UKC

I'm looking to build a small climbing wall (3m x 2.4m) in my back garden, and looking to my local Wickes for the ply. My question: which type to use?

They have hardwood non-structural for £31.75 a board (graded B/BB). But then they have structural softwood plywood for £37.25 a sheet (graded C+/C).

My confusion was around use of non-structural v structural, and also the fact that I thought ply was stronger the closer to A the grade was (so seemed weird to have B graded ply cheaper). I assumed structural would be best, but then that is softwood, which I believe has potential to have knots, etc in it (whereas the hardwood would be a more uniform finish). Which would be best?

Any help appreciated. I contemplated buying marine ply but that blew my budget in about one sheet...

Thanks - it should be noted (and is probably obvious) I am not a carpenter. But I've done some research and can't find the answer to this question anywhere...

The letter refers to the external veneer finish I believe.

Neither will be any use if left to the elements. It needs to be covered and if that's the case then go for the cheaper stuff.

Mine is indoors and I still used marine grade ply. Probably overkill. I definitely wouldn't use anything less than structural grade hardwood ply tho, eg the link below, if you aren't sure.  It takes a lot of load.  Just shop somewhere other than Wickes if they have none in stock.

https://www.travisperkins.co.uk/plywood/structural-hardwood-plywood-2440mm-...

Great, thanks (and La Benya too). I was planning on covering, but perhaps I'll bite the bullet and spend a bit more to make sure I get the best I can afford. Thanks for the link

I'm building a shed, so i went through this a few months ago.  Plywood comes in three standards, according to resistance to humidity and water.  Class 1 is for indoors, class 2 is for limited exposure to humid conditions/water while class 3 is when regular wetting is expected.  Clearly, you'd want class 3 for an outdoor wall.

Travis Perkins sell plywood which is WBP, the old 'water and boil proof' standard, it probably equates to class 2.

I suggest you go to a pucker timber merchant who will tell you which class they sell.

Marine ply is the same as class 3 but has a good finish on at least one side and very few voids inside.  Consequently, it's twice the price of class 3.

Whatever you get, take care to paint preservative on all cut edges and bolt holes.  Apparently, the end grain absorbs water a few hundred times more easily than the surfaces parallel to the grain.

The preservative is about a tenner for a litre, which should be ample for needs.

Great, thanks Dave. I think we have some timber merchants round our way that aren't wickes/b&q etc. I'll give them a go too, see what they quote me. Cheers

Far eastern WBP is good.

Definitely go to a proper timber merchant. You can set up an account at Travis Perkins which gets you a better price. It's all very variable and negotiable so potentially worth ringing someone else to see if they will beat TP's quote.

I often buy TP's standard hardwood (birch) ply and really like it. I have had some pieces of 12mm sitting outside untreated/unpainted for several years now with minimal visible degradation.

Assuming you plan to build a frame: treated timber is easily available in all sizes. Remember to seal the cut ends.

Yeah, I've done some more looking and think I'm going to go for the TP hardwood. I'm planning on building a frame - free-standing I think as the wall I'm putting it up against is not strong at all  I'll definitely go for the treated timber for that. Thanks all

I was looking at the big timber places and getting confused. Quick call to the local timber specialist and I'd got better stuff at a much cheaper price. 

Interesting fact I didn't know until looking into it- nearly all plywood is softwood ply, even the hardwood stuff.  The hardwood bit in the name refers to the exterior veneer material.  Given that this is often so thin that it cant take a scuff or any sanding- its probably never worth buying hardwood stuff unless you can get high quality thick veneer furniture quality stuff- but then that costs double.

I built my wall outside using marine grade. It cost around £50 a sheet, so a fair bit more than regular ply. I think the bond between the sheets is the important factor with marine-grade, as normal ply will delaminate easily in the wet. 

If you're putting loads of time and effort into building a wall, £50 extra to get something that will last for 10 years instead of 2 is well worth it. 

