Modify corridor floors assembly composition. about ctr HOT 14 CLOSED

We can use 4x6 pine joists as follows:

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Cool. Thx! Are you still working on the substrate layer sandwich?

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Cool. Thx! Are you still working on the substrate layer sandwich?

Yes. For the structural point of view I prefer the first sandwich. But, on the other hand, I need to check the strength of the OSB panels. I'm currently working on this.

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Cool. Thx! Are you still working on the substrate layer sandwich?

Hi Ryan. In those sandwiches there is a missing OSB layer. We checked the floor sheathing with three 19/32 structural plywood layers:

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Thats the question, essentially, can we go down to 2 layers? Perhaps (2) 3/4" layers? The gyp crete provides some fire resistant in these sandwiches, as well.

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OK. Understood.

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Then we need to put the Gypcrete between the two structural layers, otherwise there is no bearing layer in case of fire.

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Sounds good. If we do the following what's the minimum size of the OSB?

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We can use a 19/32 OSB panel with the following design capacities:

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Okay. so to summarize...

We can do?...

4x6 no. 1 pine joists 32" o.c. with the following sandwich...

• 19/32" osb spanning 32" oc.
• 3/4" gyp crete
• acoustical mat
• 19/32" osb spanning 32" oc.

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Yes, as long as the OSB panels have the capacities showed above.

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@lcpt,

In our previous assembly, we had the following sandwich....

• 3/4" gyp crete
• acoustical mat
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.

Is there anyway to go down to 2 layers like the following?...

• 3/4" gyp crete
• acoustical mat
• 3/4" (or thicker, if need be) osb spanning 32" oc.
• 3/4" (or thicker, if need be) osb spanning 32" oc.

Sorry to ask this again, but the GC has expressed concerns on the constructability of the following sandwich

• 19/32" osb spanning 32" oc.
• 3/4" gyp crete
• acoustical mat
• 3/4" osb spanning 32" oc.

With this assembly, they would put that first layer of 3/4" down, and that would be the only sheathing during construction. They are worried about large concentrated loads during construction, such as a cart full of drywall.

They also indicated that that top layer of 19/32" would be hard to nail down through the gyp. crete.

It would be ideal to do the following sandwich...

• 3/4" gyp crete
• acoustical mat
• 3/4" (or thicker, if need be) osb spanning 32" oc.
• 3/4" (or thicker, if need be) osb spanning 32" oc.

..but if it's not possible to us (2) layers of OSB, I think we should just go back the following then.

• 3/4" gyp crete
• acoustical mat
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.

from ctr.

Hi Ryan.

You can use:

• 3/4" gyp crete
• acoustical mat
• 19/32" osb spanning 32" oc.
• 1 1/8" osb spanning 32" oc.

or go back to the initial solution:

• 3/4" gyp crete
• acoustical mat
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.
• 19/32" osb spanning 32" oc.

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We need to adapt detail 4/A800 consequently.

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