Trailer decking wood type?

   / Trailer decking wood type? #1  

Gale Hawkins

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Murray, KY
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1948 Allis Chambers Model B 1976 265 MF / 1983 JD 310B Backhoe / 1966 Ford 3000 Diesel / 1980 3600 Diesel
We went to look at a new like 6'10"x12' tilt trailer that was build in Mar 2012. The ad called the decking treated. It is marked #3 and look like run of the mill yellow pine but it was dark by the time we got there but lighting was OK.

I was thinking pressure treated so I was caught off guard. After getting it home I have decided they must just be spraying stuff on it and letting people assume treated meants pressure treated. :( The trailer is an O'Neal out of west TN and the steel part looks fine and pulled great at 70 MPH on I-24 coming home. They did not even turn the best side up of the 2x8's in all cases. Thankfully as noted the metal work looks good and the welds appear to be of high quality.


Now I will have 10" on either side when loading the mower.

The seller is a trader and said he just wanted his money back out of the trailer but he sold per him for $190 less than he had in it but he was not crying when we left. In fact he loaded up the wife and kids and headed to WM I think. :laughing:
 
   / Trailer decking wood type? #2  
... They did not even turn the best side up of the 2x8's in all cases. Thankfully as noted the metal work looks good and the welds appear to be of high quality...:

I don't know what you mean by the "best" side of the wood being up, but the real deal is that you should look at the grain and the part of the board that was toward the outside of the tree should be up for longest life.
 
   / Trailer decking wood type?
  • Thread Starter
#3  
Yes that is what I meant by 'best' side up so the natural grain worked more like a 'roof' vs a cup.

Today I am not sure many have been taught things like that and bow up, etc.

There is one row of self tapping screws about a 1/3 of the way from the front. It seems they must weld the end on after the decking is in place because each end is held down by a piece of angle it seems. I may try some Thompson Water Sealer or something to make the yellow pine weather better.

On a side note there seems to be a lot of trailers on the market. We say several nice two axle (3500 pound rated) trailers for under $1000 but that was beyond what works well for us since do not have an big TV to pull them and have two equipment trailers with pintle hitches we pull behind the F700.

After pulling 5-5.5' trailers I have to keep my focus with this one because outside to outside to the tires is about 100" which is much wider than the Blazer or Nissan.

On the decking we may just run with the yellow pine if I do not find a good usage for it then replace with pressure treated one of these years. I may get HF silver tarp for it to use this winter.
 
   / Trailer decking wood type? #4  
The new treated wood is not green like the old wood was. It may still be treated but will be located on the lumber stamp on the wood. Some trailer makers dont use treated and some assume all deck are. I think we have an untreated trailer at work, no treatement stamp i dont think. Another guy i work with who knows better and is a carpenter etc (were foresters by trade) bought an untreated trailer cause he saved $50??? I was like "youll spend $50 to redeck it though?". He said well ill keep it under cover.. I still could not figure out buyig a new trailer and not spending the $50 to get treated?
 
   / Trailer decking wood type? #5  
location also affects treated needs, up here we don't get much rot. I have untreated wood trailer decks that are 12 years old and still doing great, at least from the rot point of view. Most of my decks are torn up and ready for replacement long before they could rot
 
   / Trailer decking wood type? #6  
I don't know what you mean by the "best" side of the wood being up, but the real deal is that you should look at the grain and the part of the board that was toward the outside of the tree should be up for longest life.

Exactly...I have seen many architectural drawings/specs that state "bark edge to the weather"

unfortunately many lumber processors stamp the lumber on this side...
 
   / Trailer decking wood type? #7  
I don't know what you mean by the "best" side of the wood being up, but the real deal is that you should look at the grain and the part of the board that was toward the outside of the tree should be up for longest life.

Umm, it doesn't work that way - in fact it is the exact opposite. You want the growth ring oriented so they look like they are facing up - the inside of the tree is up. This sounds counter-intuitive, and I got caught by it many years ago when I added onto my deck. The boards I laid with the outside of the tree up all cupped upward and hold water now. The ones laid with the inside of the tree up cupped downward and water rolls off them. There is solid wood technology science behind it. If you look at the growth rings, when the board dries, they will shrink along their length more than across them. This causes the board to cup towards the outside of the tree. I haven't really looked for a good reference online, but here are 2 pages from the book Understanding Wood by Bruce Hoadley - the bible of wood technology. Look at figure 4 most closely. I don't have a scanner, so I just used my camera to take photos of the pages - not the best but should be readable.

Wood Shrinkage (1) (Large).JPG
Wood Shrinkage (2) (Large).JPG
 
   / Trailer decking wood type? #8  
Umm, it doesn't work that way - in fact it is the exact opposite. You want the growth ring oriented so they look like they are facing up - the inside of the tree is up. This sounds counter-intuitive, and I got caught by it many years ago when I added onto my deck. The boards I laid with the outside of the tree up all cupped upward and hold water now. The ones laid with the inside of the tree up cupped downward and water rolls off them. There is solid wood technology science behind it. If you look at the growth rings, when the board dries, they will shrink along their length more than across them. This causes the board to cup towards the outside of the tree. I haven't really looked for a good reference online, but here are 2 pages from the book Understanding Wood by Bruce Hoadley - the bible of wood technology. Look at figure 4 most closely. I don't have a scanner, so I just used my camera to take photos of the pages - not the best but should be readable.

View attachment 277390
View attachment 277391

This is an old and tired debate...and it really depends on the way the wood is sawed....FWIW I have never seen an architect recommend other than the "bark side" be exposed...

here's some more to add to the debate...

http://www.fpl.fs.fed.us/documnts/finlines/willi95b.pdf
 
   / Trailer decking wood type? #9  
Yes, of course it depends on how the wood is sawn - note the picture in figure 4 showing the various cuts.

And no offense intended to architects, but they are not the place I would go to for technical information about wood or much else. They are primarily artists, not engineers or scientists. Undoubtedly it has become standard architect practice somewhere along the way to say "bark side exposed," but that doesn't make it technically correct. Come look at my deck for a real world example... My best advice is to put the best side out, but aim for pith side out most of the time, if at all possible. Or get quartersawn boards and don't ever have to worry about it (if you can find them).
 
   / Trailer decking wood type? #10  
Yes, of course it depends on how the wood is sawn - note the picture in figure 4 showing the various cuts.

And no offense intended to architects, but they are not the place I would go to for technical information about wood or much else. They are primarily artists, not engineers or scientists. Undoubtedly it has become standard architect practice somewhere along the way to say "bark side exposed," but that doesn't make it technically correct. Come look at my deck for a real world example... My best advice is to put the best side out, but aim for pith side out most of the time, if at all possible. Or get quartersawn boards and don't ever have to worry about it (if you can find them).

I have to disagree with your assessment of architects...much of their study is in materials and their integrity...not just design and applications...granted they are not structural engineers (loads and resistances) but material testing is a big part of required curriculum...
As for decks... as we agree it depends on the way the boards are cut to begin with...

The wider a board is the more apt it is to cup and hold water and as you make valid points as to cupping due to the way the boards are placed...

As for a "real world" example of my own experience...I have a (2x4) handrail on a stair landing (both sides) where a single 16' board was cut in half ...one half on each side...both were installed with "best looking" side up...but one was bark up and the other the opposite way...this was over 30 ago and both have since been replaced...but the side with the bark side down rotted out much faster than the one installed with the bark side up...
The exposure to direct sunlight is also a major factor (not just rain/snow)... FWIW...The same decking and landings as mentioned above get little if any direct sunlight but lots of rain water...and there is very little cupping regardless of the attitude of the grain...
 
 
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