12x16 shed roof ridge beam
sserrels
end supported 16' long ridge beam to avoid using rafter ties. Will a
16' 2x12 be sufficient, or should I nail together four overlapped 8'
2x12s? Can I get away with using 2x10s?
Scott Cox
"sserrels" <sser...@hotmail.com> wrote in message
news:1177899419....@y80g2000hsf.googlegroups.com...
If your rafters are 2x4s, then use a 2x6 for the ridge. If your rafters are
2x6s, use a 2x8.
I think anything larger is overkill for a shed.
Good luck.
Dave
news:1177899419....@y80g2000hsf.googlegroups.com...
What are you using for rafter material?
Pitch of the roof?
Will there be overhang?
If so, will the rafter act as support of the overhang (no nailed on tails)?
Composition shingles, rolled roofing, clay tiles, cedar shingles?
Is there a snow load to consider?
--
Dave
Apathy and denial are close cousins
Chuck
"sserrels" <sser...@hotmail.com> wrote in message
news:1177899419....@y80g2000hsf.googlegroups.com...
Whatever you use for the ridge beam and rafters to support the roof you need
to consider that without the rafter ties there will be a lateral force at
the top of the walls tending to push out the side walls. To prevent this
you need to have a well nailed roof sheathing to act as a diaphragm that
takes these forces to the 12' end walls. The diaphragm will also be used
for lateral wind forces/seismic depending on the area you are located.
CID...
Michael Bulatovich
"Chuck" <ci.di...@gmail.com> wrote in message
news:nsOdnUox7ucqEqjb...@comcast.com...
Not if the ridge beam is supported. That's the whole idea. Supported ridge
beam **or** collar ties.
--
MichaelB
www.michaelbulatovich.ca
Mike Hammer
says...
Is there a reason for not using ANY ties? Even 2 or 3 would help a great deal.
HerHusband
> end supported 16' long ridge beam to avoid using rafter ties. Will a
> 16' 2x12 be sufficient
It really depends on the loads you expect. For instance, you'll need a
bigger beam if you could have a few feet of snow on the roof in the
winter.
But, as a rough ballpark, let's assume 40 pounds per square foot (live
and dead loads). 12' x 16' x 40 lbs = 7680 pounds total distributed load
on the roof.
Half of that is carried by the beam, and the other half is carried by the
exterior walls (half of each span rests on the beam). So the beam needs
to support at least 3840 pounds.
The size of the beam then depends on the type of wood you use, and the
span, but I'll assume a middle of the road 1200 pound fiber stress for
the wood type (Doug-fir, or Southern Yellow Pine, should both be adequate
for this rating).
According to an old span chart I have, a solid 4x12 only supports 3809
pounds for a 16' span, so I'd probably go with a 6x12 which would support
5781 pounds. If you build that out of three 16 foot 2x12's, the load
capacity drops to 5127, still plenty for your needs.
Of course, with a 16 foot building, your supports will probably be within
that dimension, so the actual "free span" will probably be less, so you
might be able to get away with the 4x12 for a shed, especially if you
don't expect heavy snow loads.
If you can find a 4x14 beam, that would support 5288 pounds over the 16
foot span. Of course, it's fairly easy to lift 16 foot 2x12's. A 4x14
beam would be a bit more work... :)
Of course, there are other ways to create the beam, laminated beams, LVL
lumber, steel beams, plywood box beams, flitch beams, etc. But for cost
and simplicity, I'd probably opt for the built-up 6x12 beam.
Remember to tie everything together with strapping, post brackets, etc.
so the shed doesn't fall down in strong winds or earthquakes. You'll also
have some concentrated point loads under the posts at each end of the
beam, so plan your foundation footings accordingly.
Anthony
sserrels
> pounds for a 16' span, so I'd probably go with a 6x12 which would support
> 5781 pounds. If you build that out of three 16 foot 2x12's, the load
> capacity drops to 5127, still plenty for your needs.
