I just had a garage added on to our house. The ceiling joists are 2x8x24′ and are spaced 48″ apart. I am filling them in so that I have a joist every 16″ and will lay 1/2 plywood on top so that I can use this space for storage, as I will still have about 6″ at the peak. They have vertical collar ties (I think that’s what they are called) on each of their joists on both sides. Do I need to just copy this configuration for each joist I am now filling in? I already have the joists up but I need to add the vertical ties that attache to the roof joists. Any advice would greatly be appreciated.
Thanks,
George
Replies
It is had to imagine what the verticle legs are. They are not collar ties.
And if you plan to use this space rfor storage, these joists are no longer cieling joists. They are now floor joists. They will have some tremendous deflection at that length unless you put a center beam under them. That is about twice as long a span as they should have for 2x8 @ 16"oc.
What is there now were probably intended only as rafter ties to minimally keep the walls from spreading.
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The vertical legs are attached to these joists perpendicular at about 5 ft from each side. They are then attached to another horizontal beam that runs the length of the garage (30 ft.) on each side as well. With everything tied in, they are pretty solid. Plywood will be screwed down so that I have access for storage, etc. There won't be a lot of weight up there (camping gear, boat building forms, etc.).
Remember, you are not building this for you, you are building it for every dork and sucker who might buy your house down the road. Unless you are having a Viking funeral with your house as the boat, you are building this MAINLY for other people to use.
If there is enough space up there for someone to stand, then they are going to store metal filing cabinettes filled with their rock collections up there. It's just human nature.
Think wider spacing on the joists - 24" (no one is dancing up there so who cares if it bounces), thicker flooring - 3/4", and taller joists like wood I joists.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Taller joists is right
But spreading the layout loses what you gain and makes the installation harder since he has rafters already at 16".I would probably up the decking to 5/8" T&G
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Hey Piff,
Where is that stiffback detail I senrt to you sometime back? Do you remember? I can not find the drawing in SP that I did. We have used 2 x 8 joist @ 16" O.C. for storage deck using this detail with good results. I eyeballed one we did and no sagging after several years.
Maybe our OP can use the system, since he already has 2 x 8 joist members.
I had to tell my PC to search for "Stiffback" to find where I'd stored it
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I studied yours som emore,
The floor joists are 2x12 and the method of attachemnt seems to be suggesting the floor in that is lending support to a weak roof rafter. This guy needs the opposite, if the rafters can support the joists.
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Piffin,
We have used this same detail with 2 x 8 joist over a 24' span with storage deck and had no problems. The joist are 16" O.C. and we double them every 4'.
Our engineer adopted the detail, and keeps it in his library for similar situations.
Edited 1/2/2007 4:39 pm ET by txlandlord
We have used this same detail with 2 x 8 joist over a 24' span with storage deck and had no problems. The joist are 16" O.C. and we double them every 4'.
Our engineer adopted the detail, and keeps it in his library for similar situations.
I can't come up with anyconfiguration that will give a 24' span with any wood available in the US. Best I can do is a 19' span with hem-fir at 16" O.C. with a 15 psf load. I wouldn't walk on a floor with a 15 psf load rating, let alone store anything on it.
BTW, if you figure a 150 lb guy and 1 sq ft of contact area, that's 150 psf for a man. You'd have to spread that load over 10 sq ft or more to safely walk on that floor.
Unless your engineer knows something I don't - and if so, I'd like to know what it is. Always anxious to learn
Edited 1/2/2007 6:31 pm ET by woodturner9
Sorry for the misunderstanding. The detail he adopted uses 2 x 12 ceiling joist. The 2 x 8 storage we did is in a rural situation without inspections or engineering required. It saved money, created 4 more inches of headroom in the Attic and was still straight after 4 years of being storage loaded....the last time I checked.
