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Second floor elevator help

shellarchitect

haven’t seen a real architect type question here in awhile so Ilets see how smart we really are:

little F up on a project I just inherited.... 

elevator machine room on the second floor is required to have a 1 hr rating on the floor.  Floor structure is ply wd over wood trusses.  Anyone know a good way to rate the floor?  Trusses are being set, so changes will be painful at this point.

 I’m inclined to pour concrete but feel like there has to be a better way. thanks!

 
Sep 22, 20 8:18 pm
Non Sequitur

in my hood, when a floor rating is required, the supporting structure also needs to match.   A concrete topping would not fly unless the trusses are enclosed in a rated gyp assemblies too. 

Sep 22, 20 8:24 pm  · 
 · 
SneakyPete

This is spelled out in the code, for sure.

 · 
shellarchitect

understandable, found an exception for this specific construction type and rating

 · 
awaiting_deletion

off top of my head, UL# L something, 400's or 500's, googled my thought, images look close, might work

https://www.usg.com/content/usgcom/en_CA_east/design-studio/floor-ceiling-assemblies.html

Sep 22, 20 9:20 pm  · 
 · 
awaiting_deletion

if you go descriptive, your concrete idea should work. assuming your neck of the woods they lean towards allowing the architect take all the liability regardless of code (not all jurisdictions feel that way).

 · 
SneakyPete

UL is your friend. Alternatively call up any gypsum company, as that's what you're likely to be using.

Sep 22, 20 9:43 pm  · 
 · 
natematt

This.

I remember looking at something along these lines with a fairly thin floor underlayment from USG. 

I remember that requiring the deck to be enclosed from below so that the whole thing is a rated assembly, which could be complicated, but maybe there is a one-sided option. 

 · 
b3tadine[sutures]

shell, check 722.6, you might find what you need there. This saved my ass.

Sep 22, 20 9:57 pm  · 
 · 
shellarchitect

MIND BLOWN!!

1  · 
shellarchitect

I didn't know about this section, thanks!

1  · 
b3tadine[sutures]

I had the "fortunate" circumstance to deploy this when the one inspector approved something, then quit, and the new one inspector cited a mistake, and I had to figure it out. I was able to save the contractor, and owner, about $250k.

 · 
senjohnblutarsky

Might be able to use concrete panel subfloor in lieu of the plywood? 

Sep 23, 20 9:21 am  · 
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shellarchitect

Thanks all, 

I hope we all enjoyed a real-life practice question and a good example of what architects actually do, when we out-grow rendering pretty pictures

Sep 23, 20 9:23 am  · 
2  · 
SneakyPete

fix the mistakes made by the person we replace on a project? yeah, that feels right. ;)

1  · 

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