We have a small 6X16 flat roof off our new third floor addition. Soon we will be building a deck over it. The roof was recently refinished (old roof taken up, new plywood layed, and covered with 2-ply modified bitumen roofing) when we added the third floor. Since it has been finished, each time we get a rain, I get ponding on the roof over an area about 2X6, against the support beam of the new addition. The pond has a depth of about 1/2 inch, and will dry up generally over a half week or so of no rain. My contractor is trying to tell me this is ok. I'm not so sure, especially since we will be building a deck on top of it, and therefore will have little access to roof in case of needed repairs. BTW, I live in Toronto so we get plenty of freezing temps over winter.
Looking for advice on whether I should worry about this, or not.