了解边缘托梁
I hope these are appropriate questions for this forum.
1)可以使用媒体ure treated lumber for rim joists? I’ve seen mixed recommendations and comments about shrinkage. But, all else the same, I’d sure like the extra protection.
2) My floor joists extend completely on top of the foundation walls such that the rim joist (nailed or structurally screwed to the outside edges of the floor joists) would not be supported underneath (and not be supporting anything on top of them). My understanding is that rim joists are solely for the purpose of providing lateral support for the floor joists (so they don’t tip over or move closer/farther from each other). If that is correct, then unsupported rim joists are fine, right?
谢谢！
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Replies
Joseph, I am not aware of any reason you couldn't use pressure treated lumber for your rim joists, other than the shrinkage you mention, which can be extreme--I've seen as much as 1/2" shrinkage on larger-dimension PT.
除非您有悬臂或其他不寻常的情况，否则您不需要连续的边缘板，但您确实需要阻止：https://codes.iccsafe.org/content/IRC2018/chapter-5-floors#IRC2018_Pt03_Ch05_SecR502.7. (The iCodes links aren't reliably going to the correct section--check out R502.7.)
If you are using I-joists, or in certain loading conditions with sawn lumber, the rim board is also required for compressive strength. In this case, it must sit on the sill. The construction you describe in #2 would not be allowed. Your detail also makes air sealing between the framing and foundation a bit more difficult. Is there a reason you need to build it this way?
Michael: Thank you for the advice. I was going to use blocking anyway.
Peter: Using 3x10 joists. It's already built that way. I'm planning to spray foam along the inside of the rim joists.
Here's a pic:
约瑟夫，看来您有气球框架的墙壁，螺柱延伸到窗台。那是不同的情况；螺柱支撑着滚动的托梁。如果您在地板级别没有壁炉，则应添加一些。我不确定您的代码官员会说些什么，但是我认为您不需要添加边缘托梁，除非您希望它作为钉子。
Yes, that's exactly the kind of framing.
将墙螺栓钉在地板托梁上，并由门槛板支撑。
因此，燃烧将只是我将边缘托梁的内部放置在附件中吗？
是的，也可以与地下地板在同一平面之间水平安装。2x木材可能是最简单的。垂直腔遇到水平腔的任何地方都应有火力阻塞。
得到 - 有道理。
Thank you again so much.
While I know far far more about construction than most people I know, I understand that I know so very little compared to experienced builders and building scientists. I think the vast majority of people don't have a clue how much knowledge and skill is required to do this.
I'm hoping to piggyback onto this question. My house is not balloon-framed, but has a similar issue to what Joseph posted, where my floor joists extend completely on top of the foundation walls and the rim joist is attached to the ends of the joists, so the rim joist is not supporting any load above and is unsupported below. What are the implications if one wanted to attach a deck ledger to this rim joist?
您不能将甲板分类帐附加到悬臂的边缘托梁上。甲板分类帐上的大部分负载都是垂直的，由于边缘托梁不受支持，您只指望指甲的弯曲强度将边缘托梁固定在地板上。这是一个非常弱的联系。
就您而言，最好独立于整个房屋的甲板支撑甲板。运行PT从外部基础墙壁上张贴到基础上，并在柱子上放置一束横梁，以支撑地板托梁的房屋侧。您应该在甲板梁和房屋之间留出很小的缝隙，以进行排水和清除碎屑。根据高度，您将需要某种对角线支撑，以阻止甲板摇摆。您仍然可以使用Simpson甲板绑带将甲板固定在房屋上，如果您愿意。有几种不同的选择。
嗨，彼得。是否可以使用结构螺钉（例如Simpson SDWS木螺钉）将边缘托梁连接到托梁上？我的理解是，这些洗衣机头结构螺钉中的一些具有令人印象深刻的固定功率。
The problem is the rim joist has no supportive power. And it's probably attached to the joists just with nails.
我第二，让甲板在帖子上独立的想法。
I totally agree it would be a bad idea if the rim joist was attached with just nails. I'm wondering in the hypothetical situation where the rim joist was attached to the joists with structural screws.
The problem is that the structural screws will be going into the end grain of the joists, which has very limited holding power. Typically ledgers are attached to a rim-joist which relies on sitting on the foundation for its support.
