Building a trailer, Things to ponder

[Martiangod]

I've been repairing RV's for going on 29 years, When it comes to trailers, I've pretty much seen it all.

2x2 construction, with seamed aluminum, has been around forever, and going back prior to the 90's, these trailers would last what seamed like forever. My Park Trailer is a 1984, and solid as the day it was built, why ????
In the last 7 years, every major rebuild of a trailer that I have done has been on 2002 and newer, rebuilding, mostly water damage, ANd I'm not talking replace a stud or two and piece of paneling, I'm talking upwards of $8000 rebuilds
Trailers now are more air tight then they used to be, more non breathable surface treatments then the old seamed aluminum.
Poly-urethene caulks, rubber roofs, butyl , high tec bonded wall systems, all new and improved methods using wood based substrates .
These high tec systems work, but with synthetics, not with wood
A vacum boded wall with all composits, will last forever, put wood into that bonded wall, and it WILL fail
Why do these modern trailers fail?
I think most of it falls on the materials available to builders now, most species of wood available now are fast grow fir species, cheap luan, substandard plywoods. Then you wrap these products in an air tight shell put it out in the real world, and you have rot, moister breaches the barrier at seams and some of it bourn inside the trailer.
So you try to combat it by sealing your wood completly, with resin, poly's which is great for a free standing piece of wood, but then you set up the failure by penetrating it with a screw or airnail, moisture now has the opertunity to get into that wood, where it can't escape. In fact, when water does breach that screw, the wood will be so dry it will act as a sponge.
Will the trailer I'm building last, doubt it, I have available the same substandard wood products the rest of you have available.
What does last?
If I was going to do an all out build that I expected to last a long time.
I'd probably source an old derelect barn built of old growth lumber, preferably old growth pine, lots of rings
I'd ripp my own studs and spars from this old growth lumber.
I would use a breathable house wrap material under the siding, but would source seamed siding, it breaths, allowing moist air to escape and not be trapped in the walls. Roxul type batt insulation
Spars and strapping for the roof, with aluminum skin, no sheating, airspace and attic venting.
3/4 tongue and groove Bamboo floor, no sheating, span the floor joists. In a small area, plenty strong and waterproof with a breathable barrierand its also your finished floor, probably foam under it and then a protective skin that allows for air space and breathability

The reason old canvas painted airplanes lasted, AIR, the cavities of the wings were not stuffed with insulation, if it got wet, it could dry from both sides.

[Martiangod]

So why will our builds fail, lack of air, we use styrofoam for insulation, we caulk and seal till we're sick of caulking, vowing my build won't fail like the factory built units, hide it in a garage and only seeing daylight when we take it out for a few weekends a year, yet I still read on here horror stories of rot on trailers that appear to only be outside for a minute amount of time, WHY?
ALthough butyl is touted as the best, on here and by the rv industry as a whole, it has its specific uses, when sealing to synthetics, Fiberglass side, rubber and TPO roofs.
The rest of the coach IMO should be caulked with putty tape.
And design breathability into the trailer, not only for the interior, but also for walls and roof.
My roof for instance, although 2" SM styrofoam, it has an 1 1/2" air space above that.
and vents will be installed through the membrane and ply. to allow the roof to breath.
I will be making vents to allow the 4 x 10 aluminum panels that are free floating, to breath.
Its sad to see a failure like Mikes, knowing the care that went into the build, and its sickening for me to tell a customer that its going to take $8000 to repair his 4 year old trailer.
What most don't understand is that a trailer goes through in a day, what a house goes through in a year, the low mass of the trailer structure expands and contracts, many many times a day, the mass of a house takes much longer to react. So no, that tube of MONO won't cut it on you tear.
Use highly flexable caulking, the best wood you can find, build in breathability, let the sun at it
I know I'm just some scmuck and not the definitive authority on RVs, Just want to share a little of the excrement that has built up between my ears in almost 30 years of working on RV's
Ya, I know I'm long winded

