Roofs: Trusses with FG Insulation VS Rigid Block Foam?

[SoCalAngler]

I have owned only roof truss with fiberglass insulation roofs (like the VAST majority of trailers. I owned a 2005 Class C by Monaco that had a metal roof, but not sure of roof design and insulation.

My questions/discussion are not mean to start a brand war, only to bring about discussion that leads to educated trailer owners (current and future) and educated purchases of new/used trailers for the average camper camping in average conditions.

I know average use is difficult to define, but for the sake of this discussion.....Not full time living and not months in extreme cold and snowy weather. Fair weather camper if you will. Some snow and cold weather camping situations, but not many.

I'll use my scenario as "average."

I camp primarily in the Southwest (CA, NV, AZ, NM, and future visits include...ID, OR, WA).

I camp primarily between April-October and occasional trips in Nov-Dec and Feb.

I am currently looking for my next TT. It will be used.

Since I have owned an ORV product I appreciate the above average construction.

I lean towards an ORV, but am concerned about unknown mold and the clear and present danger in a roof that can easily host mold.

Roof with trusses and fiberglass insulation.....I am concerned about the potential for mold in areas that may be inaccessible when inspecting a used TT. IMO, I don't believe many sellers are going to allow you to disassemble vents to inspect attic area for mold/moisture or blackened roof plywood.

Is mold prolific and part of the design (areas exist in attic that are perfect for mold to grow) of these roofs.....prolific meaning mold is present in most trailer attics with truss / fiberglass insulation design, just not yet found?

Foam Block Roofs......Is a foam block roof much preferred in that it does not create a perfect area for mold to grow?

Are Lance one of the few TT that use foam block roof construction?

What are the additional pros / cons to foam block roofs, as in the case of Lance roofs?

Have I missed any items that need to be considered in roof design / construction that pertains to my discussion? If so, please add to this discussion.

Thanks!

[Cumminsfan]

Very good concerns. With that being said my 19 25RDS has no mold in the attic. Checked this spring. We camp pretty much the same as you do except the TT's covered from mid Oct to Mid March/April. I actually don't worry about getting mold. I don't camp in environments that would promote it.

Block foam is definitely a better roof insulation as far as attics go. Only down side is that the AC is not always vented throughout the trailer. Our 25RDS is pretty quiet with the AC vents closed on low and only using the round ceiling vents.

Forest River makes Flagstaff and Rockwood with 4" thick radius foam bonded roofs. They also vent the AC through the foam.

The upside to ORV is their floor plans and tank sizes. After that there's not a whole lot that IMO makes them that much better or worse than others.

[SoCalAngler]

Never knew that about the Flagstaff and Rockwood lines. Is that all of their products?

Yes, the ORV floorplans (ex. Rear dinette) and large capacity freshwater (80ga) are nice features. But, if most camp at hook full ups, the need for larger holding tanks may not be needed.

I just watched a FR video on the roof construction......looks like a well constructed and designed roof. Not much air space in their alum truss design, as the foam fills most f the cavity. Then the vacuum bonding and gluing adheres it substantially.

The foam block roof construction, even with ducting, appears to be a much more expensive and very good design....does mold grow on alum and foam in that roof area as easily as it does in wood and open areas of wood truss systems?

[SoCalAngler]

I'm torn between the ORV and Lance models......

Used models I have found

2019 Lance 2375 ($46K)...near MINT

2016 ORV Wind River 250RDSW ($30K... needs tires and rear ladder reinstalled...twisted/bent and then removed by owner ..result of a back up mishap)

I prefer the ORV floorplan and larger holding tanks (not afraid of ladder reinstall needed)
I prefer the Lance construction methods and finish work (get in and go! MINT cond!)

Since at some point in the future I may go to the darkside and get a 1/2 ton truck ....I lean towards the Lance...all models Truly towable by a 1/2 ton.

Decisions, decisions, decisions.....

[Vintage465]

Originally Posted by SoCalAngler

I'm torn between the ORV and Lance models......

Used models I have found

2019 Lance 2375 ($46K)...near MINT

2016 ORV Wind River 250RDSW ($30K... needs tires and rear ladder reinstalled...twisted/bent and then removed by owner ..result of a back up mishap)

I prefer the ORV floorplan and larger holding tanks (not afraid of ladder reinstall needed)
I prefer the Lance construction methods and finish work (get in and go! MINT cond!)

Since at some point in the future I may go to the darkside and get a 1/2 ton truck ....I lean towards the Lance...all models Truly towable by a 1/2 ton.

Decisions, decisions, decisions.....

A half ton!

[Dave Pelletier]

If you're going half ton, skip the ORV's; they are all just too heavy to comfortably tow with a half ton and only the smallest ones are even within the ratings.

As far as the rest, mould can obviously be an issue but there are tradeoff's with everything and I'm not worried about it myself given my climate and useage. I wanted the ORV due to the insulation/wall thickness, double pane windows, tank size, frame construction and suspension (I am boondocking 95% of the time). I like the ORV roof in that I can install another solar panel or two without worry. There have been some recent discussions regarding mould in ORV (and similar) roofs but there have been avoidable circumtances or issues that caused the problem IMO. There are also a few things that can be done to mitigate the likelihood of a problem developing if there are concerns. No RV is perfect and I could think of a construction design or two that would work better but it probably isn't cost effective.


2 cents,
Dave

[bneukam]

There are factors that determine possible mold growth in a truss and FG insulation attic.

The amount of water vapor produced inside the unit, in correlation with the temperature difference between the conditioned trailer, and the outside temperature, effects the draw of air into the attic.

