Roof Replacement - 2008 3400RL

[steckrca]

Good day to you all! First post here, more to come I'm sure.

I'm about to begin tackling the roof replacement on my new-to-me 3400RL. I'll be doing most of the work myself, and have watched a ton of AZExpert videos on YouTube over the years. I'm sure I'll make mistakes, but I'll learn in the process. This Montana will be almost a full renovation, and I want to tackle the roof first so I can protect my hard work inside.

I'll be replacing the EPDM with TPO. From what I've read it doesn't last quite as long as EPDM but I feel better about TPO due to its thickness versus EPDM. I've already bought the roofing materials so I'm sticking with TPO.

There's a lot of words here, so my apologies in advance for being wordy, and my appreciation in advance for those who read it all and reply!

Now on to the questions.

1. Relocate vents:
I boondock a lot, so I want to maximize open roof space for solar panels. My current bumper pull has four solar panels, I want more with this one. The two rooftop AC units will be removed in favor of two mini splits--one for living area, one for bedroom. Outdoor units will be on rear bumper platform. There's only one plumbing vent for the galley tank that's in the way of solar panels. I should be able to elbow this below the roof deck and relocate it to the center?

Fantastic fan, TV antenna, and both rooftop AC units will be removed.

2. Roof Vents:
There are six vents total on the roof. Two I believe are attic vents, front and rear on center. These are nowhere near tanks so I think this is right. I can't seem to wrap my head around why there are four others. Usually there is one per tank. Two grey tanks, one black tank, should be three vents. One is above the toilet room (PV(t)), one is above the washer closet (PV(w), and another is above the bedroom sink (PV(s)). I'm fairly confident the one at the top of my photo is the galley tank's vent. Should I have this many plumbing vents or is one another attic vent?

3. Strategy:
I'll be doing all of the work myself, really only getting help to install the membrane after all the mechanicals are done, so I need to be as strategic as I can in doing this. My plan is to work on it one section at a time, breaking into three areas: front, middle, rear, not necessarily in that order. Front will be everything forward of the skylight and two roof vents. Middle will be from skylight and two roof vents back to the galley plumbing vent. Rear will be the rest. I figure I can slice the roof membrane and peel it back in each section, and tarp off the roof after I finish work for the day.

4. Plywood:
I know there will be some plywood to replace, there is a large soft area among other smaller soft areas randomly around the roof. Obviously these areas will need replacement, in addition to having to replace anywhere that I'm removing roof mounted items, e.g. AC, TV antenna, fantastic fan, etc. The brochure for 2008 Montana says it should have steel roof trusses. How does the plywood attach to these? I'm thinking I'll use a construction adhesive and screws. Do I need to predrill the trusses at my screw locations? Use self-tapping sheetmetal screws? I'll probably end up replacing all of the roof plywood. What's preferred, OSB or plywood? Plywood should be lighter, so I'll probably opt for plywood.

Images!

 

[LeftOverParts]

Hello and welcome to the forum.

Ambitious projects! Will be great to see pictures of the inside, roof, and solar when you get a chance.

A couple comments:

Thinking you should have the option to have at least 1 active exhaust. Depending on how much solar you want on the roof, with panels being available in 200 and 250 watt sizes, you might be able to keep/relocate 1 or 2 exhausts. (We only have 2, 250 watt panels but found it helpful to draw a layout of them on the roof for the first 2 and future panels).

Don’t know how your roof is sloped but re your roof membrane, thinking you want to start at the rear and move forward so that the lip is downwind and with the roof slope. Or, if you meant lengthwise, then both sides and then middle for overlap with roof slope. Lengthwise seems like it would be more challenging for potential wrinkles if the roof curves side-to-side and slopes. Maybe the overlap could compensate. (I recall doing geometric drafting a long time ago in school.)

Good luck, safe travels!

 

[steckrca]

Thanks for the reply! I’ll work on getting some more pictures up.

Working incrementally is just for the teardown and plywood replacement. Roof membrane will still be in one piece, all applied at once so no overlaps or seams. The roof is relatively flat in the center 15 feet or so. The front and rear slope toward their corresponding ends. I’m hopeful that I’ll be able to “persuade” the TPO to behave at the slope changes. The slope transitions are pretty tame and the side corners are curved as well with what I’d estimate is probably a 4” radius. I’d love to hear some opinions on whether or not this will be a huge pain or not feasible.

