Cheapest way to waterproof ply?

I’m building a bike garage in a van I am converting to a campervan. I need to waterproof the ply so it will handle years of wet muddy mountain bikes. I was considering lining with lino but I’m sure there is a better way. I’m not convinced that gloss paint will be enough. I want to be able to mop it out.

Thanks for any ideas.

A bit of wood stain should do it. Easy to put on and should keep the moisture out. I wouldn’t put lino down as that will hold water under it but something breathable that you can take out if it needs drying will protect the wood surface. An off-cut of astroturf maybe

Danish oil does a good job of waterproofing; was looking for various options for waterproofing my ply shower enclosure and though it’s not as swanky as tiles or plastic cladding, it is waterproof.

http://www.toolstation.com/shop/Painting+%26+Decorating/d150/Wood+Care/sd3151/Danish+Oil/p20048

Fibreglass, same as they do flat roofs with.

uPol Raptor the lot of it.. I am

Marine ply. Then seal with varnish or paint?

Use WBP ply.

Unless the ends are fully sealed then you will struggle. Even marine ply isn’t any better as it’s only the glue that’s water proof. I found this out the hard way when I built some temporary garden sofas and have them a few coats of exterior gloss. The layers of ply just peeled apart where the water got in the ends. They were under the cover of a gazebo too.

There are lots of products here for creating high traffic deck surfaces that roll on over ply.

Ducan Tuff Deck

I power wash my deck every season with this paint system and recoat the color coast every couple of years.
Its applied over exterior grade ply.

If you’ve not already bought/fitted the ply then see if you can get hold of some phenolic faced ply – thats the stuff bus, truck and container floors are made from and it can handle wet conditions very well – is very robust and also easy to clean. Very few places hold it in stock but any timber yard should be able to order it from their wholesalers.

However.. so long as its a WPB grade board (doesn’tt need to be marine ply -unless you’re planning to be insured by Lloyds of London) then you don’t really need to worry about it too much – paint it if you fancy but its more important the wood can dry out than you prevent it from getting wet. Stuff like lino will just trap moisture against the wood and whatever you do, the more waterproof you make everything the less breathable it is and the less any moisture can escape and you end up causing more trouble than you’re trying to solve

However.. so long as its a WPB grade board

from experince of WBP plywood in the last few years there are loads of cheap chinese imports, branded as WBP, that de-laminates after a free weeks outside or even after being painted, try returing it to the BM for a replacement and reinbursement of costs incured in the replacement and removal, thy just dont want to know, they cant afford the costs involved,

Best to use a fibreglass type sealing system or a spray on foam as used in freezer trucks.

stokboard is indestructible, waterproof, and made from 100% recycled material

Checker plate if you want to go factory.

Wang a load of screwfix yacht varnish on the faces and edges.
Do it again periodically.

Thank you all for your advice.

Phenolic would be best. I wouldn’t bother with Marine, its very expensive and the main advantage is there are no voids in it so its good for boat building.

Make sure you get hardwood throughout plywood with lots of thin plys layers. I think its ‘core’ plywood that has a thicker inner plys and this is weaker.

I made the mistake of getting the cheaper WBP plywood for a horsebox ramp repair. It crunched everytime the horse walked over it, until I decided it was too risky. A few months later I pulled it up and it was like polystyrene, just broke into bits and all delaminated/wet. Replaced it with WBP hardwood throughout and took extra care to seal the edges, still doing fine about five years later.