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Can I Get By Without Joists and Collar Ties ?

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Forum topic by RonInOhio posted 561 days ago 4787 views 0 times favorited 18 replies Add to Favorites Watch
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RonInOhio

720 posts in 1462 days


561 days ago

My shed is only about 10×12. I had ceiling joists but removed them and was planning on
putting in collar ties about 2/3 of the way down the rafters. My rafters are 2×6 on 16 inch
centers. I also have a 2×6 ridge board.
The rafters connect to the ridge with metal rafter connectrs and are fastened to the wall plate with hurricane connectors.

The rafter from plate to ridge is less than 6 feet. Additionally the birds mouth is cut
deep and the rafters run along the entire top surface of the plate.

The roof slope is less than 20 degrees.

I have read up on collar ties and have found conflicting info . If they are installed at the top 1/3 of the rafter they serve to prevent uplift of the rafters and roof. If they are installed on lower third of rafter, they serve to prevent the walls from being pushed out from the weight of the roof.

I have seen some little truss roofed sheds with no joists or collar ties. I was wondering if any of you think
it would be okay to just leave both out . My rafters span less than 6 feet and are at a low angle. I would think
the forces are not great enough (even with snow) for joists or collar ties in my situation.

Leaving them out will simplify things and of course give me a lot more headroom . But of course I don’t want problems down the road. As the shed is small and I have the metal connectors and hurricane ties,and additionally the span is so small, I’m thinking I can leave them out. Your thoughts ? No building permit needed.


18 replies so far

View Whitewalls's profile

Whitewalls

54 posts in 571 days


#1 posted 561 days ago

If you are really worried about it, what about taking a 2×4 or a 2×6 and running from side wall to side wall at the front and back of the shed. Do it as close as possible to the top of the wall. I would think that would tie the walls in a little better and help prevent any movement.

-- Jared, Northern IL

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RonInOhio

720 posts in 1462 days


#2 posted 561 days ago

@ Whitewalls

Yeah, I will have those anyway. I also have gabel end studs (vertical supports). I understand if I do go with collar-ties, I can get by with one every third or so rafter since my rafters are 16 on center.

However, this will intrude on the overall look of my ceiling. I would like to omit any between both ends if possible and as long as its safe to do so.

Probably will do as you suggest and leave them out all together in-between.

Thanks.

View guitchess's profile

guitchess

82 posts in 2306 days


#3 posted 561 days ago

While it may not be immediate, you will experience wall spread/ridge sag without ceiling joists. Collar ties on such a low pitched roof may not be sufficient to offset this effect. Depending on the gable wall configuration, you would have better luck vertically sistering onto the ridge. Adding a 2×6 beneath the existing with glue, screws, and plywood gussets virtually turning it to a 2×12 ridge will combat the aforementioned effects with greater headroom gain as long as the ridge is properly braced on the gable ends.

View cutworm's profile

cutworm

1058 posts in 1391 days


#4 posted 561 days ago

Ohio gets a lot of snow. That’s a lot of weight.

-- Steve - "Never Give Up"

View REO's profile

REO

577 posts in 672 days


#5 posted 561 days ago

Guitchess hit it. the ridgeline will sag causing the walls to bow in the middle. you can either support your top plate to keep them from bowing or reinforce your ridge beam. a 9 1/4” lvl placed underneath the ridge beam and supported with a joist hanger to the center gable end support at both ends will take care of you well.

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guitchess

82 posts in 2306 days


#6 posted 561 days ago

Also, if the gable walls are framed in upper/lower sections, the ceiling joists being removed could cause weakness in the windage variable. So, to keep the structure as strong as possible, you may want to cut in a gable stud/ridge brace that goes from sill to ridge.

