I know there have been previous discussions of wood 'preferred' for the Model T. Not being a purist, yet decently 'functional' with wood, I have re-made some roof and windshield header pieces for my '25 coupe. Very dry treated wood was used. The wood was in my shop for over a year, elevated off the floor, gas heat (no freezing), plus a dehumidifier for the summer. Humidity always kept 35 to 55%, less in winter. 'Twisted' or warped wood was not used. I've not detected any stress from the pieces I've installed six months ago. Is there an adverse chemical reaction of metal to treated wood? How big of a mistake have I made or any suggestions before I start closing things up or covering anything?
Treated wood may cause a problem. I do know it will react with the metal used in house siding. I'm not sure about steel. Hopefully someone on the forum can give you a better answer.
Marv, I would think about sealing the wood if it comes in contact with metal. If it has a tag that says copper azole pressure treated there can be corrosion with iron, aluminum, and some fasteners. If you find a tag on the wood check the website. We use galvanized fasteners and galvanized metal brackets with no problem. My first thought was coat all the wood with POR 15 or similar. Jim Derocher, AuGres, MI
The old body makers used waxed paper to desperate the wood from the metal.
Marv, I am by no means an expert on wood, quite the contrary. But a couple of things that I have noticed about treated wood here. First, my deck was built about twenty years ago I think by the previous owner. It was constructed with nails mostly and treated wood. The nails keep working out because of the expansion and contraction of the wood. I have pulled some and replaced them with screws. The nails are extremely corroded from the wood treatment. About eight years ago, we had the front steps on the deck replaced. They used treated wood and over the years the top of the steps (2x8s) have pulled loose and will warp up on each end almost 3/4 of an inch as they dry out, when it rains, they will lay back down straight. I am getting ready to replace the top wood on my '25 coupe, and trust me, am NOT going to use treated wood. As they say, YMMV. JMHO. Dave
I forgot to say, I would very worried about how that wood will react to changes in humidity. I'm not sure, but I think you have much less humidity up there than we have here. I would hate to see you go on a tour somewhere and your top start warping. May never be a problem, as I said, I am by no means an expert. Again, JMHO. Dave
Am appreciating the input! My biggest concern is the windshield header, where I've used brass screws for fastening the top windshield hinge. I don't really anticipate any problem from the visor. The wood can still be accessed if I need to put some kind of sealer between the wood & metal, like spar-urethane? Silicone? Other recommendations? (Better to re-do now than bigger problems later???) Thanks!
http://www.metalconstructionnews.com/articles/magazine-features/preventing-corro sion-metal-roof-and-wall-panel-components-in-contact-with-preservative-treated-l umber.aspx
This is extremely helpful!! From what I've read by scanning through, they're saying to use the 'water & ice' barrier between the sheet metal and the treated wood. I'll re-read, but didn't see anything specific about my brass screws, and if I remember my chemistry, copper is a component of brass. The painted sheet metal will also help. They do recommend hot-zinc coated or stainless steel fasteners for treated wood. Keeping dry should prevent possible wood movement.
Thanks, guys! (Not as much re-do as I was fearing...)
Marv, brass screws will be OK I bet, the water&ice roofing material has a rough side that may be a problem. The product we use iceguard is sticky back on one side, and like 80 grit sandpaper on the side you walk on...A roll will cost about 50 bucks, you'll be able to do a hundred T's with a roll! We used treated wood on a local football field, putting on new bleacher tops. We used a thin sheet of rubber between the metal and the treated lumber, and used cad plated hardware.. Hope this helps, Jim Derocher, AuGres
I had to have my '25 roadster re-wooded a few years back, and they actually used fir for the rails! No wonder it went to hell!