Just built a 16×24 shop with 2×6 ceiling joists. I would like to
store alot of hardwood up there. Would doubling up every other joist make
it safe? Thanks
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Replies
Sorta depends on what you mean by "a lot of hardwood".
You might find some static load tables on the internet or in a code book. Otherwise, I would think it would be a pretty simple task for an engineer (who you'll likely have to pay). Make sure you have a rough idea of what you mean by "a lot of hardwood" (species, dimensions, moisture content).
No, it won't
You need something much stronger there. This assuming that the joists span 16' with no intermediary support.
Try larger size joists and make sure that the support walls, beams and posts can carry the load too.
Please,
make that sig line smaller. Looks like a banner ad and that isn't Kosher.
Know what I mean?
thanks.
yeah, what cal said....
beefing up 2x6
The walls are 2x4 .the spacing for walls and ceiling joists are 16", double top plate .
The roof has 2x10 ridge and 2x6 rafters not truss.
was going to suggest just adding king struts up to the ridge, then reread and saw
'roof has 2x10 ridge' single 2x10?? then the 16 ft 2x6 flopping about?/
like others have implied, the thing was very poorly designed to start with.
For your situation, by far the Best suggestion so far is the addition of the steel angle iron (either bolt or epoxy, epoxy probably easier if you dont know how to design for lateral shear, which you obviously do not)
beefing up 2x6
I have a 26 ft laminated 2x 10 ridge board, How many ridge bds is a 16 x24 shop suppose
to have? the 16 ft 2x6 are there to keep the 2x6 rafters from spreading. This is a pretty basic design,
designed by an enjineer and approved by the town. I only wish I mention it earlier that the attic
might be used for storage. If I had mentioned it earlier what would I have done differently ? Use
2x10 instread of 2x8? I don't want a beam or posts running down the middle for obvious reasons.
load in attic
what would I have done before??
In hindsight - if you would have known what you wanted to store in that area you would have either looked up some stat figures or consulted an engineer.
Form follows function, so the weight of the items to be stored determine what structure would have been appropriate.
Aside from that - flat floor trusses would have spanned the 16 feet and depending on their depth can be loaded pretty heavily
You don't think he should use lightweight steel beams?
Need more info.
How tall are the wall studs from concrete slab/foundation to ceiling and what is the spacing?
How are the walls sheathed outside, blocking inside, your location?
beefing up 2x6
This is located in long island ny. I told my enjineer who made up the plan after the fact about
beefing up every other 2x6 in order to handle the heavy load and his repied that it would be adequate????
Different opinions
Tell your engineer that another engineer says that doubling 2x6's doesn't work for heavy loads. If he/she still insists that doubling is OK then ask for a signed and sealed letter to this effect.
This will get his/her attention to make a better effort in providing an adequate solution, otherwise if something goes wrong with the ceiling later on then he/she will be liable for damages.
In my garage I have a span of 20' that I made a storage loft using 2x6. I laminated a piece of 1.5" angle steel to the bottom of each joist using epoxy. I have a 4:12 roof so I don't have very much headroom there.
Why didn't you build it that way
I just have to ask: If you just built it, why didn't you build it with adequate strength up front? Instead of trying to hack something together after the fact.
The 2x6 joists will sag, no doubt. They will probably not collapse, and the load will probably not compromise the structure. (I say "probably" simply because I assume but can't be sure that you will use some judgment as to how much carp you stick up there.) Many a garage has been loaded down for decades the way you suggest, and out-and-out failures are rare, in spite of the rather inferior garage construction techniques used 60-80 years ago.
You could reduce/eliminate the sagging (but not greatly increase the total load-bearing capacity) by installing king posts. Or you could sister 2x8s to the 2x6s and roughly triple the load-bearing capacity of the setup.
beefing up 2x6
Thanks, I'm thinking of sistering the 2x6 with 2x8 , as you sugested but wonder how difficult it is to get it on the top of the double plate on both sides?
