I have an 80lb or so heavy bag. We just finished a bonus room upstars
with painted ceilings and 7 foot ceilings. I was trying to figure the
best way to mount it. I will be punching and kicking it. Will this
jolting cause problems with my sheetrock or anything? The mounts I see
at the store use two lag bolts to screw into a rafter. This holds a
bracket that the bag hangs on.
I woul dlike the mount to be as invisable as possible because the wife
is not too thrilled about seing anything.
Any help would be greatly appreciated!
beam... If you're a real wiz with tools, drill a hole through your ceiling
to the joist, then have a pin go through the joist(horizontally) and have
your chain/whatever hooking on that... (you'd want some sort of sleeve on
the hole through the ceiling to avoid rub damage).
I've currently got a 4 inch screw-in that goes through the ceiling and into
a joist... not bad, but I've had it come right out(as in rip itself out of
the wood) due to jarring...
Ps.. I use beam/joist interchangeably, 'cause I know d$ck about carpentry...
No way you can do this without strengthening your joists, unless you have
a centre beam.
If you just put leg bolts into the joist every good kick will wreck joints
in the drywall. You have to run supports between the joists and lock the
entire cealing together. If you can access your attic this won't be very
tough. But it will take some wood.
You may want to get a metal brace made with a swivel hook through it to
run between two joists, brace those joists so three joists are tied
together for a good section of the span and then put a circular recessed
lighting type of thing into the ceiling and hook through the empty hole.
The diameter has to be low enough it can swing.
But I have one down in my basement running through a centre beam and the
entire house shakes when I use.
--- email address above is a non-monitored spam sink.
Do you have any specific protocols for strengthening joists?
Are joists tonic or phasic and does that have implications for their training?
How should I work my joist strengthening into my overall yearly plan?
Should it be periodized and, if so, how?
o.c. - not that it matters in this case though) with a span of
12 feet. With this size joist and this span deflection is acceptable with a
point load of ~875 lbs. And that's just hanging it off one point on one
joist. 2x10 joists with a 12' span have a load bearing capacity of ~73 lbs.
per lineal foot. And these numbers are for acceptable deflection, which is
no where near total failure.
Now in the case of the OP he's dealing with a "bonus room" with "7'
ceilings" which implies that he's probably got collar ties to hang off of
(if the ceiling is flat) or rafters/trusses (if the ceiling is sloped). If
they are indeed collar ties (usually 2x4s or 2x6s) or trusses (which
generally are made out of 2x4s) then he's dealing with substantially smaller
lumber. If they are rafters (i.e. 2x8s, 2x10s, 2x12s etc - depending
primarily what part of the country the house is located in) then it's just a
matter of figuring out what the snow/wind loads are and how they effect the
total load capacity.
You do? Why?
There is no "attic" in the traditional sense above a bonus room, since by
definition, a bonus room IS the attic.
The shaking is caused by the vibration of the beam, not because it isn't
braced well enough. Cross bracing multiple joists is not going to
significantly reduce vibration transmission.
o.c. - not that it matters in this case though) with a spanof
Yes it is more than the weight of just the bag, but is it enough to cause
unacceptable deflection? Is it enough to cause total failure? Depends upon
all the parameters but in most all cases I'd say no.
First off what are you trying to accomplish by distributing the load? You
have yours mounted to the central beam of your home correct? What's the
size of that beam? Lets say it's a 6x10 solid timber beam, so that's the
lumber equavalent of (4) 2x10s. The solid timber is going to be stronger
than 4 seperate joists ganged together. So when you mention bracing joists
together my reply is why? There's maybe some miscommunication about what
the bracing is going to do. It will not significantly reduce deflection
(bending of the joist). It could however reduce the shear force by
spreading it out to other joists. If the bag is hung at one point then your
static load is going to be straight down. Hitting or kicking the bag will
cause shearing stress (lateral deformation) but since it's hung from a chain
that helps reduce some of the shearing force into deflection (bending).
