Treatment for PT plywood for outdoor ramp

[SmallChange]

I have a wooden equipment ramp on my barn to make up a couple feet between the elevated floor level and outdoor ground level. It used to land in dirt and sink into it, but I paved and so now it lands on asphalt and sticks up. I trimmed the bottom of the ramp, tapering the support timbers as far as I thought I could, but there's about a 5" drop still to be taken care of.

So I figured I could use three thicknesses of 3/4" plywood, glued together, and tapered at the end to minimize the bump at the bottom. I bought and cut the plywood -- it's pressure treated and rated for ground contact, but I do not think that will endure, especially because I'm cutting the plywood. The pieces are now drying (they were wet to the touch when I got it at Home Depot, and I've read that they do the pressure treatment and then directly palletize those stacks of plywood, so it *should* be soaked unless it got separated and stored dry somewhere along the way.

What do folks here suggest for gluing the three layers together? I think epoxy would be safe, though perhaps a little pricy. Is there anything else preferable?

And what do folks suggest as a preservative treatment? Mostly the things I can find are water based, which doesn't seem to me like it will do much. I did find an oil based waterproofer and used it on another part of the existing ramp already. I was hoping something like creosote or bitumen, hot pitch, I dunno, something penetrating and evil smelling. These are kind of hard to find, and instead I'm finding things with trick names that sound like these but advertise water cleanup. I did find one product that is oil based with some copper compound, which sounds best so far.

This whole thing is less than 3' by 4', so I could probably use something fairly expensive in a small quantity. I'm also wondering if I can come up with a way to soak it, or at least soak the cut edges, for an extended time.

Any suggestions?
Thanks!!

 

[fatjay]

I've covered GC plywood with several generous coats of paint, and they have been trouble-free after 10 years. Just be sure to get the ends real good.

 

[CADplans]

?? How about connecting a 2X8 to the edge,, so the plywood does not touch directly??

 

[Sawyer Rob]

Titebond 111 is rated for outdoor use, I've had good luck with it.

Epoxy would be expensive but would probably be the best.

SR

 

[dstig1]

Glue isn't going to want to stick to wet wood very well, though a polyurethane might do OK as they use moisture to cure (Gorilla glue). But why glue it at all? Get a small pack of 1.25" SS screws and screw together the layers. Easy peasy. Just make sure the points face down incase any poke through at all. You can buy the pressure treatment chemical in the paint section of most home centers, if you want to hit the cut edges. Just make sure you have goggles and gloves on as it is nasty. Or just a few coats of regular paint as Jay suggested.

 

[ArlyA]

Glue isn't going to want to stick to wet wood very well, though a polyurethane might do OK as they use moisture to cure (Gorilla glue). But why glue it at all? Get a small pack of 1.25" SS screws and screw together the layers. Easy peasy. Just make sure the points face down incase any poke through at all. You can buy the pressure treatment chemical in the paint section of most home centers, if you want to hit the cut edges. Just make sure you have goggles and gloves on as it is nasty. Or just a few coats of regular paint as Jay suggested.

Glued plywood is stronger than unglued. A polyurethane type glue is what I'd use with some screws as you suggest. If they came up from the bottom and don't perforate the top layer, less water would be ingested.

 

[SmallChange]

Glued plywood is stronger than unglued.

Yes, this is a very important point. The stack will try to bend when loaded, stressing the glue in shear, and if the glue can hold the stack can carry way more weight. Just think of leaf springs on a vehicle, and imagining replacing a leaf spring with a solid chunk of steel with the same overall dimensions.

Thanks all for the replies, I'm really appreciating them as they come in!!

 

[2manyrocks]

What will hold this ramp in place so it doesn't slip now that it will rest on asphalt instead of digging into the dirt?

 

[5030]

I've covered GC plywood with several generous coats of paint, and they have been trouble-free after 10 years. Just be sure to get the ends real good.

We have a Pressure treated ramp over the front steps that is over 10 years old and we coat it with good oil based porch paint every summer and it's holding up just fine. Let it dry out first and then a couple coats of quality porch and deck enamel will do the job.

 

[Fuddyduddy1952]

I would form it up & pour concrete. Broom finish.

 

[5030]

Just did a dry pour with bagged Quickcrete. Easy peasy. Prep the ground, make a form, lay in some matting or rebar and fill it with bagged Quickrete and wet it down. Repeat daily for a week and viola. Concrete pad without back breaking mixing. I did broom it off on the second day for surface texture.

 

[Fuddyduddy1952]

As a kid my Dad, Grandfather and I poured lots of concrete. The "boat" is still at homeplace because we had to mix by formula. Nowadays as 5030 said Quickrete makes it so easy. Never paint, rot, insects, etc. Once concrete done correctly it will be there longer than barn itself.

