Tell me about Plywood... « Singletrack Forum

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Tell me about Plywood...

30 posts & 19 voices | Started 1 year ago by spooky_b329 | Latest reply from emsz

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spooky_b329 - Member

Having made a relatively expensive mistake, I'm looking for some advice...

I replaced a 12mm, plywood ramp on a horsebox, the old ramp was six years old and was only rotting as the rubber matting had ripped allowing water underneath.

I used 'standard' (C grade) 12mm WBP ply, and painted it in £100 worth of granulated rubber paint. (Rubber matting was around the same price)

First few times the horse was loaded it would creak and crunch a little, six months later its gone spongy and is breaking up. Its sodden with water and lost all strength. I'd painted the front with this rubber paint and on the advice of the timber merchant, painted the reverse side in some old gloss paint as apparently I shouldn't paint just one side.

So, replacement wise, should I use Birch Ply? Marine Ply? Wikipedia says Marine ply isn't suitable for high moisture environments?! The ply obviously wasn't strong enough in the first place, regardless of the moisture issue, but the stuff that I removed did the job fine and that was 12mm. I'm going to see if I can squeeze 18mm ply onto the ramp but not sure if it will increase the depth too much and prevent the ramp from closing.

Thanks for any help! Don't want to make another mistake as its a huge side loading ramp that is about 2 metres square so takes two 8x4 sheets and is several days work!

Posted 1 year ago #
lipseal - Member

Marine ply or checker plate(that's if you can use the plate with a horsey)

Posted 1 year ago #
spooky_b329 - Member

Can't use checker plate as the horse would go skating down it, plus its really expensive for the thick stuff.

Even the granulated rubber paint wasn't much good, horse would slide the odd foot down the ramp until it came up against one of the ally cross strips. Going back to rubber I think.

Posted 1 year ago #
lipseal - Member

What about that rubber matting they use on play grounds?

Posted 1 year ago #
spooky_b329 - Member

Rubber matting isn't a problem, various types I can get Still needs a ply base. Thanks

Posted 1 year ago #
TheFunkyMonkey - Member

Sounds to me like you've been given sheathing ply instead of wbp. wbp should last a good few years exposed without any treatment at all. I made a shelter extension on my shed with 18mm and never got round to felting it, lasted about 3 years before it started to show any degredation.

Get some proper wbp, should be hardwood in colour, if it looks like pine, it's sheathing ply. 12mm is usually around 15 quid a sheet inc vat. It's very often on offer in selco. Give it 3 or 4 coats of woodstain all round first, then fit it.

I'd definately try 18mm though.

Posted 1 year ago #
spooky_b329 - Member

Selco says trade only, are they OK with the odd normal customer?

Posted 1 year ago #
Kuco - Member

Marine plywood is good though not cheap but can last unless you back a 24 ton excavator over it

Posted 1 year ago #
Zedsdead - Member

What about that stuff that is being used for skatepark ramps now?

Posted 1 year ago #
bear-uk - Member

Does it have to plywood? Would T & G floorboard work for you?

Posted 1 year ago #
Sillyoldhector - Member

As Funky says use some wbp ply and then Id give it a liberal coating of Thompson water seal or similar and it should then last for yonks!!

Posted 1 year ago #
wrightyson - Member

Go for a hardwood solid core ply. Paying 24 quid for 18 mm this week at howarth timber, much harder wearing than wbp.

Posted 1 year ago #
epicyclo - Member

For something as valuable/potentially expensive as a horse, I'd use marine ply. It's the best.

Posted 1 year ago #
Kuco - Member

How I hate dealing with the Corby Howarth Timber branch. It always seems like your putting them out their way when you buy anything from them.

Posted 1 year ago #
spooky_b329 - Member

Thanks all. If I can find it at a reasonable price I think I'll go for marine ply, just for the piece of mind that I'm not going to have to strip £150 worth of rubber matting back off it in 12 months time!

I take it marine ply is always hardwood?

I think T&G floorboards is a no, I'm having to screw it into 50mm box section steel, that would be a lot of drilling and screwing!

Posted 1 year ago #
skidartist - Member

I think T&G floorboards is a no, I'm having to screw it into 50mm box section steel, that would be a lot of drilling and screwing!

or you could use self drilling timbadeck screws

Posted 1 year ago #
wellhung - Member

Wisadeck it's what commercial vehicle bodybuilders use as flooring in trucks and trailers

http://kcs-group.co.uk/Parts/Pages/Wisadeck.html

Posted 1 year ago #
spooky_b329 - Member

I found a local company that does Wisadeck, only problem is most of it comes in 18mm and above, I need 12mm so waiting to hear if they have any. Pics of the six month old ply below...votes on whether its softwood or hardwood?! In the first pic the board snapped in half like polystyrene, the rubberised paint is doing a good job of holding the two halves together.

Wondering if I'm going OTT with Wisadeck and should just get solid core hardwood.

