Insulation thickness

[bartholins]

I'm planning the build for a trailer that I should be getting in about a month. I've read most everything I can find here about insulating, but I don't know that I've seen anyone mention what I've been planning so I'm curious if this is just nuts I'm wanting to go with 2" of polyiso foam board on the walls and atleast that on the ceiling. The walls are constructed of 1" square tubing, so Instead of bridging the outside and inside together by stacking metal studs, I was going to offset an additional 1" square tube stud inside the outside one, but a few inches away to allow both to have insulation around them. I hope that makes sense. Is this worth the effort? Both to have 2" of insulation vs 1", and to off-set the studs so as to not bridge the aluminum skin to the interior plywood? Thanks in advance for any and all info!

--Sam

[MtnDon]

Or you could infill the space adjacent to the 1 inch steel tubes with a strip of wood, ripped to fit precisely. Some screws through that into the steel tube won't provide enough of a thermal pathway, considering you will also have a window, more than likely. Just an opinion. The wood would provide an anchor for whatever interior paneling you plan on. ion.

[CoventryKid]

I also thought about adding more insulation when I did my conversion. But I wondered how much I would gain for another 1/2" or so, over the 1 1/2" that I was planning. Sounds like what you are thinking about is a lot of extra work and expense for an extra 1/2" of insulation. Just my humble opinion!

I installed 1" rigid insulation between the ribs, attached 3" wide 5/8" plywood strips to each rib, then added 1/2" rigid insulation between the plywood strips. I put metal foil tape over each "seam". The plywood strips gave me something to attach the interior plywood to, not the studs, so I had a thermal break.

My wife and I just spent 6 months touring BC, Yukon, Washington, Oregon, and northern and central California before we returned home a couple of weeks ago. We were comfortable on those hot days (no A/C yet), and very comfortable on those cool nights (with an electric heater when needed).

Hope this helps!

[bartholins]

Thank-you both for the replies. Yeah, that's exactly why I'm asking is that it's a lot of extra work for just 1" more insulation. I do kindof like the idea of the ~1/2" thermal break with wood then another 1/2" of insulation except for the fact that I'm trying to have NO wood in the trailer. I know this may sound ridiculous to most, but after having pulled apart our current stick and tin RV twice to fix rotten wood (opposite ends of it), I'm sortof done with wood. I guess I've come to the conclusion that evidently I will have a leak and not be smart enough to find it. Yeah, metal may rust, but I believe it will be longer than how quick the wood seems to disintegrate. I'm not saying I just won't do wood furring strips, but it's not my first choice - feel free to tell me that's crazy as well

Thanks again!

[CoventryKid]

That's one of the reasons I converted a cargo trailer rather than purchase a manufactured travel trailer. We'd just heard too many stories about crappy construction, etc.

(As an aside, we bumped into friends, quite by accident, at an RV park in Whitehorse, YT a few months ago. They had purchased a manufactured travel trailer earlier in the year. The list of deficiencies was long INCLUDING the 4" tubular bumper, welded on, that was not level! Our friends were also told that they couldn't put a carrier on for their motorbike off the back bumper cause the frame wasn't strong enough!!)

Neither my wife nor I liked the floor layouts of the commercial travel trailers. We also didn't like that they were already too heavy for our van and too wide - 8'. I didn't want to have to try and find extendable mirrors (they're aren't any for the Savana van).

Our 7x7x16' Neo has served us well. I framed the inside walls with 2x2s covered with 1/4" plywood. I screwed everything together. I covered the screw heads on the plywood with gyproc mud. And after an abortive attempt to use paintable wallpaper to cover the 3/8" plywood interior (that was a joke), I put a skim coat of mud over the exposed plywood walls, even taped the corners. The walls survived, but the taped corners didn't - just way too much movement. So I ripped some 1/4" ply to about 1 1/4" wide and put 2 strips in each corner and painted them to match the walls. A simple cure and not that noticeable. (Build link is below)

Anyway, I'm rambling. What I wanted to say is that I have not had any problems with water infiltration. I have 2 - 14"x19" skylights and 1 MaxxAir fan on the roof. But my roof is not entirely flat and with the rounded roof edge, that helps shed the water.

I found the whole build exercise a lot of fun. I would definitely do it again.

Good luck with your build which ever way you choose to go.

[lrrowe]

CoventryKid, your build and tow vehicle setup is fantastic. If I did not like my F150 so much (I do use it as a truck)' I would look into your TV.

[Rainier70]

Sam, it's understandable about wanting to avoid the wood, but in a CT it is different. Even if you got a leak and your inner wood rib rotted, what are you out? Nothing. You still have your metal ribs, sides, and frame. You might have to replace a section of floor, or wall, or wood spacers, but that is it. It isn't like a travel trailer, a leak does not do significant structural damage because the main structure is your metal frame and it is still there.

If it was me, I would add wood spacers to the ribs. It is handy for rehanging your plywood walls etc.

If I was really worried about leaks developing, I would pay close attention to my roof seams and do yearly inspections and maybe a coating etc.

Wood spacer ribs aren't much different than the plywood on your walls .... that's wood too. Both are easily replaceable.

[makevx73]

Another option?

Instead of wood spacers, how about one of the cellular PVC products?

Home Depot and similar places sell products by Veranda or Azek. These and others are virtually rot-proof and still would fit the idea. A couple more dollars to buy but gets you away from any wood worries.

http://www.homedepot.com/p/AZEK-Trim-3- ... 202526971/

http://www.homedepot.com/p/Veranda-3-4- ... 100265384/

[warnmar10]

Another option?

Instead of wood spacers, how about ...

How about no spacers at all? Just overlay the first layer/studs with the second layer and attach the plywood with screws long enough to go through the second layer of insulation and into the existing studs.

[wanabxtrm]

I have 1" ribs on the trailer, I in filled them and placed 3/4 insulation on top. Then used 1x's strips and 3/4 plywood depending on the location to anchor to the studs, filled the gaps with 3/4 and attached my interior luan to the strips and plywood.

Was it worth it, I think so or at least that's what I tell myself. It allowed me to run 1/2 nmc 'in' the insulation space of the wall keeping my wiring clean, isolated/protected and easily accessible. It keeps the trailer studs from excessive holes, and gives me s clean flat wall on most spots.

[bartholins]

Thanks again everyone for the reality check. I think Cindy drove the point home - it's no different than the plywood on the floors and walls. It's funny - I Got an idea in my head and didn't stop to think it thru. Thanks again all, this also helps me with interior material selection decisions!