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I have built a pergola on my own about 1.5 years ago and it doesn't stop making those cracking wood noises (like the wood is cracking).

First of all I know I have built the pergola pretty good because I have followed the instruction of a friend who owns a wood business, and the pergola also "passed the test" of a very bad weather with very strong wind and rain this winter. I examined the pergola and I couldn't see any cracks or broken wood anywhere.

There are 2 kind of noises that I hear, I assume that 1 of the noises comes from the material that lays on top of the wooden pergola, while the other noise comes from the wood itself.

The noises comes mostly when there is a change in the weather, the noises start when the sun comes out and last for about few minutes, they start again when the sun goes away, and so on every day.

At first I assumed its because the wood is new, and I know wood tend to expand and shrink depending the weather, moist and such, but I thought that after a year it would stop, but it doesn't, the noises sounds the same.

I figured the noises come from the small wood bars that lay on top of the "main" frame and not from the frame itself, those wood bars are there just so there would be less sun inside and not for holding the structure together, when we put them on, they were not straight enough, so we had to manually put them in the right place with force to be straight, and I assume because of this I hear the crack sounds because they are trying to bend back to their first form.

  1. Should I be worried? How can I check if I should be worried or not? While I can't see any big cracks in the wood I know that in most cases it doesn't matter and the wood can break without notice anyway.

  2. How can I stop it? Is there anything I can do to stop those noises? It happens on a daily basis and it is something that really starts to bother me.

Here are some images: Wood bars that lay on top of the main frame General structure of the frame, and how it sits on the wall

  • I'm not sure this is really something that can be answered by the internet. Not without a lot more build detail at least, and describing sound is tricky. Is that plastic sheeting over the top? That's going to act as a speaker and amplify little sounds. Is it the joins moving? Hard to say. Maybe DIY is more appropriate (diy.stackexchange.com)? Maybe not, since they are going to note the same challenges. – jdv Feb 1 at 14:49
  • The fact that it occurs at sun up and sun down suggests thermal expansion and contraction. The trellis members may be rubbing against the beams. How many nails are used at each beam/trellis connection? If one nail/screw is used at the center, then the trellis pieces may be rubbing as their width increases and decreases each day. Another candidate for the rubbing sound could be wind racking the entire structure. Do you get daily breezes at those times? – Ashlar Feb 1 at 18:16
  • Jdv, thanks, i sure will contact some expert on my side, but i wanted to check online first for clues. – Art3mix Feb 1 at 18:45
  • @Ashlar, You are right, 1 screw is used on each connection (this is because there is simply no space for another one) also there are specific places where the sounds comes from, I tried to locate the exact wood piece that's making the noise, and came down to 1 trellis that made the cracking sound if it was wiggled a bit. The noise usually come at the morning and its very loud (when sun comes out), and usually in the middle of the day when it starts to be warmer or colder, there is also no noise at all when its windy, like nothing at all. – Art3mix Feb 1 at 19:01
  • First off congrats on your build, that's a very impressive structure to tackle for anyone much less an amateur woodworker. Now you Qs, 1) I doubt it. Movement noises, including creaks that sound like wood cracking, are commonplace in wood structures and generally nothing to worry about. 2) It's possible you may not be able to, but the first step has already been taken and you've narrowed it down to local areas. After finding the source(s) of a creak you then do something to prevent wood rubbing, and here that means trying to tighten up your fasteners. [contd] – Graphus Feb 2 at 8:14
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Usually this noise is created due to thermal expansion. The roofing screws for polycarbonate sheeting should have a big enough flexible washer so that you can pre drill a hole in the sheeting around twice the diameter of the screw to allow for movement. This should prevent much of the noise.

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