Rafter to Pole Plate Concealed Connection
Rafter to Pole Plate Concealed Connection
(OP)
I have a small project at the moment where the client wants to install a leanto off the front of an existing dwelling. The site is located in Australia with a very dry, hot climate and low wind loads.
The client does not want to use metal hangers to make connections between timber elements as they will be left exposed. I could not find a suitable connection in the residential framing code AS1684.2 so designed the connection for shear, bending & bearing taking the reduced section properties into consideration. I am not sure what effect notching the hardwood will have in such environment though and am concerned about potential splitting. Can you please share your thoughts on the attached detail?
I guess the other (safer?) option would be to use something like this:
http://www.dhcsupplies.com/store/p/3739-CJT6S-Conc...
Kind regards,
Jake
The client does not want to use metal hangers to make connections between timber elements as they will be left exposed. I could not find a suitable connection in the residential framing code AS1684.2 so designed the connection for shear, bending & bearing taking the reduced section properties into consideration. I am not sure what effect notching the hardwood will have in such environment though and am concerned about potential splitting. Can you please share your thoughts on the attached detail?
I guess the other (safer?) option would be to use something like this:
http://www.dhcsupplies.com/store/p/3739-CJT6S-Conc...
Kind regards,
Jake






RE: Rafter to Pole Plate Concealed Connection
Just so we can get a 'feel' for the magnitude of actions.
RE: Rafter to Pole Plate Concealed Connection
Plan size = 12m long x 2.5m span
Regards Jake
RE: Rafter to Pole Plate Concealed Connection
RE: Rafter to Pole Plate Concealed Connection
RE: Rafter to Pole Plate Concealed Connection
Thanks for your input and confirming my suspicions. There is indeed little long term load on the connection since it is only supporting the dead load of the roof however any splitting is obviously going to be just as aesthetically displeasing (if not worse) than joist hangers in my opinion.
Regards Jake
RE: Rafter to Pole Plate Concealed Connection
Or bear the joist directly on a smaller ledger/plate below the joist and infill with blocking between the joists?
Or use a deeper ledger/plate and fully notch it for the joists to insert? Have to make sure all your attachment to the wall is below the joist and that the reduced section can x-fer load.
Just some ideas...
RE: Rafter to Pole Plate Concealed Connection
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Rafter to Pole Plate Concealed Connection
RE: Rafter to Pole Plate Concealed Connection
@KootK: interesting suggestions - I will examine that option further
@Ingenuity: leanto rafters are simply supported, not cantilevered. Pole plate one end, veranda beam the other end.
RE: Rafter to Pole Plate Concealed Connection
What we did was drill lead holes vertically from the bottom of the beam up past the theoretical horizontal crack line (in our case the cracks were already there).
We then drilled larger diameter countersink holes for the lag screw heads and washers.
Then we installed lag screws up into the lead holes and used long enough screws to "develop" past the crack and draw the crack together.
Then a wood plug in the bottom to close it up and leave a "wood" beam.
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RE: Rafter to Pole Plate Concealed Connection
RE: Rafter to Pole Plate Concealed Connection
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Rafter to Pole Plate Concealed Connection
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Rafter to Pole Plate Concealed Connection
The attached sketch is more complicated, but splitting is minimized.
Mike McCann, PE, SE (WA)
RE: Rafter to Pole Plate Concealed Connection
http://www.homedepot.com/p/Simpson-Strong-Tie-12-G...
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Rafter to Pole Plate Concealed Connection
Mike McCann, PE, SE (WA)
RE: Rafter to Pole Plate Concealed Connection
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RE: Rafter to Pole Plate Concealed Connection
Glue lam beams are one thing and less susceptible to splitting than a solid stick. However, they can and do split. These are 35 mm joists - less than 1.5 inches wide. These are far more susceptible to splitting than a glue lam that does not come less than 3.125" wide.
Perhaps I am missing something here? I will have to check the AITC tomorrow, but I d not think this would be a good fix for a split 2x joist.
Mike McCann, PE, SE (WA)
RE: Rafter to Pole Plate Concealed Connection
@woodmain88: It is an existing hardwood stud wall with weatherboard on the outside.
@manstrom: thanks for taking the time to put a sketch together. Most appreciated. I might run this option by the client and see if he still wants to pursue the ‘concealed’ arrangement.
@msquared48: thanks for the link to the Simpson hanger with pricing. I am waiting for confirmation of availability in Australia from the manufacturer.
Thanks all for your comments. It is reassuring to get advice on some of these issues that are outside my area of normal practice (have mainly worked with steel up to this point).
Regards Jake
RE: Rafter to Pole Plate Concealed Connection
Perhaps you are right - but with a pre-drilled hole there would be less outward pressure upon installation of the screw - using many small diameter screws still seems feasible.
You can get 1/4" diameter x 12 inch long lags.
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RE: Rafter to Pole Plate Concealed Connection
Mike McCann, PE, SE (WA)