The only way I can think of this working is by using some mechanical attachment between the existing rim and floor joists. It might be as simple as some Simpson hardware, but it would have to be specified by an engineer.
I would read the "Ledger Connections" section of this page:
https://www.strongtie.com/resources/literature/deck-connection-fastening-guide
I'm thinking the Deck Tension Tie - DTT2 - for your situation.
我计划将它们用于横向负载支撑，但听起来他们有可能执行双重工作，以减轻对扩展边缘托梁上垂直负载的担忧。谢谢！
问题不仅在于连接，而且是它适用于您的托梁的弯曲时刻。将其视为一个大杠杆。分类帐远离您的垂直支撑，杠杆效应（弯矩）越大。
This moment can generate some pretty big tension forces on the top surface of your joist, enough to split them.
嗨，马尔科姆（Malcolm），在我的情况下，粉底有点独特，坐在混凝土的顶部是6“ x6”梁，然后地板托梁坐在那张梁的顶部。如果我要在当前的设置中安装一个分类帐，则一半的附件将面对托梁，另一半将被拧入该梁的侧面，该梁坐在基础上，没有问题。
如果您可以从6“ x6”获得支持，我看不到问题。
The 2x10 ledger will have around 2/3rd of it backed by the 6x6 beam, definitely enough room for at least a couple rows of structural screws. I also could install blocking between the joists and screw the top half of the rim joist into that blocking.
If that 2x10 is mostly secured to the 6x6 along the entire length, and just sticks up above it along the rim joist to make the floor levels even, then you should be OK -- the 6x6 will carrying the actual load. I would try to avoid anything fancy to try to adapt the rim joist -- try to get all the load carried by that 6x6 if at all possible.
If you find you have to do something with that rim joist, I'd have an engineer look at this and recommend something that will work.
Bill
Thank you Bill, I appreciate it! When I position the ledger I will have it so that as much of the 6x6 is available to screw into as possible.
I would still say no, or at least not without an engineered design. Wood members cannot be supported only by friction, or by fasteners in bending. The wood should be solidly supported from below, with the fasteners being used to hold the wood in place, not to transfer vertical loading. Ledger-to-supported-rim joist connections are a special case where the engineering work is already built into the prescriptive requirements of the code and manufacturer's (Simpson) handbooks. If you attach your ledger directly to the 6x6, then you're much closer to the prescriptive design conditions than you are if you attach a ledger to an unsupported rim board that is fastened to the 6x6.
I see what you're saying, and I appreciate the advice. It sounds like I should just forgo any sort of a rim joist solution and instead look at securing the 2x10 ledger directly to the 6x6 as much as possible.
If I were to keep the 2x12 rim joist, I would have the ability to fasten the ledger to the 6x6, by going through the rim joist, if that makes sense. I would just need to use some 10" Simpson SDWS timber screws, but it would go through the ledger, then the rim joist, then the 6x6 beam, and still have a small screw tip poking out of the backside of the 6x6 beam for the inspector to see.
Do whatever gets you connected to that 6x6, don't rely on the unsupported rim joist as a structural element.
您将在这里有一个三明治，这可能是那些紧固件的负载表的问题。通常的应用是将一件事直接拧到另一件事，您将在其中增加一些厚度。这可能会或可能不会影响那些紧固件的允许剪切负荷。我已经用钢构建了一些相关的组件，并且有可能，在结构元素之间传递负载的方式变得更加复杂。您可能会尝试询问辛普森人，如果他们没有在那些紧固件的工程数据中明确提及它，他们就可以。
BTW, BE SURE to use enough of those fasteners for your deck's design load. DIY decks have a reputation for failing at parties because some part wasn't strong enough, and the ledger is a classic failure point. As I have said on here many times, Always put SAFETY FIRST. Structural failures can and have killed people.
Bill
会做比尔，谢谢！我计划用Simpson Timber螺钉非常过分杀伤，以固定所有东西，同时坚持使用推荐的最小距离。我已经与Simpson有关其中一些问题取得了联系，但是由于代码 /法律 /法规，它们不愿意 /不愿提供结构建议。
这可能是独立甲板有意义的情况之一。
I think you may be right. I did have a lengthy conversation with an engineer at Simpson Strong-Tie today, who stated that the "ML"-series angle brackets may be a doable solution for strengthening the connection between the rim joist and the floor joists. As always, he suggested consulting with an engineer or code official.