HelloFor investing in a commercial property with a triple net lease (NNN), what factors do you consider for determining if it is a good investment? 

If you were to heavily insulate the inside wall of an old double/triple wythe brick building the external wythe may no longer dry out thoroughly and be subject to excessive freeze - thaw damage.The best way to insulate old brick buildings is from the outside - which has the added advantage of turning all that brick into a thermal mass in the conditioned space ... alas, most owners of old brick buildings are unwilling or unable (due to historic designations) to insulate over the external brick.There are some informative studies and papers by John Lstiburek and the folks at Building Sciences Corporation about dealing with old brick buildings.

I get up, phone calls made, emergency call, expensive triple overtime to the Heating Contractor, Tenant has heat.

As someone who only has one single family rental, it seems like a huge jump to get into NNN. 
Specifically, the financing part. I know banks have different LTV requirements, and seller carry for a portion is another ...

ha.and just finished Rich Dad's ABC's of Real Estate Investing.Tough I want to try my hand at a triple net property.I'm in NYC, If anyone on the East Coast wants to chat, drop me a message.

REIVAULT has probably tripled my business on the way to quadruple it.

This is likely to be an extended term lease (multiple years) and I would like to structure it such that the corporation is responsible for the maintenance and upkeep of the property as a traditional commercial lease in a triple net environment would read.

take the HELOC out and do a rental with 30-yr leverage. cheap $ out there.let me ask you this - where else are you going to get triple digit returns?

It was very successful as we were able to turn 1 asset into 3, triple our income and leverage.

WOW...Mike gave you some excellent tips...about the zoning we had a similar case so we reviewed the zoning laws for ours, a very large old single family converted to a triple illegally.We were able to get a variance based on the zoning requirements, apt sq ft, off street parking, overall lot size, two entrances fire escapes etc etc.But they would only allow us to duplex it.