My thought would be to use some sort of linolioum (is that how you spell it? It's not a word I usually type out). From my observations (and this is coming from the mouth of a high school student) it seems to be very good agains water, and if you get the pattern right, it could look like wood, maybe even get the feel of it if you do it right, but I'm not sure.

In a world with plenty of money and indoor storage I too would get as close to original as you can.
However if its outside and you don’t have the resources to roof it and paint it every 7-10 years. Also re-side it when it goes to hell. I’m for what ever will work best to save it before it’s converted into two trucks under a pile of grab irons and break gear. Restore it later when you can get it inside.
We have used corrugated sheet metal of the type used for pole barns. Works great for a “temporary” roof. A little hard to cut for siding but it works as long as there’s enough of the car left to hold a nail. Actually use the self-tapping gasket screws.
Certainteed makes a vinyl product that looks more like wood. Usually for soffit but this also is rated to be used vertically. I would use Tyvec, drip-cap, window trim, etc just like a house.
http://www.certainteed.com/products/vin ... fit/310365
Have not tried it but do not see a problem if installed properly.
I would much rather use a stabilizer like this than watch a car slowly rot while it waits for indoor storage.

If you are really concerned with imitating the weathering inside the car there are some options, Hollywood has for years employed painters who simulate that very thing as do theater set builders. You might try in that area or a college of the arts that works in those areas, They may have students there that can help. Another option is using a painter who speciality is faux finishing You probably can find one in the yellow pages. I have seen some very convincing work done by both types. Anyone in the RR biz who has hosted a movie production company has probably seen the magic the painters can perform. There are also many good books available on faux finishing, it takes practice, you might also contact one of the paint companies that make faux finsh products, they may have a rep. that exclusively does that very thing to promote the products.

Thanks for the information and ideas. This is a caboose, but it is a later steel-framed car with essentially just a wood skin. (the body itself is built around 2-1/2" x 2-1/2" steel angles.) This is a completely private, non museum related project. If I had budget and space for a pole barn, then without a doubt I would use wood, and spend time milling to the ARA profiles, and rebuild the car exactly as-built. (Construction drawings are on-hand) But as the car will be outside for the foreseeable future, I want to do what I can to extend the life of the sheathing in a maintenance-free fashion, as this will always be a "spare-time" project.

I have seen a few low budget "preservation" projects use plywood, sometimes a marine plywood with grooves routed into it to resemble siding. When prepped and painted, it looked great. A search of the internet reveals some HDPE products that probably would look great for your intended use. http://www.tangentusa.com/1b9.html Not sure how much money you would save with HDPE in the short term, but probably over the long term it would last much longer in the open weather.

We have a car, restored with plywood siding by another organization circa 1970... It has not held up well when exposed to weather... less to than traditional siding... and as it weathers it looks more fake...

As a preservationist, and swayed by this discussion, I might accept plastic lumber for outdoor restoration... if it looks and works like wood... even as it weathers...

1) proper texture (wood siding was smooth... and did not look like it had been sand blasted (one poster was aware of a material that appeared to meet this condition)

2) it works like wood, i.e. no extra framing... We use a plastic wood for the ADA ramp at our historic house in place of wood... (successfully) but we had to substantially upgrade the framing to give the material sufficient support... Adding framing is altering the artifact...

3) What does it look like on the back side? (if visible on the displayed car) This is generally not an issue with a passenger car, but on box cars the back side of the siding?g is visable above the girth... how does this stuff look? Can it be painted or stained to make it look ok?

So, with the above conditions, is there a material "out there"

Randy

Bear in mind that the plywood that was used was not your typical home depot yellow pine. It was a multi-layer marine type material which I can not find the name for at this time. Also, with regard to preservation, the intent is to preserve the car from ruination as it continues to sit outdoors. It would be much more difficult in future to restore the car if you had to sift through a mulch pile to recover the hardware. For a "private, non museum related project", he can do just about whatever he feels will work.

How about using stainless of bronze "deck screws" instead of nails on the siding?

You can get a Makita drywall-screw "flush" driver with a clutch, or a (Harbor freight special) and with that you can re-sheath a whole car in a couple of hours, and those screws can be tightened up if they ever work loose.

After watching pieces of siding fall off the C&TS rotaries over the years, I thought about this and its got to be the way to go instead of nails. It will look the same, function better and last many times long and be repairable and able to be retightened, so I don't see any drawbacks except for cost of the screws, and maybe some pre-drilling of pilot holes, but you would have to do that with nails too, if you want no splitting. The nails and screws make about the same sized hole in the wood.

If you don't want to see square drive dimples in the tops of your deck screws that are doubling for nails, fill the screw drive hole only, with a tiny dab of putty, then and after you paint the car they will be invisible, and look just like nails. When you need to get that screw out, the putty can easily be removed from your screws with a common pick.

Synthetics do have some issues with expansion, you might try a sample area first to see what it does in the sun. Most of these products are pretty expensive My experience with wood is that if you pre-prime all sides and cut ends, or use a wood preservative sealer in all sides prior to paint you should do fine it would be particularly important to ensure that you keep the water out making sure proper flashing and sealing is done. If you are going to use it in service you will especially need to regularly inspect those ares to maintain the integrity of the sealing as movement of the structure will compromise those areas. To repair areas I'd look into some of the marine epoxys such as the MAS or West system that can be used to stabilize, repair or build up areas. I've used West System, very user friendly I'm told that MAS is even better but I don't have personal experience with it. There are also "green" produced farm raised mahogany type products that will provide a better grain characteristic and rot resistance. You'll probable find it competetive in price. It mills well and doesn't bleed sap. Just avoid the temptation to varnish the car when done! Paint! You'd be choosing the wood for it's longevity not beauty. Milling grooves in ply doesn't sound too good. Any cutter that would produce a decent profile will tear into the lower layers and give poor results. There are some products made in sheet goods for this that have a thicker top layer to prevent this but it's usually pine and I wouldn't count on it's longevity in an outdoor situation. I laso would not recommend and MDF type products in this app either.

Mr. Hees, here's a shot of SRC 70 to address your requirements. The siding is milled T&G boards from Certainteed 4' x 8' sheets of their PVC siding. The sill above and window sash are mahogany. Window trim is also milled PVC.

I think it's important for everyone to remember that some of us are asking more from this equipment than the original purchasers. Our day coaches were built with some degree of planned obsolescence. We are asking the car bodies to roll and work through four extreme, humid seasons for decades under 21st century maintenance requirements. So far, the PVC is answering, though it must be kept to small dimensions in order to manage the expansion and the contraction.

We don't like the PVC any more than anyone else, but it is that or shrink the fleet.