Go easy on Tex there!;)I can see how this CAN be done, though I would hate to be the one proving it. The thing is that his way is not simply a floor plane. The combination of floor, stemwalls/stiffbacks, or whatever term, and the rafters combiunes to create a sum greater than the many parts. I alluded to the example of the cedar strip canoe this guy has built. There is no way you would want to take a sheet of 3/8" material the size of the fllor of his canoe free spanning 12' and stand on it - but hwen it is wrapped in a cylindrical shape, more or less, and the conection points can tolerate the stresses, then it becomes easy to place full confidence in it and know that even though it weighs only about fifty pounds, it could support a 250# human.Same with this attic. The floor plane alone willnever do the job, but combine it with stiffback stemwalls and a couple of roof planes and theoreticly you can pull it off. As a professional, I wouldn't be likely to try it. Not because it is not possible, but because the weak link in this other than the calculations being beyond me, is the connections. so many small pieces all jointed with nails and glue - so much time that would be wasted when it is so far much easier to just use joists sized to carry the load and loose a couple of inches of headroom
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so many small pieces all jointed with nails and glue - so much time that would be wasted when it is so far much easier to just use joists sized to carry the load and loose a couple of inches of headroom
Yes, and in a new build that would be our practise, but (as framer states) the OP had 2 x 8s already installed.
In a similar situation in which we used 2 x 8 it was for a friend in a rural area and he was trying to save money. He is still happy with no sagging after 4 years. I joist were more expensive than 2 x 12s and 2 x 12 s more expensive than 2 x 8s. All is well.
Oh yea, the 4 year old ceiling also supports an Attic stair...as framer sights in one of his project 2 x 8 Garage ceilings.
>> I can't come up with anyconfiguration that will give a 24' span with any wood available in the US. <<I use doug fir and if you read this post you will see how I've framed this many times and it works. I build scaffolds on top of 1/2" plywood of the 24'joists in between the strongbacks to frame the rafters with steep pitches and the ceiling doesn't move. After the rafters are up I nail the vertical 2x4's every 16' centers.http://forums.taunton.com/tp-breaktime/messages?msg=83383.15Joe Carola
I was rereading this post as it raised some issues. I thought of a situation that is interesting. I am not telling, or trying to be a smart azz.......just thinking and taking the issue a step further.
To preface: The Texas Department of Insurance has a Texas Windstorm Code. The Texas Windstorm code tells a builder how to build...what is required. Inspections in the past were done by the Texas Department of Insurance, and the inspectors could not deviate from the code. A builder had a choice to use the TDI inspectors, or if some of the plan elements were in violation of code the builder could use an engineer. NOTE: Now all plan reviews and inspections are done by engineers.
When an enginner performs the inspections or plan review, the engineer has the right to deviate from the code and create design elements that allow for the code violation.
If a builder or carpenter is simply relying on span charts, it is wise to follow suite. But if an architect / engineer has incorporated design elements to serve special purposes and fully analyized the design / engineering criteria......does it fly even though at first glance or without detailed consideration of the design elements it violates code and / or span charts ? Can engineers create a 2 x 8 ceiling spaning 24' for attic storage with special elements that offsets the need for 2 x 12s or engineered lumber?
Framer seems to be talking about this type of architect / engineers creative license in doing so many 2 x 8 joist spanning 24', adn his experience in seeing it work.
If Framer had built many of these with architect / engineer approval..could he go out to a rural area where there are no inspections and build a similar ceiling in the same way without an architects or engineers stamp of approval on the specific plan and expect to succeed? As butt coverge, could the engineer provide the design drawings for broad application if framer were confronted by someone with general load and span chart knowledge only?
But the way you have it drawn, there is no connection between the stiffback and the joists that would help hopld up joists. Gotta be something you aren't showing there! And what size are the roof rafters you are borrowing load bearing from - and how much snow load are you allowing for in your design.........?????????See, the whole story never seems to come along in these structural threads until somebody has a failure. You can't just ake what somebody got lucky with someplace and apply it carte blanche everywhere in all circumstances.
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But the way you have it drawn, there is no connection between the stiffback and the joists that would help hopld up joists.
The drawing might not be clear but:
DBL 2 x 8 Stiffback with 2 x 4 blocking between the 2 x 8s flush to the top of the 2 x 8 and flush to the bottom of the 2 x 12 joist.
The weak point of the design is the help of the rafters in holding up the ceiling joist, but with the DBL 2 x 8 stitffback, tie blocking, 16" O.C. joist and DBLs every 4' I can not see that the joist need any help.
how much snow load are you allowing for in your design
Snow loads in South Texas?
Like Framer, the OP had a built garge with 2 x 8 joist @ 48" O.C. I suggested adding more 2 x 8s and the stiffback detail that creates a very stout and "dipfree" ceiling when used for typical Attic storage. I know it works from experience.
I knew you have no snow down there, but I was phrasing a rhetorical Q to point this stuff out for the hundreds of other DIYs who will be reading this
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Piffin,
You can't just ake what somebody got lucky with someplace and apply it carte blanche everywhere in all circumstances.