Great article on Caulk
http://www.finehomebuilding.com/how-to/articles/making-sense-of-caulks-sealants.aspx

[Dan & Julie CO]

makes sense I mean a piece of wood buried wet in the dirt seems to last longer than it should,It's soaked so Why? well no air. Same reason old rv's last they aren't completely sealed so if moister does get in it can breath allowing the moister to vent out. if it dries sooner than later no harm no fowl in the short term, takes 20- 30 years to break down especially it it's maintained along the way

[Roly Nelson]

Wow Chris, you sure cover a lot of ground. Personally, I think putty-tape stinks. It was the cause of moisture leaks on the roof of my motorhome and was corrected only by replacing it with a quality butyl sealant. I guess I also take exception to your referance to wood being a real problem for trailer builders. My 55 year old Kenskill Standy has held up remarkably well all of these years, and has no rot within it whatsoever, since I removed all of the interior paneling during it's renovation. My 10 year old woody TD has 30,000 miles on it in rain, snow, sleet and such. All of the hundreds of wooden plugs and tight butt-jointed glued connections are as tight as when I built it. Perhaps living in So Calif, with our mild weather conditions contributes to it's long livitability, but I think you are giving a lot of wooden trailer builders a bad rap. My TDs will never make it to the moon, and ultimately will be used as chicken coops once I am gone. Long live wooden trailer construction, if it was good 80 years ago, it's good enough for me, also almost 80.
Roly, So Calif trailer enthusiast and lovin' it.

[Dan & Julie CO]

Wow Chris, you sure cover a lot of ground. Personally, I think putty-tape stinks. It was the cause of moisture leaks on the roof of my motorhome and was corrected only by replacing it with a quality butyl sealant. I guess I also take exception to your referance to wood being a real problem for trailer builders. My 55 year old Kenskill Standy has held up remarkably well all of these years, and has no rot within it whatsoever, since I removed all of the interior paneling during it's renovation. My 10 year old woody TD has 30,000 miles on it in rain, snow, sleet and such. All of the hundreds of wooden plugs and tight butt-jointed glued connections are as tight as when I built it. Perhaps living in So Calif, with our mild weather conditions contributes to it's long livitability, but I think you are giving a lot of wooden trailer builders a bad rap. My TDs will never make it to the moon, and ultimately will be used as chicken coops once I am gone. Long live wooden trailer construction, if it was good 80 years ago, it's good enough for me, also almost 80.
Roly, So Calif trailer enthusiast and lovin' it.

Funny you said chicken coops, My wife said the same of ours this morning while we were washing it

[Martiangod]

Thing with Putty, when applied proper, will expand and contract, Butyl will not return to its original state.
We may have more trouble up here due to the amount of change due to extreme weather variances. - 45* to + 120*
Not attacking wood builders, but the quality of wood available today and the need to let wood dry, when it gets wet

[prohandyman]

Chris
My experience with putty tape, both new and on restorations, is that the tape dries out rather fast (year or two at best). Once dry, leaks are iminent!
Are we talking about the same animal?

[Shadow Catcher]

When we decided we wanted a teardrop I decided to look at what fails, particularly at what restorers encounter, and in order of importance they are wood rot and rust. Compass Rose has an all aluminum frame and Filon exterior. I will keep a close eye on the wood that is present in the floor and interior.

[mikeschn]

I'm following this thread with great interest, because I intend to do a new build this summer, and I would like it to last!!!

Mike...

[Treeview]

As an arborist my duty is to get trees to live to be an old age. Rot and decay are inevitable. Anytime there is wound/break in the cambium there will be decay. There is a model that we look at to understand how trees isolate rot. If you want to know more google: "CODIT" or "compartmentalization of decay in trees" or any work done by Dr. Alex Shigo.

Even if you're not interested in trees but interested in decay, its good to understand how decay moves or is stopped in trees.

One of the things that Dr. Shigo taught me about tree decay was that it could be stopped in two ways. First, keep it absolutely dry. In a hollow tree this is a goal that will never be reached. Another unreachable goal is to keep the wood saturated. We joked about setting up a hose with a float valve like in the tank of a toilet. Again...fun talk but not practical.

