Calculating Cantilever Load Limits - Rule of Thumb?

[Beltzington]

Moments, levers and arms, oh my....

Trying to determine if my temporary scaffolding is likely to send me to the hospital, If I have a 2x6 lag screwed to the sheds framing and the screws shear strength is combined 700lbs how far past the screws (inches) can I place the walk plank and not break the bolts under my 200lbs. I am confident the lumber and mechanical connections will not fail just not sure of how to determine the safe limits of the cantilever. Sorry no pictures.

 

[LD1]

Simple answer......impossible to answer based on what you provided. Too many variables. How many screws in total? How far along the sheds framing is is screwed, and whats the screw spacing/pattern. \


How far you wanting to cantilever out? How high off the ground?

 

[brasco426]

Most Cantilevers I've seen are 2/3 secured to the structure, 1/3 for decking or whatever you are standing on.

 

[Egon]

Empirical test. Stand on the ground, put a rope on it and try and lift yourself. When you get to the breaking point cut the distance in half and use that as a working point.

 

[Beltzington]

Empirical test. Stand on the ground, put a rope on it and try and lift yourself. When you get to the breaking point cut the distance in half and use that as a working point.

Great idea, I don't need to break it only make sure it will hold my weight plus the planks 24" from the wall. Better to be sure at 1-foot high than hope the math worked at 10'.

 

[LD1]

24" out isnt much.

I'd think 4' on the building should be sufficient.

 

[GLyford]

Angle braces to points further down the structure, and legs down to the ground are cheap insurance. Side benefit is they take a bunch of the bounce out even if your scaffold is otherwise safe, and give you more confidence to work without distraction.

Related topic: when building scaffolds for working on roof edges, do you usually add hand/hip rails, knee rails and/or foot curbs?

 

[kneedeep]

Anything unsupported is unsafe

 

[CADplans]

An engineering degree tells me to never stand on anything that is cantilevered!!

 

[bcp]

An engineering degree tells me to never stand on anything that is cantilevered!!

Lots of cantilever bridges in the world. You just have to do it right.

Bruce