Regarding the vents, I’ll only be removing one of the roof air vents. Toilet room fan and bedroom vent fan will stay as they are where they are. I was referring to relocating only the galley plumbing vent.

I’ve mapped out the solar panels, I use 375 watt commercial panels 77”Wx39”L. Two at the front forward of the skylight and vents, then six rearward. Have a cad layout of the eight panels, leaving a 14” maintenance path down the center.

Thanks again, looking forward to more replies.

 

[Mikendebbie]

Sounds like you have a great plan. I suggest you watch as many “Keystone Montana Factory tour” YouTube videos as you can find. This will help you understand the original construction methods. I provide a link to a factory video from 2010 below, which is closer to your year model. There is a quick clip in the video of the factory workers spreading OSB roof sheets and a guy that looks like he is operating a powered screw gun. Montanas now use wood roof trusses and they shoot it down with staples…which won’t apply to you. They do grind off any fasteners that will protrude into the membrane. Screen shot of the roof construction detail from the factory video.

Attached below is your floor plan from the 2008 sales brochure, which might help other forum members associate locations of vents with the floor plan below. Also from the brochure is an exploded view of the roof.

 

[Carl n Susan]

<snip>
There's only one plumbing vent for the galley tank that's in the way of solar panels. I should be able to elbow this below the roof deck and relocate it to the center?
</snip>

I doubt there is enough room under the roof deck to use 90 degree, much less 45 degree, elbows. I think that vent runs up through the cabinet along the outside wall. You may be able to angle the pipe at the upper cabinet and over, close to the roof center, but it likely will interfere with the shelves and storage.

<snip>
There are six vents total on the roof. Two I believe are attic vents, front and rear on center. These are nowhere near tanks so I think this is right. </snip>

Correct the two vents at the very front and rear are attic vents.

I can't seem to wrap my head around why there are four others. Usually there is one per tank. Two grey tanks, one black tank, should be three vents. One is above the toilet room (PV(t)), one is above the washer closet (PV(w), and another is above the bedroom sink (PV(s)). I'm fairly confident the one at the top of my photo is the galley tank's vent. Should I have this many plumbing vents or is one another attic vent?

Yea, four vents seem unusual. The washer, toilet and sink are all adjacent to each other. The shower is across the hall. Knowing Keystone's Old World's Craftsmen, I would have expected they would have plumbed and vented, the washer/toilet/sink altogether into the black tank. Or the washer and toilet together at least. But it sure seems that each device has its own vent

 

[steckrca]

Thanks for the video! I've seen that link a few times here and there but never watched it all the way through.

Some things it confirmed:

Front and rear center vents - definitely attic vents. Looks like one cap has been replaced over the years.

1. That makes those other four vents plumbing vents, though still not sure why there are three vents there around the toilet/sink/washer area. I'm also not sure I care! The one on the driver's side is obviously for the galley tank. Depending on what I find when I remove roof plywood, I may merge two of them (keep black separate for sure) for fewer roof penetrations. Looking at my roof photo alongside the floor plan, I have to guess that there's one for each of the toilet, sink, and washer.

2. Steel roof trusses, though we already knew that. I'll get some flat head tek screws for installing the plywood, easy peasy. I'll sink the screw heads just below the surface and then tape the joints/screw heads for extra protection.

3. I may replace some or all of the roof insulation if it's looking shabby. This will also give me a good opportunity to inspect the ceiling from above.

Thoughts on removing AC ducts? I figure I should if I'm removing the rooftop AC units. I already need to replace most of the ceiling panels inside so removing the ducts makes sense in my head.

My solar layout is below. If I'm feeling froggy I may even run wiring through the roof trusses for the solar panels so I don't have wiring laying all over the roof like I do with my current rig. Thinking I can minimize my wire size (80V @ 10A per pair) if I install a gland box between each series pair and run everything down to the front, and run everything through the TV cabinet down into the front basement storage where I'll have my battery bank, charge controller, inverter, BMS, etc. I'll have 8 wires coming down into the hatch, then merge all to two wires into the charge controller. You can see where the galley tank vent is right now that I want to relocate to the center.

3.