Regarding these structural threads, you are right.
In general, people with structural questions should contact a local engineer or architect for guidence.
In an "innovative" situation I may have been able to make a special situation work, but the time thought and detail I put in as an onsite builder are very different than making recommendations from afar without detailed knowledge and any real responsibility.
As lead carpenter and builder I did apply the same "luck" I had in making the attached 11,650 SF frame work in 1992 to the 2002 2 x 8 ceiling joist plane in the garage and applied stiffback detail project, but I am not sure if I could send dependable saw horse plans to a poster and (because of their interpretation and construction method) the horse be able to hold up under use. We did the trim too, see pic.
OK, with that other framing member, you have a strongback purlin that is normally for providing support to the roof rafters. Old timers used this trick when the roof frame was minimal.Which raises questions about the roof frame itself...If anything, these verticle legs are transferring roof load to the existing rafter ties, not the other way around."There won't be a lot of weight up there (camping gear, boat building forms, etc.)."That sounds like a lot of weight to me, especially relative to the span. The way you plan this, I predict a three inch sag in the cieling/floor and eventually a full failure. Those joist, at that span, will already be deflecting by the time you get the plywood load added, just from the dead load. ANYTHING added after that will only increase the defelction.If you want it nice and straight and safe, use TJI25s x 11-1/4" @ 16"oc
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I also didn't mention that this garage, as was built, is tied in to the house. The roof rafters on one side are supported by an existing exterior wall and foundation. Don't forget, the builders already created this setup with 48" spacing between these joists. All I'm doing is adding joists to fill in every 16".
The support under one end of them has absolutely nothing to do with the span they cover through the middle, and as I already explained, the way these are sized and installed, they are NOT joists, they are only serving as rafter ties to prevent the ridge rom sagging.
you are adding more of them in bewteen, but they are still in total, inadequate to support any load other than themselves at that distanceNow then, you have just described another problem - if the rafters and rafter ties sit at one end on a wall of the house, then the roof has a dead valley unless it was overframed with a cricket, dormer, or something to diver the water.A dead valley is a serious design flaw. It will ALWAYS leak.
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No, it was overframed. By the way, the rest of our house was framed similar to this and the attic has always been used for storage. Boxes of tax stuff, air conditioners, books, etc. So far at 50 years +, the house is still level and plumb.
What is the top of joist to bottom of rafter height at the outside of the vertical brace?
Would you have enough storage room if you only floored from there to the wall? I think the moment would be much more acceptable. You might even be able to do 24" oc extra joists.
The suggestion of the plywood vert. ties would help that too.
You do have to consider that the next occupant might not be as bright, actually you should bet on it.
The above is more of a question to those who know rather than a suggestion.
Bob
Lapidow,I’ve framed many garages that are 24' wide with 2x8 ceiling joists with attic stairs. I come in 8' on each end with a strongback made up of 2x4 flat and 2x6 on edge. Next to the 2x6 I nail a vertical 2x4 going from the bottom of the ceiling joists and up to the top of the rafter every 16" center.It's your house and you’re just building it for some storage, not rooms above. Do with it what you want. You don't have to build it for the next guy if he wants to put a room up there or store a car. That's not your problem if some idiot is going to use the garage for a second floor room.If that's the case then you should frame all your ceilings to handle another floor if the next guy wants to come in and use your attic for rooms.All these garages I've framed were all designed by Architects and the garages are still standing. Do I still frame garages this way, yes? The last one I did was three years ago. The Architect still designs houses with 2x joists and I-joists. Does it make sense, not really, but does it work, YES. In your case, the garage is built and all you want it for is for storage. Call the Architect up and ask him if you do what I said and see if it's alright. If not then ask him what he wants.Joe Carola
Edited 12/30/2006 6:38 pm ET by Framer
There is something very important you are leaving out when you suggest doing it that way.What you are doing is transferring that load to the rafters.But you have no idea what size those rafters are and if they can handle an additional load. By doing this without knowing, he can end up not only with a large sag in the ceiling but in the roof too
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>> But you have no idea what size those rafters are and if they can handle an additional load. <<Piffin,That's why I told him that everyone that I've done was designed by an Architect and for him to call his Architect and ask him if it's alright.I'm giving him an option to frame it using 2x8's and not telling him that he can't because he can.I've framed them like this with 2x6 and 2x8 rafters with 5/12 pitches and up. We get plenty of snow here. All I'm saying is that this can be done the way I've done it obviously and it works.This guy has his garage built already and just wants to add more ceiling joists and additional support to his joists. Using the rafters is fine in my book because I've done it many times before. It's all up to his Architect now.Joe Carola
Edited 12/30/2006 7:32 pm ET by Framer
"This guy has his garage built already and just wants to add more ceiling joists and additional support to his joists. Using the rafters is fine in my book because I've done it many times before. It's all up to his Architect now."I agree, a well designed plan can work here. I've been focusing on what he plans to do and why it won't work and is gauanteed to fail.Maybe I am wrong but I get the sense that he is not into letting an architect design this right. I mean, this is a brand new garage addition. If he'd wanted right from beginning, it would have been easier to just design and build it that way.
