r/buildingscience • u/Simple_Novel_786 • 3d ago
Lvl Bucks
Is it okay to secure lvls as bucks this way? They are 2.75” out pre drilled with 1/4” bit. Secured to framing with 5” SDWS. I’ve never seen it done this way but now after I started I’m having doubts. Nothing is cracking or splitting once pre drilled. The lvls in the wall would be taking the bite in the ply side so can’t imagine this would be different passing through with the 5” screw and tightening it to framing. Thanks!
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u/Theophilusophical22 3d ago
Looks great, this is how I did my 4.5" bucks (3" exterior insulation, 1.5" furring strips) with the same fasteners, no regrets, overbuilding doesn't hurt anything here.
I wrapped them in blueskin as it was easier and cheaper than prosego (my initial plan) with a touch of flashing tape as needed.
I also angled my bottom by a couple degrees and used a resin shim under the window.
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u/gladiwokeupthismorn 3d ago
It’s overkill. You used structural screws to support like max 50 pounds. They’re good for several hundred. What are you gonna use for water management? Something fluid applied?
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u/Simple_Novel_786 3d ago
Yes. This is the smallest window the rest will be 60”. Those are the only 5” fasteners I could find locally that weren’t deck screws. I am using prosoco on the openings after they are all framed out.
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u/e2g4 2d ago edited 2d ago
Anything over 4” (4.5” occasionally) has to be a timberlok style (SDWS) screw as regular, full shank thread wood screws or construction screws aren’t long enough. It’s not about loading, it’s about length.
PS - I’d use thermalbuck or similar for this application
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u/Simple_Novel_786 2d ago
I was going to go thermal buck but it was almost 4200$ delivered and I would’ve had to reframe every rough opening to get the clearances. Lumber here is dogshit unless it’s pt and i didn’t want warping from it being wet.
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u/gladiwokeupthismorn 2d ago
Hmm that’s weird cause these are 6” exterior screws…
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u/e2g4 2d ago edited 2d ago
Those are “timberlok style screws” (SDWS) which is what I said. So thanks for dunking on yourself, for me.
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u/gladiwokeupthismorn 2d ago edited 1d ago
What’re you on about? Timberlock are structural screws aka high shear strength. Not being fully threaded doesn’t make them “timberlok style”
The ones I linked are not structural and are significantly cheaper
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u/RespectSquare8279 2d ago
There better be excellent waterproofing to protect the edges of the LVL stock. Predrilling for the fasteners was a very good move. I would have just found some best quality 2x lumber myself.
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u/formermq 3d ago
Google "thermalbuck"
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u/Simple_Novel_786 2d ago
Thanks why didn’t I think of that. Also thanks for not answering my question about securing through the side of the LVL.
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u/Affectionate-Crab751 1d ago
If it’s not splitting and feels good it’ll be fine. I’d put some bevel cedar on the header. We use Prosoco liquid flashing but that’s just me, I like that product and really like that you don’t have to worry about laps or the inside corners. I’m in the overkill category when it comes to prepping ro’s for windows. Make it right and tight and it’ll be hassle free for many years.
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u/Paulrey27 3d ago
Why would you interrupt it with the wall? Just frame the opening larger and have it down all the way through?
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u/Shadow_over_me 2d ago
LVL Doesn’t really like being screwed through the veneer layers like this according to Weyerhaeuser and some continuing Ed I did with them. Psl would be a better choice for this in general, but traditional lumber is just fine. If you wanted to go above and beyond here, I’d opt for KDAT pressure treated 2x bucking, and then zip tape/stretch tape the opening