3121CK roof trusses

[tjblocker]

I've tried to find the answer to this question but have been unable to do so.

I have just purchased a new 2022 3121CK. I take delivery next week. I want to install an additional 600 watts solar (200 watt panels). I plan to use strut channel. While doing so I want every screw that penetrates the roof to enter a roof truss. And I want to limit penetrations making each count. Only, I don't know where the trusses are.

I've emailed keystone days ago. I got a question asking for the vin which I provided. Haven't heard from them since.

Does anyone have a roof plan or some idea how I might find the trusses. I've previously tried to find the trusses using a stud finder on my Arctic Fox. This did not work. Thus I don't expect it to work on the Montana.

I know that there are trusses bordering each side of the 14X14 vents. I would expect that other trusses would be on 16 inch center from those trusses, but I saw a photo of the trusses that showed me that this is not correct. It looks like they've done some unpredictable spacing adjacent to vents.

So, how do I find the trusses? Better yet, does anyone have a roof plan?

Thank you
Tom

[Mikendebbie]

There are no construction details available. Back in 2013 or so I had a Jayco and Jayco happily abliged my request for framing plans. Keystone does not do that. I think they will tell you to go thru your dealer. The good news is that there are lots of smart folks that may be able to advise you on your solar install. There are several factory tour videos available that will give you a visual look at the roof construction. I have not looked for a factory tour video showing a 2022 model, but you can start by searching YouTube for Home with the Hoopers Keystone factory tour (2019).
The screen shot below is from that video.

[twindman]

Maybe try a stud finder???? I think I may have used it in the rig on walls, but can't remember where I used mine.

[rohrmann]

It’s interesting that it appears they are using wood roof trusses now. Our rig used stamped steel trusses. In 2014, at the fall rally, we went on the factory tour, and they were using molded plastic trusses. If you are using steel struts on the roof, I would be concerned about the metal wearing into the roof material more than I would worry not hitting trusses when attaching the struts to the roof. Also, not being able to physically see each screw location under the struts to verify that the Dicor caulking was intact could cause roof damage from leaks. I’ve not seen any solar panels laying in the roads that may have flown off of RV’s traveling down the road, so however most are attaching their panels seems to work. However you ultimately attach your panels, I’m thinking the plywood roof material is strong enough to walk on, and will be plenty strong enough to secure the panels without worrying about hitting the trusses.

[rames14]

First, a couple of things. Montana has gone from steel to aluminum and back to steel joists. I believe they are still steel. Part of the reason for changes are weight, condensation and subsequently mold issues. The metal does not contact the roof. Their is plywood or particle board sheeting attached over the joists. You should be able to find the joists with a stud finder, but also looking at where the AC units are attached. They use a common spacing, so find two and you can find the rest. The solar panels work best if they have airflow under them. So, they use steel stand-off brackets to attach to the panel and roof. Make sure to seal over your bolts. If you have roof mounted satellite, do not run your cable under the panels. Best of luck.

[tjblocker]

OP here.
I've tried hard to find something that helps me find trusses.

I've tried a stud detector on an Arctic Fox, but it didn't work at all.
I installed four panels on an Arctic Fox without finding trusses and it worked perfectly. But finding trusses would give me piece of mind. I don't want anyone hurt.
My plans... I'm going to use strut channel. I will use a double sided adhesive tap between the struts and the roof. And I'll use several screws per channel. I know I'll be able to hit at least one truss by butting the truss up against vents or ACs. I'm also going to install a wind break to keep the wind from getting under the panels.
I don't understand why the truss locations have to be such a big secret.
While panels don't come loose often, it does happen. A 200 watt panel could easily go through a windshield and kill. Don't think we can be too careful.
Thanks to everyone
Tom

[bcrvman]

Originally Posted by tjblocker

I've tried to find the answer to this question but have been unable to do so.

I have just purchased a new 2022 3121CK. I take delivery next week. I want to install an additional 600 watts solar (200 watt panels). I plan to use strut channel. While doing so I want every screw that penetrates the roof to enter a roof truss. And I want to limit penetrations making each count. Only, I don't know where the trusses are.

I've emailed keystone days ago. I got a question asking for the vin which I provided. Haven't heard from them since.

Does anyone have a roof plan or some idea how I might find the trusses. I've previously tried to find the trusses using a stud finder on my Arctic Fox. This did not work. Thus I don't expect it to work on the Montana.

I know that there are trusses bordering each side of the 14X14 vents. I would expect that other trusses would be on 16 inch center from those trusses, but I saw a photo of the trusses that showed me that this is not correct. It looks like they've done some unpredictable spacing adjacent to vents.

So, how do I find the trusses? Better yet, does anyone have a roof plan?

