Load bearing

[Fanatical Meat]

Something I have been thinking about.
Let’s say you have four screws/bolts in a square pattern in standard 2x4 lumber and it is a reasonable length let’s say two feet, if you screw four mounts that hold 60 pounds each that are level and are in a box form does the finished hanger hold 240ish pounds?
I know some will be lost to uncontrollable things like the wood or them not being perfectly level.
Is there a simple formula to know how much multiple mounting things can safely hold?

 

[herm0016]

i would de-rate each mount about 30% for multiples, because they will never be perfectly aligned and one or 2 will always hold more than the others.
also, you have to figure in leverage, the strength listed is in shear, and your load will never be in prefect shear, as some of the weight will be some distance from the wall.

 

[Fanatical Meat]

i would de-rate each mount about 30% for multiples, because they will never be perfectly aligned and one or 2 will always hold more than the others.
also, you have to figure in leverage, the strength listed is in shear, and your load will never be in prefect shear, as some of the weight will be some distance from the wall.

So in my example it would hold around 165 pounds give or take a little.

 

[snoopy7548]

Hanging a sex swing? 165lbs won't cut it.

 

[Fanatical Meat]

Hanging a sex swing? 165lbs won't cut it.

You need a smaller wife....

 

[deadlyapp]

I cannot picture what in the hell you're trying to describe. Simply put, you have to generally only concern yourself with shear and moments. A beam or connection in shear is generally fine in terms of overall strength, however deflection will be what usually results in an issue. While a moment, and how the ends are fixed, and the resistance to twisting of the beam and connection method is usually a bigger issue.

There's a decent calculator here: http://www.woodbin.com/calcs/sagulator/ that helps with certain pieces of it, however I can't tell if what you describe fits nicely into any normal calculator

 

[Greenman]

I cannot picture what in the hell you're trying to describe. Simply put, you have to generally only concern yourself with shear and moments. A beam or connection in shear is generally fine in terms of overall strength, however deflection will be what usually results in an issue. While a moment, and how the ends are fixed, and the resistance to twisting of the beam and connection method is usually a bigger issue.

There's a decent calculator here: http://www.woodbin.com/calcs/sagulator/ that helps with certain pieces of it, however I can't tell if what you describe fits nicely into any normal calculator

This is why I didn't offer a response. A simple dead load is pretty easy to figure out, once you add movement into the equation things get hairy fast.

 

[paperfist]

No guts no glory

 

[Fanatical Meat]

I was talking like a square wall plate that is secured in all four corners that is secured to a wall, not dry wall.

 

[BarkingGhostar]

Hanging a sex swing? 165lbs won't cut it.

You saying his lady is fat/heavy, or that he might be hanging something else in the sex swing?

 

[Fanatical Meat]

You saying his lady is fat/heavy, or that he might be hanging something else in the sex swing?

I mean she could be really tall or really muscular.
Also if hanging a sex swing it really should be done by the rafters because how would you swing against a wall?

 

[jmagg]

I cant put together what you're trying to explain. Draw and post.

 

[deadlyapp]

I guess I'm interpreting it as the below? And you're wondering if one bracket is rated for 60lb as installed, if the four is correspondingly rated for 240lb. Generally I'd say it would probably be pretty close, as long as your support (eg studs, block wall, etc) is very fixed as shown. If you don't have the same type of vertical supports, then you're going to have more sag with the two supports. It's a lot more complicated then just "yes" with the information you've provided so far.

 

[Fanatical Meat]

I guess I'm interpreting it as the below? And you're wondering if one bracket is rated for 60lb as installed, if the four is correspondingly rated for 240lb. Generally I'd say it would probably be pretty close, as long as your support (eg studs, block wall, etc) is very fixed as shown. If you don't have the same type of vertical supports, then you're going to have more sag with the two supports. It's a lot more complicated then just "yes" with the information you've provided so far.
View attachment 38654

yeah this is more or less what I was asking. I don’t have a specific project now, I do have this discussion with my wife frequently about hanging stuff and supporting it.
I do plan on making some basic floating shelves for the car to hang out on and to organize some stuff in a spare bedroom.

 

[deadlyapp]

yeah this is more or less what I was asking. I don’t have a specific project now, I do have this discussion with my wife frequently about hanging stuff and supporting it.
I do plan on making some basic floating shelves for the car to hang out on and to organize some stuff in a spare bedroom.

In general, for your purposes, you'd probably be able to get away with saying that yes, two 60lb rated brackets with a shelf on them can probably hold a total of 120lb, however a lot will ultimately depend on how far the load is from the wall. If we're talking about a standard construction wall with 16" studs on center, you'll probably get away with most anything, however the closer towards the center of the wall (vertically), the more load you're putting on the center of the upright beams if they aren't tied together inside the wall.

Generally, anytime I want to significantly load a wall, I make sure to also provide a support to the floor itself, and keep the load very close to the wall if possible. I have about 1000 lbs hanging on a wall constructed using steel studs that are 24ft tall without any issue, because I have wooden brackets tying about 6 of the studs together, and ultimately drive the load into a concrete floor using vertical tie-ins as well.

 

[paperfist]

Some of those fasteners are jokes though. Some are rated for 100# but snap when you insert them. Same with toggles, not all are created equally.

Bolts would be the strongest but the hardest to sink in. There’s construction screws that are used for structures that are extremely strong. It also depends on the quality of the wall.

 

[Scarpozzi]

Some of those fasteners are jokes though. Some are rated for 100# but snap when you insert them. Same with toggles, not all are created equally.

Bolts would be the strongest but the hardest to sink in. There’s construction screws that are used for structures that are extremely strong. It also depends on the quality of the wall.

Indeed. Also, when fasteners are tight enough, they tend to fail less. If they have any opportunity to flex, it provides them an opportunity to snap.

Back to the OP's question....and in relation to my statement. If the fasteners are thick enough, they should support 240lbs dead weight in your example. If you're talking live load....that could vary. I would definitely consider metal reinforcement where possible and staying away from cheap/brittle hardware. I've had too much fail since metal alloys out of China are shit the past 15 years.