Lateral restraint at supports 2006 IRC 502.7

[ajweaver]

A 2x12 floor joist system is installed in a garage.

The joists are bearing on the garage side exterior wall on one end, and the interior entry wall on the other end.

The joists are resting on the top plate, generally without attachment/solid blocking.

Tply is used as exterior sheathing.

I was rereading R502.7, and realized I may have been overlooking something for a while now.

I understand the "solid blocking, header/band/rim joist portion"...

Now,

"or shall be otherwise provided with lateral support to prevent rotation"

What are some ways you see this achieved?

I have always thought the subfloor acheived this, but rereading the section I need some help from y'all-

Let the knowledge flow...

Thanks

 

[steveray]

Bridging, let in bracing, braced to the studs ala "balloon framing"......or whatever seems reasonable to the AHJ...

 

[ajweaver]

Bridging, let in bracing, braced to the studs ala "balloon framing"......or whatever seems reasonable to the AHJ...

Bridging-

Section 502.7.1

Would you do this on the ends at the supports, or wherever ?

Let in bracing-

do you notch the bottom of the floor joists or do you mean a metal strap?

braced to the studs ala "balloon framing"-

this is covered by "to an adjoining stud" in 502.7

but generally houses are platform framed in this area.

 

[steveray]

If you are the AHJ, than whatever seems good to you.....if you are the contractor, talk to your AHJ......it can be done in hundreds of ways, and every situation is different....I have seen some where at rough framing the joists (ceiling) were already twisted almost 45 degrees out of plumb (no bracing)...it can be a real issue with strength of members....most of the time here, it is a rim, or if no room, blocking...

 

[ajweaver]

If you are the AHJ, than whatever seems good to you.....if you are the contractor, talk to your AHJ......it can be done in hundreds of ways, and every situation is different....I have seen some where at rough framing the joists (ceiling) were already twisted almost 45 degrees out of plumb (no bracing)...it can be a real issue with strength of members....most of the time here, it is a rim, or if no room, blocking...

I am trying to get some clarification for me.

I am an inspector who works for an engineering company.

I am trying to understand thoroughly what I am enforcing.

I have the certs and am trying to build more in-depth knowledge, hence my questions.

From my understanding lateral support has nothing to do with the strength of the members.

You said this post you see most of the time rim joist or solid blocking.

Previous post you mentioned bridging and let in bracing. But you never answered my questions regarding them.

I am not trying to be a !#@$head, but feeling a little bit swept to the side and I am still trying to figure this out.

 

[steveray]

The lateral supports keep the member from rotating to a point where they will fail.....I believe that code section says at the ends or something like that...there is no spelled out prescriptive method,(other than (solid blocking, header/band/rim joist portion) so it is whatever makes sense.....some joist hangers provide lateral support, some do not....

 

[ajweaver]

If anyone has some input on my original question-

What are some methods you have approved or seen R 502.7 achieved-

other than the ones spelled out prescriptively in the code (solid blocking etc..)

Thanks again

Aaron

A 2x12 floor joist system is installed in a garage.The joists are bearing on the garage side exterior wall on one end, and the interior entry wall on the other end.

The joists are resting on the top plate, generally without attachment/solid blocking.

Tply is used as exterior sheathing.

I was rereading R502.7, and realized I may have been overlooking something for a while now.

I understand the "solid blocking, header/band/rim joist portion"...

Now,

"or shall be otherwise provided with lateral support to prevent rotation"

What are some ways you see this achieved?

I have always thought the subfloor acheived this, but rereading the section I need some help from y'all-

Let the knowledge flow...

Thanks

 

[mtlogcabin]

I understand the "solid blocking, header/band/rim joist portion"... That is the norm around here

Now,

"or shall be otherwise provided with lateral support to prevent rotation" Once I saw the exterior sheathing used on a second floor similar to what you described to prevent rotation. The owner installed 2X4 blocking at the top and bottom of the joist similar to raised heel truss blocking. I did not like it due to our high seismic zone but the BO at the time approved it. It was a owner builder project and looked pretty labor intensive.

 

[RJJ]

Probably was labour intensive!

 

[DRP]

An open web floor truss usually is attached to a sill or plate and has a 2x4 ribbon let in along the upper edge. The sheathing is attached to the sill, 2x4 ribbon and joist ends.

These would work in some situations;

http://strongtie.com/products/connectors/VB.asp

 

[SCBO1]

Seen a 2x4 accross the top, accross the ends and solid blocking between each joist, all have been approved here depending on the joist layout. Plywood over the top, depends would still require something I listed here to meet the rotation issue IMO. A set of floor joist will have a rim and maybe bridging, toenailed above the center I-beam next to another joist, at that point I don't see blocking in my area. TJI's that meet above a center I-beam, there will most likly be blocking if there's a second floor and also below header point loads transfering thru the floor system to bearing point.

pc1