 

[big bubba]

in terms of a sealer, i'd use a top water based stain on ply. Olympic & Cabot are my choice.
2 coats. have not had good luck w/oil based products on horizontal surfaces esp decks where water pools up. realize yours is incline, etc. good luck, regards

 

[ArlyA]

in terms of a sealer, i'd use a top water based stain on ply. Olympic & Cabot are my choice.
2 coats. have not had good luck w/oil based products on horizontal surfaces esp decks where water pools up. realize yours is incline, etc. good luck, regards

i put a water based deck/wood sealer on a trailer deck and ran out so finished the last half with a oil based one. The oil looks sooooo much better 2 years later.

 

[big bubba]

i put a water based deck/wood sealer on a trailer deck and ran out so finished the last half with a oil based one. The oil looks sooooo much better 2 years later.

that could well be. many variables including type of wood, conditions, & location. it's all about our own experience, one of the main functions of this forum.
my only recommendation is that like paint, always go top of the line regardless of product type.

as a footnote, been staining cabin's horizontal surfaces for decades. on the horizontal deck surfaces where rain pools, oil based just didn't hold up (hardwood deck). 15 yrs ago i switched to water base top of line. good results, though pealing has occurred where rain pools & sits. best regards to OP

 

[timbatrader]

Water is what will do the damage to your ramp even treated timber that sits in water long term will rot. Often a paint that seals the water out can do more harm than good. The paint envelope around the exterior of the timber will get a split or crack at some stage and let water in, but because of the paint around it the water will have difficulty evaporating. The timber will stay wet longer than a unpainted peice of timber My preference is to absolutely soak it with a oil based stain that soaks right in as a posed to paint type system that only seals the surface several applications of a oil based stain will resist water getting in but still allow it to dry should water get in

 

[newbury]

and fill it with bagged Quickrete and wet it down.

In the bag? Cut open the bag? or Pour out and level?
I've got about 20 bags of quickcrete that soldified. Makes for a rough surface.

 

[5030]

In the bag? Cut open the bag? or Pour out and level?
I've got about 20 bags of quickcrete that soldified. Makes for a rough surface.

Dump the bags in the form and scree the dry Quickcrete level and water daily and second day, broom the top. End result is a nice concrete pad and I roast the empty bags. At 73, I'm way too old to be mixing cement in a wheelbarrow.

That stuff eventually turns into a rock if you leave it set in the weather.

I have a 3 point cement mixer in the shed, I should sell it.

 

[rScotty]

I would form it up & pour concrete. Broom finish.

So would I. I built some sail boats using laminated plywood construction. It wouldn't be my choice for a permanent ramp. Form and concrete are much better.

However, for a temporary ramp what you describe would work for light weight machines. Might need some center support.... Use screws for clamping and Resorcinol Glue for shear strength. That is the standard. Clamp from the center outwards. Plywood varies greatly, Home Depot 3/4" has less than half the strength of marine quality 3/4 inch ply. Marine ply has exterior glue on the inner plies as well as outer. Pre-drill for the screws being sure to include screw shank clearance so that the screws can clamp the wood. Without shank clearance, screws will just hold the boards in register without clamping.

Nothing wrong with a good marine epoxy like Gougeon Bros. West system epoxy (the best).....but it probably isn't necessary for this. If you can keep the ramp from the damp, you can even use inexpensive plastic resin glue - which is much cheaper glue. All the glues absolutely require wet assembly & lots of clamping pressure.

I have not had good luck using an exterior paint to keep water from plywood. Hope to eventually figure that one out.
Luck,
rScotty

 

[newbury]

Plywood varies greatly, Home Depot 3/4" has less than half the strength of marine quality 3/4 inch ply.

That's a great understatement!
About 6 to 8 years ago I was building a jury rigged enclosure to make my 18' Hudson equipment trailer usable as a cargo trailer. The purpose was to have a sort of enclosed trailer to haul stuff down to Mississippi, yet be able to switch back to an open equipment trailer to haul my tractors. I wanted to be able to load over the course of a few months and wanted to stop with the tarps.
So I bought a bunch of 4'x8'x3/4" pressure treated plywood from various sources, Home Depot, Lowes and the local lumberyard in Virginia, a few sheets at each place. All cost about the same per sheet. And were supposed to be the same quality. The Lowes was the absolute worst. After a relatively short period of drying, maybe a week or so, it was noticeably lighter per sheet. On cutting it I noticed large voids on the inner layers, I mean voids the size of 12" dinner plates. And it delaminated easily.
The Home Depot and local lumberyard were only slightly better.
After that I went to relatively solid marine plywood (which I had to paint) and Advantech waterproof OSB.