D4 wood Glues

[RickH]

In previous thread got to the bottom of how best to join some large outdoor timbers:
//www.diynot.com/forums/woodwork/end-to-end-scarf-joints.375347/

Need to have a high strength D4 rated wood glue for this job.

Originally was going to use my usual external adhesive (Resin W), but thought that a D4 adhesive with some gap filling properties might be better.

AFAIK Polyurethane while having D4 waterproof rating are not that high in structural strength, especially when they have foamed to fill gaps.

The worst gaps are less than 1mm ... but want to use gap filling adhesive to prevent water ingress in future.

I see that there are 'Gell Polyurethane' such as Lumberjack:
http://www.toolstation.com/shop/5+Minute+Polyurethane+Wood+Adhesive+Gel+310ml/p78519


Are these any stronger than standard PU glues?

 

[big-all]

d4 will fill 1-2mm gaps ok with enough glue and pressure
pu is foaming glue which will fill several millimeters but looses strength as it foams but is still extremely strong as it covers both surfaces
at 2mm gap it will be pretty much full strength [97% give or take 3 i would think]

 

[RickH]

when you mention D4 are you referring to PVA D4?
I ask as the PU glues are D4 as well.

'D' Durability ratings only refer of course to water resistance, not strength.

 

[big-all]

this d4
http://www.toolstation.com/shop/D4+Wood+Glue/p61864
and this pu
http://www.toolstation.com/shop/p52489

 

[RickH]

Those are both D4 glues.
one is PVA the other PU, but both are D4.

 

[big-all]

Those are both D4 glues.
one is PVA the other PU, but both are D4.

ok we learn something new every day
thanks for that