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>> Maybe I am wrong but I get the sense that he is not into letting an architect design this right. I mean, this is a brand new garage addition. If he'd wanted right from beginning, it would have been easier to just design and build it that way. <<Piffin,If he doesn't let the Architect redesign it, then he's a fool. Even though it's a brand new garage, I've never once seen a garage designed with ceiling joists 48" centers.If it's really an after thought, then he should call the Architect and tell him. All he can do here is ask the question and listen to the answers he's getting telling him that he can and can't do it. I'm telling him that there's a way that he can do it from the way I've framed. Now it's up to him to find out if it's alright to do it that way.Hopefully he chooses to talk to his Architect.Joe Carola
Gentlemen,
Let me clarify some things before you throw your computers at each other. There is no architect involved. This was completed by a very reputable builder in town who does a lot of additions. With that said, here is what I have so far already constructed:
a 23+ X 30 ft garage on a foundation plus footing. (I couldn't give you the exact pitch right this minute but it is average not too steep)
Ceiling joists about 9 1/2 feet off the floor constructed of 2X8s placed every 48" and closer in strategic spots.
2X6 and 2X4 horizontal members running perpandicular to the ceiling joists about 6 feet from each side.
Vertical ties at each joist tied in to the roof rafters, ceiling joist, and horizontal members.
There is one collar tie in the center.
I have started just adding joists with the above goodies to fill in at every 16 inches or to match the wall studs/roof rafters. I plan to add 1/2" plywood only in the center between the horizontal members/vertical ties. That will give me barely enough room to stand up in the center but plenty to get crap out of the way. Anyway, that's it in a nutshell! I would certainly appreciate any suggestions, especially if I am not proceeding correctly. I'm not a builder. I'm a musician and build boats and other stuff on the side. Thanks and Happy New Year!
Since there's no Architect and you want to do the right thing and you do have options and you used a reputable builder, why don't you call him up and ask him what to do.Joe Carola
don't worry, when I get ready to throw the computer at someone, Joe will not be the one.I am confused with you though - asking advice and ignoring it. You are right back to stateing that you plan to do exactly what you first planned.As for your house attic - I can gaurantee you that you are missing something. There is no damn way that you have anything like a 24' span famed with 2x8s on 16" centers and no deflection unless there is a center support somewhere! That is a trampoline design.You'd better look again if that is your model to learn from
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Well, what would you suggest? The garage is already built. Are you saying the contractor built something that is gong to sag then fail?
Are your vertical pieces on your ceiling joists anything like my drawing?Joe Carola
Yes they are. the only difference is there was only one part of your suggested strongback and that was the horizontal member that the vertical pieces are screwed/nailed into.
Happy NYr to you back!That other horizontal member encourages load sharing that helps with vibrations and to a minor degree with actuall loads when they are dispersed unevenlyAnother reply here referenced using plywood in the kneewall assembly. In some small measure, that helps make said wall ( the verticle sections) perform a little like a box beamTjhe idea behind all these is that it encourages all the frame members to work to gether to share the load.But the TOTAL load of roof and deck is still a finite one.
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I already suggested it.
Use TJIs or get an engineer/architects help.
or look deeper into Joe's kneewall stiffback thing.
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Happy New Year!
George, Happy New Year!
been watching this thread with interest, now my 2 cents,
Piffin is telling you the structure can not be used for storage in the "attic" space as built, NOT that the structure is built wrong or will fall down, UNLESS you use it for what it wasn't built for i.e. storage in the "attic" space.
Joe brings up a good point, why haven't you asked your "reputable builder" how to achieve what it is you want to do? And why didn't you build with this in mind from the start? I'm guessing you thought it would be easy to add some joists and go for it, without ever asking your builder if the use would be supported (pun intended) by the structure.
