Do you have an attic exhaust fan that is cycling during the heat of the day?

I am also in Florida. Central east coast.

I am not sure if I have a exhaust fan or not. There is a metal fan as soon as you get in the attic but it is not hooked up. Not sure if there is another one somewhere but I don;t think so. We do not have a metal roof however we do have a metal or aluminum roof over our enclosed patio but the sounds are not coming from there. They seem to be isolated (mostly) over a hall and double bathroom. I work from home and these bangs generally happen when nothing is happening near those bathrooms or the hall. I had mentioned our plumbing....when they re-piped they went through put the pipes in the attic but I cannot imagine them making the noise I am hearing. Thanks for thinking about this with me!

I was thinking maybe an outside air damper...sometimes they have spring loaded dampers.
Can you call the previous owners? They know...

I do not have access to the previous owners but yea I would LOVE to ask them! LOL The sound is similar to someone hitting a wall hard with the bottom of their fist. The loudness level is not consistent sometimes is louder and sometimes not as loud. It usually only happens a few times a day and I don;t think it has ever happened after sun down.

I'll bet your floor tile is tenting. Very common here in Florida and comes with a bang usually. This would be consistent with not happening after sundown since the tile/slab wouldn't be as expanded then.

Joseph...what does that mean? I have never heard that term before. We do have a ton of tile in the house and I am not completely sold on the quality of the installation. This "Tenting" can make a loud bang towards the ceiling area?

Do you have an air handler in the attic? Maybe your unit is causing your duct work to flex?

Alley_Cat our air handler is in our Laundry room

Ok, The plumbing you spoke of in the attic. Is it a plumbing vent that goes through the roof to the outdoors...or are they water lines?

Alley_Cat I am no plumbing expert so I am going to attach 2 pics that might answer your question. One is the main into the house and the other is just a pic under a sink.

Are you on a well.....or city water?

City water

I'd go up there and grab n shake some different areas of the pipes to see if I can simulate the noise if they are not strapped down tight.
My other thoughts are is something heating and contracting.....I'm sure it gets very hot up there during the day...and cools down at night...

That might be a good idea. Where I am hearing the sounds might be tough to get to but perhaps I can try it anywhere in the attic and it should at least make a similar sound I would assume right? It is such a loud sound sometimes that I mean I even have searched the house for cracks to make sure I am not dealing with a sinkhole or something.

well...if their not strapped down they can move...my house has 60 psi surging through the pipes...hell, we don't need soap, it's like being pressure washed here....
Btw, do you have a recirculating pump any where?
Attics are no fun but it would be good to take an inventory of what's up there...

HAHA! Not sure what a recirculating pump would be and where I would find one. Yea and a Florida attic is even less fun. I really appreciate all of your help!

"Joseph...what does that mean?"

Click on the green highlighted "tenting" above, please.

Joseph....yep I did...no I do not see any of that happening around here despite having a lot of tile...I even checked our outside stuff on the porch and it all appears very solid.

Dave:

Bounce a golf ball on your tile please. Count how many "snicks" you get and how many "thunks". Snick means the concrete, thinset, and tile are properly bonded. Thunk means they're not. The bang happens at delamination, whether or not the tile tents.

Its a demon not a ghost