Q: Should all flashings be replaced when I have my roof replaced?
Yes, the time to address all the roof issues was when the roofer was replacing the roof. Normally all flashings should be inspected and if any are damaged or rusted they should be replaced when the roof is replaced. The cost would be much less at that time, not to mention possible water damage and cost to have it repaired at a later date.
Q: Do I have to tear off my old roof when replacing? Or can I install the new roof over the old one?
On both low and steep slope roofs, it is always preferable to remove the existing roof down to the decking. Code states that existing residential shingle roofs must be removed before new shingles are installed as only one roof system may be in place at any time. However, low slope roofs are allowed to have two roof systems installed so some roofs may be eligible for a recover in certain situations. There are a numerous amount of criteria that an existing roofing system must meet in order to be eligible for a recover.
Q: I have a tile roof. The clay tiles appear to be in good shape - at least not broken, however, I have several leaks. What would cause this?
The felt underlayment dictates the water tightness of the tile roof system. Normally 3 plies of ASTM D226 heavy weight #30 felt is installed, as a minimum, under the clay tile roof system. If the old felt is deteriorated the tile must be removed and the felt underlayment replaced then the existing tile may be relayed