 

[steckrca]

I doubt there is enough room under the roof deck to use 90 degree, much less 45 degree, elbows. I think that vent runs up through the cabinet along the outside wall. You may be able to angle the pipe at the upper cabinet and over, close to the roof center, but it likely will interfere with the shelves and storage.

Correct the two vents at the very front and rear are attic vents.

Yea, four vents seem unusual. The washer, toilet and sink are all adjacent to each other. The shower is across the hall. Knowing Keystone's Old World's Craftsmen, I would have expected they would have plumbed and vented, the washer/toilet/sink altogether into the black tank. Or the washer and toilet together at least. But it sure seems that each device has its own vent

Thanks Carl!

I'll have to play it by ear when I get the roof deck off to see what I can do with that galley vent. Maybe there's enough room to do some flex or something. It's just a vent after all. I know for sure I don't want to use a cheater vent, but that roof vent has got to move somehow.

Regarding the excess vents, again I'll play it by ear and see what can be done with them. The ones above the washer and the toilet seem like they're far enough from the side of the rig that there's probably enough room in there to do something with them. If I can't do anything with them, they're not in the way of my solar plan so one or two extra roof penetrations isn't the end of the world. Here I am talking about reducing penetrations, but also adding four solar gland boxes! If it's all sealed properly, it'll be ok. Just more to inspect yearly.

I love how every unit has its own little quirks, even though they're all supposed to be identical. It's like when they were building it, someone put a hole in the wrong spot, and then they just decided "meh, we'll stick a cap on it, it'll be fine."

 

[Mikendebbie]

I took screen shots and put all your plans together to see where the roof penetrations are located. If it were my rig I would install an air admittance vent under the cabinet at the one vent you want to remove. I have never had an issue with those.
You are planning to remove the TV antenna, so I assume you have plans for getting TV signal (Starlink?).
What are the two items at the rear over the passenger side theater chair?

 

[steckrca]

I took screen shots and put all your plans together to see where the roof penetrations are located. If it were my rig I would install an air admittance vent under the cabinet at the one vent you want to remove. I have never had an issue with those.
You are planning to remove the TV antenna, so I assume you have plans for getting TV signal (Starlink?).
What are the two items at the rear over the passenger side theater chair?

Yeah, a cheater vent is a last resort. Thank you for the suggestion. I have one under the sink in my current camper (2014 Jayco 267BHS) and I swear it stinks sometimes no matter how new the vent is.

TV antenna I'm not worried about. We don't watch a lot of TV and if we do I'm fine using an external/add-on antenna connected in the convenience center. I have IPTV service hosted on a server at my house so if I have internet I can watch pretty much whatever I want, and then there's streaming. We only watch live TV for NASCAR and football. And NASCAR when we're camping, we're typically AT the races so no need for TV

The two things over that recliner are the roof mounts for the ladder. It was removed by a previous owner and I won't be replacing it. So the stubs that are still there will go bye bye.

 

[steckrca]

Ok I think I have most things sorted out. See drawing below, this is the total membraned area of the roof.

We'll be attending NASCAR races with the Montana, camped out in the infield. One thing that will come later is a rooftop aluminum platform that bolts to the top side rails. It'll come from TrickFab in Georgia or be self built using their process as a model. That's represented in the drawing by the white hatched area. 8' x 13'. I need to keep anything under that as low as possible. I'll also work with the manufacturer to have access to the penetrations underneath for yearly inspection.

I'll be using 3" tall plumbing vent caps: https://a.co/d/evAkBAb Assuming I can move the galley vent and merge two of the vents around the toilet/washer/sink area. Represented in the drawing by "PV(x)" where g is galley, t is toilet, s is sink. This should result in one vent per tank. If galley vent can't be moved, I'll just use a cheater vent in the kitchen cabinet.

This part is not really related to the roof: For solar, I'll add a gland box for wiring at each series pair of panels. https://a.co/d/8dU7cfZ 12ga wire run from each gland box to the front storage/mechanical hatch. Consolidated down to two 8ga wires for input into my charge controller. The 12ga wires will run through the roof trusses. 8 panels @ 375W, 2S4P configuration will end up with a max solar input to my charge controller of 3,224W, 80.6Vmax @ 37.32A. Running each series pair down to the storage hatch will allow me to change the wiring configuration on the fly if needed without accessing the solar panels. For example my current inverter that'll be moving over from my old rig is minimum PV input of 60V, but the one I may upgrade to in the future has a minimum PV input of 150V so I'd need to change my solar configuration to 4S2P to get that voltage. Having each series pair individual at the hatch means that change will be pretty effortless.