Also keep in mind that there already probably is some "bracing" in the form
of T&G subfloor (if there's a floor above) and gypsum board (if the ceiling
is finished). Also, unsually both ends of the joist will be nailed to a rim
joists, which acts as a form of bracing (though it serves other purposes
The shaking you experience is vibration caused by deflection (within
acceptable limits). I have a steel W6 beam that runs down the center of my
house. One end of my joists bares on the exterior wall and the other on the
center beam, and then from the beam to the opposite exterior wall are other
joists. When I jump up and down on one side of the house and it's felt on
the other that doesn't mean that it's not braced properly. The vibration is
just being passed through the floor system (and the walls and ceiling to a
small extent). The amount of bracing (and other special construction)
required to totally eliminate this would be insane (better would be a
concrete slab, which is very good in deflection, but piss poor is torsion).
Stand on a bridge as a car drives over it, you can feel it (ignore the
audible sound and wind). Obviously the bridge is braced very well but yet
you can feel a small car drive over it but yet it's still strong enough to
support the weight of a bunch of full loaded semis stopped on it during rush
A better avenue to persue would be a vibration isolator (also called
isolation mount) that is used to reduce the transmission of vibration and
noise to the supporting structure. Or even some form of resilient mounting
"that permits surfaces to vibrate normally without transmitting the
vibratory motions and associated noise to the supporting structure" (as
quoted from "A Visual Dictionary of Architecture", Francis D.K. Ching -
Clear as mud?
Nope. Sounds reasonable. I personally don't have a problem with vibration
as I only train on the bag when no one is home. I assumed in an upper room
it would wreck the drywall. Apparently I assumed RONG.
Won't be the last time. You learn something new everyday.
The email address above is a spam sink - no longer monitored
Because the loading on a single joist will allow the lateral
joist deflection to crack the drywall.
Think about that. If the vibration is at an undesirable level,
then the structure isn't stiff enough against the loading.
Actually, it will substantially reduce the vibration
transmission, because the part of the structure the bag is
acting on will be substantially heavier and and stiffer.
Keith never said that you'd break joists, so this is a red
herring. I wouldn't worry about failure of a joist (unless the
joist is already cracked, or the fastener compromises the bottom
fibers of the joist, which are loaded in tension. The real
issue is cracking of sheet rock.
Untrue. Ganging 2x10's produces a structure that is stronger
than a solid timber, because cracks and checks in one piece
don't propagate into its neighbors. A solid timber will deflect
less laterally, but not in the intended load direction.
One reason would be to limit lateral deflection of a joist,
which could crack the ceiling. Another reason would be to
increase the effective mass of the structure the bag bears upon.
You're thinking simplistically. Bending of the joist in a
vertical plane is probably not the issue here. In the lateral
direction, ganging joists will substantially reduce deflection.
Shear? Away from the walls, shear is not important. Lateral
load is still largely a bending load, as far as a joist is
A chain may (or may not) reduce the lateral load (depends on
dynamics), but that doesn't change the fact that you could crack
the ceiling with a strong kick if the bag is hung from a single
joist. I'd suggest spanning 3 joists, personally.
Over the long haul, gypsum board will not help with this kind of
loading. It will gladly crack to relieve such loading.
That may or may not help. Joists, studs, ring beams, etc. all
move somewhat relative to one another, so some motion could
occur that cracks sheetrock.
Please tell me what kind of vibration isolator will damp kicks
to a heavy bag.
Put some money in an interest generating bank account.
Get a time machine.
Travel to the 24th century (or whenever "Enterprise" is set, I'm
assuming that would be roughly when the inertial dampener had been
perfected sinec Scott Bakula is still alive).
Buy one with the money from the interest bearing account.
Unless you are sure you will center the lag bolts on the rafters, I would
bolt a 2x4 or 2x6 across 2 rafters using 2 bolts on each end, paint the
board the same color as ceiling, then bolt the plate onto the 2x4 or 2x6.
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