Posted: 10/14/2016 9:54:51 AM EDT
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I want to make a set of monkey bars for my garage. I have 19' from wall to wall. These are cinder block walls with a wood top plate. I am looking at 20ft 2x8s, but I have a transportation issue. It would be easier to get 12'-14' boards and make a composite beam for each side. I cannot put a support post in between, so the span would be 19'.
Has anyone done something like this? |
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I want to make a set of monkey bars for my garage. I have 19' from wall to wall. These are cinder block walls with a wood top plate. I am looking at 20ft 2x8s, but I have a transportation issue. It would be easier to get 12'-14' boards and make a composite beam for each side. I cannot put a support post in between, so the span would be 19'. Has anyone done something like this? Put them on the roof. |
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Put them on the roof. Quoted:
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I want to make a set of monkey bars for my garage. I have 19' from wall to wall. These are cinder block walls with a wood top plate. I am looking at 20ft 2x8s, but I have a transportation issue. It would be easier to get 12'-14' boards and make a composite beam for each side. I cannot put a support post in between, so the span would be 19'. Has anyone done something like this? Put them on the roof. You mean hang them from the rafters? |
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You mean hang them from the rafters? Quoted:
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I want to make a set of monkey bars for my garage. I have 19' from wall to wall. These are cinder block walls with a wood top plate. I am looking at 20ft 2x8s, but I have a transportation issue. It would be easier to get 12'-14' boards and make a composite beam for each side. I cannot put a support post in between, so the span would be 19'. Has anyone done something like this? Put them on the roof. You mean hang them from the rafters? Unless you plan on having multiple people get the load up to the rafters. The roof slope works to your advantage. The more slope the roof has the better. A flat roof would NOT be a good support. |
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I want to make a set of monkey bars for my garage. I have 19' from wall to wall. These are cinder block walls with a wood top plate. I am looking at 20ft 2x8s, but I have a transportation issue. It would be easier to get 12'-14' boards and make a composite beam for each side. I cannot put a support post in between, so the span would be 19'. Has anyone done something like this? 20 ft without a support beam? Make it 3 boards wide, screwed (not nailed) together and it could work. Although it will be super heavy. |
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How much weight total from the middle? Just pulling from bar to bar or major bouncing / flying leaps (how dynamic a load)? I'd think you might be able to glue laminate sheets of plywood together then screw them if you stagger the joints as a sandwich between 2x8 or 2x10. |
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How much weight total from the middle? Just pulling from bar to bar or major bouncing / flying leaps (how dynamic a load)? I'd think you might be able to glue laminate sheets of plywood together then screw them if you stagger the joints as a sandwich between 2x8 or 2x10. If you do this, I would scarf the joints between the sheets instead of a butt joint. You can do a scarf with a circular saw and a jig. |
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How much weight total from the middle? Just pulling from bar to bar or major bouncing / flying leaps (how dynamic a load)? I'd think you might be able to glue laminate sheets of plywood together then screw them if you stagger the joints as a sandwich between 2x8 or 2x10. Just pulling from bar to bar and maybe putting plywood on top to practice climbing over a wall. I pulled out my ME books last night and set pen to paper. Using some values I found from materials suppliers, and a single load in the middle of 250#, I found a beam with (2) 2x6s together with 2x4s on top and bottom gave a max deflection of .278" for one beam across an 18' 10" span. Using nail plates and gluing will give some more strength, but that is just a preliminary number in the direct middle of the beam. |
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Did you include the weight of the beam, itself?
Did you consider the long-term sag of the wooden beam? Was your load static or dynamic? Personally, I would not couple the "monkey bars" into my houses structure, especially not into my roof or roof rafters. Build up from the slab. Whatever stupidity you are planning should not be allowed to threaten your house's structure in any way. |
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Look up flitch beam.
Some steel plate anchored to one side of a wood beam can be scary strong. It does take plenty of screws and snug screw holes in the metal. A few thousandths of an inch of interference on the screw shank to the metal really matters. Correctly done pilot holes in the wood matter also. Wood on both sides with clenched over powder driven nails does an excellent job. A Hilti gun (.27 caliber) allows #10 steel to be used. Half the nails from each side. Something better than #2 wood. |
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Did you include the weight of the beam, itself? Did you consider the long-term sag of the wooden beam? Was your load static or dynamic? Personally, I would not couple the "monkey bars" into my houses structure, especially not into my roof or roof rafters. Build up from the slab. Whatever stupidity you are planning should not be allowed to threaten your house's structure in any way. Detached garage, so no potential harm to main living building. These are all good points, but I read your "stupidity" remark as a snide comment. If it wasn't, I apologize. |
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Just pulling from bar to bar and maybe putting plywood on top to practice climbing over a wall. I pulled out my ME books last night and set pen to paper. Using some values I found from materials suppliers, and a single load in the middle of 250#, I found a beam with (2) 2x6s together with 2x4s on top and bottom gave a max deflection of .278" for one beam across an 18' 10" span. Using nail plates and gluing will give some more strength, but that is just a preliminary number in the direct middle of the beam. Quoted:
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How much weight total from the middle? Just pulling from bar to bar or major bouncing / flying leaps (how dynamic a load)? I'd think you might be able to glue laminate sheets of plywood together then screw them if you stagger the joints as a sandwich between 2x8 or 2x10. Just pulling from bar to bar and maybe putting plywood on top to practice climbing over a wall. I pulled out my ME books last night and set pen to paper. Using some values I found from materials suppliers, and a single load in the middle of 250#, I found a beam with (2) 2x6s together with 2x4s on top and bottom gave a max deflection of .278" for one beam across an 18' 10" span. Using nail plates and gluing will give some more strength, but that is just a preliminary number in the direct middle of the beam. As you are swinging and climbing it will bounce at least twice that much. If that is acceptable, just pay the lumber yard to deliver them. If not, consider buying I joists, and have them delivered. Steel reinforcement suggested by Brickeye is a great idea as well |
