a frequent customer question - "are they strong enough to walk on?" ...... yea I think so!

16 foot clear span. 26 ga. skins

Chris,

How much does this vehicle weigh?  How many square feet in the clear span?  In other words, how much weight per SF?  How much deflection in the panel?  Would thicker metal skins support even more weight?  Can ceramic or porcelain tile be installed on top of a metal skin SIP?

Posted By Alton on 17 May 2011 08:06 PM

Chris,

How much does this vehicle weigh?  How much deflection in the panel?  Would thicker metal skins support even more weight?  Can ceramic or porcelain tile be installed on top of a metal skin SIP?

Alton;

according to Chevy it weighs 3155, I don't think anyone put a string on it to check deflection - but in photo looks minimal, the maximum that the roll former can handle is 24ga. and it would slightly increase spans ,but probably not worth the additional cost, Yes we have installed concrete barrel tile over steel sips see the Hart Job:
http://southernsips.com/job_hart.html a 3/12 pitch hip roof over second floor

I have also installed concrete tiles at a 4/12 pitch over aluminum skin panels on a previous home of mine

Chris,

That is a great marketing image. It really illustrates the load capability of metal SIPs.

So that was a 12" thick panel?

Almost all metal SIP roofs can be walked on, even a roof with a 3" thick panel with .024" Alum. skins, but you would have to walk gingerly and not bounce up and down at the center of span.

It is a 10" panel,            next will be a Tahoe on same panel and then the Chevy HHR on a 20 ft. span

You still have not topped Fred Fischer's elephant.

Chris,

Can a SIP be designed to carry a 60 pound live load per square foot over a 30' clear span?  What is the least costly way to increase the strength of a SIP to carry such a load over this long span?  Would it be to increase the thickness of the foam?  Do you have a feel for how thick the foam or skins would have to be to carry a 60 pound live load over a 30' clear span?

As always, your insight and experince are appreciated. 

Posted By wes on 18 May 2011 01:28 PM
You still have not topped Fred Fischer's elephant.

thats a fairy tale

Posted By Alton on 18 May 2011 03:04 PM

Chris,

Can a SIP be designed to carry a 60 pound live load per square foot over a 30' clear span?  What is the least costly way to increase the strength of a SIP to carry such a load over this long span?  Would it be to increase the thickness of the foam?  Do you have a feel for how thick the foam or skins would have to be to carry a 60 pound live load over a 30' clear span?

As always, your insight and experince are appreciated. 

Alton;

there are several ways to get there , but none are economical. 24 ga. steel will immediately add about $2.00 /sq. ft. because it is special order. All engineering is based on 26 ga. so no testing is available, an engineed could interpolate the added structural value, but there is still no testing.
another solution is to use an engineered box beam (flush) @ every panel joint ,  then your panel span is less than 4 ft. but in doing so you have given up the insulation and added unwanted thermal transfer.
the most economical solution is to add intermediate beams or bearing walls

Chris,

Thanks.

What would be the best type of intermediate beam under the SIPS?  Should it be a box beam, wide flange beam, Metwood beam, etc.?

Metwood is definitely more user freindly I have spanned as much as 34 ft. with a 14" beam as can be seen in this commercial project

http://southernsips.com/job_gunnexecutive.html

Chris,

Thanks for the answer and link.  Based on the picture, it appears that you used the throughSPAN type of Metwood Beam.

Posted By Alton on 19 May 2011 10:34 AM

Chris,

Thanks for the answer and link.  Based on the picture, it appears that you used the throughSPAN type of Metwood Beam.

Alton;  the throughspan wasn't made then, but at that time they used 2 trade ready joists welded face to face and internally reinforced with welded #7 re-bar top/bottom chords (2) and webbing - it was a similar look

the engine was removed from the van for the commercial, eh?

Posted By junkhound on 22 May 2011 10:01 AM
the engine was removed from the van for the commercial, eh?

doesn't look like it is sitting high in the front

Chris,

I just hope that Chevys do not replace the standard bags of sand that are normally used to test deflection.  I own a Prius but I do not want it lifted by a forklift.  All kidding aside, the tires on the Chevy placed four points of loading on the SIP.  None of the point loads were near the middle of the span.  Would the same results be produced if bags of sand were used to produce a uniform distributed load?

Posted By Alton on 22 May 2011 12:08 PM

Chris,

I just hope that Chevys do not replace the standard bags of sand that are normally used to test deflection.  I own a Prius but I do not want it lifted by a forklift.  All kidding aside, the tires on the Chevy placed four points of loading on the SIP.  None of the point loads were near the middle of the span.  Would the same results be produced if bags of sand were used to produce a uniform distributed load?

Alton;

I believe so ................... the weight spread out is 26 #s per q. ft.


the wheel base is 103.5" meaning an average of 44" each side from wheel centers to edge of bearing blocks,  other demonstrations I have seen the wheels are hugging the bearing points a lot closer

Also the panels are loose on the suppporting styrofoam blocks if they were attached to a stable bearing point , I would expect the deflection to be even less

Chris,

Can a metal skin EPS core SIP accommodate a 6" x 12" hole for an HVAC supply register?  If so, are there rules about cutting holes in floor SIPS?  For instance, with I-Joists there are definite rules about the size and location for knockouts in the web.  Would a hole for a supply register in a SIP weaken the SIP enough that it would require more support to keep the same span? 

Posted By Alton on 24 May 2011 06:12 PM

Chris,

Can a metal skin EPS core SIP accommodate a 6" x 12" hole for an HVAC supply register?  If so, are there rules about cutting holes in floor SIPS?  For instance, with I-Joists there are definite rules about the size and location for knockouts in the web.  Would a hole for a supply register in a SIP weaken the SIP enough that it would require more support to keep the same span? 

6" x 12" is pretty small, any hole larger than 16" x 16: should be wrapped with 18 ga. galv. channels,   remember too that engineering is done with a 2.27 safety factor.

We also cut out fireplace flue holes for wood burning fireplaces and 2ft x 4ft. skylight holes in roof panels.


testing for 2 x 4 skylight openings wrapped with 18 ga, steel have shown the panel actually gets stonger after the hole is cut out and wrapped

Posted By cmkavala on 18 May 2011 03:22 PM

Posted By wes on 18 May 2011 01:28 PM
You still have not topped Fred Fischer's elephant.

thats a fairy tale

Well,fairy tales do come true! ;)