>
> Of course, with a 16 foot building, your supports will probably be within
> that dimension, so the actual "free span" will probably be less, so you
> might be able to get away with the 4x12 for a shed, especially if you
> don't expect heavy snow loads.
>
> If you can find a 4x14 beam, that would support 5288 pounds over the 16
> foot span. Of course, it's fairly easy to lift 16 foot 2x12's. A 4x14
> beam would be a bit more work... :)
>
> Of course, there are other ways to create the beam, laminated beams, LVL
> lumber, steel beams, plywood box beams, flitch beams, etc. But for cost
> and simplicity, I'd probably opt for the built-up 6x12 beam.
That's what I was afraid of. That's one hell of a beam for a shed. But
the numbers make sense. I think I'd be better off with rafter ties,
anyway. At least I have experience with those.
Now, with 2x6 rafters and rafter ties, what size ridge is recommended?
Oh, and I think the ground snow load here is around 30 psf. And I'll
be using asphalt shingles. No overhang.
Thanks to everyone for your help.
marson
By "rafter ties" are you meaning collar ties? If you have collar
ties, no structural ridge is required. The ridge board is really just
there to make it easier to build. I'd consider buying roof trusses or
even making roof trusses.
Michael Bulatovich
>> According to an old span chart I have, a solid 4x12 only supports 3809
>> pounds for a 16' span, so I'd probably go with a 6x12 which would support
>> 5781 pounds. If you build that out of three 16 foot 2x12's, the load
>> capacity drops to 5127, still plenty for your needs.
>>
>> Of course, with a 16 foot building, your supports will probably be within
>> that dimension, so the actual "free span" will probably be less, so you
>> might be able to get away with the 4x12 for a shed, especially if you
>> don't expect heavy snow loads.
>>
>> If you can find a 4x14 beam, that would support 5288 pounds over the 16
>> foot span. Of course, it's fairly easy to lift 16 foot 2x12's. A 4x14
>> beam would be a bit more work... :)
>>
>> Of course, there are other ways to create the beam, laminated beams, LVL
>> lumber, steel beams, plywood box beams, flitch beams, etc. But for cost
>> and simplicity, I'd probably opt for the built-up 6x12 beam.
>
> That's what I was afraid of. That's one hell of a beam for a shed.
16 feet is one hell of a span for a shed ; )
> But
> the numbers make sense. I think I'd be better off with rafter ties,
> anyway. At least I have experience with those.
>
> Now, with 2x6 rafters and rafter ties, what size ridge is recommended?
> Oh, and I think the ground snow load here is around 30 psf. And I'll
> be using asphalt shingles. No overhang.
One ply of 2-by deep enough to abut the rafters.
--
MichaelB
www.michaelbulatovich.ca
Matt Whiting
You don't need a ridge at all from a load bearing perspective if you
have ties on every rafter pair. The ridge is just a construction
convenience at that point. A 1x6 would work fine.
Matt
HerHusband
A 12x16' roof can hold a lot of snow! :)
When you start calculating the loads a structure can support, it's really
kind of amazing how much weight they hold without collapsing.
Actually, if you make the end walls with 2x6's, that would put your free
span awefully close to a 15 foot span. A couple of 16 foot 2x12's should
carry that load OK if you really want the open roof structure.
> I think I'd be better off with rafter ties
It's easier, and stronger. That's what I opted for too... :)
You can also gain a little overhead storage if you plan the ceiling
joists accordingly.
If you need more headroom, just make the sidewalls taller.
> with 2x6 rafters and rafter ties, what size ridge is recommended?
Generally, the ridge is one size larger than the rafters. For 2x6 rafters
that would be a 2x8 ridge board. Of course, if the roof slope is really
steep, you might need a 2x10. Basically, the ridge should be at least as
tall as the vertical cut at the top of the rafter.
On my garage (24'x28') I used 2x6 rafters, a 2x8 ridge board, and 2x12
ceiling joists to clearspan the 24' and provide a usable attic.
However, when I built my shed (8'x12'), I made some simple site built
roof trusses. No ridge board needed. You could always order trusses from
a truss company too.