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As you are swinging and climbing it will bounce at least twice that much. If that is acceptable, just pay the lumber yard to deliver them. If not, consider buying I joists, and have them delivered. Steel reinforcement suggested by Brickeye is a great idea as well Quoted:
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How much weight total from the middle? Just pulling from bar to bar or major bouncing / flying leaps (how dynamic a load)? I'd think you might be able to glue laminate sheets of plywood together then screw them if you stagger the joints as a sandwich between 2x8 or 2x10. Just pulling from bar to bar and maybe putting plywood on top to practice climbing over a wall. I pulled out my ME books last night and set pen to paper. Using some values I found from materials suppliers, and a single load in the middle of 250#, I found a beam with (2) 2x6s together with 2x4s on top and bottom gave a max deflection of .278" for one beam across an 18' 10" span. Using nail plates and gluing will give some more strength, but that is just a preliminary number in the direct middle of the beam. As you are swinging and climbing it will bounce at least twice that much. If that is acceptable, just pay the lumber yard to deliver them. If not, consider buying I joists, and have them delivered. Steel reinforcement suggested by Brickeye is a great idea as well I might have a line on a trailer. If so, I am leaning toward doubling up a couple of 20ft 2x12s or 2x10s for each side. |
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Look up flitch beam. Some steel plate anchored to one side of a wood beam can be scary strong. It does take plenty of screws and snug screw holes in the metal. A few thousandths of an inch of interference on the screw shank to the metal really matters. Correctly done pilot holes in the wood matter also. Wood on both sides with clenched over powder driven nails does an excellent job. A Hilti gun (.27 caliber) allows #10 steel to be used. Half the nails from each side. Something better than #2 wood. |
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Build yourself a three or four foot wide scaffold that sits out of the way on one side of the garage. Put it on casters if necessary to make it easy to move around.
If you go with the 20 foot span beam, put your chinning bar on one end as close to the wall as possible. If you want the bar in the middle, then buy engineering help, or at minimum find someone that knows the difference between pin ends and fixed ends and can calculate the strength and deflection, and also knows the meaning of "Factor of Safety". |
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Build yourself a three or four foot wide scaffold that sits out of the way on one side of the garage. Put it on casters if necessary to make it easy to move around. If you go with the 20 foot span beam, put your chinning bar on one end as close to the wall as possible. If you want the bar in the middle, then buy engineering help, or at minimum find someone that knows the difference between pin ends and fixed ends and can calculate the strength and deflection, and also knows the meaning of "Factor of Safety". The purpose of the thread was to hear about real world experience. I am a PE and have the equations I need in my books. I also know that no amount of book knowledge can replace field experiences from a grizzled carpenter. |
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The purpose of the thread was to hear about real world experience. I am a PE and have the equations I need in my books. I also know that no amount of book knowledge can replace field experiences from a grizzled carpenter. Quoted:
Quoted:
Build yourself a three or four foot wide scaffold that sits out of the way on one side of the garage. Put it on casters if necessary to make it easy to move around. If you go with the 20 foot span beam, put your chinning bar on one end as close to the wall as possible. If you want the bar in the middle, then buy engineering help, or at minimum find someone that knows the difference between pin ends and fixed ends and can calculate the strength and deflection, and also knows the meaning of "Factor of Safety". The purpose of the thread was to hear about real world experience. I am a PE and have the equations I need in my books. I also know that no amount of book knowledge can replace field experiences from a grizzled carpenter. i.e., trolling. |
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I didn't think earlier... If you can't haul something long, like a LVL, you probably can't haul steel. How about something like a truss design with plywood gussets? I don't know if I have enough space above to make a truss with the right dimensions. The roof over the garage is shallow. Something to look into, though. Thank you. |
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I actually have an Army Engineering test on a flitch beam.
They screwed it up royally by NOT making the holes in teh steel plate tight to teh fastenrs. They then concluded the whole concept was bad. As opposed to their failure to consider that the clearance would allow movement of the wood relative to the flitch plate. |
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I'd have a local lumber yard deliver a 20' glu-lam beam myself. Specify you want a 24F-v4 beam. I didn't figure sizes, but a 24F beam will allow 2400 psi max bending stress, which is more than you'll get out of a 2x8.
As mentioned above though, a 250 lb static load is different from a 250 lb load suddenly applied (2x load factor), or 250 lbs jumping up and grabbing it. |
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I appreciate the tips and ideas. Won't be doing anything soon, though. My garage got broken into and tools got stolen last night. Police report filed and called the local pawn shops. Watching craigslist and fb sale groups as well. Probably SOL, though. 
I hate thieves. ETA: Our security camera/DVR setup is one of my better investments. Won't help this time, but something to consider. |
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I appreciate the tips and ideas. Won't be doing anything soon, though. My garage got broken into and tools got stolen last night. Police report filed and called the local pawn shops. Watching craigslist and fb sale groups as well. Probably SOL, though. Insurance? I have had my tools stolen a few times over the years and it sux. |
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Insurance? I have had my tools stolen a few times over the years and it sux. Quoted:
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I appreciate the tips and ideas. Won't be doing anything soon, though. My garage got broken into and tools got stolen last night. Police report filed and called the local pawn shops. Watching craigslist and fb sale groups as well. Probably SOL, though. Insurance? I have had my tools stolen a few times over the years and it sux. Not enough value to meet our deductible. Have a pretty good idea who was involved, but I had no identifying marks on them. |