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paulz
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# Posted: 7 Aug 2019 14:57
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I am putting up a 2x12 for a lean to rafter. One end attached to an existing wall, the other to a new post. 4x4 or 6x6. Is it best to sit the 2x on top with a bracket, on the side with a joist hanger, notch the post or?
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Brettny
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# Posted: 8 Aug 2019 10:42
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Notch the posts. How long is thr span? I suggest doing 2 2x?? With plywood in the middle. Plywood dosnt bend verticaly.
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Brettny
Member
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# Posted: 8 Aug 2019 10:44
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This is how it should be done.
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paulz
Member
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# Posted: 8 Aug 2019 13:39
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Yep that looks good, just have to figure out what to cut the notch with other than a chainsaw. Thanks!
Oh. 12' span, metal roof, no snow.
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Brettny
Member
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# Posted: 8 Aug 2019 14:45
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Use two 2x10 or 12s with plywood in betwen and construction adhesive for your beam. Useing a 6x6 for a post leaves alot of room to notch for your beam. 4x4s are really only 3.5x3.5.
I also highly recomend useing GRK type screws for holding the top beam/ledger board onto the existing wall.
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ICC
Member
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# Posted: 8 Aug 2019 21:11 - Edited by: ICC
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Looks like you are building a deck-like structure?
If it is, here is a superb document from the AWC. AWC link Scroll down to the section: Design for Code Acceptance (DCA) 6 - Prescriptive Residential Wood Deck Construction Guide - 2015 IRC Version. Click the Free Download link. Everything you need to know should be detailed in the DCA6.
You will note they do not use a plywood filler strip in building the built-up beam, just two 2x6's that fit in the 6x6 post cut out.
The usual reason a plywood sandwich is used is to bring the thickness of the twinned 2x's up to 3-1/2" in order to fit the beam to standard dimensional lumber sized metal brackets. If an engineer is designing the beam he/she will not count the plywood into the beam strength calculations. There are varied reasons for this. Similarly, if an engineer does spec a plywood layer in a beam he/she will not spec any glues or adhesives, just nails or screws. I usually use spiral nails for something like this; or ring shank if using a power nailer. One reason for no glue is they have no control over the in-the-field application of adhesives. Adhesives are great for reducing or eliminating floor squeaks between sheathing and joists. Factory made laminated beams are in a totally different category with controlled conditions and machines using high pressures to make a strong beam. So skip the plywood and the glue and save the expense towards a pack of really good beer or a better vintage of wine.
If you do need to size beam width to fit hardware there is nothing wrong with using a plywood, or solid wood for that matter, strip or patch on the outside of a built-up beam; just short patches inserted between beam and hardware/bracket.
Figure 4 in the linked document shows all that is needed in the way of fasteners for a built-up beam. Note that splices are to be placed over posts; if you already knew that this is directed to other readers.
A deck built to the specs in the DCA6 guide should have no problem being passed by any location in the country, except maybe some earthquake zones on the west coast.
The special fasteners made by GRK and a few other manufacturers are better than regular lag screw for ledger attachment. They are self drilling so save time over having to drill separate holes for both the shank and pilot holes sizes that should be done to correctly use a std. lag screw. I particularly like the HeadLOK screws made by Fastenmaster.
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Brettny
Member
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# Posted: 9 Aug 2019 07:55
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No im not building a deck. That plywood would be exposed and quickly rot.
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paulz
Member
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# Posted: 11 Aug 2019 14:50
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I pulled a bunch of these out of a warehouse addition a couple years ago, 5 of those solid monsters and 25 of the I beams, all about 20'. Are they suitable for outdoor use, as in a carport with a roof and 2 or 3 side walls? I've had them stored outside under tarps, seem to be ok.
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paulz
Member
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# Posted: 11 Aug 2019 22:31
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My research leads me to believe the solid beams are PSLs parallel stranded lumber and are suitable for exterior, even decks. The other I joists are not meant to get wet but ok for floor joists.
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