Any alterations you make now that involve attaching to the rafters is adding a load to the roof that it was not intended to carry. BTW, I don't recollect you mentioning the rafter dimensions. You really should have thought this through completely BEFORE you built it, it would have been so easy to design it for what you wanted ahead of time rather than after the fact.
Geoff
I did discuss this with my builder. He told me that as long as I fill in the rafters, attach the vertical ties, then attach them to horizontal beam, as has been already done then I can use this for light storage. I am not putting file cabs filled with rocks, storing a car, nor my tool chest. This space will be used for boxes of holiday decorations, clothing, lightweight lawn chairs, etc. It certainly will not be filled up. that was the intended plan for this area and the builder constructed it with that in mind. I'm just trying to save some money by filling in the rafters, add the plywood myself.
That does not sound like the kind of answer I would expect from a "reputable" builder. Sounds more like a seat of the pants, "Whatever..."I am still not recommending that you do this, just pointing out theoretical ways of load sharing so that you only failure will be a sagging and not a falling in, since it is clear that you intend to do it anyways, regardless what advice you find.Your experience with cedar strip canoes shows you are familiar with the concept of continuous diaphraghm load resistance which is to some degree what you are doing by creating this tunnel in the attic.Good luck
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That does not sound like the kind of answer I would expect from a "reputable" builder. Sounds more like a seat of the pants, "Whatever..."
I'm with you on this one. When you consider the span for a 2x12 is 16' for a storage load, there is NFW that this framing was intended to carry ANY weight - they are just collar ties. I'd be concerned about even walking up there.
Maybe the builder's reputation comes from building "high end" houses - you know, the McMansions that blow down in a wind storm but are "high quality" because he used marble window sills. Lots of those around here - and the public doesn't understand that it's the quality you can't see that matters.
One of those literally just blew over in a recent wind storm out here - and we NEVER get high winds (40 mph is NOT high winds).
Sorry, got off on a rant <climbing down off soap box>.
Keep speaking truth, Piffin - those that matter, will hear you.
George,
Would your builder be willing to warrant the design for the intended use? Did you pull a permit for this garage?, if so then you had an inspection right? Go back and ask the BI if your builders design is sufficient for the use you want it for and would he inspect and sign off on it. My guess is your builder doesn't give a rats a** what you do with the structure after he's gone. Did you have any plans drawn up ahead of time that indicated the attic would be built to any particular usage specs i.e. 20#psf loading or whatever for storage purposes? That should have been discussed in the begining. You mention your builder knew of your plans, so that's why I ask would he be willing to warrant those specs to you or the Building Inspector. Did you get a reduction in price after starting or was this your plan from the start ( you framing in the ceiling) ? I would also point out that one of the ideas floated mentioned they doubled their 2x8's every 4' , THAT is probably the best suggestion if you plan on going ahead with this. IMO tying anything into the rafters is NOT helping but hindering, especially if you have snow loads to contend with.
I would double your ceiling joists every 4' install a continuous strongback(2- 2x8's bolted together with hurricane clips attached to joists and strongback) the length of the building 6' in from each side, then install T&G ply screwed and glued to the section between the strongbacks (approx. 12').
Geoff
I think we see clearly in the fog here!;)
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No worse than a normal day in the fog er..... I mean at work! :)
To most of your questions, the answer is "yes." It was thought out ahead of time - building inspector and all. At the same time, would you be willing to put all that stuff in writing for your customer?
George,
ABSOLUTELY! and I do!!!! If you want me to do something that I think is undersized or there is a question about it's ability to perform the intended function, I would inform my customer of my uncertainties, then I would find out whether my mis-givings are warranted or not. That means checking with an enginneer or an appropriate expert.
I had a customer who had framing work done on an addition that tied into the existing garage roof, I was concerned the framing was inadequate for the potential loads (snow), He had access to a structural engineer, whom he asked to take a look at the situation, the engineer confirmed my worries and even said he thought the situation was "dangerous" . He also concurred with my suggested repair. That's what a "reputable contractor" should do!
I checked some load tables and 2x8's 16" O.C. ceiling joists- drywall ceiling no future rooms, limited storage, 20#psf live, 10#psf dead, loads, L/240... MAXIMUM span is 16' !!!!