Keep in mind that if the ends of the 2x8 are well-fastened to the 2x6, they don't need to rest on the plates. A beam doesn't need to be as thick at the ends as it is in the middle.
(OTOH, many of the failures of overloaded garage structures occur because the fasteners of (often unnecessary/useless) braces split the wood of more critical braces. So use some judgment in your fastening.)
beefing up 2x6
So the sistered 2x8 doe's not have to sit on the plates? If this is so, then that takes away my concern.
As far as how much hardwood I put up there ,I woundn't go crazy but will keep a couple layers about 4 and evenly spread out to disperse the weight. What do you think?
Having the sisters end short will maintain essentially the same stiffness as if they rested on the plates, but may cut the actual load-bearing capacity somewhat (vs the ideal). The devil's in the details -- get as close as you can to the ends and fasten solidly without harming the integrity of the 2x6s. Normally an evenly-loaded uniform beam will fail in the middle, but with this arrangement the other failure modes are either for the ends to separate from the original joists or for the original joists to splinter at the connection. (Such failure would rarely be catastrophic in this type of structure, but would occur very gradually over a period of years.)
I haven't really got a good concept of the weight of hardwood to know how much you could stick up there. But if you think of it as a floor you can probably find the numbers for 2x8s at your spacing and figure the pounds per sf.
Sistering with 2x8 will not do it either
You still did not provide information of how much wood you are going to store up there. Without this it is impossible to give you more direction but adding 2x8's is certainly undersized.
If you can drop a couple of posts inside and set a beam under the joists located more or less at their center, this will give a lot of extra load capacity and then sistering can help too.
Actually, they might be since it isn't a floor
Since this isn't a floor, then the allowable deflection tables don't really apply. They are mostly there to keep people walking on the floor comfortable, or prevent inflexible flooring like ceramic tile, from being damaged. The structure would be sound with considerably more deflection.
The sag can be considerably more, if all you and to do is hold the wood, and don't need to consider someone walking around feeling comfortable with the amount of sag they feel.
The 2X6 with a sistered 2X8 might be springy enough at mid-span to make most people uncomfortable.
If he stacks wood in there a foot deep, your only looking at a load of 50-psf.
Both 2x6 and 2x8 are undersized
For a 16' span, No. 2 SP wood, a 2x6 can carry 10 psf and a 2x8 carries 20 psf. Sistered together they can carry 30 psf. This is based on bending strength only not deflection, therefore a load larger than that will cause collapse. The load can be considered permanent dead load since it will be there for months at a time which makes everything worse because of material fatigue.
In addition to that the deflection will be so noticeable from below that it will look frightening to a casual observer.
beefing up 2x6
so I will not go crazy wth the hardwood. If I had to do it over,base on the same dementions
what should I have done different and I don't want a beam and post running in the middle.
what should I have done different
I- joists would have been one alternative.
From what you said earlier I joists might be a problem. Minimum wood I- joist I know of is 9 1/4 . Given, from the sound of your concens getting smaller dimensional lumber uo into the pocket of the top plate and the roof sheathing, You probably have to even more significantly trim the 9 1/4 I joist, cutting it more than manufacturers will allow.
I don't believe any manufacturer perscribes partial sistering to dimensional lumber as an approved method.
Still haven't really defined the load you'd like to design for and as I said earlier a standard unsistered 2x8 is reated for 10dead/20live and qualify's for limited storage under IRC. You have to really define the load and decide on where it will be distributed/concentrated before any real decisions can be made.
Structural metal joists could easily do this span in a 7 1/4 width in 14 or 16 gauge with significant capacity depending how you can mount them.
Sand, I addressed my reply to the orig. poster.
I-joists right from the get go would have been a thought. No sistering or modification of i-joists to the existing situation. I have a 30 ft clear span garage using the full 2x4 flange I joists.
I didn't say anything in this thread except the post to the Engineer about his blatant advertising with that big a s s 'd banner he uses for a sig. line.
Not much of a storage
After you figure out the weight of stored wood per sf you'll realize that a very small amount of wood can go up there.
