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aenglish
Joined: 21 Jan 2009
Posts: 78
TV/Projector: Barco BG808s (2002 build)
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| Posted: Sat Feb 21, 2009 5:49 am Post subject: Mounting to Engineered beams |
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I got my projector home tonight. My wife's eyes almost poped out of her head when she saw the size of the Marquee.
We were looking at the floor joists in the basement where we plan on mounting and have some concerns. We have engineered i-beams that I need to anchor my unistrut to. I found an old thread that talks about sandwiching the beam with some dimensional lumber and then anchoring to that.
Has anyone done this? I'm having a little bit of trouble visualising this, I assume you would sandwich the webbing above the bottom plate as I can't see running lag bolts into the tiny bottom plate. Would a 4' 2x4 sandwich on 3 joists be adequate?
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jkruger
Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA
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| Posted: Sat Feb 21, 2009 7:02 am Post subject: |
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Quoting Huggy: "Dude ,you dont need to sandwich jackshit, just screw your unistrut straight to the bottom chords with 6mm or 8 mm screws and it will go nowhere.
I am a qualified Carpenter and a domestic builder and use I-joists everday,it's a great product and very well engineered."
Aw Hell, Just cut a gap in the bottom of the beam and recess the PJ up out of the way. Those silly little thin beams don't do anything anyhow. If you cut two how many do you have left? Must be more than enough.... f*ck it, pour another cocktail!
Then you won't feel it when the floor above you falls on your head.  
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huggy
Joined: 02 Aug 2008
Posts: 927
Location: Melbourne,Australia
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| Posted: Sat Feb 21, 2009 12:12 pm Post subject: |
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This is why I deleted it
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sat Feb 21, 2009 1:18 pm Post subject: |
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| jkruger wrote: | | Then you won't feel it when the floor above you falls on your head. |
Are American houses really that poorly built? Ive got a few friends over there in various states that told me they are in alot of cases but i never really believed it... 
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Sat Feb 21, 2009 2:16 pm Post subject: |
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A very rough MSPaint cross section, should be fairly obvious. The dark grey is a flanged hanger for threaded rod, green is dimensional lumber as required to get past the bottom I flange in the engineered timber.
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"Those countries which lag behind in industry, in the application of mechanics and technical chemistry, in the careful selection and utilization of natural products, where the respect for such activities does not permeate all classes of society, will unfailingly decline in prosperity. They will sink faster when neighbor states, with an energetic exchange between science and industry, go forward with renewed vitality."
-- Baron Alexander von Humboldt: 1769-1859
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Sat Feb 21, 2009 3:49 pm Post subject: |
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If you have the type of I Beam as shown in the last post with a 2x4 top and bottom with a 1/2' plywood runner then you have no problem. Drill a hole through it up-wards then use 3/8 bolt washer, lock washer, teflon acorn style nut, with uni-strut across the three beams, and that is more than sufficient. Theses types of beams are engineered to support 100lbs of live load per sqft of floor space above.>250 lbs projector won't even phase them.
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Firefly rules. Can't stop the signal.
http://www.hulu.com/firefly
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Sat Feb 21, 2009 4:26 pm Post subject: |
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sure, they are designed to support more than a PJ weighs, but in a downward direction *pushing* on the beam. if you hang the PJ from the bottom 2x3 dimensional peice then you are relying that this piece will separate from the plywood (OSB) runner.
slapping dimensional wood on either side as per Heywood's diagram will be much better. i would add three mods to it.
1) width: cut the additional (new, green in the diagram) piece so that they fit completely between the top and bottom 2x3
2) length: make these addtional peices long. this will spread the load
3) support: attach these addional peices to the engineered beams not just with a crossways bolt as diagramed but with lots of glue, and bolts from one to the other through the runner of the engineered beam you want these new peices to be solidly attached to the engineered beam in their own right
i'm not a framer by trade (but have some casual experience). if your PJ/celing/floor/house falls down - don't sue me 
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Feb 21, 2009 4:43 pm Post subject: |
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| zaphod wrote: | | sure, they are designed to support more than a PJ weighs, but in a downward direction *pushing* on the beam. if you hang the PJ from the bottom 2x3 dimensional peice then you are relying that this piece will separate from the plywood (OSB) runner. |
true, but the pic looks like more work than necessary. I would simply cut a piece of plywood and glue-screw it across the face of the I-beam with plywood screws. Thereby tying the upper and lower runner together. Whoila, your now pulling on the entire beam. Then just bolt directly to bottom runner. I would use 5/16ths lags instead of 3/8, less chance of splitting out the side of bottom runner.
