them, the four have $4B in CRE sales over the last nine years.

With any market surge, keep in mind that things can overheat. "In 2011 in the Washington DC market, there weren't sufficient market-rate apartments to meet demand, and now theres an oversupply, Urban Igloo CEO Rick Gersten tells us. (Even supply/demand is a partisan issue that nobody can agree on.) In Philadelphia, he says these are cautionary signs you should watch: How many units have on average been absorbed each of the last eight quarters? How many are already under development?There's a narrow window to hit before the tipping point," Rick says.