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How to connect rafters to ridge beam

BarbaraD's picture

My engineer has spec'd a 32-ft long ridge beam for the garage.  The garage is 20' x 32' and the shorter ends are gable ends.  Gable roof, with 8:12 pitch, 2x6 rafters 24" o.c., and fake slate weighing 475 lbs per square.  The ridge beam measures 5 1/2" x 14" x 32'.


He said to use Simpson RR ridge/rafter connectors to connect the 2x6 rafters to the ridge beam, but when I looked in the Simpson catalog, I see that the RR has a 90 degree angle, meaning that the ridge beam is rectangular in cross-section.  Well, my ridge beam is going to be beveled on the upper corners to match the 8:12 pitch of the roof, and I do see that you can bend the flange of the RR that rests on top of the ridge beam.  So does this sound ok to go ahead and do it that way?  Would I just hammer on the RR connector until the angle is 8:12?


Don't most people use joist hangers to connect rafters to ridge beams?  What about the seat cut?  You have to make a triangular notch cut in the bottom edge of your rafter in order for it to seat itself in the hanger.  Is that the way it's done?  At the end of the Simpson catalog they show hanger options (p. 165) and I was interested in those B Sloped hangers they show there.  The one seen at the bottom corner of the page would fit my situation.  So I'm wondering, what do y'all recommend?  Has anyone used these B sloped hangers, and if so, do you have to wait a long time to get them?


Any help would be appreciated.  Thanks.


Barbara

(post #99054, reply #1 of 42)

I used Simpson RR's on my roof.  They're intended for use with two by ridge boards.  The tops of them interlock on top of the two by to locate the rafters opposite each other.  They seem not to be too popular.  The bin they were in at Pennsylvania Building Supply was the dustiest of all the Simpson stuff, and the guys there say they don't sell many.  I don't think they're one of Simpson's better efforts.  They don't seem to attach too securely to the rafters. 


The other thing I used was ST-22 straps to tie the rafters to each other across the ridge.  That's mainly for uplift from high winds, and for earthquakes.


Instead of trying to cut bevels on the actual ridge beam, why not leave it flat on top?  You can rip bevels on some smaller stuff to fill in and provide support and nailing for the sheathing there.  That would be easier to do, and stronger since you're not cutting the actual structural beam.


 


 


-- J.S.


 

 

 

-- J.S.

 

(post #99054, reply #11 of 42)

You're right.  I'll just leave it flat on top and fill in as you suggest.  Thanks.

(post #99054, reply #2 of 42)

"Don't most people use joist hangers to connect rafters to ridge beams?"

No. I've never done it before.

"What about the seat cut? You have to make a triangular notch cut in the bottom edge of your rafter in order for it to seat itself in the hanger.Is that the way it's done? "

It's called a Birdsmouth and you don't need to sit it in a hanger unless the plans call for it. The birdmouth is always nailed right on top of the top plate and into the side of the ceiling joists. If there's no ceiling joists like it sounds like in your situation then you need a hurricane tie from simpson.

Same question I have as John. Why bevel the top of the ridge if you have to use those specific hangers?

Joe Carola
Joe Carola

(post #99054, reply #3 of 42)

1-800-call-a-framer.


I have never used  hangers for my rafters but haven't had a situation as the one you describe.  If you are asking about cutting a "birdsmouth" on the opposite end of the rafter that sits on the wall top plate yes you need to do that.  But if you are asking to cut a small notch so it will sit in the joist hanger NO you don't do that.  If you cut a notch in the bottom of the rafter you have just effectivley changed the capacity of the rafter.

(post #99054, reply #4 of 42)

I've never used or seen a need for hangers at the ridge beam, but if there is a need indeed, I would use one of their angled rafter hangers there.

 

 


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(post #99054, reply #5 of 42)

If it's a ridge beam, the rafters lay over the top and meet each other from opposing sides.  There would be no place to attach joist hangars.


And you must be speaking of a ridge beam:  A 5 1/2" X 14" X 32 footer is a hurky piece of wood for a garage!


Code usually requires steel straps across the top of the rafters to tie them together at the peak.


 

(post #99054, reply #6 of 42)

Not necessarily.. A ridge beam which one does not want exposed may have its rafters attached to the faces of it w/ either metal hangers (for smaller rafters of medium slopes or less) or even to blocking nailed to the ridge beam between the rafters.

A metal strap may also be required over the beam to tie in the rafters, but if not specified, it's an unnecessary PIA (can't nail sheathing off at the top where the ties are!).

Ultimately, there are many ways to attach rafters to a ridge beam...birds mouth and/or lapped seem to be the most common--and the easiest methods. BTW, lapping the rafters over the beam (and nailing them together) eliminates the specification for metal straps in almost all cases.

(post #99054, reply #7 of 42)

I'm mostly in agreement with you, but to nail the rafters to the face of the ridge beam to hide it is going to be difficult with a beam depth of 14" supporting 2 X 6 rafters.