I kept a tumble dryer outside for 15-20 years in an external ply (not marine) kennel with initial single coat of creosote ( no longer generally available and possibly not suitable for a wall). Raised slightly off ground on bits of tile. There was an overhanging felted roof. Eventually the bottom few inches rotted/disintegrated, presumably due to splashback off patio, but above that the wood was still fine. I've recently built a shed with all walls external ply, edges stuck and sealed  (Evostik Sticks like s--t,I think) and coated with a Barritone solvent based preservative. Many other preservatives seem to require overpainting, also they all presumably only penetrate the outer layer of ply, though that should be sufficient. Not an expert.

I wouldn't use wickes ply for anything outside. It can be variable around the country tho as it doesn't come from a central supplier. Around my location (Woking) Travis Perkins hardwood WBP plywood is pretty good (you definitely need WBP) and noticeably superior (and cheaper) to Wickes, despite being part of the same company group!

Assuming the training board is going to be at least slightly overhung it's not actually going to get very wet. I built mine 4 or 5 years ago and it's in good nick now - just used WBP and painted it with fence treatment. The back of the frame is covered in roofing felt.

Marine ply is overkill and will be very expensive!

Personally I used standard 20mm ply from b&q, cheapest stuff no idea of grade.  I’ve taken apart now and reused the wood, which apart from the bottom edge still seems in good nick.  Originally built 2011 and outside all that time.  Treated of course.

You're thinking of hardwood faced ply. It's pretty easy to source proper hardwood ply where all the veneers are the same material. I agree it's not obvious to the layman though.

Either will do and both will need weather protection.

Strength wise I'm always swimming against the tide here, home walls do not need to be super strong, they just need to not fall down, some flex is fine and lower grade materials used sensibly work. Most are massively overbuilt.

I built mine (indoor) half from cheapest shuttering ply (18mm), half from decent softwood sheets of some kind (18mm) but nothing fancy, both sides had half the framing most people recommend and that's still more than I'd use if I were to do it again. Neither half gave me any trouble.

jk

you wont find it in DIY shops and probably even standard lumbar yards (TP/ Jewsons) so the vast majority (what i said) is not hardwood.

The world of plywood has always been a bit fraught! The concerns when specifying plywood are that it will be structurally strong enough, that the glue is waterproof (if necessary) and that the wood used in its construction is durable enough for the intended use.

Originally, the testing was simply used to distinguish between interior and exterior ply. To accelerate the testing process, samples were boiled so those that passed were known as waterproof / boil proof (WPB). Folklore also has it that this 'hot, wet' test was also favoured after the problems the Mosquito aircraft experienced in Burma.

The marine (and aero) industry in particular, went further; The glue was still WPB but to guarantee the strength and durability of the panel, they specified the number of plies for a given thickness, the construction quality of each individual layer, the number of voids permitted, the number of repairs allowed, and the quality of the face veneers, and the species of wood used. But to know what you were buying, the quality control had to be done at the point of manufacture and was always a bit hit and miss, so organisations like Lloyds Bureau of Shipping had inspectors in the factories stamping each sheet as it was made. It was a really expensive procedure and now long gone, but old supplier like Robbins of Bristol still do their own audit of the complete manufacturing / supply process and certify what they supply. 

But for the wider industry these days, the individual properties of glue durability, panel strength and build quality / durability are tested separately. The old 'boil test' has been dropped as it dictated that phenolic resins were used where there are other more suitable modern adhesive that are just as 'waterproof' (if not boil proof!).  So for an exterior climbing wall, that's going to get repeatedly wet, you're looking for an 18mm EN 636 Exterior sheet with glue to Class 3: https://hanson-plywood.co.uk/specification-plywood-performance-criteria/

Sadly efforts to standardise the plywood world is rather hampered by the sheers scale of the far east producers and the massive US market. So you'll still find plenty of stuff called exterior, marine, BS 1088, WPB, structural, hardwood, or American B-C type descriptions which mean these days pretty much whatever the seller wants them to mean.

If money isn't too much of an issue, you can now get "Buffalo Board" which is meant to be mega-tough and weather-proof. Also has a tread pattern so you can vaguely smear of it (?)

This thread has been a great help, and this response especially. I'm actually Bristol based so will definitely look in to Robbins Timber. I started this thread as a plywood beginner, but all the info has been much appreciated so thanks all