beam and joist details for modified 20'x30'

Started by davidj, April 14, 2009, 01:47:10 PM

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davidj

I'm building a 20x30.  Although based on John's plans, my foundation/floor setup is different as the designer didn't want to go with a single span and we're have a large beam holding up the roof (no ties).   So I've got a beam down the middle of the floor sitting on 4"x4" nominal posts.  On top of the beam I'll have 20' x 9.5" I-joists 16" oc.  The perimeter foundation walls are fully-grouted  8" block with steel.

A few questions:

i) How should I do the center beam?  It's three 7' spans and a 10' span (roughly).  The drawings spec two 1.75x7.25 LVLs for the short spans and two 1.75x9.5 LVL for the long span.  However, my supplier is suggesting 3.5" thick LVLs. Should I go for 7' lengths of the 3.5" thick LVL?  Or e.g. a 7' and a 14' length of the 1.75" LVLs and build up a beam across all three short spans (keeping the joins over the posts)?  I'll be building it alone so smaller lumber is better.  I guess it's a trade of between load-bearing strength and lateral strength?

ii)  With 9.5" I-joists spanning 9.5' at 16" oc, do I still need doubled-up joists under the bath and stove?  Both will be cast iron.

iii) I've got a couple of point loads (something like 8000lb each).  I've got the requisite footing, pier and post (4x6) underneath, but there's a doubled-up I-joist at that point (the posts holding up the main beam are in a wall).  Is there a way of transferring that kind of load through an I-joist?  Or should I just replace the doubled-up I-joist with a doubled-up LVL of the same depth (+ some extra blocking to take it out to 5.5" thick over the post)?

Thanks for any help...