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Sat Feb 21, 2009 5:42 pm Post subject: |
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Yep that will work too. Remember your not building the space shuttle,just mounting a light weight load as far as the beam is concerned,not us [my back is killing me thinking about the lift].
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http://www.hulu.com/firefly
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Bruce 09
Joined: 08 Mar 2006
Posts: 747
Location: Kamloops BC, Canada
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| Posted: Sat Feb 21, 2009 5:46 pm Post subject: |
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| draganm wrote: | | zaphod wrote: | | sure, they are designed to support more than a PJ weighs, but in a downward direction *pushing* on the beam. if you hang the PJ from the bottom 2x3 dimensional peice then you are relying that this piece will separate from the plywood (OSB) runner. |
true, but the pic looks like more work than necessary. I would simply cut a piece of plywood and glue-screw it across the face of the I-beam with plywood screws. Thereby tying the upper and lower runner together. Whoila, your now pulling on the entire beam. Then just bolt directly to bottom runner. I would use 5/16ths lags instead of 3/8, less chance of splitting out the side of bottom runner. |
This is the better way to do this, this is how half I joist repairs are done . There is nothing wrong with lag bolting to the bottom flange.
Th main thing I would be concerned about is floor bounce TJI's provide a strong floor but they also have more flex than traditional dimensional lumber .
If your projector location is midspan and you do not mind doing a little extra work you could sister on plywood gussets Like dragan described for two thirds of the span on the three joists that connect to the mount .
This would stiffen up those joists and keep the movement of the projector to a minimum when the kids are running across the floor upstairs .
Make sure that any wood you attach is glued with construction adhesive, any piece that isn't and touches the joist or floor has a potential to squeak .
Bruce
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jkruger
Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA
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| Posted: Sat Feb 21, 2009 6:34 pm Post subject: |
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Anything you do to the bottom runner will reduce it's strength. How much? Maybe not enough to cause a problem, but the method in Heywood's diagram looks like the best way to me.
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Bruce 09
Joined: 08 Mar 2006
Posts: 747
Location: Kamloops BC, Canada
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| Posted: Sat Feb 21, 2009 7:06 pm Post subject: |
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| jkruger wrote: | | Anything you do to the bottom runner will reduce it's strength. How much? Maybe not enough to cause a problem, but the method in Heywood's diagram looks like the best way to me. |
Technically Heywood's method compromises the joist the most by adding lateral load to the web .
The plywood gusset is the ONLY way that is accepted in an I joist repair , some will require web filling first . The gusset Will add so much "strength" to the joist is it not funny .
I have repaired Joists that had either the full top or bottom Flange damaged or simply completely cut out . For the simply load requirements and mounting bracket used every fix here will work . The center span of the joist is also the least critical for structural compromise.
Bruce
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aenglish
Joined: 21 Jan 2009
Posts: 78
TV/Projector: Barco BG808s (2002 build)
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| Posted: Sat Feb 21, 2009 7:23 pm Post subject: |
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Thanks for all the suggestions. I think I have enough infomation not to jepordize the sturcture in hanging this thing.
Any suggestions on convincing my wife that this is a better solution than going with a small digital pj. She's concerned about the complexity of this (both mounting and operation) and just can't understand why the projector has to hang where just in front of the couch and with lenses so big, why we can't put it closer and just zoom them!
i've tried to explain how this pj works and why it will be better, but how did the rest of you convince your better halves?
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There are 10 kinds of people in the world, those who get binary and those who don't.
