Roof Noises after Installation

[azdave]

As reported in my earlier post above, my roof is wood truss supported with plywood decking, 30# underlayment and cement tile. I figured with the different expansion rates between aluminum racking and the wood roof I would hear some noises as the structure warmed and cooled but it's pretty quiet, even at 5+ years later. My house had its own expansion and contraction noises before and after the install but I've heard those in just about every home I've owned. I'm sure some solar installs will end up with expansion and contraction noises when dissimilar materials are mechanically connected.

Related story...my large screened patio was installed with 10' length dark brown aluminum spline channels using long wood screws every 18" into the painted wood frames. The first few days, when sunlight hit the frames, the expansion force of the warming aluminum eventually overcame to hold down force of the screws and the noise inside the house was so loud it seemed like someone was firing a small handgun in our backyard. It was incredibly loud. I loosened the screws just enough to allow the frames to slip more easily and the noises are now completely gone.

[Mike90250]

My roof makes some noise and has no panels. But you have a before and after, so I don't know.

[NancyAF]

Hey @pneal, did you ever figure this out? We're having a similar problem that's continuing months after installation, and our installers are similarly stumped. They looked up there once and told us it must be a problem with the roof. I am wondering if we do have a less-than-perfect roof situation going on. The previous owners had it redone in 2015, and we're still occasionally finding random screws/nails on the ground around the outside of the house. I used to think whoever did the roof just didn't clean up well, but the fact that we are still finding bits and pieces makes me wonder if the screws/nails are coming out over time.

[J.P.M.]

Mike90250 that's what I thought too. Although, I would say the noises are more frequent at heat-up and cools down times. That's totally anecdotal, but now that I am getting some feedback here I may actually measure the time between noises. It does appear that the noises are less frequent on cloudy days (days with less temp variation.)

Hoping to find some time to post pics and measurements tomorrow.

J.P.M. The volume of the noises varies from fairly soft- maybe a tree cracking from far away, to loud, a tree cracking when being cut down. Or yes, door slamming is not a bad analogy.

More noise would probably indicate more movement and probably from thermal expansion/contraction causing relative motion of some things or some sections/parts of the same component.
Id sit on the roof on a partly cloudy day and listen up for noises.

[pneal]

Mike90250 that's what I thought too. Although, I would say the noises are more frequent at heat-up and cools down times. That's totally anecdotal, but now that I am getting some feedback here I may actually measure the time between noises. It does appear that the noises are less frequent on cloudy days (days with less temp variation.)

Hoping to find some time to post pics and measurements tomorrow.

J.P.M. The volume of the noises varies from fairly soft- maybe a tree cracking from far away, to loud, a tree cracking when being cut down. Or yes, door slamming is not a bad analogy.

[J.P.M.]

J.P.M. Wow, thank you so much for your thorough and thoughtful reply. As soon as I get a chance, I'm going to take some measurements and pictures and post.

These responses are by far the farthest I've gotten with this issue. I have spoken to my installer again and again with no results. Really appreciate the input here.

Another side of this is the pure frustration and discomfort of hearing your roof make noises at all hours of the day and night. You spend all this money, think you're doing something good, but then the quality of life actually goes down a bit. Very concerning.

I'm also concerned about leaking. To my mind, hearing noises means that things are moving, and if things are moving it stands to reason that they are getting loose. However, I haven't seen any evidence of leaking so far.

You're most welcome. Just remember to not confuse conjecture and brainstorming (or brain farting) with reality. Mine is but one opinion or set of thoughts, I'm not there, and that opinions are like noses: Everyone has one, they're all different, and most smell at least some of the time. Also, none of us is as smart as all of us. Get more opinions and question everything everyone says - including me - until you understand what's being offered.

You're installer may want to help, but resources are limited. Get self reliant. You'll be disappointed less and you'll be limited in who to blame. You'll also get to a resolution quicker.

BTW, how loud are these noises ? Loud compared to what ? A toilet flush ? A door slam ? etc. Any perceived structural vibration ? Any temporal pattern(s) ?

[J.P.M.]

I can understand noise at warm up, and cool down, but all night sounds unusual.

Part of that might depend on thermal time constant of the various components that are producing the sound(s) and also (but not taking the analogy too far), not too much unlike earthquakes and the nature of the stability of the fixations of structures that jerk rather than slide.

[Mike90250]

I can understand noise at warm up, and cool down, but all night sounds unusual.

[pneal]

J.P.M. Wow, thank you so much for your thorough and thoughtful reply. As soon as I get a chance, I'm going to take some measurements and pictures and post.

These responses are by far the farthest I've gotten with this issue. I have spoken to my installer again and again with no results. Really appreciate the input here.

Another side of this is the pure frustration and discomfort of hearing your roof make noises at all hours of the day and night. You spend all this money, think you're doing something good, but then the quality of life actually goes down a bit. Very concerning.

