Roof "Second layer Starter Course help"

In a roof over using archetechual shingles isn’t a starter course still needed?
I just want a second opinion before i write it up on the report this afternoon. Just one of many roofing issues found

best practices do call for a starter row for sure, although I’ve often seen it done with a non matching left over shingle,are You sure it wasn’t a new shingle of a different color?also starter course is turned so it wouldn’t look exactly like the dimensional above it…all that said if that is an original shingle in your picture it’s wrong imo…jim

Is this architectural roof installed over an existing roof? If so, it is not supposd to be per the manufacturer.

Its “definetly” the old shingles underneath.
Dennis I did read this morning I think on GAF or tamco web site they want the first course 4" high.

Hi. Rickie; This may help a little.

Go under Roofing ABC’s

Marcel :):smiley:

In addition to the above, the general rule is no warranty if applied over old shingles.

John Kogel

Also take advantage of the installation video’s.

Marcel :):smiley:

Great link to have Marcel.
We need to put together a best sites .
There are so many.
I started doing that last year on a wiki.


patty, ham or bacon :twisted:

Sausage. :wink:

And if that is not fatty enough, let’s all go for the Blood Sausge “Pork”. :mrgreen:

Ok, I know. ha. ha.

On a different token, try this Link;

Feel free to add to it.

Marcel :):smiley:

Tear it off and do it right, no more advise needed:mrgreen:

Bacon AND sausage! :mrgreen:

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.


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.