Looking to put a structural ridge beam in an addition and have a few questions on it.
The addition is 11 12 X 21 one story high, 8/12 pitch, ridge runs 11 1/2.
I need to support the ridge down to the foundation. Does this mean that for the end the is against the exisitng house I need to remove the sheathing and cut the bottom plates and rim joists for the 1st and second floors of the house and run a continuous post to the foundation?
Is there a rule of thumb for sizing? Only being 11 1/2 feet I would think a doubled 14″ lvl would be more than enough.
Thanks.
Replies
No you don't need an actual post to the foundation but you need something to carry the load--it could be a beam added within the wall for example, sort of a header system--but it may involve just as much work to put that in as it would a post.
And no you wouldn't generally cut plates/joists to run a post down, you'd add to what is there already. In many cases the bottom plate one floor down would have enough strength to carry the posts that carry the ridge. But not always.
The sizing depends on the load. I would also guess that your proposed ridge beam would be fine but I usually have at least the lumber yard engineer it since I don't have the training--but I've used that size LVL for larger spans than yours so...
Edited 1/29/2007 10:30 am by ScottMatson
Generally, that end would be supported over the wall that it crosses where the addition ties on.
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I once built an addition that had a structural ridge beam that spanned 22' with two dormers in tow and the ridge was designed with two 16" lvl - 2.0E.
You don't use rules of thumb for engineering things like this.
Especially since any lumberyard that sells them can engineer it for you for free.
In a low load area, I wouldn't be suprised if a single 14" or 16" would handle it.
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The continuous post is very unlikely to be the right solution. What you're doing is adding a point load to an existing wall. First you need to find out how much that load is. Then you need to see if there's a practical way to distribute it over a wide enough section of that wall with a minimum amount of modification. Here in LA, you'd have to get that designed and wet stamped by an engineer before you could pull a permit.
-- J.S.
I don't see that point load being more than three thousand pounds. A pair of jack studs coupled with the king at the end of a header sometimes gets that much.I know, I know, I'm not an engineeer...;)
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Yup, but best to CYA. Sight unseen, there could be something unusual.
-- J.S.
How is the end of that beam supported? Where does the pointload end.? Basic rule: carry the load to the foundation, directly or indirectly