Geoff
Geoff,
My builder told me this set-up would be ok with the intened purpuse that I have - that is light storage. Anything I store will be kept to the soffit sides of the vertical tie. I guess if I get really concerned I could tie in a pair of beams going perpidicular to and supporting the underside of the ceiling joists - going the 30' length of the garage.
George
I've never once seen a garage designed with ceiling joists 48" centers
Framer -
Allow me to make a small contribution to your overall fund of general knowledge. - lol
I just took this in my very own garage and it's typical of every CA garage I've ever been in that was built since the late '60's. We don't have snow loads here and many of these houses had shake roofs over skip sheathing so even the dead loads were minimal.
FWIW, I completely support you and the others who have tried to encourage the OP to get some professional buy-in on his plan. I can't count the number of times I've had to explain to some Harvey Homeowner that his garage ceiling joists exist only to hold the walls straight and are sagging because they were never intended to carry several boxes of old books, a set of unused free weights, and a few dishpacks filled with grandma's old china.
When we moved here in '79, SWMBO (aka Queen of the Packrats) positively salivated at the thought of storing junk in the garage attic. Knowing better than to just say "No", I nailed pieces of 2x2 across the joists spaced for visibility from the floor. Then, I told her she could store whatever SHE could carry up and down a ladder. It's worked reasonably well for 27 years and only one joist has any sag (~1"). Someday, I'll get the stones to ask her (again) why we can't get rid of some of the stuff that hasn't seen daylight since the mid-80's - lol
I've also framed them with 2x4 collar ties. One job I bolted the 2x4 vertical pieces to the ceiling joists and the rafters.Joe Carola
Looks good to this hillbilly. You built a truss.
For extra strength, sheet the joist / rafter connecting "walls" with 1/2" plywood.
Joe,
To begin with, Happy New Year! If I add a 2x4 Flat to go up against the 2x6 which is nailed to the verticals, should I also reinforce it with TGI's as the other guy suggested? If so, should I place it at the center, underneath the 2x8 and tie in to each gable?
Thanks,
George
I think you misunderstand the TJIs. They are joists, to replace the 2x8 ones you propose, not a part of the stiffback walls
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I will try that kneewall thing. The other thing I realized is that whatever I will store up there will be done on the sides, closest to soffits. I will keep the plywood area in the center clear. I actually don't have a lot to put up there other than lightweight bulky large items like boxes of decorations. My boatbuilding stuff will be on the ground and within reach. My boats will hang from the sides. They weigh 45 and 65lbs. I have time to think this thing through because I'm not ready to transfer stuff at this point.
;)
I've seena pair of oars weigh nearly 45#
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My boats are cedar-strip/epoxy and are pretty light. I have to say that my first paddle weighed in nearly that. Then I learned my lesson.
When I read the original post, I thought he was talking about a hanging system that we used to use quite often in simple garage situations. Ply wood ripped around 8", hung from the rafters right against the ridge, staggered side to side, string the center of the garage, raise or pull down 24 footers to the line ( actually 1/2 inch above as line was set) nail off. This was on unplastered as well as plastered ceilings, and having seen ones that were framed by us as long as 20 years ago, I can attest to how straight they stay.We would also put an L shaped strongback right against the vertical hangers end to end to tie in the gable wall to stiffen it up. While I understand your points as to transferring load in this application, I have put in some pull down staircases in a couple of these, and it effectively builds a pretty sturdy attic truss with no additional beams, as long as the vertical attachments are consistently done. Limits the span to 12 ft. on a 2x8; I can bounce on it with no bounce ( at a post Christmas 250lbs :( ) Pretty inexpensive and solid alternative (for storage)
Bing
yah, Txlandlord mentioned his stiffback detail wall too.But that does not seem to be what this guy is describing at all, and it does need to be very carefully done by somebody who understands all the load points and transferrs, something that is also apparantly above and beyond.
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I think you really need a pro to design this for you. Not only will he have access to load tables and the math to make the design, he will be aware of different solutions that will work better for you.
For example, wood I-joists are a lot cheaper than 2x dimensional lumber, and are likely stronger.
The nail pattern of the decking can also influence the design.
"For example, wood I-joists are a lot cheaper than 2x dimensional lumber, and are likely stronger." Yes if sized properly they are stronger. But, I have never seen them less expensive. Generally, with a one time design dimensional lumber is almost always a less expensive option.
ok i got pretty much the same setup and have been wanting to do something diferent check the message board under construction for dyi engineering. i'm going to do a i beam for strength. larry
hand me the chainsaw, i need to trim the casing just a hair.