White Oak Bench

[Brian Livingstone]

Hi,

I recently completed this bench.  It is 7 feet by 18 inches by 18 inches, 1.5 inches thick.  It is joined at the beveled corners with four 12 by 60 mm dominos.  All of a sudden I am wondering if the beveled joints are strong enough.  It is for the lobby of an apartment building.  I supposed I could add say a four inch wide stretcher from end to end. 

What do you think ?

Thank you.

Brian

 

[woodbutcherbower]

Not what you want to hear for sure = but joints shouldn't be your only concern. Your concern should also be the implications of an inch-and-a-half thick, 7-foot span being sat on by three average-sized NA citizens weighing around the average CDPC statistical = almost 600 pounds.

If really large people sit on there, the bench might have to support somewhere near one-third of a ton - so my advice would be to get back out there immediately, and insert a temporary stay or some kind of vertical reinforcement in the centre until you decide on the best way to strengthen it whilst keeping its clean good looks.

Plus - the 45-degree bevel joint looks great, but the seat will want to slide downwards and the uprights will want to splay outwards the microsecond Peter Griffin sits in the centre of it. So don't take the risk. Use a 90-degree joint, with the seat sitting directly on top of the uprights. Peter's weight is then transferred directly down to the floor - not down the slope.

 

[luvmytoolz]

Hi Brian, I would absolutely beef that up a bit, apart t=from the mitred corners being a likely shear point, there is really not much stopping it from collapsing sideways under load. I'd add supports at each end to reinforce the mitred joints, and a brace front and rear at the top to help with lateral support. A stretcher in the middle height and depth wise would also be an advantage.

Given it's in a public place you must assume it will be used and abused.

 

[Crazyraceguy]

I agree with both of the above. If it was for the mudroom of your own house, where your kids were putting on shoes, it would have been fine. However, is a commercial/public space, no way.
I think I would add a stretcher that stands on vertically (on edge). This does two things, tying the sides together below the miters and providing racking strength at the same time. Maybe half-lap a vertical member in the middle to support the span. This effectively cuts the distance in half.