I live in Sunnyvale ,CA. My tar & gravel roof was leaking last winter after fumigation. Would the fumigation process cause the problem? I don't plan to replace the roof. What options do I have ? thanks.
IANAR (I am not a roofer), so take the following as simply a set of opinions.
When your house was fumigated they "tented" it by putting heavy vapor proof tarps around and over the house. I doubt that the tarps would damage the roof but they had to walk on the roof to do the work and that might have damaged it.
However careful walking on a T&G roof that is fairly new is pretty safe. If, however, your roof was old and the tar was getting brittle and it was ready for replacement, then damage from being walked on is more likely to occur.
Which leads to the question: How old is the roof?
Since you are in Sunnyvale you can go to http://ecityhall.ci.sunnyvale.ca.us/cd/ and click on "eHistories" and find all the permits that have been pulled for work on your house. Doing a flat roof is a big enough deal that it is likely that a licensed contractor did the work and they will have pulled proper permits so you can see how old your roof is.
If, as I suspect, the roof is old then you may want to consider replacing it. I leave it to you to search the archives of this forum for the pros and cons of various roof types.
If you are not in a position to replace the roof at this time, then I highly recommend that you get a competent T&G roofer to fix what they can of your current roof to get you through another season while you save up for a new roof. You really don't want water damage to the interior or structure of the house, so do get it repaired if you are unable to get it replaced.
I'd recommend the company that did our T&G roof but they are not an advertiser on this site so this reply would get pulled.
Tod gave you very sound advice. Tenting can be more destructive than necessary. Several times, we have found nail holes through our foam roof and the underlaying tar membranes where wood was secured to help secure the tenting material. Naturally, workers uncaring enough to do this don't caulk the tiny holes they leave. If there is damage to your tar roof, whether cracking, holes etc. the gravel must be cleaned from the leaking areas so it can be inspected. Your tar and gravel company that installed the roof should be very interested in helping you find your leaks.
For reference, our house was built in 1958 and roofing permits were pulled in 1973 (15 years), 1986 (13 years) and 2004 (18 years). When I checked permit histories on other houses in our neighborhood it seemed like 15 to 20 years was typical between T&G roofing jobs.
Your roof is 11 years old so I would guess that it should have a little life left in it. It had not occurred to me that the people tenting for termites would nail boards to the roof. That would be a sure way to cause leaks but should be easy for a roofer to fix.