I have an upstairs room 28′ wide with 6′ high side walls then we come in to make the ceiling height 9′. With a 7 on12 roof (gable).
Using 2×8’s for rafters and ceiling joists.
My question is tieing ceiling joists to rafters the equivalent of setting them on a plate and is there a simpson connector that would work in this scenerio instead of just nailing off?
ANDYSZ2
WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
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I think I understand your question and scenario.
My interpretation: The ceiling joists you refer to are in essence a rafter tie, they will be supporting their own weight + drywall ceiling + insulation?
If yes to the above scenario, I would just nail them in place - clinch would perhaps be helpful........ If the rafter is sufficiently sized.
But the answer to your stated question: " ... is tieing ceiling joists to rafters the equivalent of setting them on a plate..." The answer is "no" - all that holds them is the nails - there is no plate or stud wall providing support.
The weight of the new ceiling will be added to the dead load already present on the rafter from the roof itself. If the rafters are already marginal / undersized / overspanned you could develop some roof problems.
Insufficient information provided to determine suitability of current rafters:
Need building width, or length of rafter (pitch is 7/12); species, grade and spacing of rafters; geographic location of building (snow load); roof covering; and intended use of space above the new "joists" (hopefully no storage).
Armed with the above info a few wizards here will probably do the calculations and render their opinions / solutions.
My question is tieing ceiling joists to rafters the equivalent of setting them on a plate and is there a simpson connector that would work in this scenerio instead of just nailing off?
It's not that it's equivalent to sitting them on the plate. They have to be set at a specific height in order for the outside walls not to spread. Who determines the height? Architect or Engineer.
Do you know how to do that? If not call them. You also don't need any kind of simpson hanger for those, unless your area calls for them. I've never used a hanger before. I just nail them, and sometimes plans call for bolts if there's another roof sitting above or the span, snow loads. The reason we use these is so that you don't have to use a structural ridge. Couple times I had to use both on an existing house.
There are many different things you have to figure on when you put these in. If the plans are drawn already by an Architect, all the information should be on there. Doesn't sound like you have Architectural plans though.
Let's see here...
At 7/12 pitch with a 14' span per rafter, when you rise that three feet from 6' to 9' you are pulling in from that bearing wall about 5'8" roughly.
For a tie to function as a rafter tie it must be placed in the lower third of the rafter.
So it sounds ( I would have to draw it up to be sure) like you are higher than that.
Also, as you do this sort of thing, you add load to the rafters, requireing that they be upsized. I don't have a cluye what your snow load requirement is, but it sounds way too light on the rafter sizing to me.
And don't forget that you need depth for insulation/ventilation,
rough guess - I think you need to drop cieling height to 8'4" or so abd go to a 2x10 rafter anyways
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Piffin do you think running a beam thru the middle and tying the joists will split my load and keep me in the span limits with2x8?
ANDYSZ2WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
It is the rafters you have a problem with. You don't split rafters in the middle.Lemmee draw this up and see iof we are both on the same page
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See here, the cieling joist is abut 18'long at nice feet off the floorIt cn handle the cielingloads just fine.But the intersetof it and the rafter is about 6' up on a 16' long rafter run.
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forgot the durn upload
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I was thinking that if I put a beam thru the center of the room to split the load of the joists this would reduce the rafter load.
But I see where the joists are hanging to high on the rafters.
Are there any alternatives such as ridge beam and or truss design?
ANDYSZ2
WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
sure
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I called code enforcement and asked about the joist to rafter issue and was told it was not a problem!
ANDYSZ2WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
oh, it's an issue all right, apparently just not for them.Are you sure you expalined al the dtails corretly? an inspector on site may have a different view than a clerk on the phone
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It was the head of building department and he looked the spans up and said they were all fine he also pointed out that the code used to call for the ties in the top third and I asked him about needing to be in the bottom third of the rafter to keep the walls from spreading and he said no problem.
ANDYSZ2WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
Put it on paper and run it by him again in person to get a signature.
That comment tells me you are dealing with a guy who knows the words in the book but does not understand the situation at all.Collar ties are placed in the upper third of the space in some locations and were required in the souythern building code in texas and several other states. The purpose of collar ties is to prevent the roof from hinging open at the ridge in high wind uplift situations.The purpose of rafter ties ( as oppossed to collar ties ) in the lower third is to prevent the walls from spreading out with snow load on the roof surfae.Two totally different things!You may very well be fine with what you propose. I don't know what your snow load is. You are cleaaly fine with the inspector, but you may find that Mother Nature is s different kind of enforcer when she dances the gravity two-step.
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