mounting panels to treated-wood frame

[RShackleford]

I received an interpretation that roof rapid shutdown issues did not apply to my patio cover array. You are probably referring to disconnects. You are correct that outside is where they generally like to see those.

Definitely don't apply to my ground-mount. Please have a look at the thread where I asked about my wiring plan:

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panel-installation/408944-wiring-details-of-ground-mount-system-w-string-inverter-plus-generator-backup

[Ampster]

Probably gonna put that about 30ft away on the side of the house. Outside, so don't have to be concerned with running high-voltage DC inside and rapid-shutdown issues.

I received an interpretation that roof rapid shutdown issues did not apply to my patio cover array. You are probably referring to disconnects. You are correct that outside is where they generally like to see those.

[RShackleford]

Need any opinions on how to mount your inverter? LOL

Probably gonna put that about 30ft away on the side of the house. Outside, so don't have to be concerned with running high-voltage DC inside and rapid-shutdown issues.

[Ampster]

Sounds like you have it figured out. Keep us informed as your build progresses.
Need any opinions on how to mount your inverter? LOL

[RShackleford]

Warpage in wood has been overblown in this thread.

I am grateful to @J.P.M. for bringing it to my attention. It has steered me towards replacing the 2x8s with XR1000 rails, which will be a superior system in a number of ways, not just for the avoidance of warp effects (as I detail in the last paragraph of post #41).

lI would tighten the connector bolts between the aluminum rails and beams.

You're right. I can always loosen them temporarily, and let the rails slip slightly in the L-feet, if I see strains developing; but I agree it probably won't be an issue.

As far as documenting the SR rails ability to span the distance, the Iron Ridge site should help. If you haven't dug the holes and poured the concrete yet, you might be able to move them closer to cantilever the rails a little more. That will allow you to shorten the span.

No need, it looks like the rails can easily span the distances involved.

[Ampster]

Yeah, especially if I were clever enough to arrange the grains on the two boards so any warpage cancelled out.

But my point was, if I use the IronRidge rails (and delete the 2x8 purlins), and attach the ends of the rails with the "L-foot" and "rail connector bolt", that bolt could be a little loose (how to calibrate that ?) so that as the 2x12s bend (warp), there's a little free play as the rail-connector bolt slides in the rail groove.
.......

Warpage in wood has been overblown in this thread. Just randomly gluing them together will produce a beam much stronger than an equivalent beam that is not laminated. I toured a laminated beam mill once and they just took the boards as they arrived at the assembly point. A tube of construction adhesive per beam should suffice. Screwing the beams together should provide sufficient clamping force to maximize the surface area of the glue and wood.

Also, I would tighten the connector bolts between the aluminum rails and beams. Those rails are strong enough in compression and tension to take any loading that slight warpage could put on them. That way the 8 rails and laminated 2x12s work as a system that will be much stronger than one with loose connections. You can test that by trying to shake the structure before and after tightening the bolts. In addition once the panels are clamped to the rails you will get a diaphragm effect that will further contribute to its stiffness. I am not an engineer but I have been working around wood frame construction most of my life and discussed similar issues with engineers and architects numerous times.

As far as documenting the SR rails ability to span the distance, the Iron Ridge site should help. If you haven't dug the holes and poured the concrete yet, you might be able to move them closer to cantilever the rails a little more. That will allow you to shorten the span. The Iron Ridge site can give you some guidance with that.

Hopefully this simple and practical advice will help other readers. If this were a bridge or a multistory apartment building I would not be offering these opinions.

[Mike90250]

Gentlemen, cool your engines. It's been said several times (all of it) by several parties.

[RShackleford]

Ever stop to think that others besides you may get some use of it ?

So which time that you said wood isn't your favorite construction material will be the time that others get some use out of it ?

[J.P.M.]

I believe you need to bone up on your memory skills, because you've said this SAME damn thing over and over again in this thread. I get the point. Please stop it, if you have nothing new to add.

My memory is fine (I think). I'm fully aware of what I write. In this case, I was responding to Amster's post and what I see as more of his argumentative B.S.

As for you: Apparently, you missed my thrice made statement about what you do being none of my business. You can make array supports out of tree branches for all I care.

Just don't tell me what to write.

You don't like what I write, stop reading it.

Ever stop to think that others besides you may get some use of it ?

This forum is more than just about you, me or any single person. I try to keep that in mind.

[RShackleford]

Glue and screw the 2x12s together and they should stay stable.

