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Heading: rooftop paving
We have a discrepancy with an architect. We would like your opinion.

We paved a roof deck with asphaltic concrete -1/2" mix. The roof was sealed with 290 mils of Strataflex HR, rubberized asphalt membrane.The roof had an asphalt layer on the deck prior to the repair. It was removed. After removal we found that the roof had low spots which were 1 1/2" - 2" deep. The drains were higher than the deck. The architect had set elevations for a new pavement at a 0.2% slope. We told him this is not adequate for proper drainage. We also told him that the low spots would have to be rectified prior to paving or there will be ponding. They did not want to pay the extra. There was also a drainage on half the roof down an entrance ramp. The ramp is 12% slope. The pavement goes down 3/4 of the way where they had installed weep holes to let the substrata water out. The weep holes have been draining for the last 6 months. Prior to paving we had applied tackcoat over the top of the membrane cover sheet. We then paved the ramp. At the top, where the cars turn to access the ramp, the asphalt pavement has slipped and produced large cracks. The whole ramp is starting sideways (horizontal) cracking We have told them that it is due to the constant water flow under the asphalt but on top of a 1/4" rubberized asphalt membrane. They are stating that we did not put enough tackcoat down. The tack was SS-1h. We also stated that the slip plain (the cover sheet which looks like roofing paper) is causing the problem along with the membrane underneath. The pavement is slowly moving down the ramp. The asphalt was above 250 degrees F when laid and the softening point of the membrane is 180 degrees F. We are maintaining that it is a design problem and not the fault of the contractor. We had also conveyed to them that a 92% compaction cannot be achieved due to the soft membrane and the flexing of the concrete deck. We had installed the pavement as per spec. Can you help me?

Murphy Murphy
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