Doing it right from the beginning requires bigger joists, say 2x12's spaced 12" will have 100 psf capacity, 9.25" LVL's the same or 10" Light-Gauge Steel joists spaced 16" o.c. allows a whopping 150 psf load, which means stacking up several feet of hardwood on top of that floor.
beefing up 2x6
It looks like I might be able to use I joist in my situation but the rating is 100 live,20 dead,
But as you mentioned I'm really interested in dead load rating which doe's not seem to help
wth hardwood. Is light steel gauge something I can use at this stage,and where can I go for info.
Thanks
Not sure why people say a 2x6 is inadequate and badly designed from the get go when we don't know what you originally indicated in the beginning, Granted if you said you wanted to store up there or there clearly was enough space to potentially use it for that , he probably should have suggested it. Did you convey your intention to store "alot" of hardwood up there.
Also not sure why people say a 2x8 wouldn't be adequate, when, as others have said, we don't know the load you are anticipating putting up there.
A 2x6 for an uninhabited attic with no storage and a dead load of 5psf (ceiling drywall if you have it and incidental hanging stuff, etc ) is prescribed per code.
A 2x8 # 2 grade or better in common framing species will meet code for "limited " storage and is defined as 10PSF dead load and 20psf live load. You would have to go above that to get to minimum "living" space code of 30psf live.
A 2x8 sistered to a 2x6 is going to come in above that depending on how you sister. But certainly doesn’t require Mid Span columns unless the loads exceed that or are point concentrated, especially in the middle of the joist.
Besides codes, there are standard forest council tables that can be utilized to figure specific load capacities. Code means it is sufficient for the load they described. The table will determine requirements when you have loads that exceed those standards for the span.
attic load
and remember:
The Code is the worst possible recommendation to get legally away with
My suggestion: spend the money for a proper engineered and sealed plan and be done with.
Think of the liability if anything ever should happen
for the time, money, and effort
it will take to correct your problem, would it be possible to simply build a lean to addition to the side of the garage area for dedicated storage?
Ah, Junkhound will love that suggestion!
beefing up 2x6
Great I will do as you say. over the years I collected so much that eithe I put up a wood
shed and be done wth it or if as you say for 200.00 bucks use the available space
for not only hardwood but storage in general. hardwood being the worst case.
Thanks alot for your input.
I think a lot of mental exercise has gone into this simple problem here. Makes for a good thread
What I would do is to add a 2x4 to the top and bottom of each joist, using glue and structural screws to convert each joist into an I-joist in place. You could even possibly introduce a good crown to each by holding the bottom chord in place with a slightly long 2x4 post under the center as you install it. Do bottom chords first, then the tops. Leave posts in place until all fasters are in and the glue kicks well.
beefing up 2x6
What kills me Is I didn,t mention I might use the attic for storage and why did the enjineer simple
ask me if I might be using the attic in the future?.Anyway I'm going to reinforce the attic with 9.5 LvLs
and I think we all beat this topic to death. Thanks everyone for your input.
Seen it Done that
Installing 2x8s is not rocket science. If you are worried about fitting them in, don't be. The trick is as follows; cut the new sisters short the width of one of the plates plus half inch(outside measurement of your framing minus 4inches if you have 2x4 walls) . If applicable, cut in the rake of the roofline for each . You should now be able to angle in each sister and have an inch and a half of bearing on the plates. I've done it many times, it can be had. If your engineer says its enough, have him sign off on it. Other wise have him design a built up truss structure that will cover his bahookee and give you peace of mind.
load on ceiling joists
Form follows function
Determine what you want to load on top of the 2x6. Once you know the maximum weight you want to load, then you can look for materials to support this weight. Get an engineer to verify.
Engineered trusses are most likely the more economical materials to use.Could be you have to reduce either the ceiling height and install deeper trusses or set the trusses on the existing walls and modify the roof at the overhang
Truss companies are usually very helpful (in house engineers), especially if you give them your business.