limit to thickness of built up top plate

[soul plate]

We had a discussion on the old board about how many layers of lumber could be stacked for a built-up sill plate or for a built-up top plate. I was not able to get to it at the ICC site. Does anyone remember any of the considerations that we came up with? I remember discussion of creating a hinge.

 

[mtlogcabin]

Is this it?

http://www4.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=10;t=001861#000034

 

[mark handler]

How Many and what size plates?

 

[soul plate]

Thanks mtlogcabin. That is what I was looking for. Mark--I don't know how may plates, but certainly less than 12.

 

[peach]

wow.. what ever happened to all those guys from the old ICC BB?

It's not very good practice.. hard to inspect... ugly... looks like trying to fix a mistake (unnecessary in new construction - maybe if you need to match an addition to an existing structure).

 

[mark handler]

More than three, I recommend solid 4x or cripples with plywood, nailed or screwed to each member

 

[peach]

unless the sheathing goes to the top most of the top plate and lower most bottom plate, a "hinge" is created. If you must cut the sheathing, you need to probably block the joint. Otherwise, you have a weak point in the wall.

 

[mark handler]

unless the sheathing goes to the top most of the top plate and lower most bottom plate, a "hinge" is created. If you must cut the sheathing, you need to probably block the joint. Otherwise, you have a weak point in the wall.

I agree...

 

[SCBO1]

I've seen three before but it's hard to verify the connection, It was done with three because the framer miscalculated an intersecting

wall. Sheeting ties it together and it may be helpful in some soffit connections. But four in a top plate would start to cost you $$.

 

[peach]

someone needs to agree what we'll accept.. then that's it. the builder's profit margin has nothing to do with code enforcement.

 

[Daddy-0-]

I like to see them bolted when you get above three.

 

[jim baird]

As the Op on that old thread, I thought one of the best comments came from tsmith, a South Carolina architect, pasted below:

"...I see it all the time, and am at a loss to understand what the problem could be.

If a triple plate is somehow worse than a double plate, then why isn't a double worse than a single?

Carry it to the logical conclusion. Lets build the entire wall by stacking up flat 2x plates full height, nailing them all together per code for plates, to achieve a solid wood wall. (We'll handle the insulation and wiring another way since there there are no voids in the wall.) Then, for good measure, we'll sheath the whole thing with APA rated sheathing, nailing it per code requiremnts for that sheathing.

I would like to see an engieering anaylsis showing how that wall has less shear resistance than a typical stud wall..."

 

[mark handler]

Carry it to the logical conclusion. Lets build the entire wall by stacking up flat 2x plates full height, nailing them all together per code for plates, to achieve a solid wood wall. (We'll handle the insulation and wiring another way since there there are no voids in the wall.) Then, for good measure, we'll sheath the whole thing with APA rated sheathing, nailing it per code requiremnts for that sheathing.

That might work if both sides of the "wall" had plywood. If you only sheathed one side and the "force" was applied perpendicular to the sheathed side you still have a hinge relying on the thickness of the sheathing to resist the force

 

[mark handler]

I would like to see an engieering anaylsis showing how that wall has less shear resistance than a typical stud wall...

Jim

Moot, noone is going to use 64 studs to achive an eight foot height. not worth the exercise.

 

[jim baird]

JimMoot, noone is going to use 64 studs to achive an eight foot height. not worth the exercise.

I agree, Mark, that tsmith's "logical conclusion" was not a rational one, but note he did specify that the layers be nailed according to plate nailing requirements. Such an exercise would be mighty like a log cabin, would it not?

As a private inspector I found a house whose hip rafters had their seats at some corners resting on stacks of tail-end cutoffs to correct some kind of wall height problems, called for engineered fixit, but never heard whether builder corrected. House was build outside any jurisdiction's area.

 

[RickAstoria]

I don't think there is a particular max. thickness for a top header but headers above 6" thick starts to actually become a beam. A beam can substitute a standard header under the right conditions and when properly supported. I think the threshold is when the terminology changes. Then we are talking about non-prescriptive path.

This becomes a very different system at a certain point.

 

[peach]

The top plate isn't a header; the top plate (among other things) is a drag strut to carry forces other than gravity.