roof flashing

[mdickmann]

In my conversations with 2 different roofing contractors there is a difference with regard to flashing.  One, who installs GAF, replaces the wall flashing with an 8 inch flashing to match the dimensions of the shingle, which are apparently, different than what I have now.  
The other contractor says there is no need to replace the wall flashing if it is in good shape.   He uses CertainTeed shingles.  I don't think he replaces the drip rail either but does replace flashing around the chimney and the pipes that go through the roof.  
Is it important to replace the wall flashing or is it better left alone?  I thought it would be messed up from removing the shingles.

thanks,
Mark

[Splinter Puller]

It's better to replace them during a reroof.  They will be disturbed most likely and they should indeed match the shingles as they are suppose to be interleaved 1 to 1 with each shingle for proper drainage.

[geek2me]

The other contractor says there is no need to replace the wall flashing if it is in good shape.   He uses CertainTeed shingles.  I don't think he replaces the drip rail either but does replace flashing around the chimney and the pipes that go through the roof.  
Is it important to replace the wall flashing or is it better left alone?  I thought it would be messed up from removing the shingles.

It's common to not replace flashing that is in good condition, especially the drip edge.  New flashing looks strange in contrast to the existing house, particular if the house has siding.

The flashing will outlast the roof many times over, so it is not really a concern if they reuse existing flashing.