A Question About Framng Materials

[Dusty82]

I've been looking around the forum, checking out designs and construction techniques, and just generally absorbing everything I can like a sponge. I have a question for the home designers/builders about the materials you used when you framed your floor and walls.

I see a lot of pine/fir/hemlock/whitewood construction, and for good reason - it's inexpensive and readily available. I'm considering using redwood for my framing because of it's rot resistant properties. I've scrapped a few travel trailers in the past and the common problem with them all has been rot in the framing - and a couple of them were less than 20 years old. All of them used standard pine/fir/hemlock/whitewood framing, and it just rotted like mad.

I've worked with redwood several times before in building decks, fences, gates, outdoor furniture, and garden arbors, but I've never framed a wall with it. I've always thought that was just due to cost, but something in the back of my mind tells me to ask the question: is there any other reason why redwood (or even cedar for that matter) isn't used? Is it a strength issue? Something else?

Maybe a professional carpenter or experienced trailer builder has an answer as to whether or not redwood has any quirks or idiosyncrasies I need to be aware of.

So, other than cost, is there any other reason why you wouldn't consider using redwood to frame your next trailer build?

[wannabefree]

Redwood would be fine. Compared to fir it's a bit softer and has lower load bearing capacity, neither of which matter for teardrop building. That said, if you keep the water out you don't have to worry about rot. I would focus my energy on making it waterproof.

Nothing wrong with belt and suspenders, though

[doug hodder]

I used some recycled redwood on the sub-frame on the last build, ripped it down to what I wanted as I had a bunch of it laying around. I also did cover it with some epoxy and paint as it's exposed to the elements on the road. I take care of my builds but don't expect the redwood will need any maintenance. Just make sure you have a workable moisture content on it before you use it....there's lots of green/wet stuff out there. They used to build septic tanks out of it! Doug

[Ageless]

Did I mention this before?

Any wood has a natural 'need' to decompose. If you go out in the woods; even the redwood and cedar in it's natural environment has the desire to rot and replenish the soil.

We stop this process with chemical methods. I have used both fir and pine in garden structures which are in contact with the ground. With very simple treatment methods; infusing chemicals into the wood, these have resisted rotting. It will not prevent it in the long term; but eal it delay it long enough.

Any untreated wood, even if it's kept away from water will absorb moisture from the air and begin it's natural process of decomposition.

If you want any type of wood to last; seal; treat, entomb in some chemical substance. Even if you create a watertight exterior structure, seal the raw wood on the inside.

I've torn down several 30 - 40 year old stick-built trailers; one tiny leak and the water migrates thru a lot of the structure. All untreated wood.

[GPW]

Wood is like a lot of little tubes glued together in a bundle ... and is porous .. water and everything else can get in the tubes... and every place where the grain of the wood is exposed (not absolutely straight grained ), is a place for water to enter... better to use straight grained wood , accomplished by better picking of the boards at the lumberyard...
That and properly sealing each piece of wood ... close off the tubes , no water can enter... no rot ... just like Ageless said !!!

Around here we have the native cypress which seems to be an Ideal TD framing material ... Light -ish' .. strong , and doesn't seem to mind if it gets wet now and then ...as proven by many of the older cypress houses around here that are hundreds of years old and the wood is still in good shape , despite the extremely humid climate , and the occasional flooding ...

[Dusty82]

Yeah, I understand how wicking works, and I know that all woods decompose (rot) - my question was more about structural strength rather than the mechanics of how wood rots.

I was a custom cabinetmaker for a few years (until repetitive motion injuries forbade me from doing it for a living) so I understand the "ins and outs" of woodworking. I just don't know whether or not framing with redwood would be better than framing with the industry norm. I mean, I can afford to buy redwood over, for the sake of argument, pine or fir - the question is: should I?

I value every opinion posted so far - thank you! You've basically validated my reasoning. (Funny how we all LOVE opinions that mirror our own, ain't it?)

Because redwood is so cheap and plentiful out here on the left coast, I'm seriously considering framing our proposed TTT with it. I'm counting on you designers and builders to talk me out of it. Consider that a challenge - and I'm serious here - talk me out of it. I really want to know why you WOULDN'T frame your next build in redwood - and please leave the cost out of it.

No, my mind isn't made up - I'm really open to any discussion on the subject.

