Wall Support Beam Replacement Wood Options

[khantroll]

Hi all,


I've got an oddball question. I have, sadly, discovered areas of rot in the support beam on my passenger side wall. It appears to be a 2x4, so and it doesn't appear to be too hard to replace; thus, my plan is to install additional temporary supports inside the rv and replace the beam.


Which leads me to my question: what type of wood to use? My preference would be for redwood, which is naturally rod resistant. I called, and a enough lumber is going to cost me about $100, but I'll have to drive roughly 300 miles one way to get redwood, plus overnight stay and gas. So, really, it's going to cost me about $200.


Meanwhile, pressure treated lumber is available in my hometown, for the whopping cost of $20. However, I am paranoid about the chemicals in pressure treated wood, and the only way I'd use it was if it were saturated in Safe-T-Coat, which bumps the cost up a little. It'd still be less then $100 though.


Is redwood worth the time and cost, or should I use the pressure treated wood?

[LJ-TJ]

Have you considered Cedar. Hm? It doesn't rot either.

[skloon]

Todays pressure treated is safe(r) but it will dissolve screws and nails- cedar is a good alternative or you can just use regular lumber and coat it with a few coats of paint- should be good for 20 years

[DRMousseau]

Wow,.... preference is for redwood. mmmmm,.... most redwood today is second growth. Not nearly the quality of old-growth sources. Sapwood content is important here. That's a long ways to go for wood that MAY not be quality or value you hope for! Second growth redwood is considered "moderately resistant",.... others in the same category include old growth white pine, old growth longleaf and slash pines, and Douglas fir. I would personally opt for the Douglas Fir, since old growth yellow pines are practically non-existent and old growth white pine is hard to come by.


In the category of slightly better "resistant/very resistant", is old growth cypress, old growth redwood, and red cedar (both eastern and western) among others that evade me right now.


"Exceptionally resistant" is Pacific Yew (hard to come by) and RED MULBERRY,... strange that I would know that, but for some reason it's quite prominent I'm my head!!


I know there's many others too,.... exotics, and old growth teak is "exceptional" while second growth is only "moderately resistant", a big difference between them.


I might consider good clear red cedar,... more readily available, but not as durable maybe as redwood, cypress or pressure treated wood. Personally,... I'd likely go with Douglas Fir if I could, durable, strong, light, holds screw and fasteners well, and is plenty resistant enough for the use intended, and reasonably economical in value. But probably settle for standard grades of pine,... maybe painted, maybe not.


BTW,... the hazards of treated wood is not the same as that of jus 10-15yrs ago. CCA is no longer used much anymore, and most available to you today would be ACQ(?) an CA treated materials. Both copper based, but lack the dangers of arsenic that was so prevalent in the past.

[yellowrecve]

The original Wood was probably Spruce and it lasted 45 Years. Think of the Spruce Goose. Strong and light. It holds screws good and is less likely to split when driving screws near an end. My 2 bits and 37 years.

[LJ-TJ]

Hey Doc, I thinks you may have been up North in the bush a little to long this time. You got way to much time on your hands. :)rotflmao :)rotflmao :)rotflmao

[Rickf1985]

I have mentioned this company in the past. I have used their products extensively when working on boats and an older slide in camper. http://www.rotdoctor.com/, They have some fantastic products when it comes to working with rotted wood and protecting good wood from rotting. CPES is the top thing to look at. You can use standard framing lumber and coat it with the CPES and never worry about water or rot.

[khantroll]

Hi All,


I really appreciate the responses!


To those that are suggesting cedar, I have always been told not use cedar for structural work. How would the cedar work holding up that wall? If it will hold up to it, there is a cedar mill close to me.


Cypress was actually my first choice, but it's even harder to get and requires further travel for me to obtain.


The MSDS on the CPES Warm Weather stuff is a little scary.

[DRMousseau]

Cedar is certainly not the best for structural framing applications.


But it is a common misconception that the wood found in RV's, is structural framing! In most cases, it isn't!!! The exception, is often found in either the front end and/or the rear end, where box framing is often prevalent. The rear of my particular RV has no such framing and is a solid laminate, much the same as the side walls and roof. The front, is mostly "a hollow wall" box construction, framed of wood with a bit of some metal framing also.


In general, the wood serves only for anchorage and fastening of various components,... window frames, door frames and access frames, vents frames, AC frames, skylight frames, etc., and for attachment of interior "hollow framed" walls and box framed cabinets. Perimeter wood, serves to attach roof to walls and walls to back and front, the lower perimeter wood serves to attach protective trim, and a perimeter wood above the lower edge, serve to attach the walls to the floor frame. Even the wood around door openings is not "structural", but serves to attach an aluminum door frame that provides rigidity to the unsupported opening.


Most importantly, the wood needs to grip staples and screws well, resist moisture and decay, stand to the "crush" of mounting frames, and be porous enough to be "re-laminated" into the wall panel, roof panel or door panel.


IF this IS a 2x4, and is also an important support member,... then forget cedar, and use something strong enough to support whatever is necessary, and securely attach to adjoining supports.

[Rickf1985]

Hi All,








The MSDS on the CPES Warm Weather stuff is a little scary.

I don't see anything there out of the ordinary for working with fiberglass resins. You would use the normal precautions and wear a respirator with organic vapor cartridges and wear gloves and long sleeve shirt and protective safety glasses. This is pretty much common safety gear anymore for any kind of boat work. A little different for RV's but just something to consider of you want it to last. Due to the flammability of the solvents in the CPES you would want to shut off the propane and take the necessary precautions. I have used this stuff for 15 years with 0 problems in hot weather all the way down to sub freezing weather. You will think the smell will never go away but it dissipates pretty quickly after the solvent evaporates in a couple days. The plywood can be coated outside before hand to keep the smell out of the RV, The only time you would get the smell inside is when you have to treat rotted wood in the walls. If you prefer to rip all the walls out instead....... well there is always that option.

[CapnDirk]

X2 on Spruce.  There was a reason (or many) it was used for structural parts in planes.  A good penetrating sealer and it will out live you.