(post #99054, reply #8 of 42)

True...But LVLs are coyote-ugly..the more that can be hidden, the better. And casing (or plastering) a small portion of a beam is always easier and prettier than trying to disguise the whole 14" enchilada.

Nevertheless, my point was just that there are other methods to consider for attaching rafters to beams.

(post #99054, reply #23 of 42)

Any beam, ridge or otherwise, can be let-in or toploaded

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
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We did the best we could...

(post #99054, reply #30 of 42)

Piffin, by "let-in" (I'm picturing diagonal let-in braces in walls), do you mean you cut a little mortise into the side of the beam and set the end of the rafter in there?

(post #99054, reply #32 of 42)

Some thoughts on this, based on a conversation with a building inspector who was also an engineer.


About 7 years ago he required rafters joined to a ridge beam to be hangered.


When asked why we had to do this, his explanation was that with a 1x or 2x ridge board, 16s driven through the face of the ridge into the end of the rafters held well enough, but toenails did not. Sinse the beams were built up, I couldn't nail it proper and had to use hangers.


We toenailed the rafters in place, then used joist hangers and put a small triangle block in the saddle of the hanger. One side of the block was against the bottom edge of the rafter, another against the face of the beam, and the third side bearing on the hanger.  We used the next size up hanger or larger. (2x6 rafter uses 2x8 or 2x10 hanger)


Sinse then I have always done this on ridge beams, (maybe 8 more) as I assumed it was now a requirement. 


However  I wonder if there may be a seismic load requiring the originally speced hangers for the original poster?


Bowz

(post #99054, reply #34 of 42)

16s driven through the face of the ridge into the end of the rafters held well enough, but toenails did not.


 I would question that explanation.


blue


 

"...

keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #99054, reply #38 of 42)

That inspector was suffering from his own mythology. toenails, properly placed, will always hold better than nails driven to endgrain, as anyone who has done much demo work can tell you.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #99054, reply #41 of 42)

 


 


 


 


 


 


 

That inspector was suffering from his own mythology


He was one of those who you didn't want to get on the wrong side of. Had heard horror stories about him, as he was known as "Little Napolean" to a few other builders.


Gonna ask his replacement about it when I get the chance. 


Bowz

(post #99054, reply #42 of 42)

Yeah, I know - those guys are always right, no matter how wrong they are.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #99054, reply #37 of 42)

no, I mean the beam is "let-in" to the rafter spaces so in using that term, the beam/rafter configuration is as you have been describing, with top corner of beam ~ top edge of rafters.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #99054, reply #9 of 42)

The Ridge Rafter connector is different from a joist hanger in that the rafter doesn't sit on a metal ledge of the hanger like a joist does. The rafter is simply cut to the right angle to be flush with the ridgeboard/beam and then nailed off. It seems to me that the four beefy joist-hanger nails that go into the rafter are probably better than old-fashioned toe nailing, especially if you don't toe nail well!


If you are going to have a ridge vent, you won't be running the sheathing all the way to the peak anyway, so that's another reason not to bevel the beam.


Dr. Work

(post #99054, reply #13 of 42)

Thanks to all of you for excellent answers.  For those of you who said (referring to using joist hangers to attach the rafters to the ridge beam) "I've never done it", why didn't you then go on to tell me what you do do?  I guess you just toenail them.


The suggestion to consult my engineer would be good if only my engineer were good.  But he's a hack. There's tons of stuff on the plan set that I've had to call him on, and he says "oh yeah, that's right; I guess you don't need that; just delete that", or "Oh, what was I thinking?  That should have been...." (!!!)  I talked to him on the phone yesterday to ask about H1's versus A35's, and he was obviously confused.  So he got testy and said, "Look, just ask your framer" and when I said, "I'm the framer", he said, "well I can't teach you how to frame, and this is going to be the last time you can call me without being charged."  What had prompted my call was that he'd spec'd HTT16 holdowns with the kind of anchor bolts that insert into freshpoured cement, and I called to tell him that the foundation was existing and to please specify different anchor bolts for the HTT16s.  If he wants to charge me extra for clarifying mistakes he makes, what a putz!!  He should be apologizing to me for wasting my time.


Anyway, back to the rafters/ridgebeam connection, I'm going to go with the RRs afterall, and just not bevel the edges of the beam.  I would love to be able to put the rafters atop the beam, but outbuildings are limited by code to 18 feet of height, so it makes more sense to hang the rafters to the side of the ridge beam.  Not trying to hide the beam, since it's in the garage attic, which is just going to be a storage attic.  Again, thanks to all who kindly responded.


Barbara

(post #99054, reply #20 of 42)

Wow, that sounds just like a guy I used to work for.  Only he was an arrogant *&%#^ as well, so maybe not the same person.

 

 

(post #99054, reply #39 of 42)

I see this stuff on a daily basis.....engineers who couldn't build a doghouse....best bet, if your inspector isn't the kind who pores through the prints and demands that you do what aforesaid hack engineer drew, is to use the bevel hangers, or even toe-nail & add angle plates w/joist hanger nails, if your local code accepts that. I am curious as to the ridge spec....why are you using a bearing ridge in a garage?