Yeah, especially if I were clever enough to arrange the grains on the two boards so any warpage cancelled out.

But my point was, if I use the IronRidge rails (and delete the 2x8 purlins), and attach the ends of the rails with the "L-foot" and "rail connector bolt", that bolt could be a little loose (how to calibrate that ?) so that as the 2x12s bend (warp), there's a little free play as the rail-connector bolt slides in the rail groove.

I think I've sold myself on this plan to replace the 2x8s with XR1000s. Gonna add a few hundred dollars to the overall cost (out of about $7000, before federal credit), but will make it easier to install (imprecisions in the carpentry can readily be cancelled out with rail mounting, and no panel-mounting holes to drill), should address some of JPM's concerns with wood (the warpage issue, if not the issue of deterioration of the wood), and should make it look better (more of a "floaty" effect).

[RShackleford]

... there are better materials for the structural support of PV arrays than wood.

I believe you need to bone up on reading comprehension skills.

I believe you need to bone up on your memory skills, because you've said this SAME thing over and over again in this thread. I get the point. Please stop it, if you have nothing new to add.

[J.P.M.]

Are you suggesting the OP should walk away from his design and the cost of engineering and go to an entirely metal structure? Or are you just saying he should use metal racking on his wood structure.

No. You smokin' something ? Or just trying to give me some B.S. ?

If you infer something like that into what I write, you're seeing more than is there.
Read what I wrote in the context of the post I was responding to and don't read things into my post that are not there.
If you examine my posts to this thread, or any other post I've ever written for that matter, nowhere will you find where I suggested walking away from a design based on materials alone.
I just think that, based on what I think I might know from experience, training and education, that for the safest, most fit for purpose and when all factors are considered, there are better materials for the structural support of PV arrays than wood.

In the post I responded to above, the OP stated he was trying to minimize costs. Looks to me that he is considering only first costs. If so, and keeping in my mind that others may be reading all this stuff, what I am suggesting, for others' benefit more than the OP's, is that there may be other things to consider in costing a project besides initial or first costs - things like maintenance (painting/treating/replacing the wood comes to mind) and wear/tear, not to mention what are, IMO only anyway, the more likely negative effects an aged wood structure may have on perceived resale values. As stated previously in the same post I was responding to, NOMB what RShackleford does. If so, why would you think I would be contradicting "NOMB" by suggesting he walk away ?

I believe we (he and I) understand that we see the value of wood as a construction material differently. I believe you need to bone up on reading comprehension skills.

[Ampster]

...... (I suppose the dual-2x12 beams could warp a little, but that's just slippage at the ends of the XR1000s.

Glue and screw the 2x12s together and they should stay stable.

[RShackleford]

AHJ is fine replacing the 2x8s with rails, if I can document the rails' ability to span the dual-2x12 beams. I can do that simply by showing a design created by IronRidge's design tool, for a similar 4x4 array. It comes up with eight 14ft XR1000 rails supported by two pipes separated by 7'6". And outlined how I would address the diagonal bracing (in the absence the 2x8s) and it seemed like he could be satisfied without too much trouble.

There's a local supplier who will sell me the XR1000s and the 40 UFO's for about $680. No delivery fee, if delivery is at his convenience (has already has a truck in the area), which is great. It's still a lot of cost to add to this design I'm trying to do on the cheap. All I save is the 8 2x8s, the 16 connectors to attach them to the beams, the clamps and lag bolts, and the ground clips - I'm thinking about $300-400. And I still need some hardware to attach the XR1000s to the beams (I guess that's only about $50 for16 L-foots and 16 rail-connector bolts). Of course, I also get some ease of construction (e.g. don't have to precisely locate the positions of the clamp/lagbolts, or ground each panel), and, the main reason I'm considering this: less concern with wood warpage (I suppose the dual-2x12 beams could warp a little, but that's just slippage at the ends of the XR1000s.

An intermediate plan would be to keep the frame with 2x8s as designed, but add rails, but that needn't be beefy enough to span the beams. Rails must be IronRidge or QuickMount brand, because that's all this no-delivery-fee outfit carries.

[Ampster]

While there may be something to the logic in your tinker toy analogy, sometimes folks consider only first cost and not long term costs, including the cost of increased maintenance/repair/servicing, and/or they put little or no value on their labor or sweat equity.

Are you suggesting the OP should walk away from his design and the cost of engineering and go to an entirely metal structure? Or are you just saying he should use metal racking on his wood structure.