And thanks, Doug! I didn't know septic tanks were made of redwood back in the day!

[tk]

In typical teardrop construction, the load-bearing capabilities of the framing members are virtually irrelevant. Most people either use thick (1/2" or bigger) plywood with no framing members for the walls or they do sandwich construction in which case the the framing serves to stiffen the plywood on either side and the whole sandwich then bears the load (think of it as a vertical I-beam). In short redwood would be plenty strong.

Best,
Tom

[Lgboro]

I just finished my floor made out of cedar. I did have to plane each piece of wood as the only wood I could find locally was 1 inch rough on one side. It reduced the weight of the overbuilt floor it replaced by a bunch. I plan on using cedar throughout in a sandwich build.

[Dusty82]

Ok, good point TK - I'm talking about sandwich construction. I guess I should have mentioned that. Oops...

Thanks for the input, y'all! Now that I know what to build it out of, I need to figure out what I'm gonna build! Decisions, decisions, decisions...

[cracker39]

Some may disagree with me, but if you're using plywood with framing sandwiched between the plywood sheets, I'd be more concerned about the plywood getting wet than I would the framing.

I learned the hard way about proper sealing of the exterior surface to keep water out. If the plywood is sealed properly, the framing is also protected.. I just use fir or spruce 1 x 8s or 1 x 10s ripped to the widths I need. The wider and longer the boards, the fewer knots are in them. Not that a few knots matter for framing as there is no lead bearing to be concerned with. You just want it to help keep the walls plywood flat. A curved roof uses spars and when curved won't bend in the other direction.

Since I don't use framing in my floor (3/4" plywood bolted to the chassis), that's a moot point. I do protect the bottom of my floor with fiberglass resin and then a coat of rubbarized roof coating before gluing foam beneath that and painting the foam with another coat of roof coating.

[Frank J. Kaimer]

As a cabinet maker,I question the use of redwood for framing. I have found dry redwood not to take glue up and screws very kindly (to soft). Would recommend poplar as the best both for low cost and strength. Use white oak in the areas that require high strength (hinge areas). You could use a good wood sealer before closing in the walls for added protection. Good luck.

[Dusty82]

I guess I should keep up with my own threads...

I've gone back and forth over the framing issue since I posted this. I was thinking along the lines of framed walls with paneling on the inside and aluminum on the outside. I've since changed my mind (fancy that) about the wall construction, and as it sits right now, I'm leaning more toward sandwich construction.

That'll most likely mean 1/4" ply outside skin, 3/4" white wood (fir, hemlock, etc...) framing, and either 1/8" or 1/4" ply inner skin.

As to redwood taking glue and fasteners, I've made several picnic tables and other outdoor furniture from redwood and have never had a problem with it taking glue or fasteners. I do understand that there's a big difference between framing and furniture, and that was the reason for my original question.

Thanks for all the feedback, folks! I really do appreciate every comment!

[DogStar]

Given equal availability and cost not being a factor. If I bought all new lumber I would use Poplar for all internal framing and bracing.

BTW it also takes paint real well for exposed situations.

Mills easily, take fasteners really well, glues well and paints great to.

FWIW
Eric

[Dusty82]

I agree with you 100%, Eric. In fact, I've been keeping my eye open for a local source for poplar at a reasonable price. I do like working with poplar for certain projects, and I agree that in the case of sandwich construction, it's a very good choice. I like the fact that it's pretty light weight and it cuts, sands, and finishes easily. It also takes glues and hardware like a champ. It's great for furniture that's going to be upholstered, making prototypes, and as you said, painted items.

I know I gave the "price is no factor" impression, but I guess I should have said the difference in the price of redwood and white wood isn't a factor. The price difference between poplar and white wood could very well be a big factor.

Given my "druthers" I think I'd prefer to use poplar. My problem is finding a decent priced supply of it here locally.

It sounds like I'm talking myself into using poplar. Looks like I'll have to do some telephone recon this week...

[Classic Finn]

Here in the country of Finland known Worldwide for its different ply. I used Marine Ply with "Phenolic Film on bothsides and sealed on the edges.
It is wear, as well as moisture resistant and it is very durable.

Here it is used for many purposes such as caravans, utility trailers as well as horse box trailers and much more.

Been very satisfied with it and no complications.

Here you can see a bit of it shown on the flooring. No need for extra goop or goo.