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Thread: Joist Hanger Size
02-26-2010, 02:53 PM #1
Joist Hanger Size
I just had an End-of-builders-warranty inspection on a modular home. The floor joists were attached to beams or headers with Simpson Strong-Tie hangers type MMLU26, which must be a special component because Simpson doesn't list any standard product with a MM prefix. However, the LU26 series is listed. The 26 indicates use with 2x6 sawn lumber. The floor joists were all 2x10, #2 SPF.
According to the Simpson tables, an LU28 is for use with single 2x8 or 2x10 lumber. BUT, all there specifications are based upon design loads and uplift forces. I did not find anything on the Simpson Site permitting or not permitting a larger joist in a given hanger. The loading factors appear to have more to do with how many of what size nails are required. I expect the house was designed to use 2x8 #2 SYP floor joists, the factory couldn't get the SYP and had to go to 2x10 SPF to meet the span loading requirements. However, they probably had a ton of 2x8 hangers setting in the supply room and decided that since the load factors had not changed, they could use the smaller hangers they had on hand.
From what I could find in the 2006 IRC, it only says to use an approved device or ledger board. Would anyone have a pointer to better info? I would like to find information that would provide more specific hanger height requirements if at all possible. Otherwise, I'll have to defer to a SE or design professional or have the client request a letter from the manufacturer.
The contracting outfit is apparently another one of our local red-neck Billy-Bob, good-ole-boy outfits with a brother-in-law who is a county building code inspector. According to my client, they have been very unresponsive to any inquiries. I will go out of my way to find anything I can that can cost them to fix. Or, at least try.
Similar Threads:The above statements are expressed solely as my opinion and in all probability will conflict with someone else's.
Stu, Fredericksburg VA
02-26-2010, 05:22 PM #2
Re: Joist Hanger Size
Modular home = engineered = whatever-the-engineer-signs-and-seals regarding the structure.
Those conditions sometimes result in "stupid is as stupid does" component uses, but ... if the numbers work based on rational analysis and the engineer signs and seals the engineering - nothing can be done until, and if, it fails.
Go here: http://www.uspconnectors.com/pdfs/national2006.pdf scroll down to page 45 / 68.
And here: http://www.ihrc.fiu.edu/lwer/docs/DE...structural.pdf scroll down to page 18 / 81 "“We have many products that are used in the manufactured housing industry. Some are installed in the field and some are installed in the factory. Examples of these products are MMLU hangers, MMLUI hangers, A35 framing anchors, "
02-27-2010, 04:31 AM #3
Re: Joist Hanger SizeModular home = engineered = whatever-the-engineer-signs-and-seals regarding the structure.Those conditions sometimes result in "stupid is as stupid does" component uses
02-27-2010, 04:35 AM #4