Marine plywood..

[Keithmac]

Hello all, about 10 years ago I ordered some marine plywood sheets (12mm iirc) to use as falt surface for working on our cars (gravel drive), it's lasted very well and still in use.

I ordered some more a couple of years back and it's completely delaminated and lost all it's strength.

I need a few more big sheets really to roll my Golf around on trolleys but wondering what to buy really and where from.

The sheets are either stored upright outside or laid under a car.

Cheers for any input, Keith.

 

[motorbiking]

There is marine ply and marine ply. Your second source probably wasn't resin impregnated to a waterproof grade (B-B). Can you not use something non wood based or treat the ply with a wood/paint stain?

 

[carmanmemoranda]

Hello all, about 10 years ago I ordered some marine plywood sheets (12mm iirc) to use as falt surface for working on our cars (gravel drive), it's lasted very well and still in use.

I ordered some more a couple of years back and it's completely delaminated and lost all it's strength.

I need a few more big sheets really to roll my Golf around on trolleys but wondering what to buy really and where from.

The sheets are either stored upright outside or laid under a car.

Cheers for any input, Keith.

Try OSB maybe instead?

 

[RandomGrinch]

Phenolic plywood?

 

[Keithmac]

Is this reasonable, Class 3?.

I don't mind paying for something that will last to be honest.

Maybe treat it as well?.

I'd prefer to stick with plywood as the first lot was excellent, held the weight very well and lasted a long time.

 

[Justin Passing]

WBP "water and boil proof" shouldn't delaminate. It can have soft layers though. At least the outer ones on Marine are hardwood of sorts.

@JobAndKnock will know.

Ah - found this. Clsas 3 looks OK.

from one supplier:

To what quality specifications do we qualify?​

Our plywood is compliant to EN314 and EN636.

Plywood has two material components, wood and glue, EN314;1993 and EN636;2003 are standards that work in tandem with each other with EN314; referring to bonding quality and EN636 referring to the durability of wood species.

EN636 defines the specification of plywood regarding the type of glue, the durability of the timber and its suitability for structural use.

The number following the EN636 code defines the durability of the timber used in the manufacture of the plywood

EN636 – 1 (Class 1) Defines product that is suitable for dry interior use only

EN636 – 2 (Class 2) Defines that the product contains timber that is classed as non-durable and is suitable for use in humid areas or exposure to occasional wetting. It can be used in the exterior application when fully covered or given a fully external decoration.

EN636 - 3 (Class 3) Defines that the product is made from timber that is durable (hardwood throughout) and is suitable for all exterior application including frequent wetting. Prolonged use in an external application would require boards to be covered or decorated.

The final part of EN636 deals with its suitability for structural use. All the plywood we stock of a thickness 9mm or over is suitable for structural use and is defined by the addition of the letter "S". Boards below 9mm show the letter "G" in their description and are only suitable for General use (non-structural)

 

[Keithmac]

Just ordered 4 sheets from Jewsons, what's best stuff to seal the board and mainly the edges ?.

 

[motorbiking]

A fence / shed wood stain will do it.

 

[nicam49]

Yatch varnish... or wood hardener (the stuff you use to repair wood before applying wood filler)

 

[Deleted member 174758]

Your second source probably wasn't resin impregnated to a waterproof grade (B-B).

Whilst I agree with you that marine plywood normally uses a melemine formaldehyde (MF) or resorcinol formaldehyde (RF) glue, doesn't the "B-B" refer to the surface veneer visual grading? You used to see plywood grade "A-B" at one time, but these days you are lucky to find even "B-B" which have some veneer patches and filled holes

As to edges I think I'd go with a PU lacquer or even oil-based gloss paint. I find true spar varnish to be horrible stuff which never quite sets and can be sticky for a long time.

 

[^woody^]

Phenolic plywood?

Lots going cheap. Look for a block of flats with scaffold around it.

 

[motorbiking]

B-B Yes its about the quality of the wood used. Oddly it retails for the same money as the lower grades if you shop around B-B (single face and single back)low number of repairs, low Sap content etc. But this does have a significant effect on the durability of the wood, particularly if its getting left out in the wet and getting stressed from loads.

TravisPerkins charge the same for their lower grades (£80 a board) and have a disclaimer that its not suitable for marine uses. Still call it Marine ply though.

I agree about yacht varnish - There is a reason yachts are built from GRP and carbon fibre now.

 

[Keithmac]

The sheets have a very nice finish, could do with some creosote really!.