LMHmedchem
Well-Known Member
- Joined
- Aug 20, 2012
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Hello,
I am in the process of rebuilding part of the front porch following some termite damage. For a number of reasons, the front rim joist will be a triple of 1.5"x8" ground contact pressure treated. This is being installed in stages as the remaining supports are being jacked up and secured. There porch is long enough that there will be some butt joints in the rim joist. Each butt joint will be secured with a 14 gauge mending plate and each butt joint will be supported by a post. Also, the butt joints in the 3 boards will not be lined up but will be spaced several feet apart.
I am not planning on gluing the 3 layers of boards together. The second layer of boards cannot be secured very strongly at this point because of the jacking up and leveling process. I think that makes adhesive impractical because I don't know how long it will take to get it all level. The 3rd (outer) layer of boards could be glued on because everything will be level at that point, but I'm not sure it's worth it to bother.
When everything is in place, there will be a number of 20D 4" galvanized nails securing the 3 layers of boards. Most of the strain will be shear and I think nails are the best solution for that. Some of these boards are long (~16') and I don't often find ground contact pressure treated lumber that is true at that length, so I am assuming that I will need some screws to pull and hold everything together.
For now, I have been using Grip-Rite #10 exterior wood to wood screws in various lengths, but I have never known how strong these were compared to nails. I would like some very strong 4" screws to put in at the end to make sure that this all holds together. There will be trim over the rim joist, so the screws need to sit flush. Otherwise I would just use 1/4" or 5/16" galvanized lag screws and washers or galvanized hex bolts secured with a washer and nut on the inside. I have thought about adding some through hex bolts anyway since the 3 layers are not glued, but this would involve using a spoon bit to counter sink the bolt head and washer on the outside.
These are the screws I have been considering,
Power Pro #10x4" Epoxy Exterior Wood Screws, 50-Count ($10.98)
GRK 5/16"x4" Polymer Exterior Wood Screws, 45-Count ($21.98)
Simpson Strong-Tie #12x4" Double-Barrier Strong-Drive SDWS Timber Exterior Wood Screws, 12-Count ($14.48)
I am open to any other options as well. The Simpson screws are the most expensive per screw by far, but I don't think I will need more than 12 so $14 is not too bad. It doesn't look like the GRK come in a count smaller than 45. Some of these don't look like they sit exactly flush but it's hard to say.
Any advice would be appreciated.
LMHmedchem
I am in the process of rebuilding part of the front porch following some termite damage. For a number of reasons, the front rim joist will be a triple of 1.5"x8" ground contact pressure treated. This is being installed in stages as the remaining supports are being jacked up and secured. There porch is long enough that there will be some butt joints in the rim joist. Each butt joint will be secured with a 14 gauge mending plate and each butt joint will be supported by a post. Also, the butt joints in the 3 boards will not be lined up but will be spaced several feet apart.
I am not planning on gluing the 3 layers of boards together. The second layer of boards cannot be secured very strongly at this point because of the jacking up and leveling process. I think that makes adhesive impractical because I don't know how long it will take to get it all level. The 3rd (outer) layer of boards could be glued on because everything will be level at that point, but I'm not sure it's worth it to bother.
When everything is in place, there will be a number of 20D 4" galvanized nails securing the 3 layers of boards. Most of the strain will be shear and I think nails are the best solution for that. Some of these boards are long (~16') and I don't often find ground contact pressure treated lumber that is true at that length, so I am assuming that I will need some screws to pull and hold everything together.
For now, I have been using Grip-Rite #10 exterior wood to wood screws in various lengths, but I have never known how strong these were compared to nails. I would like some very strong 4" screws to put in at the end to make sure that this all holds together. There will be trim over the rim joist, so the screws need to sit flush. Otherwise I would just use 1/4" or 5/16" galvanized lag screws and washers or galvanized hex bolts secured with a washer and nut on the inside. I have thought about adding some through hex bolts anyway since the 3 layers are not glued, but this would involve using a spoon bit to counter sink the bolt head and washer on the outside.
These are the screws I have been considering,
Power Pro #10x4" Epoxy Exterior Wood Screws, 50-Count ($10.98)
GRK 5/16"x4" Polymer Exterior Wood Screws, 45-Count ($21.98)
Simpson Strong-Tie #12x4" Double-Barrier Strong-Drive SDWS Timber Exterior Wood Screws, 12-Count ($14.48)
I am open to any other options as well. The Simpson screws are the most expensive per screw by far, but I don't think I will need more than 12 so $14 is not too bad. It doesn't look like the GRK come in a count smaller than 45. Some of these don't look like they sit exactly flush but it's hard to say.
Any advice would be appreciated.
LMHmedchem