For a 12' deep shed, I'd use 2x4 rafters, a 2x6 ridge, and a 2x6 ceiling
joist, spaced at 24" OC. If you want to increase the strength, decrease
the spacing to 16" OC and/or use 2x6 rafters with a 2x8 ceiling joist.
If you think you might insulate the shed someday, you might want to think
ahead and use rafters or joists that will provide space for insulation.
For example, I installed 2x12 rafters on the cathedral ceilings of our
house, even though I only needed 2x8's for the span. That let me install
R30 and still leave airspace under the sheathing.
One final option, you could put a "shed" roof on your shed. Basically,
make the front wall taller than the back wall, and set your rafters
directly on the walls spanning front to back. Strong, easy to build,
inexpensive, and provides high ceilings. You could even install windows
in the upper part of the front wall to let in additional light. The
biggest downside.... It looks like a shed (or a chicken coop, depending
on your viewpoint. :) ).
Anthony
Glenn
from a forth to a third of the rafter. Their primary use is to
keep the two sides of roof from blowing apart in a high wind.
They will not hold the sides of the building from spreading, if
anything make it spread worse as it goes down, ie sags, it spreads
the walls out. Now a tie that is equal to a ceiling joist, or in
other words down on the plate will hold it forever with absolutely
no sag or spread. One every 4 foot is plenty. Then the ridge
does nothing. a 1 x 6 just to alien the tops is plenty or you can
even forget that and it will hold just as good on that little of
roof. a larger roof and I like collar ties down about a
third,every 4 feet spaced over the every four foot joists. A 1 x
4 tie would be plenty, because it's holding it together not up, ie
it's use would be in tension holding down the reverse side of the
wind direction lifting.
"marson" <brian...@gmail.com> wrote in message
news:1177974253.2...@n76g2000hsh.googlegroups.com...
sserrels
> Collar ties in my neck of the woods mean a horizontal tie down
> from a forth to a third of the rafter. Their primary use is to
> keep the two sides of roof from blowing apart in a high wind.
> They will not hold the sides of the building from spreading, if
> anything make it spread worse as it goes down, ie sags, it spreads
> the walls out. Now a tie that is equal to a ceiling joist, or in
> other words down on the plate will hold it forever with absolutely
> no sag or spread. One every 4 foot is plenty. Then the ridge
> does nothing. a 1 x 6 just to alien the tops is plenty or you can
> even forget that and it will hold just as good on that little of
> roof. a larger roof and I like collar ties down about a
> third,every 4 feet spaced over the every four foot joists. A 1 x
> 4 tie would be plenty, because it's holding it together not up, ie
> it's use would be in tension holding down the reverse side of the
> wind direction lifting.
>
>
> news:1177974253.2...@n76g2000hsh.googlegroups.com...
>
> > By "rafter ties" are you meaning collar ties? If you have
> > collar
> > ties, no structural ridge is required. The ridge board is
> > really just
> > there to make it easier to build. I'd consider buying roof
> > trusses or
> > even making roof trusses.
Thanks all! You've helped a ton.
I'll definitely be going with the rafter ties now that I think about
it. I don't really need vaulted ceilings in my woodshop and I could
use some extra storage space above me.
willshak
I built a 12' x 16' shed that turned out to be a pool cabana. The 16'
foot length has an 8" x 2" ridge beam. The ceiling is a cathedral
ceiling with insulation and wood paneling and there are no collar ties.
The shed is about 18 years old now and there is no noticeable pushing
out of the side walls. The paneling is painted and there are no visible
signs of paint cracking on the edges. I live in NY which does get snow
falls of 12" to 16"
on occasion.
--
Bill
In Hamptonburgh, NY
DanG
yes. Rafter ties, no.
I do think you could do well on your original plan with a
manufactured beam. I don't have time to do the numbers, but look
at LVL or I joist.
--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
dgri...@7cox.net
"sserrels" <sser...@hotmail.com> wrote in message
news:1177980734.3...@n59g2000hsh.googlegroups.com...