IMG_0409 by Ollie and Sally, on Flickr

IMG_0405 by Ollie and Sally, on Flickr

IMG_0399 by Ollie and Sally, on Flickr

IMG_0397 by Ollie and Sally, on Flickr

Posted 1 year ago #
grannygrinder - Member

I think 12mm is way too thin. My wife's horse is only 14.2 but the ramp on our box is 2x18mm ply. To stop slipping and to allow the ply to breath we put heavy hessian under the timber cross bars. Hope this helps.

Posted 1 year ago #
deadlydarcy - Member

Selco says trade only, are they OK with the odd normal customer?

You need a card to purchase from them. Or someone with a customer number (which I have )

My initial thoughts were that 12mm is too thin as well. Marine ply - more to do with the resins used than hardwood/softwood. Make sure it's "exterior" grade.

12mm isn't designed to take weight really - minimum structural (underfoot) is 18mm if it's a house for example.

Posted 1 year ago #
spooky_b329 - Member

grannygrinder...is your ramp just timber? Ours is metal box section, fibreglass skin on the outside, came with 12mm ply on the inside. I've been out and measured it, there is no way to put anything thicker than 12mm ply on the ramp as it closes flush to the door frame. The only way would be to use a router to take out a 15mm wide strip around the top and sides of the ramp to reduce the ply down to 12mm. The old stuff lasted six years though.

Posted 1 year ago #
TheFunkyMonkey - Member

That stuff definately looks like sheathing ply to me.
As wrighty said, blockboard is your best bet, it's very tough stuff. Only ever seen it in 18mm+ thickness though.
Try some proper wbp, should be about 15 quid a sheet and medium dark in colour, like hardwood.
Wisadeck, couldn't think of the name before, it unbelievablely tough stuff though. Last time I saw it, it was about 60 quid a sheet maybe?

Posted 1 year ago #
Phototim - Member

I know lots about boat building so know a bit about this:

Don't use WBP, despite the name (Waterproof Board), its not that good at coping with wet environments. Its cheap for good reason, generally low quality wood and only water resistant resins.

If you want something to last, use proper marine ply. 12mm sounds too thin if its an unsupported 2m ramp holding a horse, it must bend a massive amount?!

These people are good: http://www.robbins.co.uk/marine/sheet_materials.asp
Different grades of BS approved marine ply with impressive guarantees.

Protect it first, best thing to use is neat epoxy or something like G4. Then when you attach the rubber matting to it, stick a blob of sikaflex on each screw before screwing them in. Basically, you want to minimise anywhere the water can get in. Even the best quality marine ply can fall apart if water is allowed to get in between the plies through holes or the end grain.

Posted 1 year ago #
grantway - Member

Marine ply be more than what you need but i would suggest exterior ply
as cheaper and bound to replace these panels more than often
and exterior ply is much cheaper and easier to purchase IE B&Q

Posted 1 year ago #
Phototim - Member

Yeah marine ply is not cheap, expect to pay £40-50+ per sheet depending on quality compared to £20-30 for WBP.

Posted 1 year ago #
chiefgrooveguru - Member

I'd be looking at a 100% birch marine-grade ply. Birch (with as many plies as possible) will give you the greatest strength for the 12mm thickness. Its downside is weight but that's not much a problem when it's attached to a horsebox! As Phototim says, seal it as well as possible - bear in mind that a horse with shoes on is putting some serious pressure through the ramp, so whatever is keeping it waterproof should not puncture or crack under a skittering horse. If you can keep the water out though, it should last indefinitely...

Good plywood will be stronger and tougher than hardwood. That plywood you were using before was not good, not good at all! I have some non-marine (but still nice) ply garage doors which I haven't yet treated or painted and they've not been the least bit bothered by a year of wind and rain in an exposed spot.

Posted 1 year ago #
spooky_b329 - Member

Thanks guys...ramp box section is at about 600mm centres (possibly 400mm, can't remember!) so its not unsupported.

I think I can reasonably confident that both exterior or marine solid core birch ply will do the job this time Would be good to get wisadeck but I suspect the local place won't have 12mm, they are a builder of hospitality/catering/exhibition trailers rather than a supplier so will only have their own squirrel stocks available.

Posted 1 year ago #
crispy796 - Member

I think you would find Wisadeck (or similar make) suitable. Its a birch ply board with a phenolic coating. It's used in alot of commercial vehicles (trailers, rigid trucks, busses etc). It's a great product provided its fitted correctly. All cuts and holes have to sealed with an acrylic based paint in order to keep a watertight surface. Once in place and fitted correctly, the flooring will repel almost all liquids and stay in one piece (heavy acids etc will eat through the coating). Horse wee, engine oil, water etc would have no long lasting effects on the floor as long as its not left on the floor for extended periods of time. It's avaliable in 9mm, 12mm, 15mm, 18mm, 21mm, 24mm, 27mm and 30mm as standard and comes in 2440mmx1220mm sheets. Other thicknesses are out there and other sheet sizes are avaliable subject to quantities.
Just google it to find suppliers.

Posted 9 months ago #
wwaswas - Member

the thread resurrection spammers strike again...

[edit] which as the mods have deleted the offending post now makes me look like the culprit...

Posted 9 months ago #
emsz - Member

You're talking about wood!

FFS.

Posted 9 months ago #