WBP plywood help!!

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WBP plywood - what is it??

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Hi

I am having an extension built and the upstairs level is to be built from timber and the plywood cladding is meant to be WBP ply. Water and Boil Proof is what WBP stands for isn't it?

The plywood has gone up and today it absolutely chucked it down with rain and I noticed that the plywood that they have used for the job seems to have absorbed a lot of water (dark stain patches appeared after it rained).

I thought WBP plywood would not absorb any water, am I wrong? Is it just that the glue in the veneers is waterproof, but the veneers are not actually sealed?

How can I tell if they have used proper WBP ply?

Thanks!
 
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Corrado said:
Water and Boil Proof is what WBP stands for isn't it?
Yes. The rating refers to the glue bond.

Corrado said:
I thought WBP plywood would not absorb any water, am I wrong? Is it just that the glue in the veneers is waterproof, but the veneers are not actually sealed?

How can I tell if they have used proper WBP ply?
The face veneers aren't sealed and will absorb water. Providing there isn't a soaking/drying cycle repeated over many months it won't make much difference to the plywood - the biggest problem is probably soaking then freezing which can damage plywood but is unlikely at this time of year. As for checking the grade, all construction plywood sheets (i.e. those without a fancy show veneer face) have a grading stamp somewhere on the face, normally in one corner, which identifies the mill and grade of plywood and there will be the legend "WBP" or "Exterior grade" clearly visible.

Scrit
 
Hi Scrit, Thanks for that!

I have been and looked at the sheets and they do not say WBP or exterior. There is a CE stamp on them, which reads something like:

CE 1224-CPD-0099

Sumantna Timber - I think - very blurred text...

Do you think they have fitted standard ply? Should I be worried? This will be covered in a pebbledash render.
 
Corrado said:
CE 1224-CPD-0099
CE-marking of plywood became mandatory in April 2004 but to date all the stuff I've had from suppliers has still carried the old "WBP" marking as well and I've not taken much notice, so far........ I've just looked up the full marking and "CE 1224-CPD-0099 Sumantna Timber" breaks down to:

CE - CE approval
1224 - identity of notified body (?)
CPD - European Constructions Programme Directive
0099 - number of the product
Sumantna Timber - manufacturers name

after that on the same line there should be some other detail starting with the year of production (e.g. 06), etc and there may also be a standard such as "EN 636", a standard for exterior use, although it might also state "EN 13986" which indicates that the panel has been bonded with a phenolic resin, which is waterproof :confused:

There should also be a line below that which has the product name, structural grading, etc. something like this (from a board in my workshop):

"WISA-Spruce STRUCTURAL 2+ BS:5268-2:2002"

That means that this board here is a spruce plyboard tested to EU standards "Structural 2+" and meeting BS:5268-2:2002 - the required standard for structural building boards used in floors, walls and roofs. It is the "Structural 2+" bit which will tell you that the boards are OK for structural use and generally implies exterior. Sorry if this is a bit arcane, but I rarely need to know that much detail about plywood - this has been an education as I have tried in vain to find a single source of information on this topic on the web :evil:

Scrit
 
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Hi

I swear that there are no other markings on my wood... yikes - do you think that they used internal use ply!?? I am really worried now.

If it was for internal use would it still have a number for internal use??

Sorry to go on!
 
Sorry I didn't mean to alarm you! I wouldn't worry so much, though. The name sounds like a Malaysian or Indonesian mill in which case it is in all probablilty a hardwood with a WBP bond. The only hardwood plywood I regularly see which is not exterior grade is certain classes of Baltic birch plywood destined for the furniture trade - any they are mainly weird sizes like 5 x 5 ft. Why not ask the builder on Monday? BTW, interior grade would have different EN or BS numbers as there are standards for them, too.

Scrit
 
do you know who the builders merchants or timber yard your builder uses!!!!

phone them up and see if they sell sheets marked up as such

another point to note if they aint full sheets you could have part of the codeing missing

so if your sheets are only say 7ft 8" the relevent information may be lying on the floor or in the skip ;)
 
will ask them tomorrow, cheers!

I was just paranoid as I had not seen any markings that I understood as being external (or internal).
 
EN 636", a standard for exterior use, although it might also state "EN 13986" which indicates that the panel has been bonded with a phenolic resin, which is waterproof


Hi Scrit!! Thanks so much for the info, I went and found some blurred text, which read:

the year - 04

EN 636-3
EN13986

Thank goodness, it is the right wood! No WBP stamp, though but thanks to you I have my mind at rest :)
 
WBP plywood - what is it??
hi weather and boil proof ply is made to conform to a certain standard and is pretty good too good quality veneers and waterproof glues the next standard is marine ply where all all veneers are the same type of wood and no gaps atall and very expensive
wbp will resist wearher and will stand the odd soaking as long as it is allowed to dry out but it is just wood so if it gets wet it may stain and constant soakings and dryings will eventually assist it to rot by encouraging fungi and bacteria to take up residence and munch.
a stain does not mean rot. if the ply is going to be exposed to weather once the job is complete then it will need to be protected with paint or varnish old school says when wood is properly dry [please weather] apply knotting [like a yellow varnish readily available at hardware shops etc to stop knots leaking and staining the paint] then prime then stop {put a suitable filler in any visible dints and holes then 2 coats undercoat and2 coats gloss/topcoat the better the paint the longer the interval between repaints.
I would use International boat paint boats have a hard life so it has to be good.
However most modern paints have had the guts ripped out of them by modern pollution and safety laws and price wars. tho the boat paint is still best
so if you are on naked wood you could go a different route with one of the modern systems such as breathable paints which allow moisture to flow in and out of the timber at a molecular level and so prevents wetness getting trapped and pushing the paint off and so on so theory says both wood and paint will last longer seems to work too.
option 3 is one of these modern water based wood stain type things like the stuff you put on fences easy to apply therefore cheap but probably needs a recoat every year which again will be quick and easy therefore still cheap hope this helps billyo
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Hi

I am having an extension built and the upstairs level is to be built from timber and the plywood cladding is meant to be WBP ply. Water and Boil Proof is what WBP stands for isn't it?

The plywood has gone up and today it absolutely chucked it down with rain and I noticed that the plywood that they have used for the job seems to have absorbed a lot of water (dark stain patches appeared after it rained).

I thought WBP plywood would not absorb any water, am I wrong? Is it just that the glue in the veneers is waterproof, but the veneers are not actually sealed?

How can I tell if they have used proper WBP ply?

Thanks!
 
Hi Billiyo
Thank you for that excellent description & I don’t disagree with any of it but do you realise that this thread is over 5 years old. Corrado’s almost certainly finished his extension by now & may even have sold up & moved on.

Welcome to the Forum but please check the “last post” date before posting yourself.
 
Hi Billiyo
Thank you for that excellent description & I don’t disagree with any of it but do you realise that this thread is over 5 years old. Corrado’s almost certainly finished his extension by now & may even have sold up & moved on.

Welcome to the Forum but please check the “last post” date before posting yourself.

Yes but Corrado's not the only person who will read this.
 
Hi Billiyo
Thank you for that excellent description & I don’t disagree with any of it but do you realise that this thread is over 5 years old. Corrado’s almost certainly finished his extension by now & may even have sold up & moved on.

Welcome to the Forum but please check the “last post” date before posting yourself.

Yes but Corrado's not the only person who will read this.
Gah Darwood you Muppet! Stop dragging up old posts. :evil:
 

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