Laminating wood for outdoor bench

[Rob D]

Evening all
Wanting to make an outdoor bench, I’ve found plans that I want to follow along with but it specifies legs over 3 inches thickness.
Would I be ok laminating 2 pieces of oak for outdoor use or would it cause issues?

 

[Beau]

I'm going to say a cautious yes. Even solid wood can crack when exposed to wet and dry cycles but modern glues are pretty good. Make sure your oak is thoroughly dry first to limit tension as much as possible. I would probably use epoxy resin to be on the safe side but its not cheap stuff.

 

[Eshmiel]

Laminated oak glued with a waterproof glue such as Titebond 3, meant for outdoors (and perhaps reinforced with oak dowels or those rot-resistant dominoes) will be OK outdoors. Make sure its a durable oak (not red oak, for example) and only the heartwood (the sapwood is full of sugars and has little tannin, so is enjoyed by the wee burrowing beasties).

It helps a lot if any laminations can have the grain of the pieces arranged so that any expansion/contraction warps of the parts that are laminated will tend to move in unison. A major difference in grain direction of two or more parts glued together is more likely to cause a parting of the parts.

 

[niall Y]

I would say forget about trying to laminate wood for outside, just using glue, or rather glue alone. Outside joinery traditionally never used glue for the reason that it doesn't survive the rigours of outside no matter how waterproof it claims to be. I have in the past laminated large Iroko gate posts though I took the precaution of also screwing them together with coach screw, with heads dropped below the surface and a wood plug to their top. I also added a lead capping to the top of the post to stop water finding its way into the join.
So, if one must - then belt and braces would be the wisest approach.

 

[okeydokey]

Fence posts? Worth considering?

 

[johnnyb]

Don't do it, . They always move and basically fall apart.

 

[Eshmiel]

Don't do it, . They always move and basically fall apart.

How many samples have you observed in order to form this judgement?

I've made some laminated parts myself for outdoor things and have seen the odd failure but also plenty of still-together items, even after 16 years outdoors in all weathers. Orienting the grain; Making a well-fitted join; putting in some reinforcement of the join in addition to glue; keeping the finish good to minimise the chance of water ingress ..... .

It comes down to: how long do you want the item to survive and in what degree of outdoor "stresses". If it'll last the N years you're happy with, then it's a reasonable thing to do. After all, every wood item eventually "falls apart" or rots or otherwise becomes dysfunctional beyond repair.

 

[HOJ]

I have had to do it in the past, without any issues, I only use Cascamite glue though.

Can you not revise the design to match more available stock sizes, for a 75mm finish I would be hesitant to buy in 80mm stock, that's very close to the mark for finishing at 75mm, next size up would be 100mm and very wasteful.