Hello,

I recently moved to a 12 year old home 1 story ranch w/ full walkout basement, on inspection they found that the joist on one side of the center beam in the basement are 12" oc, and on the other side are 16". Both are 2x10's with a 14ft span. I was what possible reasons for this would be. The inspector said that they wouldn't pass local code in the county he was from because they didn't join side by side in the middle, but other than that had no other safety concerns.

The 12" OC support a livingroom and 2 bedrooms, the 16" OC support a kitchen, dining room, 2 bathrooms and 1 bedroom. There is some flex to the floors but nothing I would write home about (just under 300 lbs would flex many floors...).

Thanks!

Joists of different spacing carried on the same beam are not common, but they can occur when there are widely different spans on one side of the bean relative to the other. As long as there is correct cross-bridging between all joists, I don't see a code problem. I don't know why it was done in your house where the spans are apparently equal on both sides of the beam.

I can't think of any reason to do this. Maybe they ran out of SPF No1 and they had to use SPF No3 on one side and had to use a closer spacing to make it work. Regardless of what passes "code", there is no inherent risk with not having the joists touch as they bear on the girder. The section is braced by the floor sheathing and that's the most important thing.

This is a very common practice where, for example, a kitchen on one side of the center beam will be carrying heavier loads from tile or other heavy flooring materials than on the other side.

It is very common in cases like these to see 12" on center spacing under the kitchen and 16" on center spacing for the living room located on the other side of the beam.

This method allows the same depth of joist to be used on both sides of the center beam.

The inspector was correct. Building codes require the ends of joists where they meet over a center beam to be restrained to keep the joists from falling over.

Normally the joists are simply lapped and fastened to one another when the spacing is the same on both sides of the beam.

When the spacing is varied from one side of the beam to the other, solid blocking must be used to fasten the 16" on center joists to the 12" on center joists.

What would the best way to remedy this oversight be? Taking sections of 2x10's adding them to the ends of joists that do not have either AC or plumbing through them and toeing them in?

Also between the flooring (I think 3/4 OSB) and the metal cross braces what are the chances of the joists falling over?

Thanks for your replies!

No chance of the joists falling over. If it were my house, I wouldn't worry about it at all. If it will make you feel better, you could nail in solid blocking, same size as the joists, fitted between them wherever possible, but to me that seems like overkill, building code or no building code. The existing cross-bridging and the subfloor will prevent the joists from rotating.

The chances of the joists collapsing may be remote, but the potential is still there.

Especially during large wind loads against the gable ends of the structure, as they did druing the F3 tornado in Richard Hetzel's county last week.

This is why building codes and responsible structural desgin requires the ends of joists to be laterally restrained at the ends.

Without the legally required lateral restraint at the ends of joists that Codes and standard engineering practice demand, one can find himself on the losing end of an insurance claim after a contastrophe.

End joist blocking is mandatory under codes, and sheathing and bridging do not replace the need for end blocking.

And remember, Mr. Hetzel only draws pictures of homes and has never actually built any...

It may be required now, but was it required 12 years ago? I don't think I have ever seen the ends of the joists blocked over a center girder, regardless of the spacing. In any case, no residential structure is designed to withstand tornado-scale winds, and there is no requirement that they be so designed. Most designs are based on 90 MPH winds. If a structure fails in a 150 MPH tornado, it won't be because the ends of the joists weren't blocked. More likely, it will be because the roof and maybe some walls are removed.

Mr. Homebild may have built many homes, but has he truly actually designed any?

As much as it pains me (jk), I have to agree with Richard. The ends of the joist need to be restrained against rotation or lateral displacement. The floor sheathing achieves this lateral restraint. Regardless of what the building code says, you need to think of the behavior of the member. In your scenario of lapping the joists and nailing them together, what is preventing the two of them from rolling together? There is little to no benefit from lapping them and nailing together without providing blocking. The blocking, however, is effective whether they are lapped or not. I am failing to see a scenario in which the joist is not adequately braced by the floor sheathing. The only exception I might take to that is at the ends of the floor where you are trying to distribute lateral (wind/seismic/lateral EP) into the diaphragm.

Ahhh, I knew we'd be friends sooner or later. =)

Again...

The ONLY thing that matters in cases like these is what legal BUILDING CODE was in place at the time of construction...and whether this home was constructed to that legal standard.

An 'engineered' design CAN be approved, but only when it actually WAS 'designed'.

That said, the engineering and architectural 'theorists' here can argue all day long until they are blue in the face about what they 'might', 'could', or 'possibly' find acceptable....

But unless any submitted designs MET or EXCEEDED the legally adotped Code in place at the time the building was constructed, OR was ENGINEERED and APPROVED by the Code Official at the time the building was constructed....

Nothing else matters.
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Make freinds...because you remain BOTH WRONG...

A code official has no right or legal standing to "engineer" anything, and to attempt to do so is practicing engineering or architecture without a license, in a jurisdiction where a license is required.

I'd still like to see quoted the exact clauses in the current code that make such requirements. Quoting code to support one's rulings or opinions IS one of the duties of a code official.

I think Homebild means that the building official approved an engineered designed, rather than the code official engineering it him or herself. At least that's how I read it.

Yep, now that I read it again, I see it the same way. Thanks, Jay, and sorry, homebild.

I don't know. Is there really any engineering calcs to be done that will show the floor diaphragm braces the beam? I certainly wouldn't do any. I'm a structural engineer and I wouldn't bat an eyelash at joists not being lapped and nailed together - provided they are adequately attached to the floor diaphragm.