It's a flat roof. My son just sent me pictures and it looks like the plumber who came out to fix the water leak (in the faucet) pulled the pipe up through the roof and broke the original seal around the pipe. So now he does not have a leaky faucet but his roof leaks when it rains. Is it ok to use a siliconized caulk to seal around the pipe until he can get a qualified roofer to come out and do a more permanent fix?