Chuck
"Michael Bulatovich" <Ple...@dont.try> wrote in message
news:f14os...@news1.newsguy.com...
You still have a lateral component reaction at the top of the wall from the
rafters if there is no other way to resist it by a tie or diaphragm.
Otherwise you have two way bending on the ridge beam to take the lateral
component. Then the wall displacement is depending on the ridge beam
deflection due to the lateral deflection. You only have three reactions for
a determinate condition.
CID...
Chuck
functions ceiling framing and collar ties for lateral components.
CID...
"DanG" <dgri...@7cox.net> wrote in message
news:yazZh.4589$ZD3...@newsfe01.lga...
Chuck
"willshak" <will...@00hvc.rr.com> wrote in message
news:133d57g...@news.supernews.com...
Is the wood paneling nailed to all rafters? Were the rafters what you call a
cathedral ceiling? What thickness is the wood panels? Are they considered
as roof sheathing nailed to each rafter? Did you have other sheathing on
top of the rafters?
I think that you had a internal/external diaphragm on the rafters which
resisted the lateral component on the walls and distributed it to the end
walls. What were the end walls framed with if plywood they act as shear
walls to resist the end reaction of the diaphragm. You had the resistance
somewhere if no wall deflection was noticed.
CID...
DanG
last 40 years.
--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
dgri...@7cox.net
"Chuck" <ci.di...@gmail.com> wrote in message
news:wYmdnXubAaDgYKvb...@comcast.com...
HerHusband
> foot length has an 8" x 2" ridge beam. The ceiling is a cathedral
> ceiling with insulation and wood paneling and there are no collar ties.
> The shed is about 18 years old now and there is no noticeable pushing
> out of the side walls. The paneling is painted and there are no visible
> signs of paint cracking on the edges. I live in NY which does get snow
> falls of 12" to 16" on occasion.
Wow, that seems like a really undersized beam if it's spanning the 16'
dimension of the shed. I'm surprised it hasn't started sagging over the
years.
I can only think of a couple of reasons why it's still sound:
1. The connections at the ridge are so strong that they can't pull apart,
and thus the ridge can't drop. But I'd think that would take some steel
brackets to pull off. I have a 8'x8' pump house which uses brackets like
this to create a gambrel shaped roof without using any rafter ties. It's
the same approach most "shed kits" use, except they usually use plywood
gussets instead of metal brackets.
2. The building is almost square and the top plate of the wall is acting
like a ring to tie everything together. Kind of like the way a gazebo stays
up without rafter ties. Essentially, the side walls keep the front and back
walls from moving outward. This would only work if the building was small,
and the top plates are strong enough to resist the sideways pressure from
the rafters pushing out.
Then again, it could be the combination of all three, the ridge beam, the
connections, and the top plates that are holding it all together.
I'm glad it has held up for you, but I wouldn't design it that way. Then
again, I'm no architect, just an amateur builder...
Anthony
willshak
> "willshak" <will...@00hvc.rr.com> wrote in message
> news:133d57g...@news.supernews.com...
>
>> sserrels wrote:
>>
>>> I'm putting together plans for 12'x16' shed. I'm planning on using an
>>> end supported 16' long ridge beam to avoid using rafter ties. Will a
>>> 16' 2x12 be sufficient, or should I nail together four overlapped 8'
>>> 2x12s? Can I get away with using 2x10s?
>>>
>>>
>>>
>> I built a 12' x 16' shed that turned out to be a pool cabana. The 16' foot
>> length has an 8" x 2" ridge beam. The ceiling is a cathedral ceiling with
>> insulation and wood paneling and there are no collar ties. The shed is
>> about 18 years old now and there is no noticeable pushing out of the side
>> walls. The paneling is painted and there are no visible signs of paint
>> cracking on the edges. I live in NY which does get snow falls of 12" to
>> 16"
>> on occasion.
>>
>> --
>>
>> Bill
>> In Hamptonburgh, NY
>>
>
> Is the wood paneling nailed to all rafters?