The two solar panels at the rooftop platform will mount to the platform itself, and will either be removable easily or hinged and pinned so they can just become part of the railing around the platform. Probably the latter will make more sense rather than taking them down and putting them up if the platform is needed.

I'll remove the skylight in the shower and replace it with a 6" round vent fan. https://a.co/d/hPlmDH1 These fans are super low profile and shouldn't interfere with the roof platform down the road. I'll also add a pushbutton flush mount light in the shower. Wiring for this will be run while the roof plywood is off.

14" vent fan in the toilet room will be removed for the same 6" round vent fan. Wiring for this already present.

Rooftop AC units will be removed and those areas won't receive any new penetrations.

Attic vents will remain where they are, just with new caps.

Center fantastic fan will be removed, new round vent fan will be added in living area.

All in, going from 13 roof penetrations to 12. What an improvement!!

Thoughts??

 

[Mikendebbie]

Sounds like you have a good plan. Take pics along the way and post them to the forum!

 

[LeftOverParts]

Wow! Good plan.

Thinking about your 14” aisle down the middle. The only downside I see is you’d be surrounded by panels and a gust of wind or a bee could lead to an expensive misstep. Wondering if one or both rows should be able to flip up so you have a wider aisle when needed or if you had to get underneath a panel.

 

[steckrca]

Wow! Good plan.

Thinking about your 14” aisle down the middle. The only downside I see is you’d be surrounded by panels and a gust of wind or a bee could lead to an expensive misstep. Wondering if one or both rows should be able to flip up so you have a wider aisle when needed or if you had to get underneath a panel.

That’s also a good idea! Hopefully having all the roof penetrations in accessible locations will hopefully make that moot though. It does give me some other thoughts.

I haven’t quite determined how I’m going to attach the panels to the roof. I first thought about mounting aluminum strut channel lengthwise to the roof, then cross bars on those for mounting the panels. That would be over $600 just in the rails, not to mention all the hardware and other items I'd need to mount the panels. Now I’ve been thinking of using aluminum ladder rack cross bars that bolt to the side of the Montana. Amazon.com I could use two of these cross bars per pair of panels, shorten the uprights to keep height down, and lop off the upper part above the cross bar. Still would need to figure up a way to secure the panels to the cross bars. Hinges would make sense at the outside edge of the panels so the centers can be higher for water runoff. Actually now that I picture it, hinges on the outside edge for one row, then inside edge for the other row so that they can be angled the same direction.

Now that I think about it more, using the ladder racks will raise everything up to where I don't even need to move the galley tank vent!

 

[Daryles]

Putting the panels up on racks would save you having to move plumbing vents.
To add a 5th 200W panel forward of the bathroom skylight I made extensions to raise that edge of the panel over the skylight. I made my own mounting brackets so I can Tilt the panels to clean under them.
The outboard brackets I made slightly taller than the inboard ones to try to level the panels.

 

[PSFORD99]

Nothing to add to your project . But having bought new ,and owned the 2008 3400 RL , for nearly 13 years , It was by far out of the four fifth wheels we have owned our favorite . Having ordered it ,and went to Indiana to pick it up ,was a great experience . If you were to ask my wife about it , she would probably say she's still mad about me talking her into the one we have now . After having the one we have now , I agree with her , we should have kept it . It was getting a bit long in the tooth , and needed new graphics , and the roof like what you are doing was getting to the point of needing to be replaced . The interior ,and upholstery was still near perfect ,carpet was getting a bit worn ,but nothing serious .

The great thing about it was ,comparing to the newer units , that it was built so much better . Very minimal problems with it . The biggest one was having to replace all the hydraulic lines ,but even that was not that big of deal ,just ordered new more heavy duty ,and installed them . Hardest part was dealing with the underbelly covers . IMO you got one of the best floor plans that Montana has come up with . The only drawback to the floor plan was having the shower ,and sink in the bedroom , the newer side bathrooms with everything in a separate room is much nicer , but that was sure not a deal breaker . Anyway ,good luck with your project .