Wrong rafter hanger used in framing - thoughts?
Wrong rafter hanger used in framing - thoughts?
(OP)
Good morning all,
I am pretty sure I know how I will be responding to this, but was wondering if anyone has ever seen such a blatant misuse of a simpson hanger? The Building Official requested that an engineer look at a lvl 'ridge beam' as the supplier would not stamp it (i was already going in with eyebrows raised). It turns out that the ridge beam (2-ply 11 3/4" LVL) is okay, but the rafter hangers are hurricane/earthquake ties (Simpson H1 tie) - not rafter hangers. Snow loads in this area are 55 psf and this simply does not bold well for these 'hangers'. Any thoughts?
Much Appreciated.
I am pretty sure I know how I will be responding to this, but was wondering if anyone has ever seen such a blatant misuse of a simpson hanger? The Building Official requested that an engineer look at a lvl 'ridge beam' as the supplier would not stamp it (i was already going in with eyebrows raised). It turns out that the ridge beam (2-ply 11 3/4" LVL) is okay, but the rafter hangers are hurricane/earthquake ties (Simpson H1 tie) - not rafter hangers. Snow loads in this area are 55 psf and this simply does not bold well for these 'hangers'. Any thoughts?
Much Appreciated.






RE: Wrong rafter hanger used in framing - thoughts?
www.idecharlotte.com
RE: Wrong rafter hanger used in framing - thoughts?
As for the hangers, I definitely would use a bottom bearing hanger with a top bearing flange too. Simpson makes some that could be placed over the hangers that are there now, or the hangers could also be removed if they interfere too much.
Use something similar to the IT hangers for TJI's, but made for the solid joists you have, that can be spread tempoorarily for easier installation.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Wrong rafter hanger used in framing - thoughts?
firstly, the nails to the rafter will be too close to the end and will therefore have much less capacity than in the simpson catalogue diagram where it is a continuous rafter.
Secondly, thers is very little top restraint.
Thirdly this is not a very good detail for uplift where there will be tension at this connection.
I would definately look at putting some additional brackets as msquared has suggested though I would think that a couple of angle brackets would do the trick and would be easier to install.
RE: Wrong rafter hanger used in framing - thoughts?
BA
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
The finer older houses here all have heart pine ridge beamw and use a ledger board. Some rafters have a bird's mouth and some don't. Some of the beams are massive 3 or 4" tk x 12"-16" deep. Most of the larger beams have a collar beam toching the bottom of the ridge beam.
I would give Simpson a call. The few times I've called they have been quite helpful
RE: Wrong rafter hanger used in framing - thoughts?
VTEIT....hopefully you'll never have to testify to that effect. Toe-nailing is a miserable way to make a shear or tension connection. The main reason most of them have not failed is because they have never felt the loads for which they were supposed to be designed and constructed to resist, or the structure was not really designed, but built with a great deal of "overdesign". Test 10 different toe-nailed connections by 10 different carpenters and you'll get 10 significantly different values.
Yes, there are many wood structures with no "engineered" connectors of any type. Most have more capacity in the seat of the pants overdesign than they'll ever need. In more recent times, there is a tendency to mix old methods with new designs, which are much more optimized, and the results can be disastrous.
In this case, you have a competent ridge beam with collar ties. All you need is good rafter connections!
unclesyd is right...Simpson is very helpful.
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
That is the way it appears to me too. Looks like the rafter would fail in bending at the tie connection.
BA
RE: Wrong rafter hanger used in framing - thoughts?
Toe nails are perfectly acceptable per NDS. There is a reduction in shear capacity. You should be able to add enough of them to obtain the capacity.
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
I agree with the sloped Simpson hangers for unusually long rafters and/ or very high snow load regions. But to specify them all the time is a waste of money and too conservative.
RE: Wrong rafter hanger used in framing - thoughts?
But they are allowed, so specify whatever you want if you are comfy with them. I am not... I also am in Florida so we are talking uplift also.
RE: Wrong rafter hanger used in framing - thoughts?
