Repainting Trailer and Replacing Trailer Deck

[BoylermanCT]

Since I am stuck at home for a while and the weather is turning nice, I've decided to repaint and replace the deck on my 6x10 trailer. My question is do I simply use 2x pressure treated wood for the deck, or would untreated douglas fir that I coat with preservative be better or something else like red or white oak? Its a single axle trailer rated at 3500 lbs, so I'm leaning towards pressure treated lumber. My other question is does it matter if I use 2x6, 2x8 or 2x10 for the deck? The current deck is 7 2x10's and one 2x6. I could do the same, or I could use 13 2x6's or a combination of any of them. Are 2x10's stronger that 2x6's or 2x8's? Or does it not matter. Using all 2x6's would cost $90. Using 2x10's with 1 2x6 would be $110. All tips or advice welcome. Thanks!

 

[i7win7]

I would use treated lumber the same size as the original wood. Then place the old board on the new one and use it as a pattern for the bolt holes. Also use new carriage bolts.

 

[redman135]

Hello BoylermanCT, In terms of deck strength, the limiting factors are timber thickness AND distance btween the cross members.
Cost wise you will notice that 6x2 timber is cheaper than 10x2 timber for the same area.
When you say "preassure treated" I assume you mean pine. If it is straight out of the teatment, there can be significant shrinkage leaving gaps between the boards. If you carry fine product like morter sand it may be a nuisance. If possible try to select drier boards to minimise the gaps between boards.

I can't comment on non pine board decking.
On my trailer I have gone for 2 thicknesses of plywood(pine) on the floor. How would this cost out for you?

 

[denchen]

If you want it to last, then I like many farmers use Keruing. (we pronounce it Kero-win). Its often used for cart bottoms or window sills. A word of warning, if you get a splinter, it WILL go septic, and, it soon takes the edge off tools. Other than that it should last for years. Or, although I`ve never used it, there are `boards` made out of reprocessed plastic waste. They last years without treatment, are easy to use and will outlive the bolts that hold them in.

 

[Hay Dude]

Doug Fir oozes sap. It may get on items you put in trailer or the bottoms of your shoes.
#1 PT pine is excellent. It doesnt have the larger, looser knots of #2 which tend to fall out, exposing the wood to weakening or further decay.

 

[Egon]

Treated lumber at whatever width. Suits you.

When it’s disassembled make sure it’s all cleaned up & painted with a rust coat paint. Also isolate the rails and deck boards with strips of rubber ??

Do not paint the finished wood product but stain if colour is required.

 

[KennyG]

Use PT and be prepared to do some clamping, wedging, or whatever to get them close to straight. I installed mine as tight as possible and, after drying, they have small gaps. Of course, I store my trailer inside. If you store it outside, you might want larger gaps. Look at the ring pattern and install all of them crown up. I used 2x6 and they are easier to fit. Technically, a larger board will have more load carrying capability for point loads, but that really isn't a concern for most people. One of the best things I did was install recessed D-Rings in the deck, bolted through to the frame cross members.

On mine I cleaned up the rust and primed and painted with Rustoleum. All brushed on on the frame and sprayed on the exposed parts.

 

[GLyford]

PT yellow pine or white oak. Red oak has pores that make it hold water and starts to rot quickly.

Since you are laying flat, the strength comes from the the thickness, not the width. When on edge like a joist or rafter, wider is stronger (think of it as very narrow and super thick).

I have used the urethane window flashing to separate steel from the PT chemicals with pretty good results. Comes in a 6" wide roll, usually in the same aisle as all the roofing stuff.

And same as for decks, use either hot dipped galvanized, stainless, or coated "PT rated" bolts or screws. The make a self-drilling, self tapping screw just for trailer decks.

 

[fried1765]

I would use treated lumber the same size as the original wood. Then place the old board on the new one and use it as a pattern for the bolt holes. Also use new carriage bolts.

The OP should use marine grade PT Southern Yellow Pine.
Material width dimension does not matter.
Standard grade (Lowe's/HD) PT is treated to .06 retention level.
Marine grade is treated to .60 retention level, TEN times the retention level of that sold at Lowe's & HD.

 

[s219]

I redid a trailer last year. It had used 2x6 "above ground" treated, but I changed to 2x10 "ground contact" treated. The wider boards worked out better for spacing -- was able to get the gap I wanted and did not need to rip any boards (when you cut or rip treated lumber, the exposed wood is no longer rot-resistant). So do the math on that to get the ideal board size among 2x6, 2x8, etc. Wider boards tend to be stiffer even when laid on the flat, which may be another consideration.

The trailer originally had the 2x6 boards jammed tight. I assume they had dry lumber in order to do that, since wet treated wood normally shrinks a lot when it dries. Despite my perceived benefit of having a tight deck, I found that it seemed to trap water and I think that contributed to rot. So when I put on the new boards I specifically put a 1/4" gap between boards and I am sure it opened up more as the lumber dried. I want that deck to drain.

I was able to find the self-tapping trailer deck screws at Lowes, which made it easy to put on the new decking. These screws are meant to self-drill through the wood, then self tap through the metal. I think they have a 1/4-20 thread. These screws had a nice coating on them and are supposed to be corrosion resistant and rated for treated lumber (the original screws were raw steel and had rusted badly).

After taking off the old rotten deck and all the old screws, I used rust converter on any parts of the frame with rust, then primer, then paint. Before I put the new deck down, I put strips of roofing felt (tar paper) over the top of the frame cross members. So that would prevent direct contact between the lumber and frame.

Here are some pics. This was a small 4x8 trailer, but I plan to do the same with my larger tandem-axle 7x16 soon.





Here's one of the old screws: