MDO vs plywood for small utility trailer

[wahoowad]

I need to put a deck on my Harbor Freight 4x8 trailer I just finished assembling. Somewhere it was suggested using MDO (Medium Density Overlay) instead of marine plywood.

I don't know anything about the suitability of MDO aside from this description from Lowes: A smooth resin (water resistant phenolic) impregnated cellulose fiber is bonded to the face and then primed for a durable and weather resistant surface that is ready for paint

This trailer isn't going to see heavy use - mostly transporting a riding lawnmower. I'm thinking 1/2" is fine as there is a lot of crossmember support underneath.

 

[finn]

Is the MDO a smooth surface? If so, it will probably be slippery when wet.

I would go with plywood or treated deck boards, or, possibly rough sawn oak planks.

 

[larry4406]

We use MDO for cornice details on new home construction (soffit, bay windows, etc). Ours is approximately 3/8” thick. Smooth primed one side, back side raw. It’s a plywood type construction. Finishes nicely.

I wouldn’t use it for a trailer floor. The marine plywood I’m familiar with is like 7/8” thick and I would say much better suited for a trailer floor. Better yet parallel slats of pressure treated 5/4 boards. The parallel slates will allow for drainage.

 

[NUTTSGT]

I'd agree with Larry, for the little trailer, deck boards.

 

[shelteredV]

Rough sawn oak or 5/4 x 6 P.T. would be my choice. My heavy duty dump trailer (12,000 lb) has 8/4 x 6 oak, the light duty has 5/4 p.t.

 

[Stuart in MN]

MDO is used for road signs, so it should be pretty resistant to weather, but it will depend on the thickness - if as mentioned above it's only 3/8" that wouldn't be enough, but if you can get it in 3/4" it would probably work okay.

 

[manwithtools]

MDO is available in many thicknesses. As mentioned above, it could be pretty slippery when wet unless you add a traction additive to what you might paint it with.

5/4 Deck boards may be your best bet, due to the drainage between boards. Lay them tight to one another and once they dry you will have a nice gap between.

 

[CTyankee]

I used 3/4 inch plywood for my 4x8 trailer, painted with oil base. Spends its life outside year round. Has held up fine 4 years and counting.

 

[wahoowad]

I used 3/4 inch plywood for my 4x8 trailer, painted with oil base. Spends its life outside year round. Has held up fine 4 years and counting.

Have you had any cracking where it has tho bend a little bit due to the outside rails being slightly higher?

 

[JoeMcGov]

True marine grade 3/4" plywood has incredible life span. I'm talking about just life in the elements and not resistance to use and occasional abuse. The last sheet I ran in the back of my truck bed was at ten years when I replaced it and upon removing it and seeing the underside (which I apparently had not looked at since putting it in the truck) it probably had another 10 years of life for 20 by just flipping it over.

 

[wahoowad]

Yes, i’m Just gonna keep this simple and put marine plywood in it

 

[Git]

The main difference between 'marine plywood' and other exterior grades of plywood is the quality of the inner cores/veneers. (no knotholes or other voids - it uses a higher grade) It is not specially treated with a chemical or anything to help prevent rot or decay. It doesn't have any special waterproofing added (unless you spend the big $$$)

You can basically get the same performance with an exterior 'AC plywood'. But, in any case, if the exterior surface is not sealed in some fashion (paint for example) it can still check and splinter. That is where the MDO comes in.

Do you really care about higher quality inner cores for a trailer floor? And, if you buying 'marine grade' plywood from a Big Box store and it is about the same price as exterior grade ply, it really is not that good of a grade

Price out some 3/4" exterior AC ply or 3/4" MDO. I love MDO - and it is what I use for all my sheet goods. By the time you paint any plywood, isn't the surface fairly smooth like MDO? (just get the MDO)

 

[Lynden]

Here is a better description of HDO and MDO plywood than the description you got from Lowes. I think either one in a 3/4" thickness would make a good floor for your trailer.

https://www.apawood.org/overlaid

 

[teamextreme]

I didn't want to deal with plywood and it's inevitable failing, so I used 3/16" (I think) aluminum diamond plate. It's been on my HF trailer for 15 years now. It was $100 back then, so I'm afraid what it would cost now, but no painting, totally maintenance free and durable.

 

[Bretny]

I have 8yr old plain pine boards on the center of my car trailer. Never stained, painted or oiled. I recently took them off to paint the trailer and put them right back on. I live in a very humid climate. I dont see the need for PT on a trailer. Infact you will prob corrode the hardware you use to attach it before the wood rots.

 

[ez-duzit]

MDO is great stuff, but I would not choose it over marine ply for your application.

 

[vtcat]

I put pressure treated plywood from Lowes on my 5x8 trailer about 6 years ago.
It sits outside and still looks fine.

 

[Showkey]

I put pressure treated plywood from Lowes on my 5x8 trailer about 6 years ago.
It sits outside and still looks fine.

Similar .........my Triton trailer came with PT plywood lasted 15 years, replaced with PT plywood, that was 7 years ago. Stored outside 100% of the time.