Due to the small size of a trailer with multiple people living inside the amount of water vapor can escalate quickly. It will find the path of least resistance, and if it can’t find the attic vents before condensing on a cold surface first you get mold over time.

That’s why the fans offer a quick inspection point as they allow for a easy path to the attic space. All it takes is 4 screws, and pull down the bottom trim of the fan. Reach up and pull down the insulation with a bright flash light, and inspect the underside of the roof sheathing. Knowing where the vents are on the roof allows for the direction to inspect.

Most sellers should not have an issue with this, it’s not anything major, but needs to be done before purchasing. It is rare to find, unless it was used in colder temps on a consistent basis.

Sounds like your heart is set on the ORV, so inspect, and knowledge going forward will ensure no problems.

[Dave Pelletier]

Originally Posted by bneukam

That’s why the fans offer a quick inspection point as they allow for a easy path to the attic space. All it takes is 4 screws, and pull down the bottom trim of the fan. Reach up and pull down the insulation with a bright flash light, and inspect the underside of the roof sheathing. Knowing where the vents are on the roof allows for the direction to inspect.

Yep; easy check and one that I'd highly recommend.

Dave

[SoCalAngler]

Thanks for the input.

I'm trying to live a simpler life, (smaller trailer, lighter truck, less stuff, etc.) but man is it hard!

I do like the ORV but also like the Lance 2375/2465.

The Lances are very nicely constructed, designed, and appointed. And they are proud of their products.... $$$$$!!

[billyw]

Just food for thought. Regular residences have wood trusses and fiberglass batting. There's literally millions of 'em. Without extenuating circumstances, I don't think they're moldy. Same goes for RVs. The ORV attics are vented. Good maintenance and humidity practices will forgo any issues. It's been a couple years since I've looked, but my 17 year old RV attic is mold free.

I too am a Lance fan, but:
1)No ducted A/C
2) Of the three I would consider, the 2375 has very little kitchen prep space. The 2075 has less. The 2465 is bad too.
3) 2075 & 2465 have separate black and gray tank drain valves, which means you can't use the gray to rinse the black from the hose, and you have to disconnect, move, and reconnect to drain both tanks.
4) Their rear cargo hitch is only good for 110 lbs.
5) And you get the added bonus of paying $$$$$

[Cumminsfan]

House attics are built differently than RV attics. For one house attics have enormous amounts of volume between the insulation and the roof. House attic require a certain amount of soffit vents per roof vents. One vent in an RV attic is not enough. and where are you getting the fresh air draw from?

I'm not pro Lance or ORV but you can't compare either to a house attic. I would even venture to say that depending on placement of the attic vent it may or may not even be functional enough for just part of the RV attic. If the batt insulation is piled real thick in one section then the attic vent will only vent the area that has air flow.

I agree though that with due diligence a batt insulated attic should be fine under normal recreational use. But thats where the Lance scores points against the ORV. With virtually zero chance of mold developing in a block foam composite roof, the Lance could be used in more extreme weather for longer periods of time.

One thing for sure though I can replace my roof a couple times over for the price of an equivalent Lance TT of which they don't make.

YMMV

[Dave Pelletier]

Originally Posted by billyw

Just food for thought. Regular residences have wood trusses and fiberglass batting. There's literally millions of 'em. Without extenuating circumstances, I don't think they're moldy. Same goes for RVs. The ORV attics are vented. Good maintenance and humidity practices will forgo any issues. It's been a couple years since I've looked, but my 17 year old RV attic is mold free.

I agree that most won't be a problem but while the design is similar;

- there is far more humidity due to the small space volume vs. occupant load, shower load, cooking load etc. For eg. my ORV has about 1100 cubic feet vs. my house at 54,000 cubic feet.....and we breath, shower and cook the same for the two of us in either one.

- vapor barrier is poor or non-existant compared to our home

- the ORV has one small attic vent about 4" round; the house has a full 2' perimeter vented soffit and eight 12" x 12" ventilation goosenecks

- the ORV has R9 walls and R19 roof vs. the house at R22 walls and R50 roof

- the house has a 250CFM continuous ERV constantly removing moisture laden air.


......not saying that a wood truss/fiberglass insulated roof on an RV is a problem but it has a much larger potential to be one than a house with the same design. In particular, full time use, use in extremely low ambient conditions and inadequate ventilation can lead to problems. Since I use my trailer for 6-8 months a year and not in the winter, my use is limited to a maximum of 7-10 days at a time and I make sure to keep a window open, run the Maxair fans, etc., and I intend to store it under cover I think the likelihood of a roof moisture problem is extremely unlikely in my case. For those that have more severe usage, I'd consider adding attic ventilation, ensuring space ventilation and perhaps consider bolstering the vapor barrier as well as monitoring the attic occassionally for signs of moisture.

2 cents,

Dave

[bneukam]

Many homes have also suffered from this same issue with all the vents installed correctly. Personally seen several homes with mold on the underside sheathing. Best time to inspect your attic is during a really hard cold spell. Snow can block vents on the roof and reduce air flow.

Lived in AK for 16 years, moisture control inside the house must be managed depending on the outside temperature.

[Papa_Jim]

My trailer had insulation voids in the roof, which of course meant the trailer was hard to cool in the summer, hard to heat in the winter. I filled the voids that I found. The trailer is much more comfortable.



I was surprised that there is no ceiling vapor barrier. I had never heard of using fiberglass insulation with no vapor barrier. In cold weather, when the moisture laden air inside the trailer comes in contact with the cold roof sheeting, I would think it has to cause mold.



We'll see..