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jkruger
Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA
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| Posted: Sat Feb 21, 2009 7:48 pm Post subject: |
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I didn't convince the other half, I got rid of her.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Feb 21, 2009 9:57 pm Post subject: |
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| aenglish wrote: | | i've tried to explain how this pj works and why it will be better, but how did the rest of you convince your better halves? |
you can't, not unless you try to convince her that the PJ has feelings 
The way the rest of us did it is just mount it, set-it up, and watch a movie. The thrill of a HT is enough to stop the bitching in all but the most extreme cases
Aftter the movie is over and everyone is talking about how great it Tell here a new bulb for the cute ones is at least $300. every 1500 hours.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Feb 21, 2009 11:22 pm Post subject: |
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| jkruger wrote: | | Anything you do to the bottom runner will reduce it's strength. How much? Maybe not enough to cause a problem, but the method in Heywood's diagram looks like the best way to me. |
| Bruce09 wrote: | Technically Heywood's method compromises the joist the most by adding lateral load to the web .
The plywood gusset is the ONLY way that is accepted in an I joist repair , some will require web filling first . The gusset Will add so much "strength" to the joist is it not funny . I have repaired Joists that had either the full top or bottom Flange damaged or simply completely cut out . For the simply load requirements and mounting bracket used every fix here will work . The center span of the joist is also the least critical for structural compromise.
Bruce |
At my work there is a designation to a job title called "line staff authority". It means that the person in question is regarded as an expert in their field and their opinion has the most value and is considered the "final word" on a situation requiring their feedback. In this case, I think Bruce's opinion has "line staff authority"
It's good to know these things are repairable though, I think they're a much better product than most people assume. While i love natural wood and it's imperfections can be beautiful in furniture those flaws not really very good in a structure. engineered lumber is cheaper and stronger in every case.
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jkruger
Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA
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| Posted: Sat Feb 21, 2009 11:33 pm Post subject: |
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| draganm wrote: | | jkruger wrote: | | Anything you do to the bottom runner will reduce it's strength. How much? Maybe not enough to cause a problem, but the method in Heywood's diagram looks like the best way to me. |
| Bruce09 wrote: | Technically Heywood's method compromises the joist the most by adding lateral load to the web .
The plywood gusset is the ONLY way that is accepted in an I joist repair , some will require web filling first . The gusset Will add so much "strength" to the joist is it not funny . I have repaired Joists that had either the full top or bottom Flange damaged or simply completely cut out . For the simply load requirements and mounting bracket used every fix here will work . The center span of the joist is also the least critical for structural compromise.
Bruce |
At my work there is a designation to a job title called "line staff authority". It means that the person in question is regarded as an expert in their field and their opinion has the most value and is considered the "final word" on a situation requiring their feedback. In this case, I think Bruce's opinion has "line staff authority"
It's good to know these things are repairable though, I think they're a much better product than most people assume. While i love natural wood and it's imperfections can be beautiful in furniture those flaws not really very good in a structure. engineered lumber is cheaper and stronger in every case. |
I have to agree with you. I did not consider the lateral load, and the plywood gusset is the best way to repair a damaged joist.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Sun Feb 22, 2009 4:54 am Post subject: |
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This whole discussion only applies to engineered lumber right..? My PJ is going up fairly soon and I'm planning on just driving lag bolts into my natural wood joists...Don't want it to fall on my head tho 
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Sun Feb 22, 2009 5:08 am Post subject: |
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Yes only engineered beams need some reinforcement. Standard dimensional lumber like a 2x10 is safe to lag bolt directly into. And my oh my we are all just so worried abouut lateral load down- ward load man it just ain't that much weight to worry about.Not across 3 joists.
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Firefly rules. Can't stop the signal.
http://www.hulu.com/firefly
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MikeEby
Joined: 24 Jun 2007
Posts: 5237
Location: Osceola, Indiana
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| Posted: Sun Feb 22, 2009 5:19 am Post subject: |
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| CRT_Ben wrote: | | This whole discussion only applies to engineered lumber right..? My PJ is going up fairly soon and I'm planning on just driving lag bolts into my natural wood joists...Don't want it to fall on my head tho |
Just make SURE you hit the joists square and in the center.
I guess its fine I just didn't like the idea. For my Cheif lift I used Uni-Strut "L" brackets and drilled holes in joists bolted threw the joist then attacted the uni-strut to the "L" bracket. Sorry it might not be clear in the image, these were from 2002 and so far no bumps on the head.
The projector is also recessed into a sofit making the photos more confusing.
Mike
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