Stucco on corrugated steel?

[onlineeng]

Wire lath screwed to the ribs of the steel wall, two layers of paper, no other substrate.
Weep screed at the bottom.
Appropriate control joints.

What do you think? Is some additional substrate, such as plywood, necessary?

Thanks.

 

[a2mfk]

The stucco will have to span between the valleys of the ribs, which with lathe (didn't mention this) a couple of inches should be fine. But over time I may be worried about waviness in your stucco since I don't think the steel sheeting has much in-plane stiffness (if we are talking about the type used on PEMBs)...

The other thing I would be concerned with is temperature expansion/contraction stresses of steel sheeting causing cracking in the stucco. If anything I would use densglass screwed to the ribs. This would somewhat isolate the densglass from the steel panels because the screws would yield/rotate slightly with expansive/contractive movements of the panels. Also it may help with your moisture barrier and temperature change issue in your wall section.

I've seen a lot of ugly stucco on plywood applications, moisture can wreak havoc on this system, so I would never recommend it. But maybe it works OK in dry climates, certainly is bad in Florida.

However, you may also be creating a moisture barrier/intrusion problem:
-Project location? Climate? More heat or AC?
-Type and usage of structure?
-Interior finish and insulation?

May also see what the Stucco Mfrs Association has to say about this type of installation...

http://www.stuccomfgassoc.com/

Also a good one to bounce of some architect friends to see if they have heard of this and had issues with it.

 

[Ron]

No other substrate required, but expect more cracking as your substrate will likely move quite a bit thermally. Try to make sure that when the stucco is applied, that it doesn't end up with big thickness variations corresponding to the corrugations in the steel wall. That will produce lots of cracking. Also make sure that the lath is furred from the surface to get adequate embedment.

A three-coat stucco system would be required for this, installed in accordance with ASTM C926.

 

[dhengr]

What kind of structure are you applying this stucco veneer to? You are potentially applying a very stiff, but not particularly strong, veneer to a very flexible structure both in the plane of the walls, where the stucco will try to act as a shear resisting element, and perpendicular to the plane of the walls, where the stucco will act in bending btwn. steel framing members.

 

[onlineeng]

Thank you for the intelligent responses, a2mfk, Ron, and dhengr.

 

[Preeng1]

Would it not be simpler to use stucco coated cladding ?

Lots on the market...

Bob
MBC International
Pre-engineered Building Systems

 

[onlineeng]

Thanks for the thought, Preeng1. That was our first thought, too, but the client wanted to go with three-coat.

 

[jooferna]

This is not my area of expetise but I will tell you what my friend experinced with his steel structure. He built a large steel garage to house his valuable oldies including an AC Cobra. He had sheet steel(for safety) over which had 1" styrofoam and then nylon mesh, base coat & finally top coat. The structure looked really nice. He built it around February (in Toronto Canada) when the ambient temp was about 6-7C. In June July the stucco started cracking. The Temp was around 22-28C. It appears that the underlying metal started expanding at higher Temp and caused the problem. He then ripped up all the stucco and did a paint job on the steel shell. For whaterver its worth - hope this helps

 

[onlineeng]

Thanks for the info, jooferna. Interesting. It sounds like your friend created his own EIFS panels, in a way. He was walking on the edge of acceptable temperatures for application at 6-7C, I believe. Also, ideally, the temperature should have not gone below around 4.5C for 48 hours after application. Do you remember if he had control/expansion joints?