Roof "Second layer Starter Course help"

[Rick K. Kie]

Originally Posted by Ed Fako

For a re-roof over an existing one layer shingle roof, you do not NEED a starter course, but the 5" exposure at the bottom row SHOULD have been filled in with a starter course if they were concerned about that hump from the transition to the second course.

Also, the bottom course should have the top =~ 2" cut off the top of it, so that all of the successive courses "Nest" into the course layout neatly and uniformly without any further hums at the transitions.

But, the Primary reason for the starter course, is to ensure that there is a roofing material under the slot cutouts or at the side edge butt joints, to prevent leakage directly through those gaps.

Ed

I thought the starter course had more to do with the adhesion of the first layer of shingles to the roof to prevent ice daming or water wicking up the roof and wind.

[Ed Fako]

Originally Posted by rkie

I thought the starter course had more to do with the adhesion of the first layer of shingles to the roof to prevent ice daming or water wicking up the roof and wind.

That too is a valid reason.

But, do you realize how many contractors just use upside down 3-tabs.

If they do use 3-tabs left over from another job, they are supposed to cut off the tabs and have the sealant line at the bottom edge.

The reality, is that that line of sealant has less to do with decreasing the blow off of the bottom row of shingles, than the correct nail placement.

Ed