Thank you
Tom

There is no need to find the trusses. My 6 panels are only fastened to the roof decking, 2 screws at each corner. I first fastened the feet with that heavy duty 3M double sided tape but on my roof that doesn't do much but it was free. Just use stainless, puddle Dicor first of course and 3/4" long IIRC. I don't know of anybody fastening to studs, just not needed and many RV's don't have them or can't find them.

[tjblocker]

Thanks for the response. I did it as you say for my Arctic Fox, but I would rather find the trusses. Allow me to explain why. And part of this reason has to do with wanting to use strut channels, for the problem I'm about to describe would be more prone if trusses are missed.



I've one not so obvious reason to want to find the trusses. If you place a screw about midway between the trusses, it will appear to be tightly fastened. However, if you step on the roof adjacent to the screw the roof would try to good give a little. I've seen this give before. This slight deflection would put stress on the screws holding power by pushing the roof away from the mounts. Over time this could become a problem and maybe introduce a leak. The roof at the trusses would have no give.



However, on my Fox I did not find trusses and I mounted them using tilt kits. I never had a problem with it, and it held perfectly for four years.



bcrvman, I've done as you said and it worked. I'm just looking to do it a little better. Thanks again for your response.

[bigdawgfinley]

Like you I tried every stud finder available and nothing worked. I even drilled some test holes hoping to hit paydirt. I checked videos of the roof construction and determined that the roofing material was 3/8-1/2” OSB. After I calculated the wind load on my three 200 A panels was extremely low I decided to use 8 lag bolts thru 4 angle brackets to mount each panel. I’ve done extensive traveling in the 3 years since monting them with no signs of loosening. Before installing the screws I taped the surface to prevent surface wear and then used self leveling sealant to ensure water integrity. I think you should be fine.

[Daryles]

I used a stud finder to find the rafters when I installed my panels. Works great. Once I located the rafters I used blue Frog painters tape and chalk to mark them.
If I was doing mine again I would use unistruts as you are doing, then you can be sure every screw goes into a stud. I was only able to have the leading edge mounting feet on a stud.
When I determined where the mounting feet went I put down Eternabond. Then drilled a pilot hole, the put Dicor in the hole and where the foot went. Then mounted the foot and covered the screw with dicor. So far so good.
I may yet re-do my roof panels if I add more.
I will use aluminum unistrut and Renogy tilt brackets.

[tjblocker]

Daryl,
Thanks for the response.



If I wasn't planning to use unistrut then I'd not be as concerned about finding the trusses. But the use of the struts makes it more likely that roof deflection could cause a screw to lose it's hold. However, I think strut channels offer far more advantages than disadvantages.



I used eternal bond tape in my last install just as you did to cushion the panel mounts against the roof membrane. That membrane is so thin I wanted the extra cushion.



I'm thinking that my stud finder might be flawed. I may try with another.



I really like the idea of strut channel. It minimizes the number of roof penetrations. I think 3 or 4 screws per strut would be enough if each penetrated a truss. It's also more scalable and modifiable. Adding or removing panels is much easier. If I sell the RV I can more easily take my panels with me while the next owner will have a system they can use. It lifts the panels a little more off the roof allowing for more air flow underneath and thus more efficiency. Besides, it just looks much nicer.

This video explains my ideas well

https://www.youtube.com/watch?v=UY98-WQ0VTw&t=413s

Thanks again
Tom

[RipNC]

FYI - Toured factory 2-3 weeks ago and the trusses were wood with nominal 1x2 chords.

[tjblocker]

Original poster here...

I contacted Keystone trying to obtain information regarding truss locations. I was hoping for roof plans. What I got was less than nothing.

They do not give out this information to anyone except service department employees. They do not want the customer installing solar themselves. I asked the salesman but I think I just glazed his eyes over.

Other manufacturers do share roof plans, but Keystone does not.

I might have the dealer's service department do it. All they have to do is install two 300 watt panels and a controller next to the one that's already there. All wires internal to the RV have already been run. They are rated at 30amp so I will have to wire panels in series.

It's past time for manufactures to run 8 or 6 gauge wire. Some people need more than 400 watts of solar. I want 1kw for those cloudy days in Quartzsite.

On an aside, our 2022 3132CK is brand new. We took delivery last Thursday. And we love it.

Tom

[Foldbak]

https://walabot.com/diy?gclid=CjwKCA...hoCqHMQAvD_BwE

[1wayhighway]

Not too far off subject but what panels (brand/manufacture) are you all installing?

Looking to do an addition to our new trailer.

[tjblocker]

IWayHighway,
I want to install two 300 watt panels, but I'm working alone and I don't want to lift these. So I am thinking of installing three 200 watt panels to compliment the 400 watts factory panels that are there already. They will have to be in series if I'm to use the factory port.... which is rated at 30 amps. Haven't made a decision, but something like this
https://www.amazon.com/gp/product/B0...HZDTPF1LD&th=1
And I will probably use the Victron 150 | 45 controller. The 400 watts factory panels are controlled using a Victron Controller.