I thought I'd seen it all. 5

[dik]

This morning on one of my projects came across a detail for an OH door lintel where the Architect had spec'd that 1/2" holes were to be drilled in the HSS section @ 2'-0" o/c to fill with rigid spray foam insulation... had to shake the sawdust out...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[jayrod12]

Oh we've seen this often. That new energy code is causing even more ridiculous requests to come along lately. Sacrificing structural robustness to minimize cold strikes is the norm.

 

[dik]

as noted... first I've seen it... you have to give your head a shake. Did they do a FEM study?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[phamENG]

At least they didn't specify roughing the interior surface to improve the the bond between the foam and the steel...

 

[jayrod12]

Actually they may have done a thermal transfer FEM analysis. I know on one of the projects here (think people that live there shouldn't throw stones), they did this for the balcony support beams.

 

[rb1957]

this lintel beam is a square tube, yes?

why not fill with foam before installation ??

another day in paradise, or is paradise one day closer ?

 

[Enable]

rb1957 that would require several different trades to handle the material before even making its way to site. The metal guy would need to fab and send to the sprayfoam guy who would need to send it to site. And on top of that, the sprayfoam guy then needs to make his way to site anyways to do other items that cannot be shop done.

That route would cost $$ and be a PIA for all involved. Not that it cannot be done but I wouldn't want to be part of that (speaking as a metal fabricator / GC). Also, not sure how that helps all that much as I am sure you would still need ports to spray through-out the length (depending on how long the member is). It's not even as if shop spraying allows you to re-weld the ports as sprayfoam is technically a combustible material.

 

[dik]

I like your humour... possibly because stuff is welded to the HSS... it was the effectiveness of the foam in the first place that caught my attention... it's about time the Architect woke up...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[SwinnyGG]

hate to be the naysayer... but are we really saying that holes in a HSS are a structural dealbreaker?

 

[rb1957]

"possibly because stuff is welded to the HSS" ... did not know.

"are we really saying that holes in a HSS are a structural dealbreaker?" ... I don't think so, but they aren't ideal. At a minimum more analysis I'd expect.
But I think the anguish expressed is "why eff with the structure for such a trivial reason ?"

another day in paradise, or is paradise one day closer ?

 

[SwinnyGG]

But I think the anguish expressed is "why eff with the structure for such a trivial reason ?"

I guess that's where my feeling diverge with the feelings of the OP - in the LEED era extra insulation is not by definition trivial.

 

[dik]

I'm all for proper thermal envelopes... it's essential and it will get more stringent. I'm concerned about climate change, more than most people. The proposed detail, if it follows LEED is wrong and does not achieve anything and is a waste of resources.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Brad805]

If you want thermal performance, put the structure inside the building envelope. I agree with Dik this is wasteful, and achieves little. I have seen many similar details, and I am certain none have had any FEA to test the benefit of the detail.

 

[MIStructE_IRE]

I had one recently where the architect wanted a circular insulation board at the base of every circular RC column supporting a 3 storey concrete frame! WTF!

 

[hokie66]

dik,
Those silly holes are 1.5".

 

[dik]

Could be, Hokie... I thought it was Beam 1... dunno. I didn't look any further; it was because filling the HSS with insulation was so silly. I had to share it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Craig_H]

Can they even achieve proper spray foam installation? If "rigid" means closed cell, my experience tells me it will not work. That stuff is super hard to control, gets hard immediately, and cannot flow to fill a void. That, and the entire effort being negated by the thermal conductivity of steel.

 

[dik]

I can see the foam being 'injected'... it doesn't matter if there are a few voids, the overall behaviour of it would not change in a significant manner. It was one of the silliest things I've seen lately, and had to share.


Can't you use DOW 10000 or something similar?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[BridgeSmith]

I guess that's where my feeling diverge with the feelings of the OP - in the LEED era extra insulation is not by definition trivial.

Compare the conduction heat transfer of the steel to the convection heat transfer of the air inside, and you'll understand what the OP means by trivial. There are much better and easier ways to accomplish the minuscule gain in insulation value afforded by spray-foaming the inside of a closed steel section.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[NorthCivil]

even if they fill the middle of the steel with foam, the heat will just hit the steel and conduct around the steel from in to out.

the thermal bridge by conductivity is vastly higher than the thermal bridge by convectivity within the hollow of the steel.

just another bit of plastic that can float around the ocean in a million years time.