Yes, 4' x 8' x 1/8" plywood wall paneling, grooved like wainscoting, to
all rafters. Nailed with 1" panel nails about 4" spacing along each rafter.
> Were the rafters what you call a
> cathedral ceiling?
Yes, with the paneling attached.
> What thickness is the wood panels?
About 1/8"
> Are they considered
> as roof sheathing nailed to each rafter?
They are nailed to each rafter as paneling.
> Did you have other sheathing on
> top of the rafters?
>
3/8" plywood sheathing with asphalt shingles on the roof.
> I think that you had a internal/external diaphragm on the rafters which
> resisted the lateral component on the walls and distributed it to the end
> walls. What were the end walls framed with if plywood they act as shear
> walls to resist the end reaction of the diaphragm.
1/8" plywood paneling
> You had the resistance
> somewhere if no wall deflection was noticed.
>
> CID...
Just in case there are other questions, the shed was built to the usual
housing standards (other than the foundation, since there is none. The
shed joists just sit on a bed of gravel). 2 x 4 studs 16" OC center. The
floor joists, underlayment and wall floor plates is PT. the roof pitch
is about 4/12. The ridge beam is 2 x 8", the rafters are 2" x 6", 16"
OC. The insulation between the 2 x 6 rafters is the usual R-13, 4" x
16", fiberglass to allow a couple of inches for air circulation between
insulation and roof sheathing. Soffit vents and ridge vent for air
circulation. Also has a working cupola that was used when it was an
unpaneled and uninsulated garden shed. The cupola still works but it is
not open to the ceiling, only to the air space below the roof sheathing,
as does the ridge vent.
Steve Barker
the same.
http://www.tpub.com/content/construction/14044/css/14044_68.htm
--
Steve Barker
"DanG" <dgri...@7cox.net> wrote in message
news:oLFZh.5652$ZD3....@newsfe01.lga...
Glenn
rafters, pitch unknown. The length of the wall is only 16'.
That's not much more than a dog house, Plywood sheathing nailed
right even with no ridge would hold it. I would put a tie down on
the plate every 4' but it really isn't needed for something that
small.
"Chuck" <ci.di...@gmail.com> wrote in message
news:A8GdnS991ukPnarb...@comcast.com...
Dave
"Ceiling joists and collar ties are the same except the joists have two
functions ceiling framing and collar ties for lateral components.
CID..."
The link you provided says nothing otherwise.
2/3 the way up or 1/3 down from the ridge, those are collar ties. A collar
tie cannot support a ceiling in that location as you indicate that weblink
indicated. A collar tie is usually 1X lumber. Fun attaching sheetrock to
that for ceiling even if possible to act as a ceiling joist.
A collar tie still allows flex where the rafter is nailed to the second top
plate (top plate is attached directly to the wall studs). A ceiling joist
prevents that flex from occurring.
Go Dan, go.
--
Dave
Apathy and denial are close cousins
"Steve Barker" <ichase...@some.yahoo.com> wrote in message
news:d5mdnae4vtYuxarb...@giganews.com...
Chuck
are indicating and providing the correct connections. You are the designer
and you can size any structural member to the size you think is necessary as
long as you know the functionality. True, if 1/3rd of the vertical
distance it is then basically a collar tie. When the members are considered
ceiling joists that are bearing on the top of stud walls and also attached
to the rafters then they are doing double service.
CID...
"Dave" <kill...@smacksofvirii.net> wrote in message
news:laUZh.2808$296....@newsread4.news.pas.earthlink.net...
Chuck
I am sorry but a 2"X8" ridge beam spanning 16'-0" is not enough for what you
are describing. You are going to have wind and snow loading on the roof.
The snow can drift on one side of the roof if there is wind forcing this
situation. Unbalance loading with wind loading more wind pressure is on one
side of the roof which causes loading on one set of rafters and not on the
other. Not to mention the critical conditions for wind that are along the
gable ends and corners of the building. These are the first areas that you
will find damage in a critical wind storm.
By the way a 3/8" sheathing is a good diaphragm for what you are building.
CID...