View Grandpa's profile

Grandpa

3046 posts in 1273 days


#7 posted 561 days ago

+1 for ceiling joists. The walls will bow out and the ridge will sag. Finally the building will collapse. It might be years but it will probably happen. You might tie in a 2×4 to the side of the rafter on the top plate. Place the other end about 2 ft. from the ridge on th eopposite rafter. Glue it and nail it with ring shank nails. Then do the same on the opposit side. This would pull the wall to the opposite side. It would be a scissor truss effect. Do this in 3 place in your building and you will have head room and still should be able to hold thing together. Without something you will be in trouble I am afraid.

View kdc68's profile (online now)

kdc68

1940 posts in 874 days


#8 posted 561 days ago

To me you have these options

1) re-install your ceiling joists
2.) add collar ties at just below midway or as you state the lower 2/3
3.) re-inforce the ridge at the gable ends

If the ridge beam is supported ridgid and stable at each end, then the rafter will provide a vertical reaction at the wall. If the ridge beam isn’t supported at both ends, ridgid and stable, any deflections will transfer to the rafters, then the rafters react by pushing the wall out.

I wouldn’t be too concerned with uplift. The low pitch ,joist hangers at the ridge, and hurricane ties at the top plate should prevent any of that.

Guitchess has a great illustration on how to re-inforce the ridge

-- Measure "at least" twice and cut once

View RonInOhio's profile

RonInOhio

720 posts in 1462 days


#9 posted 561 days ago

All great replies. Thanks. Yes cutworm, I live along the lake in the snowbelt. Get quite a lot of
snow. The big issues are the melt and refreeze cycles where the stuff up there turns into heavy ice
and rain soaked snow.

I have a picture posted below of the old gable end with the gable studs visible as well as a gable stud under the ridge. I haven’t taken it out yet.

This is similar to how I will do the new gable end, except I have additionally nailed 2×6 boards on edge horizonally across the outside and inside of the gable resting on the plates and running from one wall to the opposite for additional stability.

The shed has been up around 5 years. I haven’t noticed any sagging and the building seems quite solid. I will carefully consider my options and the suggestions. I don’t want to compromise the integrity of the roof supports to gain a few inches of headroom.

I have to make sure the new gable end is properly supported especially since it is practically an open wall. Thus the reasons for the 2×6 s on edge running from gable end wall plate to the opposite gable end wall plate.

Thanks.

View Grandpa's profile

Grandpa

3046 posts in 1273 days


#10 posted 561 days ago

The metal hangers and clips you have used are great but they don’t really support the building. They will move with the walls and the angles will change. I have seen homes with this problem.

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RonInOhio

720 posts in 1462 days


#11 posted 561 days ago

@grandpa

Yeah good point. I think maybe one advantage this little shed has is the foundation
is floating. So theoretically the building will move as a unit on top of the ground.Hopefully
not just one side .

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RonInOhio

720 posts in 1462 days


#12 posted 561 days ago

@ guitchess.

Are the studs in the pic above in the center what you were referring too ? Running from ridge board to sill ?

Seems pretty obvious I suppose. Thanks for that nice graphic ! Explains a lot.

View Grandpa's profile

Grandpa

3046 posts in 1273 days


#13 posted 561 days ago

I built a 20×30 shop once. I used joist on 48 inch centers just to hold the walls in. it is still up and going after 35 years. I haven’t looked at it in a few years but I know it is up. I just never liked problems 10 or 15 years down the road.

View RonInOhio's profile

RonInOhio

720 posts in 1462 days


#14 posted 561 days ago

@grandpa.

I’m considering maybe using collar ties after all. I just can’t decide.

Another question. If I forgo collar-ties, and just insulate up each rafter side using those baffles and eave vents. Will that be sufficient ventilation ?

Or would there need to be an escape vent in the gable ends below the ridge board ?

That was another consideration for using collar ties. I could have better ventilation and hopefully
avoid condensation issues .

I like that scissor truss suggestion.

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RonInOhio

720 posts in 1462 days


#15 posted 561 days ago

@kdc68. Yep, pretty much have decided against joists. Am leaning toward collar ties.

I’m thinking eave vents will be plenty ventilation for such a small shed. No need for gable/ridge end vent .
What do you think ?

Thanks.

showing 1 through 15 of 18 replies

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