Check beam bearing
No OSB sheathing spacer clips
Missing blocking for drywall
Far side rafters looks like they are 2x4s
Frame out sheathing penetrations (far side)
Consider a strong back for ceiling joists
RE: Wrong rafter hanger used in framing - thoughts?
Also keep in mind that the cut angles for roof rafters and other conventional framing allow gravity to work WITH the connection. Uplift works AGAINST the connection angle, so more load is placed on the fastener.
Nice observations, boo1!
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
But as I said before, you are free to specify them since they are allowed. I just never will because I don't buy the cost savings argument over using hangers, especially on the total cost of the framing. That is a good investment in my mind. A framer isn't making six figures and an extra few minutes is no biggie.
RE: Wrong rafter hanger used in framing - thoughts?
If you have a 5:12 pitch, 2x10 rafters at 16" spanning up to 14' or so, most engineers here would specify sloped hangers? For commercial work I understand, but for residential I think most framers would think you're a little nutty.
When you add the cost for the hanger and additional labor, I think you're talking about $5 each connection - maybe $500 to $600 extra on the average roof of a house. Not a whole lot more, but if you carry this conservatism design approach throughout a decent size home, you could be adding thousands of unnecessary dollars to the cost of the house. I have had long conversations with very experienced framers on these types of things that drive them crazy.
RE: Wrong rafter hanger used in framing - thoughts?
As some have pointed out, it looks like the rafters have been notched above the collar ties. Why is that? I would be concerned about that.
RE: Wrong rafter hanger used in framing - thoughts?
To clarify, the rafters have not been notched, and are continuous 2x6 rafters from the ridge beam to the supporting walls. Collar ties were strapped to the sides of the rafters with common wire nails (no nail gun). I sketched up a proper hanger detail for him using more preferred methods than hurricane clips as hangers - consequently the supplier provided him with these as hangers (so he says........).
RE: Wrong rafter hanger used in framing - thoughts?
This might be a little off topic but I was wondering what the 2x8's below the 2x6 rafters are all about. If my attached drawing is somewhat accurate (can't see exterior walls), why not just use stronger rafters all the way to the ridge and save labor? I've seen this design used in trusses but never in my years of building stick framed homes, additions etc. I guess I could see it in an upgrade to an existing building but this appears to be new construction. Just curious.
Doug
RE: Wrong rafter hanger used in framing - thoughts?
The additional 2x8 framing, from what I can see in the photo provided, is most likely scabbed on undrframing to allow maximum batt insulation to be installed (probably R-38 batts and allowing for a 1" air space for venting) for the volume ceiling built. If it was me, I would be checking the adequacy of the rafter span (2x6's) to make sure that they are not overspanned and with all of the underframing applied, sloped and flat (collar ties). It appears the rafters are 2x6's @ 16" O.C., but I don't think the length of the rafter span was given. 55 psf roof snow load is pretty high.......it does confirm the colder climate application.
I would have liked to see the framed the roof with a larger dimension rafter, forget the scabbed on underframing (because your ceiling wall transition is still at the same height) and treated the whole roof system as a cathedral ceiling, thus rafter span & correct hanger selection for rafter connectors might not be a question?????
Just what I can decifer..........
RE: Wrong rafter hanger used in framing - thoughts?
The 2X6's, if not overstressed in bending, will surely deflect down at the collar tie connection under full load allowing the deflection to be read outside in the roofing, and will probably become a permanent deflectior, if the snow load is long term. Moreover, lateral spreading of the exterior walls may become an issue with interior sheetrock damage seen.
I strongly suspect that a structural was not involved in the design prior to the picture being taken. Sharp Building Official though in my opinion.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Wrong rafter hanger used in framing - thoughts?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Wrong rafter hanger used in framing - thoughts?
BA
RE: Wrong rafter hanger used in framing - thoughts?
Good point BA, but with residential construction, I would expect tension.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Wrong rafter hanger used in framing - thoughts?
RE: Wrong rafter hanger used in framing - thoughts?
Collar ties located near the end of the ridge beam will tend to compress with snow load because the ridge beam deflection is minimal and the rafter deflection is normal to the roof slope.
BA
RE: Wrong rafter hanger used in framing - thoughts?
have you contacted Simpson yet?