Wood cannot get damp...the rougish fungiis will move in and then we all know what happens.

I'm close to starting the interior work/insulation/paneling on my ToyBox:

http://stonerradiator.com/images/dsc00667.jpg

The walls are FRP. My first inclination was to glue firing strips inside and infill with sheet foam. In the past few weeks I've decided to take a different tack. The firing strips are going to be H or hat channels filled with foam strips. The channels will be glued to the inside. Any holes in the FRP will be reamed out and plugged with epoxy. More than likely the inner skin will be plastic/fiberglass sheeting. There's a chance I might use thin plywood.

When I ran my tree company I took burr and white oaks that went to the mill. This is old growth trees with thin growth increments. At first I considered ripping and planing these decay resistant planks into firring strips. I may still...depends on weight and cost of channel.

keep it dry!

Tom

[Martiangod]

Butyl tape in itself is not the problem, its a wonderful product, its the application, because butyl stretches extremely well, it has no ability to snap back.
Proper application involves having shims to prevent full compression, some RV specific trims have this but they have a tendancy to bulge between the screws and compress to easily at the screws.
Also if it slinks while installing, it stretches and gets thin.
Butyl also has a tendancy to creep during expansion and contraction, Putty tape does to, but at a lesser rate.
Butyl also works best on hard or synthetic surfaces.
I still have to question why the old trailers, No synthetics, or Butyl lasted, but wood construction using new sealants, fail ???
Why ?

I continually ask myself this question when I'm repairing

[Dan & Julie CO]

butyl is what is used in window frames and it will dry out over time, it causes seal failure or weeping due to expansion and contraction from extreme cold and heat
That's why we see fogged up window panes. the butyl fails allowing moisture to be pulled into between panes of glass. I'm assuming this will allow leaks into a camper as well.
It probably wouldn't hurt to vent our campers a little so the interior wouldn't super heat as much which could cause premature butyl seal failure. just a thought

[Martiangod]

I rebuilt a stick and tin trailer last year, 4 years old, rubber roof, 2x2 construction, 5/8"plywood floor and luan paneling and 1/4 ply under roof membrane, had to replace roof spars front 8 feet of trailer, studs paneling and floor, all rotted beyound repair.
When I tear down, i take my time, inspect and analize to try and determin the fault, so I can repair it and stop the leak.
Not just make it pretty again.
What bothered me was I expected to find a manufacture fault, what I found was everything appeared to be assembled correctly. The only thing I found that I could question was that they had put a clear tape on the underside of the aluminum, where the seams were? And that screws on the roof to wall trim were rusted.
OK, steel screw in aluminum, electralisis from disimiliar metals.
Butyl tape, failed to prevent water intrusion.
Tape over inside of seams prevented air flow to permit drying.

Screws through butyl, the butyl will grab the screw and wind up,
Putty being petrol based tends not to wadd up, now does the petrol based putty coat the screw and carry into the penetrated wood, technically sealing the wood penetration and slowing the rusting of the screw ???
Modern screw guns, too high of a speed, causing over tightening and over compression of the butyl ???

[Martiangod]

The only changes made in reassembly, no butyl, putty tape instead, cordless screw gun instead of high speed air guns at factory and no tape on backside of siding joints. And probably more care in assembly then at the factory, But I state again, no sign of careless assembly error to blame this one on.
I'm staring to wonder, set all your aluminum trim, run all screws and then remove, seal all screw holes and reassemble?
With Butyl ???
With Putty ???
With a liquid caulk gun poly set trim in it and screw while poly is wet so it can carry with the screw ???

Treeviews articles on trees self repairing got me thinking.
When a tree is limbed, we seal the cut.

So should we seal the inside of screw holes ?

[Martiangod]

Another thought just hit me, prior to the 90's, batten strips where used to seam the paneling, now they use seam tape,

Batten strips breath, seam tape does not???
Hmmm