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Discussion Starter #1
Does anyone have experience adding a rooftop tent to a roof rack in a PM? I wasn't able to come across anything in the search. I've seen it done on Sprinters before but wondering if anyone has done it on a PM? If so, what roofrack / tent combo did you go with?
 

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The roof is limited to about 300# so plan carefully and don’t fall, 10 feet is enough to kill you.
 

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Discussion Starter #5
Ugh didn't know about the 300lb rating. I was hoping to have 200-400w of PV (50-100lbs), rooftop tent (~150lbs), roof rack (weight varies), plus two kids to sleep up there. Definitely going over the 300lb rating.
 

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It may mean 300# while traveling but there may be some who have more when static. How big are the kids? The equipment could be <300# but the kids are all overload.
 

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It may mean 300# while traveling but there may be some who have more when static. How big are the kids? The equipment could be <300# but the kids are all overload.
Kids weigh 80-100lbs each but I would prefer a system where adults could sleep up there as well. Does anyone have an idea of the static weight rating of a 3500 159" extended? I'm assuming the weight rating is the same as the normal 159" WB.
 

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Kids weigh 80-100lbs each but I would prefer a system where adults could sleep up there as well. Does anyone have an idea of the static weight rating of a 3500 159" extended? I'm assuming the weight rating is the same as the normal 159" WB.
I have never seen manufacturer “static” weight ratings for these vans. I would assume the static would be a “crush & deflection/deformation” calculation of the 10 factory mounting lugs and the transfer of the additional weight from those lugs to the factory roof system.

An alternate engineering design would be to somehow design supports that take the 10 point loads ”roof lugs” & structurally transfer these loads via steel supports to the van floor (spread load @ floor not point load).

None of which will increase the 300# traveling load limit, which I assume is set by Ram to reduce their liabilities when these vans roll over in motion.

If you find a “static” weight spec from Ram please post it here 👍

Edit; just an added thought - If we mount weight to the roof (from the inside - ceiling panels / cabinets / storage bags / fan / AC / etc), then by engineering standards we are “loading the roof” and that weight should be calculated and included in the 300# roof travel weight limit.
 

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Is the weight rating based on the lugs at the outer edges, or sitting on the actual sheet metal of the roof?
I remember someone recently posting about a factory promaster camper conversion with the pop up roof tent. I'm assuming all it's weight was transfered to the outer edges and wall framing. And it was set up to sleep 2 adults, so overall weight would be well over 300.
I'll see if I can find the camper.
 

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Is the weight rating based on the lugs at the outer edges, or sitting on the actual sheet metal of the roof?
I remember someone recently posting about a factory promaster camper conversion with the pop up roof tent. I'm assuming all it's weight was transfered to the outer edges and wall framing. And it was set up to sleep 2 adults, so overall weight would be well over 300.
I'll see if I can find the camper.
I would assume/guess Ram’s 300# weight limit is a travel “roll over” dynamic load calculation to reduce their liabilities. I also assume this “moment” is calculated @ the roof lugs to “where the rubber meets the road”

But without Ram’s P.Eng‘s papers and calculations which I also assume they will not produce for us, it is all speculation on my part
 

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Discussion Starter #11
Is the weight rating based on the lugs at the outer edges, or sitting on the actual sheet metal of the roof?
I remember someone recently posting about a factory promaster camper conversion with the pop up roof tent. I'm assuming all it's weight was transfered to the outer edges and wall framing. And it was set up to sleep 2 adults, so overall weight would be well over 300.
I'll see if I can find the camper.
Would love to see this. I did some searching but can't find anything.
 

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Discussion Starter #12
Edit; just an added thought - If we mount weight to the roof (from the inside - ceiling panels / cabinets / storage bags / fan / AC / etc), then by engineering standards we are “loading the roof” and that weight should be calculated and included in the 300# roof travel weight limit.
Good point. In previous builds (not PM) I've added a lot of weight on the ceiling but have never considered this in the weight limit.
 

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Good point on cantilevered storage bins and ceiling design weights though I'd think its all about the shear & pull out strength of the provided OEM lugs... Just as a refresher, here is a reading from the Book of Mopar:

FITTING A ROOF RACK: The ProMaster roof contains unique attachments in the roof that allow the mounting of Mopar or aftermarket roof racks. The roof rack must be fitted using the attachments on the roof, following the instructions of the roof rack manufacturer.

Maximum admissible load condition (including roof rack) must not be exceeded. Short wheelbase -150 Kg Medium wheelbase -150 Kg Long wheelbase -150 Kg

NOTE: The limit of 25kg for each attachment on the roof must not be exceeded.

The maximum permitted weight of 150 kg is an absolute limit, even if the wheelbase is lengthened.
 

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All good points. Another thing to consider would be roof seam separation and leakage. PM roof seams do have a history of leaking, although it's not common.
The topic of roof loading comes up often here. Some have even reported putting major overloads up there in the past, including sun/observation decks. I don't recall any of them reporting problems later. Still, it would be nice to get some actual updates from them.
 

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Ugh didn't know about the 300lb rating. I was hoping to have 200-400w of PV (50-100lbs), rooftop tent (~150lbs), roof rack (weight varies), plus two kids to sleep up there. Definitely going over the 300lb rating.
Your concept is good, but none of the vans out there are designed for this. Transit / Promaster / Sprinter are all similar - Sprinter is slightly less actually.

The information is published in the body builder guides.

In addition to the roof strength, roll over is a factor.

Roof racks look cool, but do not add weight carrying capacity to these ratings.

The balancing act in general for these conversion vans is that roof space is so valuable. By the time you add enough solar panels to run the appliances and have some basics like a fan, antennae, etc, the roof is almost completely full - regardless of brand and model.

Kids don't mind sleeping in a tent on the ground. Just get one that has the 2 layer roof / fly for ventilation. In general they are safer closer to the ground than 10 ft up in the air.
 

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I have a Pleasure Way Tofino which has a pop top that will only accommodate 200 lbs. This is per the conversion. The whole roof was cut away from just behind the drivers seat to just in front of the rear doors. This conversion is based on the 1500 136 WB.
 

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IIRC, this structure was built to support a viewing platform that rest on the roof itself, not sure what the live load was going to be, but it would have exceeded 300 lbs.
search for danvandam for more
60606
 

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Umnn - I'm thinking it's a dynamic load limit, for static loads when parked like a few people & platform won't endanger the general public though putting ten people dancing could loosen stuff not meant to be loose!

That back axle sprung to carry 4000 pound loads while in motion catapults up EVERYTHING from uneven road surfaces - but that snatch back down as the chassis rebounds leaves things hanging in midair like Wylie E Coyote hanging out over the edge... now lookit the teeny attachment points and their 55-pound weight limit makes better sense as those lift-and-rebound events would be nearly infinite, washboard roads and such - and G-forces & gravity wins again...
 

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Man, I can't find that pop top that someone posted here.
But if you Google promaster pop top or promaster penthouse pop top, lots of stuff......pops up.
Ha! See what I did there? Get it?
 
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