(post #99054, reply #10 of 42)

If your engineer speced the beam and connection, I suggest you use exactly what he says. If there are issues you do not understand, you should direct them to the engineer.

(post #99054, reply #12 of 42)

That is a valid point.

(post #99054, reply #14 of 42)

I'm not your engineer, but 2x6 rafters 24" OC sounds kinda spindley for a 500# per square roof, no matter how you attach them.


Joe H


 

(post #99054, reply #15 of 42)

Joe, I really appreciate that you took the trouble to say that!  I need all the help I can get.  The engineer did do calcs on the rafters, that I do know.  And maybe it's ok too because the roof is sorta steep at 8 in 12.  I'm pretty sure that matters.  I still remember doing vector problems in high school physics class.  The rafter span is 9'6", and it seems to me that's not so much.  Do you still think it's a problem?


Barbara

(post #99054, reply #16 of 42)

I typed a long response, then heard thunder and saw a flash - and poof - it was all gone... :-( - the power stayed up but the internet connection (cable) went down :-(


Anyway, here is the summary.  More often than not 2x6 would be adequate for that small span, but also would normally be installed on 16" centers. - unless your roof sheathing is thicker than 1/2".


Tip for connecting rafters to ridge beam: toe nail the rafters in first, then come back and install your Simpson brackets.   You will get a more even roof deck that way.

(post #99054, reply #19 of 42)

> Tip for connecting rafters to ridge beam: toe nail the rafters in first, then come back and install your Simpson brackets.   You will get a more even roof deck that way.


That'll work with hangers and A-35's and a lot of Simpson stuff, but alas, not with the RR's.  They go between the rafters and the ridge.  It's no fun trying to get the rafters even with RR's.  Bottom line, they're a bad choice, especially since this isn't a two by ridge.


 


 


-- J.S.


 

 

 

-- J.S.

 

(post #99054, reply #28 of 42)

John, I just took a look at the RRs in the Simpson catalog and came up with an idea.  Install the RRs first, to both sides of the ridge beam.  Then take a few 1x8s and tack them on top of the ridge beam, along its entire length, overhanging each edge equally.  A 1x8 would overhang a 5-1/4" wide ridge beam about one inch on each edge. Then since the RRs are open at the bottom, slip each rafter up into the RR until it contacts the 1x8.  Nail off at the sides of the RRs and then remove the 1x8s off the top of the beam.  Et voila! All rafters level with each other.  Ya know, I'm just an owner-builder, doing my first and only house.  There are only two of us working on it, and we're taking our time.  We work about 5-6 hours a day.  The point is, we can afford extra time to do extra steps that professionals would roll their eyes at or consider a PITA. 

(post #99054, reply #36 of 42)

Using a stopper block of some sort on the top of the beam means that you're guiding off the acute angle at the top of the plumb cut to position the rafters.  That pointy end will crush to varying degrees.  The rounded bent inside corners of the RR will give you some variation in where the plumb cut seats, especially if there's any twist in your rafters.  This is more a problem with a solid sawn ridge like mine, but the stopper block method lines the rafters up to a ridge that may not be straight, instead of using them to force it closer to being straight.


Another thing to think about with the RR's is that you have 2x6 rafters and an 8 in 12 slope.  So the height of the plumb cut will be about 6 5/8".  The RR will cover roughly the top half of that, it's only 3 1/4" high.  Simpson also says that the maximum slope for the RR is 30 degrees, which is about 7 in 12.  With those big 14" LVL's, you have plenty of room and nailing surface for more substantial hangers.


To get your roof surface even, start by crowning your rafter stock.  Set them side by side, crown up, supported on straight pieces of whatever near the ends.  Then sort them by the amount of crown.  Next, decide which ones go where and mark or number them.  Put the straightest ones at the rakes, and work up to the most crowned ones in the middle.  That way you keep the change from one rafter to the next to a minimum. 


If you want to use some kind of guide to get the rafters in plane, you need to rig a straight edge near the ridge in the plane of the tops of the rafters.  For a ridge this long, maybe do it in two parts, start with a rafter in the middle and the rakes, and clamp your straight edge to the middle and one rake.


 


 


-- J.S.


 

 

 

-- J.S.

 

(post #99054, reply #26 of 42)

Matt, I just pulled out the sheet the building dept gave me, and it's got rafter, header, and joist span tables.  I live in Sacramento and we never get snow, so load isn't like it would be back east (I don't know where you live).  Anyway, in the table, it says allowable span for 2x6 rafters at 24" oc is 11'7", based on L/240, 20 lb DL + 10 lb LL. Since my span is 9'7", it would seem to be ok, according to my building department.  Previously, this same garage (in other words, same span) had 2x4 rafters 24"oc, and just a 5:12 pitch.  And we demo'd it ourselves, and every rafter was quite straight, after a 45 year life up there, with a heavy WRC shake roof over 3/4" plywood.