I'm also concerned about leaking. To my mind, hearing noises means that things are moving, and if things are moving it stands to reason that they are getting loose. However, I haven't seen any evidence of leaking so far.

[J.P.M.]

Some questions: What are array dimensions, L X W ? How old is the building ? Any roof work since building construction ? What's the array to roof deck clearance ? Racking attachment type - clips, posts, whatever ?

While relative dimensional changes due to thermal expansion/contraction between panels and racking and racking to roof are usually checked, depending on the physical situation as questioned above, I'm wondering if the expansion noise (if thermal expansion is the cause) might be due to the roof under the array being at a different temperature than the rest of the roof, and the roof itself is what's creaking.

Racking, even when black, doesn't get that warm mostly because not much of it is exposed to the sun, and the rails are usually in pretty poor thermal contact with the panels meaning most of the heat transfer from panels to rails will be from thermal radiation from the back of the panels to the rails. Also, racking rails, by their very configuration make a pretty good fin for heat transfer which helps keep them cool(er) than if they didn't have all that nice surface to transfer the thermal radiation gain to the ambient air circulating beneath the array.

Anecdotally, I'm on my roof and around my array on most sunny days close to the time of minimum solar incidence angle on the array and I've observed, but not measured (yet !) that racking rails are probably about 10 C warmer than ambient at the ends and maybe 5 C or so warmer than ambient under the panels. Now, my array has enough clearance under it to allow me to get under the array (~ 10-12" or so) so that may help keep the rails cooler, but 4-6 " clearance will probably do almost as well for rail cooling.

So, for the OP's situation, maybe it isn't rail thermal expansion relative to the roof that's making the noise (and not necessarily so much the noise as possible induced stresses from possible thermal expansion.

Under sunny conditions at min. incidence angle, the temp. of the deck surface under my array is usually somewhere between the array cell temp. and ambient temp.

A typical example of several hundred such measurements:

Date: 08/15/2015. Time: 1253 P.D.T.
Temp. adjusted GHI: 905 W/m^2
POA irradiance: 955 W/m^2.
Wind vector: 1.9 m/sec, bearing WNW.
Amb. air temp. at the array: 40.7 C

Solar exposed roof deck temp.: 81.1 C
Roof deck temp. under array: 54.7 C
Average back of panel temp.: 68.0 C
Average array cell temp. of 16 panels each measured in 4 random places, 2 times ~ 8 min. apart : 70.9 C. (range 66.1 C to 74.4 C., leading to trailing edge ) - a long, boring detailed description on request.

The roof is flat, lightweight concrete tile, med-dark brown in color.

Note the ~ 26 C temp. diff. between the roof deck exposed to solar radiation and the roof deck under the array.
The OP's particulars are different, but the driving forces may well be similar and, depending on the array to deck clearance, array dimensions, roof condition, age and racking configuration, and the OP's statement that the noises "sound like popping and creaking" and "sound like wood on wood", as well as the dearth of reports of noisy arrays, maybe it's the roof and not the array making the noises.

Or, maybe something else, or several things acting synergistically. Hard to troubleshoot or analyze without being there or at least some pictures.

Take what you want of the above. Scrap the rest.

[pneal]

Thanks so much for your responses.

Ampster, I have panels installed in 2 locations on my roof. The first location has 3 arrays and the second has 2. I'd have to get up there and measure to be sure, but if I had to guess, I would say the length of the first location is about 25'-35' and the second location is about 20'-30'.

solarix, forgive my ignorance. How many spacers should there be between the plywood decking? Just want to know what to look for. Can they be added after the fact, or only at installation?

one thing, the roof made no noises before the install. Would the spacer theory still work?
thanks again, everybody

[Ampster]

pneal , how long are your arrays?

[ButchDeal]

It would very much have to do with the length and if the rails had expansion joints. All of the major solar racking manufacturers have expansion joints and specifications on the required distances of them to be installed. That does NOT mean that the installer put them in though.

For Ironridge it is rails over 100 foot length need to have the expansion joint (see page 7) http://files.ironridge.com/pitched-r...ion_Manual.pdf

[Ampster]

Just guessing here but could it have anything to do with the length of the array? Several years ago I provided some oversight on a city ballast mount set of arrays that were over 100 feet and the installer provided for some expansion of the rails due to temperature expansion and contraction.
Question for the OP, how long is your array?.

[solarix]

We've done over 300 installs, almost all on roofs - and have never heard this problem occur. Have see plenty of less than perfect roofing done however. I suspect you have a roofing issue that has been exacerbated by the solar mounting. Its quite common for the decking nails (or staples) to miss hitting the framing which would allow the decking to move and make noise. Get in the attic and inspect all the fasteners if possible, or hire a home inspector (they are good at being nit-picky) to check it out and go after whoever was negligent to fix it.