CFS Building 3

[dik]

I have a small CFS building; it has steel 2x8 studs and 2x12 roof joists. I am using prefinished metal cladding and prefinished metal roofing (not sure if standing seam).

Does anyone have a source showing details of attaching these to the CFS building? Is plywood normally used for roof and then hat sections and then roofing? or is the plywood normally eliminated? Same with walls? are Z sectons attached to the steel studs with vertical direction cladding attached?

What fasteners are common, and are load tables available?

Thanks, Dik

 

[kmart30]

I have no experience with CFS buildings but down here in sunny Florida, roofing and cladding products usually have product approvals which are based on testing of these products with different fastenings to different substrates. The product approval lists out what fasteners to use, spacing, substrates, allowable pressures, ect. ect. Contractor has to install them in accordance with the product approvals and they get inspected accordingly. You might already know all this already making this post useless to you but maybe if you start looking at different products you will find what you need. If not, you can just engineer it!

 

[dik]

Thanks, KMart... I spent the better part of an hour trying to find construction drawings for siding and roofing connection to CFS framing without success.

Dik

 

[hokie66]

dik,

This may not help much where you are, but illustrates what I consider to be the right way to do it.

https://www.lysaght.com/sites/default/files/InstallationManual-Roofing-and-Walling-2017-Edition.pdf

 

[dik]

Thanks Hokie. I'll take a look at it tonight...

Dik

 

[bhiggins]

Hi Dik,

This is a quintessential guide to CFS detailing:

http://www.steelframing.org/PDF/quicklinks/Low-RiseResidentialConstructionDetails.pdf

The majority of details you need will be on the Clark Dietrich CAD library:

https://www.itools.clarkdietrich.com/cad_library.php?cat=56

Here are some basic load tables:

https://www.clarkdietrich.com/support-tools/support-docs/load-tables

I use this free Simpson program to design walls, ceilings, floors. This program only works with uniform loads but covers roughly 90% of my needs. I believe Simpson makes an awesome CFS paid program that everyone raves about, but I haven't used it. I will use RISA3d for any other scenarios.

https://www2.strongtie.com/software/aisiwin.html

10# or 8# Tek screws are the most common way to fasten everything together.

I believe these values are valid for the screw connections:

https://www.hilti.com/medias/sys_ma...chnical_information_ASSET_DOC_LOC_1577675.pdf

Good luck!

 

[dik]

bhiggins... excellent material on first glance.

Thanks. I'll use #10, I don't want to mix fasteners. and use the PPCH fasteners. The last link has more fastener information than I likely need.

Dik

 

[hokie66]

dik,
If I were the builder, I would ask you why not the hex head screws. Phillips self driving metal screws are a pain. And don't forget the neoprene washers if you don't want leakage.

 

[dik]

Thanks Hokie, I was going to use the low profile, but, hex heads are a lot easier... Already have the washers included for the siding and roof areas.

Dik

 

[dik]

Planning to use Hilti Kwik Flex, Hex Head where possible #10 with 16 TPI with #3 point. Hex head complete with washers, and will 'stick' things together with butyl tape... Cannot find length info, but 3/4" seems to be reasonable, and cannot find spacing info... also 3/4" seems to be reasonable.

Dik

 

[dik]

Found This:

I'll use 5/8 spacing and 3/8 edge distance... Spacing of Z clips... 4' for roof and 6' for walls?

Dik

 

[P205]

@hokie66 In my experience, flat head screws are used anywhere that will receive drywall and you need the low profile otherwise the sheet doesn't sit flat on the studs. Such as stud to track screws.

 

[dik]

P205... I've spec'd the hex head for areas that don't require low profile.

Dik

 

[dik]

I cannot find any reference to using Z clips with Densglass and have switched to 5/8" plywood... Still waiting to hear back from VicWest.

Dik

 

[XR250]

dik,

On most CFS jobs i have been involved with, the Arch. dictates the exterior sheathing based on fire and insurance requlations. Have you checked to see if plywood is allowed in this instance?

In my experience, flat head screws are used anywhere that will receive drywall and you need the low profile otherwise the sheet doesn't sit flat on the studs. Such as stud to track screws.

This has been the opposite of my experience except for interior 25ga stuff.

 

[P205]

XR250 How do you offset the sheet from the studs? Resilient channel? The head of a hex head screw sticks out from the studs, does the drywall installer rout out a hole at each screw head? I'm curious how you can get around this issue.

 

[jayrod12]

You likely won't find a direct reference for installing the z-girts over the densglass. But I've always just treated it like a shim between the stud and the girt. That fasteners are still only fastened at the stud locations.

 

[XR250]

How do you offset the sheet from the studs? Resilient channel? The head of a hex head screw sticks out from the studs, does the drywall installer rout out a hole at each screw head? I'm curious how you can get around this issue

Got me. Would have to ask a drywaller. But I have never seen them use RC to address this issue. I think the sheetrock just gives or it does not fit tight. It is tough using flat head screws for heavier gage metal.

 

[dik]

XR250... can be combustible construction...

Dik

 

[XR250]

XR250... can be combustible construction...

Why use CFS and not wood framing? Will be alot cheaper and easier to design and construct.