Noise from copper pipe in the attic
We are doing some energy improvements in our house. The insulation in our attic was completely removed and attic air sealing work was completed today morning. Since today we have been noticing a noise(more like a thud noise) whenever we open the hot water in one of our bathrooms. This bathroom is the only place to which the pipe goes through the attic(rest of the house has plumbing through the crawl space) This happens only for the first time when we open the tap. We don't hear the noise if the tap is opened frequently after that. However, the noise is back if we wait for a long time and then open the tap again. My husband went up the attic to make sure that everything was ok with the pipe. He feels that the copper pipe is expanding and that's what is probably causing the noise as it is nailed to the stud. I am very confident that we are hearing this noise because something changed after the folks went up there for the air sealing. Otherwise we would have heard this noise all along and not just starting today. Could there be anything that might have been displaced? Are there any fittings around the copper pipe( that typically mask the expansion/contraction noise) that could have been accidentally moved or removed while walking over the pipes? Before I run about calling a plumber to come and take a look, wanted to check with the knowledgeable folks in this forum. Would really appreciate if folks can provide any pointers. Thanks!